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  Subjects -> BIOLOGY (Total: 2987 journals)
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BIOLOGY (1424 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 20)
Achievements in the Life Sciences     Open Access   (Followers: 4)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Biologica Colombiana     Open Access   (Followers: 6)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Biologica Sibirica     Open Access  
Acta Biomaterialia     Hybrid Journal   (Followers: 25)
Acta Biotheoretica     Hybrid Journal   (Followers: 5)
Acta Chiropterologica     Full-text available via subscription   (Followers: 6)
acta ethologica     Hybrid Journal   (Followers: 4)
Acta Limnologica Brasiliensia     Open Access   (Followers: 3)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Musei Silesiae, Scientiae Naturales : The Journal of Silesian Museum in Opava     Open Access  
Acta Parasitologica     Hybrid Journal   (Followers: 9)
Acta Scientiarum. Biological Sciences     Open Access   (Followers: 2)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
Actualidades Biológicas     Open Access   (Followers: 1)
Advanced Health Care Technologies     Open Access   (Followers: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Bioinformatics     Open Access   (Followers: 18)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4)
Advances in Biology     Open Access   (Followers: 8)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 6)
Advances in Cell Biology     Open Access   (Followers: 23)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Ecological Research     Full-text available via subscription   (Followers: 39)
Advances in Ecology     Open Access   (Followers: 13)
Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 20)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Genome Biology     Full-text available via subscription   (Followers: 12)
Advances in High Energy Physics     Open Access   (Followers: 20)
Advances in Human Biology     Open Access   (Followers: 1)
Advances in Life Science and Technology     Open Access   (Followers: 14)
Advances in Life Sciences     Open Access   (Followers: 4)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3)
Advances in Regenerative Biology     Open Access   (Followers: 1)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Virus Research     Full-text available via subscription   (Followers: 5)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 6)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 1)
Ageing Research Reviews     Hybrid Journal   (Followers: 7)
Aging Cell     Open Access   (Followers: 9)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
AJP Cell Physiology     Full-text available via subscription   (Followers: 13)
AJP Endocrinology and Metabolism     Full-text available via subscription   (Followers: 23)
AJP Lung Cellular and Molecular Physiology     Full-text available via subscription   (Followers: 3)
Al-Kauniyah : Jurnal Biologi     Open Access  
Alasbimn Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Biology Teacher     Full-text available via subscription   (Followers: 12)
American Fern Journal     Full-text available via subscription   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 10)
American Journal of Bioethics     Hybrid Journal   (Followers: 10)
American Journal of Biostatistics     Open Access   (Followers: 9)
American Journal of Human Biology     Hybrid Journal   (Followers: 12)
American Journal of Medical and Biological Research     Open Access   (Followers: 5)
American Journal of Plant Sciences     Open Access   (Followers: 19)
American Journal of Primatology     Hybrid Journal   (Followers: 15)
American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 64)
Amphibia-Reptilia     Hybrid Journal   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4)
Analytical Methods     Full-text available via subscription   (Followers: 7)
Anatomical Science International     Hybrid Journal   (Followers: 2)
Animal Cells and Systems     Hybrid Journal   (Followers: 4)
Annales de Limnologie - International Journal of Limnology     Hybrid Journal   (Followers: 1)
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Biologia     Open Access   (Followers: 1)
Annals of Applied Biology     Hybrid Journal   (Followers: 8)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18)
Annals of Human Biology     Hybrid Journal   (Followers: 4)
Annual Review of Biomedical Engineering     Full-text available via subscription   (Followers: 17)
Annual Review of Biophysics     Full-text available via subscription   (Followers: 25)
Annual Review of Cell and Developmental Biology     Full-text available via subscription   (Followers: 37)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 18)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 10)
Anthropological Review     Open Access   (Followers: 23)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antibiotics     Open Access   (Followers: 8)
Antioxidants     Open Access   (Followers: 4)
Antioxidants & Redox Signaling     Hybrid Journal   (Followers: 8)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apidologie     Hybrid Journal   (Followers: 4)
Apmis     Hybrid Journal   (Followers: 1)
APOPTOSIS     Hybrid Journal   (Followers: 8)
Applied Bionics and Biomechanics     Open Access   (Followers: 8)
Applied Vegetation Science     Full-text available via subscription   (Followers: 9)
Aquaculture Environment Interactions     Open Access   (Followers: 2)
Aquaculture International     Hybrid Journal   (Followers: 22)
Aquaculture Reports     Open Access   (Followers: 3)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 6)
Aquatic Biology     Open Access   (Followers: 4)
Aquatic Ecology     Hybrid Journal   (Followers: 30)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 13)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 19)
Archaea     Open Access   (Followers: 3)
Archiv für Molluskenkunde: International Journal of Malacology     Full-text available via subscription   (Followers: 3)
Archives of Biomedical Sciences     Open Access   (Followers: 7)
Archives of Microbiology     Hybrid Journal   (Followers: 8)
Archives of Natural History     Hybrid Journal   (Followers: 7)
Archives of Oral Biology     Hybrid Journal   (Followers: 2)
Archives of Virology     Hybrid Journal   (Followers: 5)
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2)
Arid Ecosystems     Hybrid Journal   (Followers: 3)
Arquivos do Instituto Biológico     Open Access   (Followers: 1)
Arquivos do Museu Dinâmico Interdisciplinar     Open Access  
Arthropod Structure & Development     Hybrid Journal   (Followers: 2)
Arthropods     Open Access   (Followers: 1)
Artificial DNA: PNA & XNA     Hybrid Journal   (Followers: 2)
Artificial Photosynthesis     Open Access   (Followers: 1)
Asian Bioethics Review     Full-text available via subscription   (Followers: 1)
Asian Journal of Biodiversity     Open Access   (Followers: 5)
Asian Journal of Biological Sciences     Open Access   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 5)
Asian Journal of Developmental Biology     Open Access   (Followers: 2)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 2)
Asian Journal of Nematology     Open Access   (Followers: 3)
Asian Journal of Poultry Science     Open Access   (Followers: 4)
Australian Life Scientist     Full-text available via subscription   (Followers: 2)
Australian Mammalogy     Hybrid Journal   (Followers: 5)
Autophagy     Hybrid Journal   (Followers: 2)
Avian Biology Research     Full-text available via subscription   (Followers: 3)
Avian Conservation and Ecology     Open Access   (Followers: 7)
Bacteriology Journal     Open Access   (Followers: 2)
Bacteriophage     Full-text available via subscription   (Followers: 3)
Bangladesh Journal of Bioethics     Open Access  
Bangladesh Journal of Plant Taxonomy     Open Access  
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Berita Biologi     Open Access   (Followers: 1)
Between the Species     Open Access   (Followers: 1)
Bio Tribune Magazine     Hybrid Journal  
BIO Web of Conferences     Open Access  
BIO-Complexity     Open Access  
Bio-Grafía. Escritos sobre la Biología y su enseñanza     Open Access  
Bioanalytical Reviews     Hybrid Journal   (Followers: 2)
Biocatalysis and Biotransformation     Hybrid Journal   (Followers: 6)
Biochemistry and Cell Biology     Hybrid Journal   (Followers: 14)
Biochimie     Hybrid Journal   (Followers: 7)
BioControl     Hybrid Journal   (Followers: 5)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 5)
Biodemography and Social Biology     Hybrid Journal   (Followers: 1)
Biodiversidad Colombia     Open Access  
Biodiversity : Research and Conservation     Open Access   (Followers: 26)
Biodiversity and Natural History     Open Access   (Followers: 5)
Biodiversity Data Journal     Open Access   (Followers: 3)
Biodiversity Informatics     Open Access  
Bioedukasi : Jurnal Pendidikan Biologi FKIP UM Metro     Open Access  
Bioeksperimen : Jurnal Penelitian Biologi     Open Access  
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Bioelectromagnetics     Hybrid Journal   (Followers: 1)
Bioenergy Research     Hybrid Journal   (Followers: 2)
Bioengineering and Bioscience     Open Access   (Followers: 1)
BioEssays     Hybrid Journal   (Followers: 10)
Bioethics     Hybrid Journal   (Followers: 14)
BioéthiqueOnline     Open Access  
Biofabrication     Hybrid Journal   (Followers: 3)
Biogeosciences (BG)     Open Access   (Followers: 10)
Biogeosciences Discussions (BGD)     Open Access   (Followers: 1)
Bioinformatics     Hybrid Journal   (Followers: 236)
Bioinformatics and Biology Insights     Open Access   (Followers: 14)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 6)
Biointerphases     Open Access   (Followers: 1)
Biojournal of Science and Technology     Open Access  
Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 4)
Biological Control     Hybrid Journal   (Followers: 5)
Biological Invasions     Hybrid Journal   (Followers: 16)
Biological Journal of the Linnean Society     Hybrid Journal   (Followers: 14)
Biological Letters     Open Access   (Followers: 4)
Biological Procedures Online     Open Access  
Biological Psychiatry     Hybrid Journal   (Followers: 41)
Biological Psychology     Hybrid Journal   (Followers: 6)
Biological Research     Open Access  
Biological Rhythm Research     Hybrid Journal   (Followers: 2)
Biological Theory     Hybrid Journal   (Followers: 1)
Biological Trace Element Research     Hybrid Journal  
Biologicals     Full-text available via subscription   (Followers: 9)
Biologics: Targets & Therapy     Open Access   (Followers: 1)
Biologie Aujourd'hui     Full-text available via subscription  
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42)
Biologija     Open Access  
Biology     Open Access   (Followers: 5)
Biology and Philosophy     Hybrid Journal   (Followers: 16)
Biology Bulletin     Hybrid Journal   (Followers: 1)
Biology Bulletin Reviews     Hybrid Journal  
Biology Direct     Open Access   (Followers: 7)
Biology Letters     Full-text available via subscription   (Followers: 35)
Biology Methods and Protocols     Hybrid Journal  

        1 2 3 4 5 6 7 8 | Last

Journal Cover Acta Biomaterialia
  [SJR: 2.02]   [H-I: 104]   [25 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1742-7061
   Published by Elsevier Homepage  [3034 journals]
  • Native and solubilized decellularized extracellular matrix: A critical
           assessment of their potential for improving the expansion of mesenchymal
           stem cells
    • Authors: Aida Shakouri-Motlagh; Andrea J. O'Connor; Shaun P. Brennecke; Bill Kalionis; Daniel E. Heath
      Pages: 1 - 12
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Aida Shakouri-Motlagh, Andrea J. O'Connor, Shaun P. Brennecke, Bill Kalionis, Daniel E. Heath
      Capturing the promise of mesenchymal stem cell (MSC)-based treatments is currently limited by inefficient production of cells needed for clinical therapies. During conventional ex vivo expansion, a large portion of MSCs lose the properties that make them attractive for use in cell therapies. Decellularized extracellular matrix (dECM) has recently emerged as a promising substrate for the improved expansion of MSCs. MSCs cultured on these surfaces exhibit improved proliferation capacity, maintenance of phenotype, and increased differentiation potential. Additionally, these dECMs can be solubilized and used to coat new cell culture surfaces, imparting key biological properties of the native matrices to other surfaces such as tissue engineering scaffolds. Although this technology is still developing, there is potential for an impact in the fields of MSC biology, biomaterials, tissue engineering, and therapeutics. In this article, we review the role of dECM in MSC expansion by first detailing the decellularization methods that have been used to produce the dECM substrates; discussing the shortcomings of current decellularization methods; describing the improved MSC characteristics obtained when the cells are cultured on these surfaces; and considering the effect of the passage number, age of donor, and dECM preparation method on the quality of the dECM. Finally we describe the critical roadblocks that must be addressed before this technology can fulfil its potential, including elucidating the mechanism by which the dECMs improve the expansion of primary MSCs and the identification of a readily available source of dECM. Statement of Significance Current mesenchymal stem cell (MSC) culture methods result in premature cellular senescence or loss of differentiation potential. This creates a major bottleneck in their clinical application, as prolonged expansion is necessary to achieve clinically relevant numbers of cells. Recently, decellularized extracellular matrix (dECM) produced by primary MSC has emerged as an attractive substrate for the improved expansion of MSC; cells cultured on these surfaces retain their desired stem cell characteristics for prolonged times during culture. This review article describes the inception and development of this dECM-based technology, points out existing challenges that must be addressed, and suggests future directions of research. To our knowledge, this is the first review written on the use of dECM for improved mesenchymal stem cell expansion.
      Graphical abstract image

      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.014
      Issue No: Vol. 55 (2017)
       
  • Protein-gold nanoparticle interactions and their possible impact on
           biomedical applications
    • Authors: Jingying Liu; Qiang Peng
      Pages: 13 - 27
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Jingying Liu, Qiang Peng
      In the past few years, concerns of protein-gold nanoparticles (AuNP) interaction have been continuously growing in numerous potential biomedical applications. Despite the advances in tunable size, shape and excellent biocompatibility, unpredictable adverse effects related with protein corona (PC) have critically affected physiological to therapeutic responses. The complexity and uncontrollability of AuNP-PC formation limited the clinical applications of AuNP, e.g. AuNP-based drug delivery systems or imaging agent. Thus, even intensive attempts have been made for in vitro characterizations of PC around AuNP, the extrapolation of these data into in vivo PC responses still lags far behind. However, with accumulated knowledge of corona formation and the unique properties of AuNP, we are now encouraged to move forward to seeking positive exploitations. Herein, we summarize recent researches on interaction of protein and AuNP, aiming at provide a comprehensive understanding of such interaction associated with subsequent biomedical impacts. Importantly, the emerging trends in exploiting of potential applications and opportunities based on protein-AuNP interaction were discussed as well. Statement of Significance Gold nanoparticles (AuNPs) have shown great potentials in biomedical areas. However, its practical use is highly limited by protein corona, formed as a result of protein-AuNP interaction. This protein corona surrounding AuNPs is a new identity and the real substance that the organs and cells firstly encounter, and finally makes the behavior of AuNPs in vivo uncontrollable and unpredictable. Therefore, comprehensively understanding such interaction is of great significance for predicting the in vivo fate of AuNPs and for designing advanced AuNPs systems. In this review, we would provide a detailed description of protein-AuNP interaction and launch an interesting discussion on how to use such interaction for smart and controlled AuNPs delivery, which would be a topic of widespread interest.
      Graphical abstract image

      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.055
      Issue No: Vol. 55 (2017)
       
  • Raman spectroscopy of biomedical polyethylenes
    • Authors: Giuseppe Pezzotti
      Pages: 28 - 99
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Giuseppe Pezzotti
      With the development of three-dimensional Raman algorithms for local mapping of oxidation and plastic strain, and the ability to resolve molecular orientation patterns with microscopic spatial resolution, there is an opportunity to re-examine many of the foundations on which our understanding of biomedical grade ultra-high molecular weight polyethylenes (UHMWPEs) are based. By implementing polarized Raman spectroscopy into an automatized tool with an improved precision in non-destructively resolving Euler angles, oxidation levels, and microscopic strain, we become capable to make accurate and traceable measurements of the in vitro and in vivo tribological responses of a variety of commercially available UHMWPE bearings for artificial hip and knee joints. In this paper, we first review the foundations and the main algorithms for Raman analyses of oxidation and strain of biomedical polyethylene. Then, we critically re-examine a large body of Raman data previously collected on different polyethylene joint components after in vitro testing or in vivo service, in order to shed new light on an area of particular importance to joint orthopedics: the microscopic nature of UHMWPE surface degradation in the human body. A complex scenario of physical chemistry appears from the Raman analyses, which highlights the importance of molecular-scale phenomena besides mere microstructural changes. The availability of the Raman microscopic probe for visualizing oxidation patterns unveiled striking findings related to the chemical contribution to wear degradation: chain-breaking and subsequent formation of carboxylic acid sites preferentially occur in correspondence of third-phase regions, and they are triggered by emission of dehydroxylated oxygen from ceramic oxide counterparts. These findings profoundly differ from more popular (and simplistic) notions of mechanistic tribology adopted in analyzing joint simulator data. Statement of Significance This review was dedicated to the theoretical and experimental evaluation of the commercially available biomedical polyethylene samples by Raman spectroscopy with regard to their molecular textures, oxidative patterns, and plastic strain at the microscopic level in the three dimensions of the Euclidean space. The main achievements could be listed, as follow: (i) visualization of molecular patterns at the surface of UHMWPE bearings operating against metallic components; (ii) differentiation between wear and creep deformation in retrievals; (iii) non-destructive mapping of oxidative patterns; and, (iv) the clarification of chemical interactions between oxide/non-oxide ceramic heads and advanced UHMWPE liners.
      Graphical abstract image

      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.015
      Issue No: Vol. 55 (2017)
       
  • Regulation of human nucleus pulposus cells by peptide-coupled substrates
    • Authors: Devin T. Bridgen; Bailey V. Fearing; Liufang Jing; Johannah Sanchez-Adams; Megan C. Cohan; Farshid Guilak; Jun Chen; Lori A. Setton
      Pages: 100 - 108
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Devin T. Bridgen, Bailey V. Fearing, Liufang Jing, Johannah Sanchez-Adams, Megan C. Cohan, Farshid Guilak, Jun Chen, Lori A. Setton
      Nucleus pulposus (NP) cells are derived from the notochord and differ from neighboring cells of the intervertebral disc in phenotypic marker expression and morphology. Adult human NP cells lose this phenotype and morphology with age in a pattern that contributes to progressive disc degeneration and pathology. Select laminin-mimetic peptide ligands and substrate stiffnesses were examined for their ability to regulate human NP cell phenotype and biosynthesis through the expression of NP-specific markers aggrecan, N-cadherin, collagen types I and II, and GLUT1. Peptide-conjugated substrates demonstrated an ability to promote expression of healthy NP-specific markers, as well as increased biosynthetic activity. We show an ability to re-express markers of the juvenile NP cell and morphology through control of peptide presentation and stiffness on well-characterized polyacrylamide substrates. NP cells cultured on surfaces conjugated with α3 integrin receptor peptides P4 and P678, and on α2, α5, α6, β1 integrin-recognizing peptide AG10, show increased expression of aggrecan, N-cadherin, and types I and II collagen, suggesting a healthier, more juvenile-like phenotype. Multi-cell cluster formation was also observed to be more prominent on peptide-conjugated substrates. These findings indicate a critical role for cell-matrix interactions with specific ECM-mimetic peptides in supporting and maintaining a healthy NP cell phenotype and bioactivity. Statement of Significance NP cells reside in a laminin-rich environment that deteriorates with age, including a loss of water content and changes in the extracellular matrix (ECM) structure that may lead to the development of a degenerated IVD. There is great interest in methods to re-express healthy, biosynthetically active NP cells using laminin-derived biomimetic peptides toward the goal of using autologous cell sources for tissue regeneration. Here, we describe a novel study utilizing several laminin mimetic peptides conjugated to polyacrylamide gels that are able to support an immature, healthy NP phenotype after culture on “soft” peptide gels. These findings can support future studies in tissue regeneration where cells may be directed to a desired regenerative phenotype using niche-specific ECM peptides.
      Graphical abstract image

      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.019
      Issue No: Vol. 55 (2017)
       
  • Macromolecular crowding for tailoring tissue-derived fibrillated matrices
    • Authors: Valentina Magno; Jens Friedrichs; Heather M. Weber; Marina C. Prewitz; Mikhail V. Tsurkan; Carsten Werner
      Pages: 109 - 119
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Valentina Magno, Jens Friedrichs, Heather M. Weber, Marina C. Prewitz, Mikhail V. Tsurkan, Carsten Werner
      Tissue-derived fibrillated matrices can be instrumental for the in vitro reconstitution of multiphasic extracellular microenvironments. However, despite of several advantages, the obtained scaffolds so far offer a rather narrow range of materials characteristics only. In this work, we demonstrate how macromolecular crowding (MMC) – the supplementation of matrix reconstitution media with synthetic or natural macromolecules in ways to create excluded volume effects (EVE) – can be employed for tailoring important structural and biophysical characteristics of kidney-derived fibrillated matrices. Porcine kidneys were decellularized, ground and the obtained extracellular matrix (ECM) preparations were reconstituted under varied MMC conditions. We show that MMC strongly influences the fibrillogenesis kinetics and impacts the architecture and the elastic modulus of the reconstituted matrices, with diameters and relative alignment of fibrils increasing at elevated concentrations of the crowding agent Ficoll400, a nonionic synthetic polymer of sucrose. Furthermore, we demonstrate how MMC modulates the distribution of key ECM molecules within the reconstituted matrix scaffolds. As a proof of concept, we compared different variants of kidney-derived fibrillated matrices in cell culture experiments referring to specific requirements of kidney tissue engineering approaches. The results revealed that MMC-tailored matrices support the morphogenesis of human umbilical vein endothelial cells (HUVECs) into capillary networks and of murine kidney stem cells (KSCs) into highly branched aggregates. The established methodology is concluded to provide generally applicable new options for tailoring tissue-specific multiphasic matrices in vitro. Statement of Significance Tissue-derived fibrillated matrices can be instrumental for the in vitro reconstitution of multiphasic extracellular microenvironments. However, despite of several advantages, the obtained scaffolds so far offer a rather narrow range of materials characteristics only. Using the kidney matrix as a model, we herein report a new approach for tailoring tissue-derived fibrillated matrices by means of macromolecular crowding (MMC), the supplementation of reconstitution media with synthetic or natural macromolecules. MMC-modulation of matrix reconstitution is demonstrated to allow for the adjustment of fibrillation kinetics and nano-architecture, fiber diameter, alignment, and matrix elasticity. Primary human umbilical vein endothelial cells (HUVEC) and murine kidney stem cells (KSC) were cultured within different variants of fibrillated kidney matrix scaffolds. The results showed that MMC-tailored matrices were superior in supporting desired morphogenesis phenomena of both cell types.
      Graphical abstract image

      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.018
      Issue No: Vol. 55 (2017)
       
  • Age-dependent functional crosstalk between cardiac fibroblasts and
           cardiomyocytes in a 3D engineered cardiac tissue
    • Authors: Yanzhen Li; Huda Asfour; Nenad Bursac
      Pages: 120 - 130
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Yanzhen Li, Huda Asfour, Nenad Bursac
      Complex heterocellular interactions between cardiomyocytes and fibroblasts in the heart involve their bidirectional signaling via cell-cell contacts, paracrine factors, and extracellular matrix (ECM). These interactions vary with heart development and pathology leading to changes in cardiac structure and function. Whether cardiac fibroblasts of different ages interact differentially with cardiomyocytes to distinctly impact their function remains unknown. Here, we explored the direct structural and functional effects of fetal and adult cardiac fibroblasts on cardiomyocytes using a tissue-engineered 3D co-culture system. We show that the age of cardiac fibroblasts is a strong determinant of the structure, function, and molecular properties of co-cultured tissues. In particular, in vitro expanded adult, but not fetal, cardiac fibroblasts significantly deteriorated electrical and mechanical function of the co-cultured cardiomyocytes, as evidenced by slower action potential conduction, prolonged action potential duration, weaker contractions, higher tissue stiffness, and reduced calcium transient amplitude. This functional deficit was associated with structural and molecular signatures of pathological remodeling including fibroblast proliferation, interstitial collagen deposition, and upregulation of pro-fibrotic markers. Our studies imply critical roles of the age of supporting cells in engineering functional cardiac tissues and provide a new physiologically relevant in vitro platform to investigate influence of heterocellular interactions on cardiomyocyte function, development, and disease. Statement of Significance Previous studies have shown that cardiomyocytes and fibroblasts in the heart interact through direct contacts, paracrine factors, and matrix-mediated crosstalk. However, whether cardiac fibroblasts of different ages distinctly impact cardiomyocyte function remains elusive. We employed a tissue-engineered hydrogel-based co-culture system to study interactions of cardiomyocytes with fetal or adult cardiac fibroblasts. We show that the age of cardiac fibroblasts is a strong determinant of the structure, function, and molecular properties of engineered cardiac tissues and that key features of fibrotic myocardium are replicated by supplementing cardiomyocytes with expanded adult but not fetal fibroblasts. These findings relate to implantation of stem cell-derived cardiomyocytes in adult myocardium and warrant further studies of how age and source of non-myocytes impact cardiac function and maturation.
      Graphical abstract image

      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.027
      Issue No: Vol. 55 (2017)
       
  • Cell sheet engineering using the stromal vascular fraction of adipose
           tissue as a vascularization strategy
    • Authors: Marina Costa; Mariana T. Cerqueira; Tírcia C. Santos; Belém Sampaio-Marques; Paula Ludovico; Alexandra P. Marques; Rogério P. Pirraco; Rui L. Reis
      Pages: 131 - 143
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Marina Costa, Mariana T. Cerqueira, Tírcia C. Santos, Belém Sampaio-Marques, Paula Ludovico, Alexandra P. Marques, Rogério P. Pirraco, Rui L. Reis
      Current vascularization strategies for Tissue Engineering constructs, in particular cell sheet-based, are limited by time-consuming and expensive endothelial cell isolation and/or by the complexity of using extrinsic growth factors. Herein, we propose an alternative strategy using angiogenic cell sheets (CS) obtained from the stromal vascular fraction (SVF) of adipose tissue that can be incorporated into more complex constructs. Cells from the SVF were cultured in normoxic and hypoxic conditions for up to 8days in the absence of extrinsic growth factors. Immunocytochemistry against CD31 and CD146 revealed spontaneous organization in capillary-like structures, more complex after hypoxic conditioning. Inhibition of HIF-1α pathway hindered capillary-like structure formation in SVF cells cultured in hypoxia, suggesting a role of HIF-1α. Moreover, hypoxic SVF cells showed a trend for increased secretion of angiogenic factors, which was reflected in increased network formation by endothelial cells cultured on matrigel using that conditioned medium. In vivo implantation of SVF CS in a mouse hind limb ischemia model revealed that hypoxia-conditioned CS led to improved restoration of blood flow. Both in vitro and in vivo data suggest that SVF CS can be used as simple and cost-efficient tools to promote functional vascularization of TE constructs. Statement of Significance Neovascularization after implantation is a major obstacle for producing clinically viable cell sheet-based tissue engineered constructs. Strategies using endothelial cells and extrinsic angiogenic growth factors are expensive and time consuming and may raise concerns of tumorigenicity. In this manuscript, we describe a simplified approach using angiogenic cell sheets fabricated from the stromal vascular fraction of adipose tissue. The strong angiogenic behavior of these cell sheets, achieved without the use of external growth factors, was further stimulated by low oxygen culture. When implanted in an in vivo model of hind limb ischemia, the angiogenic cell sheets contributed to blood flux recovery. These cell sheets can therefore be used as a straightforward tool to increase the neovascularization of cell sheet-based thick constructs.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.034
      Issue No: Vol. 55 (2017)
       
  • Distributed vasculogenesis from modular agarose-hydroxyapatite-fibrinogen
           microbeads
    • Authors: Ana Y. Rioja; Ethan L.H. Daley; Julia C. Habif; Andrew J. Putnam; Jan P. Stegemann
      Pages: 144 - 152
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Ana Y. Rioja, Ethan L.H. Daley, Julia C. Habif, Andrew J. Putnam, Jan P. Stegemann
      Critical limb ischemia impairs circulation to the extremities, causing pain, disrupted wound healing, and potential tissue necrosis. Therapeutic angiogenesis seeks to repair the damaged microvasculature directly to restore blood flow. In this study, we developed modular, micro-scale constructs designed to possess robust handling qualities, allow in vitro pre-culture, and promote microvasculature formation. The microbead matrix consisted of an agarose (AG) base to prevent aggregation, combined with cell-adhesive components of fibrinogen (FGN) and/or hydroxyapatite (HA). Microbeads encapsulating a co-culture of human umbilical vein endothelial cells (HUVEC) and fibroblasts were prepared and characterized. Microbeads were generally 80–100µm in diameter, and the size increased with the addition of FGN and HA. Addition of HA increased the yield of microbeads, as well as the homogeneity of distribution of FGN within the matrix. Cell viability was high in all microbead types. When cell-seeded microbeads were embedded in fibrin hydrogels, HUVEC sprouting and inosculation between neighboring microbeads were observed over seven days. Pre-culture of microbeads for an additional seven days prior to embedding in fibrin resulted in significantly greater HUVEC network length in AG+HA+FGN microbeads, as compared to AG, AG+HA or AG+FGN microbeads. Importantly, composite microbeads resulted in more even and widespread endothelial network formation, relative to control microbeads consisting of pure fibrin. These results demonstrate that AG+HA+FGN microbeads support HUVEC sprouting both within and between adjacent microbeads, and can promote distributed vascularization of an external matrix. Such modular microtissues may have utility in treating ischemic tissue by rapidly re-establishing a microvascular network. Statement of Significance Critical limb ischemia (CLI) is a chronic disease that can lead to tissue necrosis, amputation, and death. Cell-based therapies are being explored to restore blood flow and prevent the complications of CLI. In this study, we developed small, non-aggregating agarose-hydroxyapatite-fibrinogen microbeads that contained endothelial cells and fibroblasts. Microbeads were easy to handle and culture, and endothelial sprouts formed within and between microbeads. Our data demonstrates that the composition of the microbead matrix altered the degree of endothelial sprouting, and that the addition of hydroxyapatite and fibrinogen resulted in more distributed sprouting compared to pure fibrin microbeads. The microbead format and control of the matrix formulation may therefore be useful in developing revascularization strategies for the treatment of ischemic disease.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.050
      Issue No: Vol. 55 (2017)
       
  • Enzyme-responsive peptide dendrimer-gemcitabine conjugate as a
           
    • Authors: Chengyuan Zhang; Dayi Pan; Jin Li; Jiani Hu; Ashika Bains; Nicholas Guys; Hongyan Zhu; Xiaohui Li; Kui Luo; Qiyong Gong; Zhongwei Gu
      Pages: 153 - 162
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Chengyuan Zhang, Dayi Pan, Jin Li, Jiani Hu, Ashika Bains, Nicholas Guys, Hongyan Zhu, Xiaohui Li, Kui Luo, Qiyong Gong, Zhongwei Gu
      Stimuli-responsive peptide dendrimer-drug conjugates have presented significant potential for cancer therapy. To develop an effective nanoscale chemotherapeutic prodrug, we developed a novel enzyme-responsive PEGylated lysine peptide dendrimer-gemcitabine conjugate (Dendrimer-GEM) based nanoparticle via the highly efficient click reaction. Owing to the glycyl phenylalanyl leucyl glycine tetra-peptide (GFLG) as an enzyme-cleavable linker to conjugate gemcitabine (GEM), the prepared nanoparticles were able to release drug significantly faster in the tumor cellular environments, which specifically contains secreted Cathepsin B, quantifiably more than 80% GEM was released with Cathepsin B compared to the condition without Cathepsin B at 24h. This nanoparticle demonstrated enhanced antitumor efficacy in a 4T1 murine breast cancer model without obvious systemic toxicity, resulting in significantly suppressed relative tumor volumes (86.17±38.27%) and a 2-fold higher value of tumor growth inhibition (∼90%) than GEM·HCl treatment. These results suggest that the PEGylated peptide dendrimer-gemcitabine conjugate can be an effective antitumor agent for breast cancer therapy. Statement of Significance We found that the functionalized dendrimer based nanoscale drug delivery vehicles exhibited enhanced therapeutic indexes and reduced toxicity as compared to the free drug gemcitabine. Compared with current nanoparticles, such as dendritic anticancer drug delivery systems, the new design was capable of self-assembling into nanoscale particles with sizes of about 80–110nm, which is suitable as antitumor drug delivery vehicle due to the potential longer intravascular half-life and higher accumulation in tumor tissue via EPR effect. Owing to the optimized architecture, the system was given the enzyme-responsive drug release feature, and showed excellent antitumor activity on the 4T1 breast tumor model due to the evidences from tumor growth curves, immunohistochemical analysis and confocal laser scanning microscopy. Meanwhile, no significant side effect was observed by histological analysis. This study demonstrated that PEGylated peptide dendritic architecture may be used as efficient and safe nanoscale drug delivery vehicle for cancer therapy.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.02.047
      Issue No: Vol. 55 (2017)
       
  • Targeted delivery of hyaluronic acid to the ocular surface by a
           polymer-peptide conjugate system for dry eye disease
    • Authors: David Lee; Qiaozhi Lu; Sven D. Sommerfeld; Amanda Chan; Nikhil G. Menon; Tannin A. Schmidt; Jennifer H. Elisseeff; Anirudha Singh
      Pages: 163 - 171
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): David Lee, Qiaozhi Lu, Sven D. Sommerfeld, Amanda Chan, Nikhil G. Menon, Tannin A. Schmidt, Jennifer H. Elisseeff, Anirudha Singh
      Hyaluronic acid (HA) solutions effectively lubricate the ocular surface and are used for the relief of dry eye related symptoms. However, HA undergoes rapid clearance due to limited adhesion, which necessitates frequent instillation. Conversely, highly viscous artificial tear formulations with HA blur vision and interfere with blinking. Here, we developed an HA-eye drop formulation that selectively binds and retains HA for extended periods of time on the ocular surface. We synthesized a heterobifunctional polymer-peptide system with one end binding HA while the other end binding either sialic acid-containing glycosylated transmembrane molecules on the ocular surface epithelium, or type I collagen molecule within the tissue matrix. HA solution was mixed with the polymer-peptide system and tested on both ex vivo and in vivo models to determine its ability to prolong HA retention. Furthermore, rabbit ocular surface tissues treated with binding peptides and HA solutions demonstrated superior lubrication with reduced kinetic friction coefficients compared to tissues treated with conventional HA solution. The results suggest that binding peptide-based solution can keep the ocular surface enriched with HA for prolonged times as well as keep it lubricated. Therefore, this system can be further developed into a more effective treatment for dry eye patients than a standard HA eye drop. Statement of Significance Eye drop formulations containing HA are widely used to lubricate the ocular surface and relieve dry eye related symptoms, however its low residence time remains a challenge. We designed a polymer-peptide system for the targeted delivery of HA to the ocular surface using sialic acid or type I collagen as anchors for HA immobilization. The addition of the polymer-peptide system to HA eye drop exhibited a reduced friction coefficient, and it can keep the ocular surface enriched with HA for prolonged time. This system can be further developed into a more effective treatment for dry eye than a standard HA eye drop.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.043
      Issue No: Vol. 55 (2017)
       
  • Surface immobilized antibody orientation determined using ToF-SIMS and
           multivariate analysis
    • Authors: Nicholas G. Welch; Robert M.T. Madiona; Thomas B. Payten; Christopher D. Easton; Luisa Pontes-Braz; Narelle Brack; Judith A. Scoble; Benjamin W. Muir; Paul J. Pigram
      Pages: 172 - 182
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Nicholas G. Welch, Robert M.T. Madiona, Thomas B. Payten, Christopher D. Easton, Luisa Pontes-Braz, Narelle Brack, Judith A. Scoble, Benjamin W. Muir, Paul J. Pigram
      Antibody orientation at solid phase interfaces plays a critical role in the sensitive detection of biomolecules during immunoassays. Correctly oriented antibodies with solution-facing antigen binding regions have improved antigen capture as compared to their randomly oriented counterparts. Direct characterization of oriented proteins with surface analysis methods still remains a challenge however surface sensitive techniques such as Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) provide information-rich data that can be used to probe antibody orientation. Diethylene glycol dimethyl ether plasma polymers (DGpp) functionalized with chromium (DGpp+Cr) have improved immunoassay performance that is indicative of preferential antibody orientation. Herein, ToF-SIMS data from proteolytic fragments of anti-EGFR antibody bound to DGpp and DGpp+Cr are used to construct artificial neural network (ANN) and principal component analysis (PCA) models indicative of correctly oriented systems. Whole antibody samples (IgG) test against each of the models indicated preferential antibody orientation on DGpp+Cr. Cross-reference between ANN and PCA models yield 20 mass fragments associated with F(ab′)2 region representing correct orientation, and 23 mass fragments associated with the Fc region representing incorrect orientation. Mass fragments were then compared to amino acid fragments and amino acid composition in F(ab′)2 and Fc regions. A ratio of the sum of the ToF-SIMS ion intensities from the F(ab′)2 fragments to the Fc fragments demonstrated a 50% increase in intensity for IgG on DGpp+Cr as compared to DGpp. The systematic data analysis methodology employed herein offers a new approach for the investigation of antibody orientation applicable to a range of substrates. Statement of Significance Controlled orientation of antibodies at solid phases is critical for maximizing antigen detection in biosensors and immunoassays. Surface-sensitive techniques (such as ToF-SIMS), capable of direct characterization of surface immobilized and oriented antibodies, are under-utilized in current practice. Selection of a small number of mass fragments for analysis, typically pertaining to amino acids, is commonplace in literature, leaving the majority of the information-rich spectra unanalyzed. The novelty of this work is the utilization of a comprehensive, unbiased mass fragment list and the employment of principal component analysis (PCA) and artificial neural network (ANN) models in a unique methodology to prove antibody orientation. This methodology is of significant and broad interest to the scientific community as it is applicable to a range of substrates and allows for direct, label-free characterization of surface bound proteins.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.038
      Issue No: Vol. 55 (2017)
       
  • Rational design of charged peptides that self-assemble into robust
           nanofibers as immune-functional scaffolds
    • Authors: Hangyu Zhang; Jaehyung Park; Yonghou Jiang; Kim A. Woodrow
      Pages: 183 - 193
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Hangyu Zhang, Jaehyung Park, Yonghou Jiang, Kim A. Woodrow
      Self-assembling peptides programed by sequence design to form predefined nanostructures are useful for a variety of biomedical applications. However, assemblies of classic ionic self-complementary peptides are unstable in neutral pH, while charged peptide hydrogels have low mechanical strength. Here, we report on the rational design of a self-assembling peptide system with optimized charge distribution and density for bioscaffold development. Our designer peptides employs a sequence pattern that undergoes salt triggered self-assembly into β-sheet rich cationic nanofibers in the full pH range (pH 0–14). Our peptides form nanofibrils in physiological condition at a minimum concentration that is significantly lower than has been reported for self-assembly of comparable peptides. The robust fiber-forming ability of our peptides results in the rapid formation of hydrogels in physiological conditions with strong mechanical strength. Moreover, fiber structure is maintained even upon dense conjugation with a model bioactive cargo OVA257-264 peptide. Nanofibers carrying OVA257-264 significantly enhanced CD8+ T cell activation in vitro. Subcutaneous immunization of our peptide fiber vaccine also elicited robust CD8+ T cell activation and proliferation in vivo. Our self-assembling peptides are expected to provide a versatile platform to construct diverse biomaterials. Statement of Significance This work is an attempt of rational design of materials from molecular level for targeted properties and an exploration in molecular self-assembly. Current widely studied self-assembling peptides do not have stable nanofiber structures and form weak hydrogels under physiological conditions. To address this issue, we develop charged self-assembling peptides with a novel sequence pattern for strong fiber-forming ability under physiological conditions. Our designer peptides can undergo salt-triggered self-assembly into nanofibers that are ultrastable in extreme pH (0–14) and dilute solutions, and into hydrogels with strong mechanical strength. Upon conjugation with a model bioactive cargo, our self-assembled peptides exhibit great potential as bioscaffolds for multiple applications.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.041
      Issue No: Vol. 55 (2017)
       
  • pH-responsive pHLIP (pH low insertion peptide) nanoclusters of
           superparamagnetic iron oxide nanoparticles as a tumor-selective MRI
           contrast agent
    • Authors: Yushuang Wei; Rufang Liao; Abdulrahman Ahmed Mahmood; Haibo Xu; Qibing Zhou
      Pages: 194 - 203
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Yushuang Wei, Rufang Liao, Abdulrahman Ahmed Mahmood, Haibo Xu, Qibing Zhou
      Superparamagnetic iron oxide nanoparticles (SPION) are contrast agents used for noninvasive tumor magnetic resonance imaging (MRI). SPION with active targeting by tumor-specific ligands can effectively enhance the MRI sensitivity and specificity of tumors. However, the challenge remains when the tumor specific markers are yet to be determined, especially in the case of early tumor detection. In this study, the effectiveness of pH-responsive SPION via a pH low insertion peptide (pHLIP) to target tumor acidic microenvironments was investigated. Polylysine polymers were first successfully modified with pHLIP to have the pH-responsive capability. SPION pHLIP nanoclusters of 64, 82, 103, and 121nm size were then assembled by the pH-responsive polymers in a size-controlled manner. The pH-responsive SPION nanoclusters of the 64nm size exhibited the most effective pH-responsive retention in cells and tumor selective imaging in MRI. More importantly, the unique contrast enhancement of tumor inner core by the pH-responsive SPION in three different tumor models demonstrated the clinical potential to target tumor acidic microenvironment through pHLIP for tumor early detection and diagnosis by MRI. Statement of Significance Detection and diagnosis of tumors at early stage are critical for the improvement of the survival rate of cancer patients. However, the challenge remains when the tumor specific markers are yet to be determined, especially in early tumor detection. pH low insertion peptide (pHLIP) has been used as a specific ligand to target the tumor acidic microenvironment for tumors at early and metastatic stages. Superparamagnetic iron nanoparticles (SPION) are contrast enhancing agents used in the noninvasive magnetic resonance imaging for tumors. This research has demonstrated that pH-responsive pHLIP nanoclusters of SPION were able to target different tumors and facilitate the noninvasive diagnosis of tumors by MRI.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.046
      Issue No: Vol. 55 (2017)
       
  • Choose your cell model wisely: The in vitro nanoneurotoxicity of
           differentially coated iron oxide nanoparticles for neural cell labeling
    • Authors: Freya Joris; Daniel Valdepérez; Beatriz Pelaz; Tianqiang Wang; Shareen H. Doak; Bella B. Manshian; Stefaan J. Soenen; Wolfgang J. Parak; Stefaan C. De Smedt; Koen Raemdonck
      Pages: 204 - 213
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Freya Joris, Daniel Valdepérez, Beatriz Pelaz, Tianqiang Wang, Shareen H. Doak, Bella B. Manshian, Stefaan J. Soenen, Wolfgang J. Parak, Stefaan C. De Smedt, Koen Raemdonck
      Currently, there is a large interest in the labeling of neural stem cells (NSCs) with iron oxide nanoparticles (IONPs) to allow MRI-guided detection after transplantation in regenerative medicine. For such biomedical applications, excluding nanotoxicity is key. Nanosafety is primarily evaluated in vitro where an immortalized or cancer cell line of murine origin is often applied, which is not necessarily an ideal cell model. Previous work revealed clear neurotoxic effects of PMA-coated IONPs in distinct cell types that could potentially be applied for nanosafety studies regarding neural cell labeling. Here, we aimed to assess if DMSA-coated IONPs could be regarded as a safer alternative for this purpose and how the cell model impacted our nanosafety optimization study. Hereto, we evaluated cytotoxicity, ROS production, calcium levels, mitochondrial homeostasis and cell morphology in six related neural cell types, namely neural stem cells, an immortalized cell line and a cancer cell line from human and murine origin. The cell lines mostly showed similar responses to both IONPs, which were frequently more pronounced for the PMA-IONPs. Of note, ROS and calcium levels showed opposite trends in the human and murine NSCs, indicating the importance of the species. Indeed, the human cell models were overall more sensitive than their murine counterpart. Despite the clear cell type-specific nanotoxicity profiles, our multiparametric approach revealed that the DMSA-IONPs outperformed the PMA-IONPs in terms of biocompatibility in each cell type. However, major cell type-dependent variations in the observed effects additionally warrant the use of relevant human cell models. Statement of Significance Inorganic nanoparticle (NP) optimization is chiefly performed in vitro. For the optimization of iron oxide (IO)NPs for neural stem cell labeling in the context of regenerative medicine human or rodent neural stem cells, immortalized or cancer cell lines are applied. However, the use of certain cell models can be questioned as they phenotypically differ from the target cell. The impact of the neural cell model on nanosafety remains relatively unexplored. Here we evaluated cell homeostasis upon exposure to PMA- and DMSA-coated IONPs. Of note, the DMSA-IONPs outperformed the PMA-IONPs in each cell type. However, distinct cell type-specific effects were witnessed, indicating that nanosafety should be evaluated in a human cell model that represents the target cell as closely as possible.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.053
      Issue No: Vol. 55 (2017)
       
  • Structural transitions in torsionally constrained DNA and their dependence
           on solution electrostatics
    • Authors: Jaspreet Singh; Prashant K. Purohit
      Pages: 214 - 225
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Jaspreet Singh, Prashant K. Purohit
      Experimental studies on single molecules of DNA have reported a rich variety of structural transitions, including coexistence of three phases, in a torsionally constrained molecule. A comprehensive knowledge of these structural transitions is useful for unraveling the in vivo and in vitro behavior of DNA. Our objective is to understand the structural transitions in a torsionally constrained DNA molecule when it is pulled using optical or magnetic tweezers. We use foundational concepts from the Zimm-Bragg helix-coil transition theory and merge them with ideas from the theory of fluctuating elastic rods to model the mechanics of DNA. We also account for the electrostatic interactions between the ions and the negatively charged phosphate backbone of DNA. Using our model, we calculate the force and torque corresponding to the overstretching transition characterized by a 70% jump in the contour length of the molecule and examine the effect of salt concentration on this transition. We also deduce conditions under which the co-existence of B-, S- and P-DNA is possible. We examine how the cooperativity parameter for each transition affects the force-extension curve or torque-rotation curve. We attempt to rationalize the non-monotonic dependence of external work done on the ion concentration by connecting it to the electrostatic dependence of the interfacial energy between two phases of DNA. Our theoretical results are in agreement with multiple experiments documented in the literature and they generate falsifiable predictions that can be tested in new experiments. Statement of significance The overarching objective of this paper is to explore the implications of variation in ion concentration on the structural transitions driven by external forces in a torsionally constrained DNA molecule. A comprehensive understanding of the phase behavior of torsionally constrained DNA is useful because DNA in cells is tightly packaged and is acted upon by molecular machines in different ionic environments. We examine the mechanics of the overstretching transition, characterized by a 70% jump in contour length, wherein a mixture of B- and S-DNA converts into a mixture of S- and P-DNA through a triple point in the phase diagram. Our results are corroborated by experimental data at every step and we make predictions that are experimentally verifiable.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.052
      Issue No: Vol. 55 (2017)
       
  • Mesenchymal stem cell fate following non-viral gene transfection strongly
           depends on the choice of delivery vector
    • Authors: T. Gonzalez-Fernandez; B.N. Sathy; C. Hobbs; G.M. Cunniffe; H.O. McCarthy; N.J. Dunne; V. Nicolosi; F.J. O'Brien; D.J. Kelly
      Pages: 226 - 238
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): T. Gonzalez-Fernandez, B.N. Sathy, C. Hobbs, G.M. Cunniffe, H.O. McCarthy, N.J. Dunne, V. Nicolosi, F.J. O'Brien, D.J. Kelly
      Controlling the phenotype of mesenchymal stem cells (MSCs) through the delivery of regulatory genes is a promising strategy in tissue engineering (TE). Essential to effective gene delivery is the choice of gene carrier. Non-viral delivery vectors have been extensively used in TE, however their intrinsic effects on MSC differentiation remain poorly understood. The objective of this study was to investigate the influence of three different classes of non-viral gene delivery vectors: (1) cationic polymers (polyethylenimine, PEI), (2) inorganic nanoparticles (nanohydroxyapatite, nHA) and (3) amphipathic peptides (RALA peptide) on modulating stem cell fate after reporter and therapeutic gene delivery. Despite facilitating similar reporter gene transfection efficiencies, these nanoparticle-based vectors had dramatically different effects on MSC viability, cytoskeletal morphology and differentiation. After reporter gene delivery (pGFP or pLUC), the nHA and RALA vectors supported an elongated MSC morphology, actin stress fibre formation and the development of mature focal adhesions, while cells appeared rounded and less tense following PEI transfection. These changes in MSC morphology correlated with enhanced osteogenesis following nHA and RALA transfection and adipogenesis following PEI transfection. When therapeutic genes encoding for transforming growth factor beta 3 (TGF-β3) and/or bone morphogenic protein 2 (BMP2) were delivered to MSCs, nHA promoted osteogenesis in 2D culture and the development of an endochondral phenotype in 3D culture, while RALA was less osteogenic and appeared to promote a more stable hyaline cartilage-like phenotype. In contrast, PEI failed to induce robust osteogenesis or chondrogenesis of MSCs, despite effective therapeutic protein production. Taken together, these results demonstrate that the differentiation of MSCs through the application of non-viral gene delivery strategies depends not only on the gene delivered, but also on the gene carrier itself. Statement of Significance Nanoparticle-based non-viral gene delivery vectors have been extensively used in regenerative medicine, however their intrinsic effects on mesenchymal stem cell (MSC) differentiation remain poorly understood. This paper demonstrates that different classes of commonly used non-viral vectors are not inert and they have a strong effect on cell morphology, stress fiber formation and gene transcription in MSCs, which in turn modulates their capacity to differentiate towards osteogenic, adipogenic and chondrogenic lineages. These results also point to the need for careful and tissue-specific selection of nanoparticle-based delivery vectors to prevent undesired phenotypic changes and off-target effects when delivering therapeutic genes to damaged or diseased tissues.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.044
      Issue No: Vol. 55 (2017)
       
  • Viscoelastic properties of normal and cancerous human breast cells are
           affected differently by contact to adjacent cells
    • Authors: Nicolas Schierbaum; Johannes Rheinlaender; Tilman E. Schäffer
      Pages: 239 - 248
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Nicolas Schierbaum, Johannes Rheinlaender, Tilman E. Schäffer
      Malignant transformation drastically alters the mechanical properties of the cell and its response to the surrounding cellular environment. We studied the influence of the physical contact between adjacent cells in an epithelial monolayer on the viscoelastic behavior of normal MCF10A, non-invasive cancerous MCF7, and invasive cancerous MDA-MB-231 human breast cells. Using an atomic force microscopy (AFM) imaging technique termed force clamp force mapping (FCFM) to record images of the viscoelastic material properties, we found that normal MCF10A cells are stiffer and have a lower fluidity at confluent than at sparse density. Contrarily, cancerous MCF7 and MDA-MB-231 cells do not stiffen and do not decrease their fluidity when progressing from sparse to confluent density. The behavior of normal MCF10A cells appears to be governed by the formation of stable cell-cell contacts, because their disruption with a calcium-chelator (EGTA) causes the stiffness and fluidity values to return to those at sparse density. In contrast, EGTA-treatment of MCF7 and MDA-MB-231 cells does not change their viscoelastic properties. Confocal fluorescence microscopy showed that the change of the viscoelastic behavior in MCF10A cells when going from sparse to confluent density is accompanied by a remodeling of the actin cytoskeleton into thick stress fiber bundles, while in MCF7 and MDA-MB-231 cells the actin cytoskeleton is only composed of thin and short fibers, regardless of cell density. While the observed behavior of normal MCF10A cells might be crucial for providing mechanical stability and thus in turn integrity of the epithelial monolayer, the dysregulation of this behavior in cancerous MCF7 and MDA-MB-231 cells is possibly a central aspect of cancer progression in the epithelium. Statement of Significance We measured the viscoelastic properties of normal and cancerous human breast epithelial cells in different states of confluency using atomic force microscopy. We found that confluent normal cells are stiffer and have lower fluidity than sparse normal cells, which appears to be governed by the formation of cell-cell contacts. Contrarily, confluent cancer cells do not stiffen and not have a decreased fluidity compared to sparse cancer cells and their viscoelastic properties are independent of cell-cell contact formation. While the observed behavior of normal cells appears to be crucial for providing the mechanical stability and therefore the integrity of the epithelial monolayer, the dysregulation of this behavior in cancer cells might be a central aspect of early stage cancer progression and metastasis in the epithelium.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.006
      Issue No: Vol. 55 (2017)
       
  • Combined chemical and structural signals of biomaterials synergistically
           activate cell-cell communications for improving tissue regeneration
    • Authors: Yachen Xu; Jinliang Peng; Xin Dong; Yuhong Xu; Haiyan Li; Jiang Chang
      Pages: 249 - 261
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Yachen Xu, Jinliang Peng, Xin Dong, Yuhong Xu, Haiyan Li, Jiang Chang
      Biomaterials are only used as carriers of cells in the conventional tissue engineering. Considering the multi-cell environment and active cell-biomaterial interactions in tissue regeneration process, in this study, structural signals of aligned electrospun nanofibers and chemical signals of bioglass (BG) ionic products in cell culture medium are simultaneously applied to activate fibroblast-endothelial co-cultured cells in order to obtain an improved skin tissue engineering construct. Results demonstrate that the combined biomaterial signals synergistically activate fibroblast-endothelial co-culture skin tissue engineering constructs through promotion of paracrine effects and stimulation of gap junctional communication between cells, which results in enhanced vascularization and extracellular matrix protein synthesis in the constructs. Structural signals of aligned electrospun nanofibers play an important role in stimulating both of paracrine and gap junctional communication while chemical signals of BG ionic products mainly enhance paracrine effects. In vivo experiments reveal that the activated skin tissue engineering constructs significantly enhance wound healing as compared to control. This study indicates the advantages of synergistic effects between different bioactive signals of biomaterials can be taken to activate communication between different types of cells for obtaining tissue engineering constructs with improved functions. Statement of Significance Tissue engineering can regenerate or replace tissue or organs through combining cells, biomaterials and growth factors. Normally, for repairing a specific tissue, only one type of cells, one kind of biomaterials, and specific growth factors are used to support cell growth. In this study, we proposed a novel tissue engineering approach by simply using co-cultured cells and combined biomaterial signals. Using a skin tissue engineering model, we successfully proved that the combined biomaterial signals such as surface nanostructures and bioactive ions could synergistically stimulate the cell-cell communication in co-culture system through paracrine effects and gap junction activation, and regulated expression of growth factors and extracellular matrix proteins, resulting in an activated tissue engineering constructs that significantly enhanced skin regeneration.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.056
      Issue No: Vol. 55 (2017)
       
  • Oligomeric proanthocyanidins released from dentin induce regenerative
           dental pulp cell response
    • Authors: Daniel Kulakowski; Ariene A. Leme-Kraus; Joo-won Nam; James McAlpine; Shao-Nong Chen; Guido F. Pauli; Sriram Ravindran; Ana K. Bedran-Russo
      Pages: 262 - 270
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Daniel Kulakowski, Ariene A. Leme-Kraus, Joo-won Nam, James McAlpine, Shao-Nong Chen, Guido F. Pauli, Sriram Ravindran, Ana K. Bedran-Russo
      Proanthocyanidins (PACs) are plant-derived, multifunctional compounds that possess high interactivity with extracellular matrix (ECM) components. The documented affinity of PACs for type-I collagen is directly correlated with their structural features and degree of polymerization. In this investigation, centrifugal partition chromatography (CPC) was used to sequentially deplete less active monomeric and polymeric PACs from a crude Pinus massoniana bark extract to create refined mixtures enriched in oligomeric PACs. The ability of these oligomeric PACs to modify the mechanical properties of the dentin collagen matrix and their biocompatibility with dental pulp cells (DPCs) was evaluated in an innovative biomimetic environment. The refined mixtures displayed high interactivity with dentin collagen as demonstrated by a significant increase (>5-fold) in the modulus of elasticity of the dentin matrix. In a simplified model of the dentin-DPC complex, DPCs embedded within their native ECM in the presence of PAC-treated dentin exhibited increased proliferation. Quantitative gene expression analyses indicated that exposure to PAC-treated dentin increased the expression of key biomineralization and odontogenic differentiation regulators, including RUNX2, BMP2, OCN, and DSPP. LC-MS/MS analysis revealed that PACs two to four units long (dimers, trimers, and tetramers) were being released from dentin into media, influencing cell behavior. Overall, the results suggested that PAC dimers, trimers, and tetramers are not only biocompatible, but enhance the differentiation of DPCs towards a phenotype that favors biomineralization. PAC-enriched refined mixtures can influence the field of biomaterials and regeneration by serving as renewable, non-cytotoxic agents that can increase the mechanical properties of biomaterials. Statement of Significance Pine bark extract is a renewable source of structurally diverse proanthocyanidins (PACs), multifunctional compounds whose interaction with collagen can be tailored to specific purposes by enrichment of selected PACs from the complex mixture. Oligomeric PACs were enriched from the extract and were shown here to sustain desired tissue modification and were thus assessed for cellular response in a model of the dentin-pulp interface. This model was developed to mimic leaching of potentially reactive compounds into pulp tissue. Dental pulp cells exposed to PAC-treated dentin showed increased proliferation and expression of genes necessary for extracellular matrix deposition and biomineralization, processes crucial for forming new dentin. Thus, collagen-interactive PACs may also enhance tissue regeneration and have broad impact in tissue engineering.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.051
      Issue No: Vol. 55 (2017)
       
  • Comparative analysis of biological effect of corannulene and graphene on
           developmental and sleep/wake profile of zebrafish larvae
    • Authors: Xiang Li; Yuan Zhang; Xu Li; DaoFu Feng; ShuHui Zhang; Xin Zhao; DongYan Chen; ZhiXiang Zhang; XiZeng Feng
      Pages: 271 - 282
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Xiang Li, Yuan Zhang, Xu Li, DaoFu Feng, ShuHui Zhang, Xin Zhao, DongYan Chen, ZhiXiang Zhang, XiZeng Feng
      Little is known about the biological effect of non-planar polycyclic aromatic hydrocarbons (PAH) such as corannulene on organisms. In this study, we compared the effect of corannulene (non-planar PAH) and graphene (planar PAH) on embryonic development and sleep/wake behaviors of larval zebrafish. First, the toxicity of graded doses of corannulene (1, 10, and 50μg/mL) was tested in developing zebrafish embryos. Corannulene showed minimal developmental toxicity only induced an epiboly delay. Further, a significant decrease in locomotion/increase in sleep was observed in larvae treated with the highest dose (50μg/mL) of corannulene while no significant locomotion alterations were induced by graphene. Finally, the effect of corannulene or graphene on the hypocretin (hcrt) system and sleep/wake regulators such as hcrt, hcrt G-protein coupled receptor (hcrtr), and arylalkylamine N-acetyltransferase-2 (aanat2) was evaluated. Corannulene increased sleep and reduced locomotor activity and the expression of hcrt and hcrtr mRNA while graphene did not obviously disturb the sleep behavior and gene expression patterns. These results suggest that the corannulene has the potential to cause hypnosis-like behavior in larvae and provides a fundamental comparative understanding of the effects of corannulene and graphene on biology systems. Statement of Significance Little is known about the biological effect of non-planar polycyclic aromatic hydrocarbons (PAH) such as corannulene on organisms. Here, we compare the effect of corannulene (no-planar PAH) and graphene (planar PAH) on embryonic development and sleep/wake behaviors of larval zebrafish. And we aim to investigate the effect of curvature on biological system. First, toxicity of corannulene over the range of doses (1μg/mL, 10μg/mL and 50μg/mL) was tested in developing zebrafish embryos. Corannulene has minimal developmental toxicity, only incurred epiboly delay. Subsequently, a significant decrease in locomotion/increase in sleep at the highest dose (50μg/mL) was detected in corannulene treated larvae while no significant locomotion alterations was induced by graphene. Finally, the impact of corannulene or graphene on hypocretin system and sleep/wake regulator such as hcrt, hcrtr and aanat2 was evaluated. Corannulene increased sleep, reduced locomotor activity and the expression of hcrt and hcrtr mRNA while graphene did not obviously disturb the sleep behaviors and gene expression patterns. This result may indicate the potential effect of corannulene to cause hypnosia-like behavior in larvae and provide the fundamental understanding for the biological effect of curvature on biology system.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.047
      Issue No: Vol. 55 (2017)
       
  • One-dimensional poly(L-lysine)-block-poly(L-threonine) assemblies exhibit
           potent anticancer activity by enhancing membranolysis
    • Authors: Yu-Fon Chen; Ai-Li Shiau; Sue-Joan Chang; Nai-Shin Fan; Chung-Teng Wang; Chao-Liang Wu; Jeng-Shiung Jan
      Pages: 283 - 295
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Yu-Fon Chen, Ai-Li Shiau, Sue-Joan Chang, Nai-Shin Fan, Chung-Teng Wang, Chao-Liang Wu, Jeng-Shiung Jan
      Herein, we report the oncolytic activity of cationic, one-dimensional (1D) fibril assemblies formed from coil-sheet poly(L-lysine)-block-poly(L-threonine) (PLL-b-PLT) block copolypeptides for cancer therapy. The 1D fibril assemblies can efficiently interact with negatively charged cellular and mitochondrial membranes via electrostatic interactions, leading to necrosis via membrane lysis and apoptosis via the mitochondria-lytic effect. The concept is analogous to that of 1D drug carriers that exhibit enhanced cell penetration. In comparison to free PLL chains, PLL-b-PLT fibril assemblies exhibit selective cytotoxicity toward cancer cells, low hemolysis activity, enhanced membranolytic activity, and a different apoptosis pathway, which may be due to differences in the peptide-membrane interactions. Antitumor studies using a metastatic LL2 lung carcinoma model indicate that the fibril assemblies significantly inhibited tumor growth, improved survival in tumor-bearing mice and suppressed lung metastasis without obvious body weight loss. An additive efficacy was also observed for treatment with both PLL-b-PLT and cisplatin. These results support the feasibility of using 1D fibril assemblies as potential apoptotic anticancer therapeutics. Statement of Significance We report that cationic, one-dimensional (1D) fibril assemblies formed by coil-sheet poly(L-lysine)-block-poly(L-threonine) (PLL-b-PLT) block copolypeptides exhibited potent anticancer activity by enhancing membranolysis. The 1D fibril assemblies can efficiently interact with negatively charged cellular and mitochondrial membranes via electrostatic interactions, leading to necrosis via membrane lysis and apoptosis via mitochondria-lytic effect. Moreover, the fibril assemblies exhibited low hemolytic activity and selective cytotoxicity toward cancer cell, which is advantageous as compared to PLL and most antimicrobial/anticancerous peptides. This study provides a new concept of using cationic, 1D fibril assemblies for cancer therapy.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.009
      Issue No: Vol. 55 (2017)
       
  • Prompt peripheral nerve regeneration induced by a hierarchically aligned
           fibrin nanofiber hydrogel
    • Authors: Jinrong Du; Jianheng Liu; Shenglian Yao; Haiquan Mao; Jiang Peng; Xun Sun; Zheng Cao; Yongdong Yang; Bo Xiao; Yiguo Wang; Peifu Tang; Xiumei Wang
      Pages: 296 - 309
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Jinrong Du, Jianheng Liu, Shenglian Yao, Haiquan Mao, Jiang Peng, Xun Sun, Zheng Cao, Yongdong Yang, Bo Xiao, Yiguo Wang, Peifu Tang, Xiumei Wang
      Fibrin plays a crucial role in peripheral nerve regeneration, which could occur spontaneously in the format of longitudinally oriented fibrin cables during the initial stage of nerve regeneration. This fibrin cable can direct migration and proliferation of Schwann cells and axonal regrowth, which is very important to nerve regeneration. In the present study, we prepared a three-dimensional hierarchically aligned fibrin nanofiber hydrogel (AFG) through electrospinning and molecular self-assembly to resemble the architecture and biological function of the native fibrin cable. The AFG displayed a hierarchically aligned topography as well as low elasticity (∼1.5kPa) that were similar to nerve extracellular matrix (ECM) and the native fibrin cable. Rapid, directional cell adhesion and migration of Schwann cells (SCs) and dorsal root ganglions were observed in vitro. The AFG was then used as a potential intraluminal substrate in a bioengineered chitosan tube to bridge a 10-mm-long sciatic nerve gap in rats. We found that the AFG served as a beneficial microenvironment to support SCs cable formation and axonal regrowth within 2weeks. Further histological and morphological analyses as well as electrophysiological and functional examinations were performed after AFG implantation for up to 12weeks. The results from morphological analysis and electrophysiological examination indicated that regenerative outcomes achieved by our developed graft were close to those by an autologous nerve graft, but superior to those by hollow chitosan tubes (hCST) and random fibrin nanofiber hydrogel (RFG). Our results demonstrate that the AFG creates an instructive microenvironment by mimicking the native fibrin cable as well as the oriented and soft features of nerve ECM to accelerate axonal regrowth, thus showing great promising potential for applications in neural regeneration. Statement of Significance In peripheral nervous system defect repair, a wide variety of strategies have been proposed for preparing functionalized nerve guidance conduits (NGC) with more complex configurations to obtain optimal repair effects. Longitudinally oriented fibrin cables were reported to form spontaneously during the initial stages of peripheral nerve regeneration in an empty NGC, which can direct the migration and proliferation of Schwann cells and promote axonal regrowth. Therefore, based on the biomimetic idea, we prepared a three-dimensional hierarchically aligned fibrin nanofiber hydrogel (AFG) through electrospinning and molecular self-assembly, resembling the architecture and biological function of the native fibrin cable and serving as an intraluminal filling to accelerate axon regeneration. We found that the AFG was a beneficial microenvironment to support SCs cable formation and accelerate axonal regrowth with improved motor functional recovery.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.010
      Issue No: Vol. 55 (2017)
       
  • 3D screening device for the evaluation of cell response to different
           electrospun microtopographies
    • Authors: G. Criscenti; A. Vasilevich; A. Longoni; C. De Maria; C.A. van Blitterswijk; R. Truckenmuller; G. Vozzi; J. De Boer; L. Moroni
      Pages: 310 - 322
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): G. Criscenti, A. Vasilevich, A. Longoni, C. De Maria, C.A. van Blitterswijk, R. Truckenmuller, G. Vozzi, J. De Boer, L. Moroni
      Micro- and nano-topographies of scaffold surfaces play a pivotal role in tissue engineering applications, influencing cell behavior such as adhesion, orientation, alignment, morphology and proliferation. In this study, a novel microfabrication method based on the combination of soft-lithography and electrospinning for the production of micro-patterned electrospun scaffolds was proposed. Subsequently, a 3D screening device for electrospun meshes with different micro-topographies was designed, fabricated and biologically validated. Results indicated that the use of defined patterns could induce specific morphological variations in human mesenchymal stem cell cytoskeletal organization, which could be related to differential activity of signaling pathways. Statement of Significance We introduce a novel and time saving method to fabricate 3D micropatterns with controlled micro-architectures on electrospun meshes using a custom made collector and a PDMS mold with the desired topography. A possible application of this fabrication technique is represented by a 3D screening system for patterned electrospun meshes that allows the screening of different scaffold/electrospun parameters on cell activity. In addition, what we have developed in this study could be modularly applied to existing platforms. Considering the different patterned geometries, the cell morphological data indicated a change in the cytoskeletal organization with a close correspondence to the patterns, as shown by phenoplot and boxplot analysis, and might hint at the differential activity of cell signaling. The 3D screening system proposed in this study could be used to evaluate topographies favoring cell alignment, proliferation and functional performance, and has the potential to be upscaled for high-throughput.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.049
      Issue No: Vol. 55 (2017)
       
  • Silk I and Silk II studied by fast scanning calorimetry
    • Authors: Peggy Cebe; Benjamin P. Partlow; David L. Kaplan; Andreas Wurm; Evgeny Zhuravlev; Christoph Schick
      Pages: 323 - 332
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Peggy Cebe, Benjamin P. Partlow, David L. Kaplan, Andreas Wurm, Evgeny Zhuravlev, Christoph Schick
      Using fast scanning calorimetry (FSC), we investigated the glass transition and crystal melting of samples of B. mori silk fibroin containing Silk I and/or Silk II crystals. Due to the very short residence times at high temperatures during such measurements, thermal decomposition of silk protein can be significantly suppressed. FSC was performed at 2000K/s using the Mettler Flash DSC1 on fibroin films with masses around 130–270ng. Films were prepared with different crystalline fractions (ranging from 0.26 to 0.50) and with different crystal structures (Silk I, Silk II, or mixed) by varying the processing conditions. These included water annealing at different temperatures, exposure to 50%MeOH in water, or autoclaving. The resulting crystal structure was examined using wide angle X-ray scattering. Degree of crystallinity was evaluated from Fourier transform infrared (FTIR) spectroscopy and from analysis of the heat capacity increment at the glass transition temperature. Silk fibroin films prepared by water annealing at 25°C were the least crystalline and had Silk I structure. FTIR and FSC studies showed that films prepared by autoclaving or 50%MeOH exposure were the most crystalline and had Silk II structure. Intermediate crystalline fraction and mixed Silk I/Silk II structures were found in films prepared by water annealing at 37°C. FSC results indicate that Silk II crystals exhibit endotherms of narrower width and have higher mean melting temperature Tm(II)=351±2.6°C, compared to Silk I crystals which melt at Tm(I)=292±3.8°C. Films containing mixed Silk I/Silk II structure showed two clearly separated endothermic peaks. Evidence suggests that the two types of crystals melt separately and do not thermally interconvert on the extremely short time scale (0.065s between onset and end of melting) of the FSC experiment. Statement of Significance Silkworm silk is a naturally occurring biomaterial. The fibroin component of silk forms two types of crystals. Silk properties depend upon the amount and type of crystals, and their stability. One measure of stability is crystal melting temperature. Crystals which are more stable have a higher melting temperature. Until now, it has been challenging to study thermal behavior of silk crystals because they degrade at high temperature. To avoid degradation, and study the melting properties of silk biomaterial, we heated silk at a very fast rate of 2000K/s using a special calorimeter. We have shown that the two crystal types have very different melting temperatures, indicating that one crystal type is much more stable than the other.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.001
      Issue No: Vol. 55 (2017)
       
  • Regional mechanical properties of human brain tissue for computational
           models of traumatic brain injury
    • Authors: John D. Finan; Sowmya N. Sundaresh; Benjamin S. Elkin; Guy M. McKhann; Barclay Morrison
      Pages: 333 - 339
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): John D. Finan, Sowmya N. Sundaresh, Benjamin S. Elkin, Guy M. McKhann, Barclay Morrison
      To determine viscoelastic shear moduli, stress relaxation indentation tests were performed on samples of human brain tissue resected in the course of epilepsy surgery. Through the use of a 500µm diameter indenter, regional mechanical properties were measured in cortical grey and white matter and subregions of the hippocampus. All regions were highly viscoelastic. Cortical grey matter was significantly more compliant than the white matter or hippocampus which were similar in modulus. Although shear modulus was not correlated with the age of the donor, cortex from male donors was significantly stiffer than from female donors. The presented material properties will help to populate finite element models of the brain as they become more anatomically detailed. Statement of Significance We present the first mechanical characterization of fresh, post-operative human brain tissue using an indentation loading mode. Indentation generates highly localized data, allowing structure-specific mechanical properties to be determined from small tissue samples resected during surgery. It also avoids pitfalls of cadaveric tissue and allows data to be collected before degenerative processes alter mechanical properties. To correctly predict traumatic brain injury, finite element models must calculate intracranial deformation during head impact. The functional consequences of injury depend on the anatomical structures injured. Therefore, morbidity depends on the distribution of deformation across structures. Accurate prediction of structure-specific deformation requires structure-specific mechanical properties. This data will facilitate deeper understanding of the physical mechanisms that lead to traumatic brain injury.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.037
      Issue No: Vol. 55 (2017)
       
  • Study on the deformations of the lamina cribrosa during glaucoma
    • Authors: Hanjing Tian; Long Li; Fan Song
      Pages: 340 - 348
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): Hanjing Tian, Long Li, Fan Song
      The lamina cribrosa is the primary site of optic nerve injury during glaucoma, and its deformations induced by elevated intraocular pressure are associated directly with the optic nerve injury and visual field defect. However, the deformations in a living body have been poorly understood yet so far. It is because that integral observation and precise measurement of the deformations in vivo are now almost impossible in the clinical diagnosis and treatment of glaucoma. In the present study, a new mechanical model of the lamina cribrosa is presented by using Reissner’s thin plate theory. This model accurately displays the stress and deformation states in the lamina cribrosa under elevated intraocular pressure, in which the shear deformation is not presented by the previous models, however, is demonstrated to play a key role in the optic nerve injury. Further, the deformations of the structures, involving the optic nerve channels and the laminar sheets in the lamina cribrosa, are first investigated in detail. For example, the dislocation of the laminar sheets reaches 18.6μm under the intraocular pressure of 40mmHg, which is large enough to damage the optic nerve axons. The results here confirm some previously proposed clinical speculations on the deformations of the pore shape in the lamina cribrosa under elevated intraocular pressure during glaucoma. Finally, some essentially clinical questions existed during glaucoma, such as the pathological mechanism of the open-angle glaucoma with normal intraocular pressure, are discussed. The present study is beneficial to deeply understanding the optic nerve injury during glaucoma. Statement of Significance The lamina cribrosa is the primary site of the optic nerve injury induced by elevated intraocular pressure during glaucoma. Under high intraocular pressure, the optic nerve channel near to the periphery of the lamina cribrosa (Channel A) is deformed to become into a tortuous elliptical horn from a straight cylinder, while the optic nerve channel near to the center of the lamina cribrosa (Channel B) is deformed to become into a straight horn from a straight cylinder. These deformations cause both the axoplasm flow obstacle in the axon fibers and the blocked blood flow in the capillaries which pass through the channels, and trigger the visual field defect during glaucoma.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.03.028
      Issue No: Vol. 55 (2017)
       
  • Crack driving force in twisted plywood structures
    • Authors: F.D. Fischer; O. Kolednik; J. Predan; H. Razi; P. Fratzl
      Pages: 349 - 359
      Abstract: Publication date: June 2017
      Source:Acta Biomaterialia, Volume 55
      Author(s): F.D. Fischer, O. Kolednik, J. Predan, H. Razi, P. Fratzl
      Twisted plywood architectures can be observed in many biological materials with high fracture toughness, such as in arthropod cuticles or in lamellar bone. Main purpose of this paper is to analyze the influence of the progressive rotation of the fiber direction on the spatial variation of the crack driving force and, thus, on the fracture toughness of plywood-like structures. The theory of fiber composites is used to describe the stiffness matrix of a twisted plywood structure in a specimen-fixed coordinate system. The driving force acting on a crack propagating orthogonally to the fiber-rotation plane is studied by methods of computational mechanics, coupled with the concept of configurational forces. The analysis unfolds a spatial variation of the crack driving force with minima that are beneficial for the fracture toughness of the material. It is shown that the estimation of the crack driving force can be simplified by replacing the complicated anisotropic twisted plywood structure by an isotropic material with appropriate periodic variations of Young’s modulus, which can be constructed based either on the local stiffness or local strain energy density variations. As practical example, the concepts are discussed for a specimen with a stiffness anisotropy similar to lamellar bone. Statement of Significance Twisted plywood-like structures exist in many natural fiber composites, such as bone or insect carapaces, and are known to be very fracture resistant. The crack driving force in such materials is analyzed quantitatively for the first time, using the concept of configurational forces. This tool, well established in the mechanics of materials, is introduced to the modeling of biological material systems with inhomogeneous and anisotropic material behavior. Based on this analysis, it is shown that the system can be approximated by an appropriately chosen inhomogeneous but isotropic material for the calculation of the crack driving force. The spatial variation of the crack driving force and, especially, its local minima are essential to describe the fracture properties of twisted plywood structures.
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      PubDate: 2017-05-29T12:13:44Z
      DOI: 10.1016/j.actbio.2017.04.007
      Issue No: Vol. 55 (2017)
       
  • Engineered Myocardium Model to Study the Roles of HIF-1α and HIF1A-AS1 in
           Paracrine-only Signaling under Pathological Level Oxidative Stress
    • Authors: Aylin Acun; Pinar Zorlutuna
      Abstract: Publication date: Available online 16 June 2017
      Source:Acta Biomaterialia
      Author(s): Aylin Acun, Pinar Zorlutuna
      Studying heart tissue is critical for understanding and developing treatments for cardiovascular diseases. In this work, we fabricated precisely controlled and biomimetic engineered model tissues to study how cell-cell and cell-matrix interactions influence myocardial cell survival upon exposure to pathological level oxidative stress. Specifically, the interactions of endothelial cells (ECs) and cardiomyocytes (CMs), and the role of hypoxia inducible factor-1α (HIF-1α), with its novel alternative regulator, HIF-1α antisense RNA1 (HIF1A-AS1), in these interactions were investigated. We encapsulated CMs in photo-crosslinkable, biomimetic hydrogels with or without ECs, then exposed to oxidative stress followed by normoxia. With precisely controlled microenvironment provided by the model tissues, cell-cell interactions were restricted to be solely through the secreted factors. CM survival after oxidative stress was significantly improved, in the presence of ECs, when cells were in the model tissues that were functionalized with cell attachment motifs. Importantly, the cardioprotective effect of ECs was reduced when HIF-1α expression was knocked down suggesting that HIF-1α is involved in cardioprotection from oxidative damage, provided through secreted factors conferred by the ECs. Using model tissues, we showed that cell survival increased with increased cell-cell communication and enhanced cell-matrix interactions. In addition, whole genome transcriptome analysis showed, for the first time to our knowledge, a possible role for HIF1A-AS1 in oxidative regulation of HIF-1α. We showed that although HIF1A-AS1 knockdown helps CM survival, its effect is overridden by CM-EC bidirectional interactions as we showed that the conditioned media taken from the CM-EC co-cultures improved CM survival, regardless of HIF1A-AS1 expression. Statement of Significance: Cardiovascular diseases, most of which are associated with oxidative stress, is the most common cause of death worldwide. Thus, understanding the molecular events as well as the role of intercellular communication under oxidative stress is upmost importance in its prevention. In this study we used 3D engineered tissue models to investigate the role of HIF-1α and its regulation in EC-mediated cardioprotection. We showed that EC-mediated protection is only possible when there is a bidirectional crosstalk between ECs and CMs even without physical cell-cell contact. In addition, this protective effect is at least partially related to cell-ECM interactions and HIF-1α, which is regulated by HIF1A-AS1 under oxidative stress.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.023
       
  • Enhanced Nutrient Transport Improves the Depth-Dependent Properties of
           Tri-Layered Engineered Cartilage Constructs with Zonal Co-Culture of
           Chondrocytes and MSCs
    • Authors: Minwook Kim; Megan J. Farrell; David R. Steinberg; Jason A. Burdick; Robert L. Mauck
      Abstract: Publication date: Available online 16 June 2017
      Source:Acta Biomaterialia
      Author(s): Minwook Kim, Megan J. Farrell, David R. Steinberg, Jason A. Burdick, Robert L. Mauck
      Biomimetic design in cartilage tissue engineering is a challenge given the complexity of the native tissue. While numerous studies have generated constructs with near-native bulk properties, recapitulating the depth-dependent features of native tissue remains a challenge. Furthermore, limitations in nutrient transport and matrix accumulation in engineered constructs hinders maturation within the central core of large constructs. To overcome these limitations, we fabricated tri-layered constructs that recapitulate the depth-dependent cellular organization and functional properties of native tissue using zonally derived chondrocytes co-cultured with MSCs. We also introduced porous hollow fibers (HFs) and HFs/cotton threads to enhance nutrient transport. Our results showed that tri-layered constructs with depth-dependent organization and properties could be fabricated. The addition of HFs or HFs/threads improved matrix accumulation in the central core region. With HF/threads, the local modulus in the deep region of tri-layered constructs nearly matched that of native tissue, though the properties in the central regions remained lower. These constructs reproduced the zonal organization and depth-dependent properties of native tissue, and demonstrate that a layer-by-layer fabrication scheme holds promise for the biomimetic repair of focal cartilage defects. Statement of Significance Articular cartilage is a highly organized tissue driven by zonal heterogeneity of cells, extracellular matrix proteins and fibril orientations, raising depth-dependent mechanical properties. Therefore, the recapitulation of the functional properties of native cartilage in a tissue engineered construct requires such a biomimetic design of the morphological organization, and this has remained a challenge in cartilage tissue engineering. This study demonstrates that a layer-by-layer fabrication scheme, including co-cultures of zone-specific articular CHs and MSCs, can reproduce the depth-dependent characteristics and mechanical properties of native cartilage while minimizing the need for large numbers of chondrocytes. In addition, an introduction of a porous hollow fiber (combined with a cotton thread) enhances nutrient transport and depth-dependent properties of the tri-layered construct. Such a tri-layered construct may provide critical advantages for focal cartilage repair. These constructs hold promise for restoring native tissue structure and function, and may be beneficial in terms of zone-to-zone integration with adjacent host tissue and providing more appropriate strain transfer after implantation.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.025
       
  • Adiponectin improves the osteointegration of titanium implant under
           diabetic conditions by reversing mitochondrial dysfunction via the AMPK
           pathway in vivo and in vitro
    • Authors: Xiao-Fan Hu; Lin Wang; Yi-Zhao Lu; Geng Xiang; Zi-Xiang Wu; Ya-Bo Yan; Yang Zhang; Xiong Zhao; Yuan Zang; Lei Shi; Wei Lei; Ya-Fei Feng
      Abstract: Publication date: Available online 15 June 2017
      Source:Acta Biomaterialia
      Author(s): Xiao-Fan Hu, Lin Wang, Yi-Zhao Lu, Geng Xiang, Zi-Xiang Wu, Ya-Bo Yan, Yang Zhang, Xiong Zhao, Yuan Zang, Lei Shi, Wei Lei, Ya-Fei Feng
      Diabetes-induced reactive oxygen species (ROS) overproduction would result in compromised osteointegration of titanium implant (TI) and high rate of implant failure, yet the underlying mechanisms remain elusive. Adiponectin (APN) is a fat-derived adipocytokine with strong antioxidant, mitochondrial-protective and anti-diabetic efficacies. We hypothesized that mitochondrial dysfunction under diabetes may account for the oxidative stress in osteoblasts and titanium-bone interface (TBI) instability, which could be ameliorated by APN. To test this hypothesis, we incubated primary rat osteoblasts on TI and tested the cellular behaviors when subjected to normal milieu (NM), diabetic milieu (DM), DM + APN, DM + AICAR (AMPK activator) and DM + APN + Compound C (AMPK inhibitor). In vivo, APN or APN + Compound C were administered to diabetic db/db mice with TI implanted in their femurs. Results showed that diabetes induced structural damage, dysfunction and content decrease of mitochondria in osteoblasts, which led to ROS overproduction, dysfunction and apoptosis of osteoblasts accompanied by the inhibition of AMPK signaling. APN alleviated the mitochondrial damage by activating AMPK, thus reversing osteoblast impairment and improving the osteointegration of TI evidenced by Micro-CT and histological analysis. Furthermore, AICAR showed beneficial effects similar to APN treatment, while the protective effects of APN were abolished when AMPK activation was blocked by Compound C. This study clarifies mitochondrial dysfunction as a crucial mechanism in the impaired bone healing and implant loosening in diabetes, and provides APN as a novel promising active component for biomaterial-engineering to improve clinical performance of TI in diabetic patients. Statement of Significance The loosening rate of titanium implants in diabetic patients is high. The underlying mechanisms remain elusive and, with the rapid increase of diabetic morbility, efficacious strategies to mitigate this problem have become increasingly important. Our study showed that the mitochondrial impairment and the consequent oxidative stress in osteoblasts at the titanium-bone interface (TBI) play a critical role in the diabetes-induced poor bone repair and implant destabilization, which could become therapeutic targets. Furthermore, adiponectin, a cytokine, promotes the bio-functional recovery of osteoblasts and bone regeneration at the TBI in diabetes. This provides APN as a novel bioactive component used in material-engineering to promote the osteointegration of implants, which could reduce implant failure, especially for diabetic patients.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.020
       
  • Strontium- and cobalt-substituted bioactive glasses seeded with human
           umbilical cord perivascular cells to promote bone regeneration via
           enhanced osteogenic and angiogenic activities
    • Authors: Saeid Kargozar; Nasrin Lotfibakhshaiesh; Jafar Ai; Masoud Mozafari; Peiman Brouki Milan; Sepideh Hamzehlou; Mahmoud Barati; Francesco Baino; Robert G. Hill; Mohammad Taghi Joghataei
      Abstract: Publication date: Available online 15 June 2017
      Source:Acta Biomaterialia
      Author(s): Saeid Kargozar, Nasrin Lotfibakhshaiesh, Jafar Ai, Masoud Mozafari, Peiman Brouki Milan, Sepideh Hamzehlou, Mahmoud Barati, Francesco Baino, Robert G. Hill, Mohammad Taghi Joghataei
      Designing and developing new biomaterials to accelerate bone healing are currently under progress. In this study, we attempted to promote osteogenesis using strontium- and cobalt- substituted bioactive glasses (BGs) seeded with human umbilical cord perivascular cells (HUCPVCs) in a critical size defect in the distal femur of rabbit animal model. The BG particles were successfully synthesized in the form of granules using the melt-derived route. After being isolated, HUCPVCs were expanded and then characterized to use during in vitro and in vivo procedures. The in vitro effects of the synthesized glasses on the isolated HUCPVCs as well as on cell lines SaOS-2 (selected for screening the osteogenetic potential) and HUVEC (selected for screening the angiogenic potential) were assessed by analyzing cytotoxicity, cell attachment, bone-like nodule formation, and real time PCR. The results of in vitro tests indicated cytocompatibility of the synthesized BG particles. For in vivo study, the HUCPVCs-seeded BGs were implanted into the animal’s body. Radiographic imaging, histology and immunohistology staining were performed on the harvested specimens at 4 and 12 weeks post-surgery. The in vivo evaluation of the samples showed that all the cell/glass constructs accelerated bone healing process in comparison with blank controls. The best in vitro and in vivo results were associated to the BGs containing both strontium and cobalt ions. This group of bioactive glasses is able to promote both osteogenesis and angiogenesis and can therefore be highly suitable for the development of advanced functional bone substitutes. Statement of Significance Bone regeneration is considered as an unmet clinical need. The most recent researches focused on incorporation of strontium (Sr2+) and cobalt (Co2+) ions into bioactive glasses structure. Strontium is an alkaline earth metal which is currently used in the treatment of osteoporosis. Also, cobalt is considered as another promising element in the bone regeneration field that may induce hypoxia-mediated angiogenesis. In this study, the osteogenic potential of the strontium- and cobalt-substituted bioactive glasses in granule form seeded with human umbilical cord perivascular cells (HUCPVCs) was evaluated in vitro and in vivo. Indeed, the main goal of this study was to improve the osteogenenic and angiogenic properties of bioactive glasses through the incorporation of strontium and cobalt ions in the glass composition. Although some researches have been conducted on this subject, the influence of the simultaneous use of strontium and cobalt ions on the improvement of bone healing in vivo has been not yet well understood and, therefore, deserves further investigation.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.021
       
  • Biological responses to M13 bacteriophage modified titanium surfaces in
           vitro
    • Authors: Yuhua Sun; Yiting Li; Baohua Wu; Jianxin Wang; Xiong Lu; Shuxin Qu; Jie Weng; Bo Feng
      Abstract: Publication date: Available online 15 June 2017
      Source:Acta Biomaterialia
      Author(s): Yuhua Sun, Yiting Li, Baohua Wu, Jianxin Wang, Xiong Lu, Shuxin Qu, Jie Weng, Bo Feng
      Phage-based materials have showed great potential in tissue engineering application. However, it is unknown what inflammation response will happen to this kind of materials. This work is to explore the biological responses to M13 bacteriophage (phage) modified titanium surfaces in vitro from the aspects of their interaction with macrophages, osteoblasts and mineralization behavior. Pretreated Ti surface, Ti surfaces with noncrosslinked phage film (APP) and crosslinked phage film (APPG) were compared. Phage films could limit the macrophage adhesion and activity due to inducing adherent-cell apoptosis. The initial inflammatory activity (24h) caused by phage films was relatively high with more production of TNF-α, but in the later stage (7-10 days) inflammatory response was reduced with lower TNF-α, IL-6 and higher IL-10. In addition, phage films improved osteoblast adhesion, differentiation, and hydroapatite (HA)-forming via a combination of topographical and biochemcial cues. The noncrosslinked phage film displayed the best immunomodulatory property, osteogenic activity and HA mineralization ability. This work provides better understanding of inflammatory and osteogenetic activity of phage-based materials and contributes to their future application in tissue engineering. Statement of significance In vivo, the bone and immune cells share a common microenvironment, and are being affected by similar cytokines, signaling molecules, transcription factors and membrane receptors. Ideal implants should cause positive biological response, including adequate and appropriate inflammatory reaction, well-balanced bone formation and absorption. Phage-based materials have showed great potential in tissue engineering application. However, at present it is unknown what inflammation response will happen to this kind of materials. A good understanding of the immune response possibly induced by phage-based materials is needed. This work studied the osteoimmunomodulation property of phage films on titanium surface, involving inflammatory response, osteogenic activity and biomineralization ability. It provides more understanding of the phage-based materials and contributes to their future application in tissue engineering.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.019
       
  • Folate-targeted Polymersomes Loaded with both Paclitaxel and Doxorubicin
           for the Combination Chemotherapy of Hepatocellular Carcinoma
    • Authors: Dunwan Zhu; Shengjie Wu; Chunyan Hu; Zhuo Chen; Hai Wang; Fan Fan; Yu Qin; Chun Wang; Hongfan Sun; Xigang Leng; Deling Kong; Linhua Zhang
      Abstract: Publication date: Available online 13 June 2017
      Source:Acta Biomaterialia
      Author(s): Dunwan Zhu, Shengjie Wu, Chunyan Hu, Zhuo Chen, Hai Wang, Fan Fan, Yu Qin, Chun Wang, Hongfan Sun, Xigang Leng, Deling Kong, Linhua Zhang
      Combination chemotherapy is a promising method of improving cancer treatment, but the distinct pharmacokinetics of combined drugs and non-specific drug distribution slow down the development in the clinic. In this study, folate (FA) receptor-targeted polymersomes with apparent bilayered lamellar structure were successfully developed to co-encapsulate a hydrophobic-hydrophilic chemotherapeutic drug pair (PTX and DOX) in a single vesicle for enhancing the combination chemotherapeutic effect. Hydrophobic PTX was loaded into the thick hydrophobic lamellar membrane by the self-assembly of triblock copolymer PCL8000-PEG8000-PCL8000, while hydrophilic DOX was encapsulated into the hydrophilic reservoir using a trans-membrane ammonium sulfate gradient method. In vitro release study indicated that the drugs were released from the polymersomes in a controlled and sustained manner. Cellular uptake study indicated that FA-targeted Co-PS had higher internalization efficiency in FA receptor-overexpressing BEL-7404 cells than non-targeted Co-PS. In vitro cytotoxicity assay demonstrated that FA-targeted Co-PS exhibited less cytotoxic effect than free drug cocktail, but suppressed the growth of tumor cells more efficiently than non-targeted Co-PS. Ex vivo imaging biodistribution studies revealed that FA-targeted Co-PS led to highly efficient targeting and accumulation in the BEL-7404 xenograft tumor. Furthermore, the in vivo antitumor study showed that the combination chemotherapy of polymersomes to BEL-7404 tumor via intravenous injection was superior to free drug cocktail treatment, and the FA-targeted Co-PS exhibited significantly higher tumor growth inhibition than non-targeted Co-PS group. Therefore, the newly developed FA-targeted co-delivery polymersomes hold great promise for simultaneous delivery of multiple chemotherapeutics and would have great potential in tumor-targeting and combination chemotherapy. Statement of Significance Combination chemotherapy is a promising method of improving cancer treatment, but the distinct pharmacokinetics of combined drugs and non-specific drug distribution slow down the development in the clinic. In our study, novel folate-targeted co-delivery polymersomes (Co-PS) were successfully developed to encapsulate a hydrophobic-hydrophilic chemotherapeutic drug pair (paclitaxel and doxorubicin) into the different compartments of the vesicle. In vivo studies revealed that the combination chemotherapy of polymersomes to BEL-7404 xenograft tumor via intravenous injection was superior to free drug cocktail treatment, and the FA-targeted Co-PS exhibited significantly higher tumor growth inhibition than non-targeted Co-PS group. Therefore, the newly developed FA-targeted co-delivery polymersomes hold great promise for simultaneous delivery of multiple chemotherapeutics and would have great potential in tumor-targeting and combination chemotherapy.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.017
       
  • Angiogenic peptide nanofibers repair cardiac tissue defect after
           myocardial infarction
    • Authors: Abdul Jalil Rufaihah; I. Ceren Yasa; Vaibavi Srirangam Ramanujam; Suganya Cheyyatraivendran Arularasu; Theo Kofidis; Mustafa O. Guler; Ayse B. Tekinay
      Abstract: Publication date: Available online 6 June 2017
      Source:Acta Biomaterialia
      Author(s): Abdul Jalil Rufaihah, I. Ceren Yasa, Vaibavi Srirangam Ramanujam, Suganya Cheyyatraivendran Arularasu, Theo Kofidis, Mustafa O. Guler, Ayse B. Tekinay
      Myocardial infarction remains one of the top leading causes of death in the world and the damage sustained in the heart eventually develops into heart failure. Limited conventional treatment options due to the inability of the myocardium to regenerate after injury and shortage of organ donors require the development of alternative therapies to repair the damaged myocardium. Current efforts in repairing damage after myocardial infarction concentrates on using biologically derived molecules such as growth factors or stem cells, which carry risks of serious side effects including the formation of teratomas. Here, we demonstrate that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization in cardiovascular tissue after myocardial infarction, without the addition of any biologically derived factors or stem cells. When the GAG mimetic nanofiber gels were injected in the infarct site of rodent myocardial infarct model, increased VEGF-A expression and recruitment of vascular cells was observed. This was accompanied with significant degree of neovascularization and better cardiac performance when compared to the control saline group. The results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair. Statement of Significance We present a synthetic bioactive peptide nanofiber system can enhance cardiac function and enhance cardiovascular regeneration after myocardial infarction (MI) without the addition of growth factors, stem cells or other biologically derived molecules. Current state of the art in cardiac repair after MI utilize at least one of the above mentioned biologically derived molecules, thus our approach is ground-breaking for cardiovascular therapy after MI. In this work, we showed that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization and cardiomyocyte differentiation for the regeneration of cardiovascular tissue after myocardial infarction in a rat infarct model. When the peptide nanofiber gels were injected in infarct site at rodent myocardial infarct model, recruitment of vascular cells was observed, neovascularization was significantly induced and cardiac performance was improved. These results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair.
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      PubDate: 2017-06-18T16:48:31Z
      DOI: 10.1016/j.actbio.2017.06.009
       
  • Improvement of endothelial progenitor outgrowth cell (EPOC)-mediated
           
    • Authors: Jiayin Fu; Christian Wiraja; Hamizan B. Muhammad; Chenjie Xu; Dong-An Wang
      Abstract: Publication date: Available online 10 June 2017
      Source:Acta Biomaterialia
      Author(s): Jiayin Fu, Christian Wiraja, Hamizan B. Muhammad, Chenjie Xu, Dong-An Wang
      In addition to chemical compositions, physical properties of scaffolds, such as pore size, can also influence vascularization within the scaffolds. A larger pore has been shown to improve host vascular tissue invasion into scaffolds. However, the influence of pore sizes on vascularization by endothelial cells directly encapsulated in hydrogels remains unknown. In this study, micro-cavitary hydrogels with different pore sizes were created in gelatin-methacrylate hydrogels with dissolvable gelatin microspheres (MS) varying in sizes. The effect of pore sizes on vascular network formation by endothelial progenitor outgrowth cells (EPOCs) encapsulated in hydrogels was then investigated both in vitro and in vivo. When cultured in vitro, vascular networks were formed around pore structures in micro-cavitary hydrogels. The middle pore size supported best differentiation of EPOCs and thus best hydrogel vascularization in vitro. When implantation in vivo, functional connections between encapsulated EPOCs and host vasculature micro-cavitary hydrogels were established. Vascularization in vivo was promoted best in hydrogels with the large pore size due to the increased vascular tissue invasion. These results highlight the difference between in vitro and in vivo culture conditions and indicate that pore sizes shall be designed for in vitro and in vivo hydrogel vascularization respectively. Pore sizes for hydrogel vascularization in vitro shall be middle ones and pore sizes for hydrogel vascularization in vivo shall be large ones. Statement of Significance This study reveals that the optimal pore size for hydrogel vascularization in vitro and in vivo is different. The middle pore size supported best differentiation of EPOCs and thus best hydrogel vascularization in vitro, while vascularization in vivo was promoted best in hydrogels with the large pore size due to the increased vascular tissue invasion. These results highlight the difference between in vitro and in vivo culture conditions and indicate that pore sizes shall be designed for in vitro and in vivo hydrogel vascularization respectively. Pore sizes for hydrogel vascularization in vitro shall be middle ones and pore sizes for hydrogel vascularization in vivo shall be large ones.
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      PubDate: 2017-06-13T16:41:37Z
      DOI: 10.1016/j.actbio.2017.06.012
       
  • Chondrogenesis of Human Bone Marrow Mesenchymal Stem Cells in
           3-Dimensional, Photocrosslinked Hydrogel Constructs: Effect of Cell
           Seeding Density and Material Stiffness
    • Authors: Aaron X. Sun; Hang Lin; Madalyn R. Fritch; He Shen; Pete G. Alexander; Michael DeHart; Rocky S. Tuan
      Abstract: Publication date: Available online 10 June 2017
      Source:Acta Biomaterialia
      Author(s): Aaron X. Sun, Hang Lin, Madalyn R. Fritch, He Shen, Pete G. Alexander, Michael DeHart, Rocky S. Tuan
      Three-dimensional hydrogel constructs incorporated with live stem cells that support chondrogenic differentiation and maintenance offer a promising regenerative route towards addressing the limited self-repair capabilities of articular cartilage. In particular, hydrogel scaffolds that augment chondrogenesis and recapitulate the native physical properties of cartilage, such as compressive strength, can potentially be applied in point-of-care procedures. We report here the synthesis of two new materials, [poly-L-lactic acid/polyethylene glycol/poly-L-lactic acid] (PLLA-PEG 1000) and [poly-D,L-lactic acid/polyethylene glycol/poly-D,L-lactic acid] (PDLLA-PEG 1000), that are biodegradable, biocompatible (>80% viability post fabrication), and possess high, physiologically relevant mechanical strength (∼1,500 to 1,800 kPa). This study examined the effects of physiologically relevant cell densities (4, 8, 20, and 50 x 106/mL) and hydrogel stiffnesses (∼150kPa to ∼1,500 kPa Young’s moduli) on chondrogenesis of human bone marrow stem cells incorporated in hydrogel constructs fabricated with these materials and a previously characterized PDLLA-PEG 4000. Results showed that 20 x 106 cells/mL, under a static culture condition, was the most efficient cell seeding density for extracellular matrix (ECM) production on the basis of hydroxyproline and glycosaminoglycan content. Interestingly, material stiffness did not significantly affect chondrogenesis, but rather material concentration was correlated to chondrogenesis with increasing levels at lower concentrations based on ECM production, chondrogenic gene expression, and histological analysis. These findings establish optimal cell densities for chondrogenesis within three-dimensional cell-incorporated hydrogels, inform hydrogel material development for cartilage tissue engineering, and demonstrate the efficacy and potential utility of PDLLA-PEG 1000 for point-of-care treatment of cartilage defects. Statement of Significance Engineering cartilage with physiologically relevant mechanical properties for point-of-care applications represents a major challenge in orthopedics, given the generally low mechanical strengths of traditional hydrogels used in cartilage tissue engineering. In this study, we characterized a new material that possesses high mechanical strength similar to native cartilage, and determined the optimal cell density and scaffold stiffness to achieve the most efficient chondrogenic response from seeded human bone marrow stem cells. Results show robust chondrogenesis and strongly suggest the potential of this material to be applied clinically for point-of-care repair of cartilage defects.
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      PubDate: 2017-06-13T16:41:37Z
      DOI: 10.1016/j.actbio.2017.06.016
       
  • Atomic Layer Deposited ZrO2 Nanofilm onMg-Sr Alloy for Enhanced Corrosion
           Resistance and Biocompatibility
    • Authors: Qiuyue Yang; Wei Yuan; Xiangmei Liu; Yufeng Zheng; Zhenduo Cui; Xianjin Yang; Haobo Pan; Shuilin Wu
      Abstract: Publication date: Available online 10 June 2017
      Source:Acta Biomaterialia
      Author(s): Qiuyue Yang, Wei Yuan, Xiangmei Liu, Yufeng Zheng, Zhenduo Cui, Xianjin Yang, Haobo Pan, Shuilin Wu
      The biodegradability and good mechanical property of magnesium alloys make them potential biomedical materials. However, their rapid corrosion rate in the human body’s environment impairs these advantages and limits their clinical use. In this work, a compact zirconia (ZrO2) nanofilm was fabricated on the surface of a magnesium-strontium (Mg-Sr) alloy by the atomic layer deposition (ALD) method, which can regulate the thickness of the film precisely and thus also control the corrosion rate. Corrosion tests reveal that the ZrO 2 film can effectively reduce the corrosion rate of Mg-Sr alloys that is closely related to the thickness of the film. The cell culture test shows that this kind of ZrO 2 film can also enhance the activity and adhesion of osteoblasts on the surfaces of Mg-Sr alloys. Statement of Significance The significance of the current work is to develop a zirconia nanofilm on biomedical MgSr alloy with controllable thickness precisely through atomic layer deposition technique. By adjusting the thickness of nanofilm, the corrosion rate of MgSr alloy can be modulated, thereafter, the degradation rate of Mg-based alloys can be controlled precisely according to actual clinical requirement. In addition, this zirconia nanofilm modified MgSr alloy showed excellent biocompatibility than the bare samples. Hence, this work provides a new surface strategy to control the degradation rate while improving the biocompatibility of substrates.
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      PubDate: 2017-06-13T16:41:37Z
      DOI: 10.1016/j.actbio.2017.06.015
       
  • Bottom-up synthesis of WS2 nanosheets with synchronous surface
           modification for imaging guided tumor regression
    • Authors: Shige Wang; Jiulong Zhao; Hailun Yang; Chenyao Wu; Fei Hu; Haizhou Chang; Guixiang Li; Dan Ma; Duowu Zou; Mingxian Huang
      Abstract: Publication date: Available online 10 June 2017
      Source:Acta Biomaterialia
      Author(s): Shige Wang, Jiulong Zhao, Hailun Yang, Chenyao Wu, Fei Hu, Haizhou Chang, Guixiang Li, Dan Ma, Duowu Zou, Mingxian Huang
      Two-dimensional transition metal dichalcogenides (TMDs) have been receiving great attention as NIR photothermal transducing agent in tumor photothermal therapy. Keeping in mind the low efficiency of the conventional top-down exfoliation method to produce 2D TMDs and the complexity of their surface modifications, we herein proposed a bottom-up strategy for the one-pot and controlled synthesis of surface polyvinyl pyrrolidone (PVP) modified WS2 nanosheets, by hydrothermally treating the mixture solution of tetrathiotungstate and PVP. The material design was based on the chelating-coordinating effect between the lone pair electrons of oxygen belonging to the carbonyl group of PVP and the unoccupied orbital (5d orbitals) of tungsten. The WS2 nanosheets with synchronous surface PVP grafting showed an excellent photothermal conversion performance, while the surface anchored PVP guaranteed its colloidal stability. Moreover, the strong X-ray attenuation ability and near-infrared (NIR) absorbance of WS2-PVP360kDa enable the sensitive in vitro and in vivo computed tomography and photoacoustic imaging. The WS2-PVP360kDa nanosheets were biocompatible and exhibited promising in vitro and in vivo anti-cancer efficacy. Findings in this report may greatly promote the design of colloidal stable and biocompatible 2D TMDs and their future clinical translations. Statement of Significance A bottom-up strategy for the one-pot and controlled synthesis of surface polyvinyl pyrrolidone (PVP) modified WS2 nanosheets was proposed for the first time by hydrothermally treating the mixture solution of tetrathiotungstate and PVP. PVP was synchronously graphed on WS2 nanosheets surface owing to the chelating-coordinating effect between the lone pair electrons of oxygen belonging to the carbonyl group of PVP and the unoccupied orbital (5d orbitals) of tungsten. WS2-PVP nanosheets were biocompatible and showed excellent photothermal conversion performance and colloidal stability. WS2-PVP nanosheets exhibited promising computed tomography, photoacoustic imaging and anti-cancer efficacy both in vitro and in vivo.
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      PubDate: 2017-06-13T16:41:37Z
      DOI: 10.1016/j.actbio.2017.06.014
       
  • An in situ-forming phospholipid-based phase transition gel prolongs the
           duration of local anesthesia for ropivacaine with minimal toxicity
    • Authors: Hanmei Li; Tao Liu; Yuxuan Zhu; Qiang Fu; Wanxia Wu; Jie Deng; Li Lan; Sanjun Shi
      Abstract: Publication date: Available online 10 June 2017
      Source:Acta Biomaterialia
      Author(s): Hanmei Li, Tao Liu, Yuxuan Zhu, Qiang Fu, Wanxia Wu, Jie Deng, Li Lan, Sanjun Shi
      An injectable, phospholipid-based phase transition gel (PPTG) has been developed for prolonging the release of ropivacaine (RO) for local anesthesia. PPTG was prepared by mixing phospholipids, medium-chain triglyceride and ethanol. Prior to injection, the PPTG is in a sol state with low viscosity. After subcutaneous injection, the PPTG rapidly forms a gel in situ, which acts as a drug release depot as verified by in vitro release profiles and in vivo pharmacokinetics. Administering RO-PPTG to rats led to a significantly smaller initial burst release than administering RO solution or RO base suspension. Nerve blockade in guinea pigs lasted 3-fold longer after injection of RO-PPTG than after injection of RO solution. RO-PPTG showed good biocompatibility and excellent degradability in vivo. These results suggest that this PPTG-based depot system may be useful for sustained release of local anesthetics to prolong analgesia without causing systemic toxicity. Statement of Significance The sustained release of local anesthetics at the surgical site after a single injection is the optimal method to control post-surgical pain. In situ forming implant is an attractive alternative for the sustained release of local anesthetics. However, its practical use is highly limited by certain drawbacks including high viscosity, involved toxic organic solvents and fast drug release. To date, phospholipids-based phase transition gel (PPTG) is emerging for clinical development because of the non-toxicity, biocompatibility and ready availability of phospholipids in body. Thus, we present a novel strategy for sustained release of local anesthetics to control post-surgical pain based on PPTG, which showed a prolonged duration of nerve blockade and excellent biocompatibility.
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      PubDate: 2017-06-13T16:41:37Z
      DOI: 10.1016/j.actbio.2017.06.013
       
  • Tailored Design of Multifunctional and Programmable pH-responsive
           Self-assembling Polypeptides as Drug Delivery Nanocarrier for Cancer
           Therapy
    • Authors: Tzu-Wei Wang; Chia-Wei Yeh; Chen-Hsiang Kuan; Li-Wen Wang; Liang-Hsin Chen; Hsi-Chin Wu; Jui-Shen Sun
      Abstract: Publication date: Available online 9 June 2017
      Source:Acta Biomaterialia
      Author(s): Tzu-Wei Wang, Chia-Wei Yeh, Chen-Hsiang Kuan, Li-Wen Wang, Liang-Hsin Chen, Hsi-Chin Wu, Jui-Shen Sun
      Breast cancer has become the second leading cause of cancer-related mortality in female wherein more than 90% of breast cancer-related death results from cancer metastasis to distant organs at advanced stage. The purpose of this study is to develop biodegradable nanoparticles composed of natural polypeptides and calcium phosphate (CaP) with sequential pH-responsivity to tumor microenvironments for active targeted drug delivery. Two different amphiphilic copolymers, poly(ethylene glycol)3400-aconityl linkage-poly(L-glutamic acid)15-poly(L-histidine)10-poly(L-leucine)10 and LyP1-poly(ethylene glycol)1100-poly(L-glutamic acid)15-poly(L-histidine)10-poly(L-leucine)10, were exploited to self-assemble into micelles in aqueous phase. The bio-stable nanoparticles provide three distinct functional domains: the anionic PGlu shell for CaP mineralization, the protonation of PHis segment for facilitating anticancer drug release at target site, and the hydrophobic core of PLeu for encapsulation of anticancer drugs. Furthermore, the hydrated PEG outer corona is used for prolonging circulation time, while the active targeting ligand, LyP-1, is served to bind to breast cancer cells and lymphatic endothelial cells in tumor for inhibiting metastasis. Mineralized DOX-loaded nanoparticles (M-DOX NPs) efficiently prevent the drug leakage at physiological pH value and facilitate the encapsulated drug release at acidic condition when compared to DOX-loaded nanoparticles (DOX NPs). M-DOX NPs with LyP-1 targeting ligand effectively accumulated in MDA-MB-231 breast cancer cells. The inhibition effect on cell proliferation also enhances with time, illustrating the prominent anti-tumor efficacy. Moreover, the in vitro metastatic inhibition model shows the profound inhibition effect of inhibitory nanoparticles. In brief, this self-assembling peptide-based drug delivery nanocarrier with multifunctionality and programmable pH-sensitivity is of great promise and potential for anti-cancer therapy. Statement of Significance This tailored-design polypeptide-based nanoparticles with self-assembling and programmable stimulus-responsive properties enable to 1) be stable in physiological pH value with a low level of drug loss and effectively release the encapsulated drug with pH variations according to the tumor microenvironment, 2) enhanced targeting ability to hard-to-treat breast cancer cells and activated endothelial cells (tumor region), 3) significantly inhibit the growth and prevent from malignant metastasis of cancer cells in consonance with promising anti-tumor efficacy, and 4) keep tumors stick to localized position so that these confined solid tumors can be more accessible by different treatment modalities. The contribution of this work is how to design a p rogrammable pH-responsive drug delivery system based on the tailor-designed polypeptides.
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      PubDate: 2017-06-13T16:41:37Z
      DOI: 10.1016/j.actbio.2017.06.008
       
  • Highly antibacterial polypeptide-based amphiphilic copolymers as
           multifunctional non-viral vectors for enhanced intracellular siRNA
           delivery and anti-infection
    • Authors: Li Zhou; Yuewei Xi; Meng Yu; Min Wang; Yi Guo; Peng Li; Peter X. Ma; Bo Lei
      Abstract: Publication date: Available online 7 June 2017
      Source:Acta Biomaterialia
      Author(s): Li Zhou, Yuewei Xi, Meng Yu, Min Wang, Yi Guo, Peng Li, Peter X. Ma, Bo Lei
      For next-generation regenerative medicine and cancer therapy applications, the development of multifunctional biodegradable biomaterials with good antibacterial activity, biocompatibility and gene delivery capability is showing increased interests. As a natural cationic polypeptide, poly(ε-L-lysine) (EPL) has been as attractive antibacterial agent and non-viral gene vectors, however, its gene therapy is still limited probably due to the cytotoxicity, low stability in physiological environment and poor transfection efficiency. Herein, series of EPL-based amphiphilic copolymers composed of polyethylene glycol-block-poly(3-hydroxybutyrate-co-4-hydroxybutyrate)-block-EPL (PEG-b-P3/4HB-b-EPL, EHE) was synthesized and evaluated for siRNA delivery and anti-infection applications. EHE copolymers could effectively condense siRNA, protect it from degradation by nucleases and easily release the siRNA under heparin competition. The EHE2 copolymer displayed a good hemocompatibility, significantly high siRNA loading ability (N/P ratio of 1.5-3.0) and lower cytotoxicity compared to commercial branched polyethyleneimine (PEI 25kDa) and EPL, efficient cellular uptake of siRNA in MCF-7 cells. Additionally, EHE2 copolymers-mediated siRNA delivery revealed a significantly over 3 times high target gene silencing efficiency (62%) as compared to PEI (22%) and EPL (15%) in MCF-7 cells. The EHE2/siRNA also showed better capability than PEI/siRNA complex to drastically reduced VEGF mRNA level down to 46% in A549 cells. Furthermore, EHE copolymers exhibited excellent antimicrobial activity towards positive bacteria (S. aureus) in vitro and in vivo. The high gene transfection efficiency, low cytotoxicity and excellent antibacterial activity make EHE polymers highly promising applications in multifunctional gene therapy. Statement of significance This paper reports a highly antibacterial polypeptides-based EHE copolymer for enhancing siRNA delivery and anti-infection applications. The EHE copolymer displayed a good hemocompatibility, significantly high siRNA loading ability and lower cytotoxicity compared to commercial branched polyethyleneimine (PEI 25kDa) and EPL, efficient cellular uptake of siRNA in various cancer cells. Additionally, EHE2 copolymers-mediated siRNA delivery revealed a significantly over 3 times high target gene silencing efficiency (62%) as compared to PEI (22%) and EPL (15%) in MCF-7 cells. Furthermore, EHE copolymers exhibited excellent antimicrobial activity towards positive bacteria (S. aureus) in vitro and in vivo. The high gene transfection efficiency, low cytotoxicity and excellent antibacterial activity make EHE polymers highly promising applications in multifunctional gene therapy.
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      PubDate: 2017-06-09T04:30:10Z
      DOI: 10.1016/j.actbio.2017.06.010
       
  • Decellularized tongue tissue as an in vitro model for studying tongue
           cancer and tongue regeneration
    • Authors: Long Zhao; Linxuan Huang; Shuyi Yu; Junheng Zheng; Hua Wang; Yan Zhang
      Abstract: Publication date: Available online 7 June 2017
      Source:Acta Biomaterialia
      Author(s): Long Zhao, Linxuan Huang, Shuyi Yu, Junheng Zheng, Hua Wang, Yan Zhang
      The decellularization of tissues or organs provides an efficient strategy for preparing functional scaffolds for tissue engineering. The microstructures of native extracellular matrices and biochemical compositions retained in the decellularized matrices provide tissue-specific microenvironments for anchoring cells. Here, we report the tongue extracellular matrix (TEM), which showed favorable cytocompatibility for normal tongue-derived cells and tongue squamous cell carcinoma (TSCC) cells under static or stirring culture conditions. Our results show that TEM retained tongue-specific integrated microstructures and abundant matrix components, which offer mechanical support and spatial signals for regulating cell behavior and function. Reconstructed TSCC by TEM presented characteristics resembling clinical TSCC histopathology, suggesting the possibility for TSCC research. In addition, TEM might be capable of guiding tongue-derived cells to the niche, benefiting cell survival, proliferation and differentiation. Statement of significance In this study, we prepared decellularized tongue extracellular matrix (TEM) and evaluated the possibility for tongue squamous cell carcinoma (TSCC) research and tongue regeneration. TEM has six irreplaceable advantages: (1) tongue-specific intricate structures of TEM, which offer mechanical support for the cells; (2) abundant matrix components and spatial signals benefiting for cell attachment, survival, differentiation, and long-term viability of the highly functional phenotypes of tongue cells or TSCC cells; (3) reconstructed TSCC by TEM exhibited tumor heterogeneity, extremely resembling clinical TSCC histopathology; (4) ideal model to evaluate TSCC movement mode; (5) guiding tongue-derived cells to the site-appropriate niche; and (6) the possibility for static or stirred cell culture. These properties might be considered in TSCC research or tongue regeneration.
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      PubDate: 2017-06-09T04:30:10Z
      DOI: 10.1016/j.actbio.2017.05.062
       
  • Chemical Template-assisted Synthesis of Monodisperse Rattle-type Fe3O4@C
           Hollow Microspheres as Drug Carrier
    • Authors: Lin Cheng; Weimin Ruan; Bingfang Zou; Yuanyuan Liu; Yongqiang Wang
      Abstract: Publication date: Available online 6 June 2017
      Source:Acta Biomaterialia
      Author(s): Lin Cheng, Weimin Ruan, Bingfang Zou, Yuanyuan Liu, Yongqiang Wang
      A chemical template strategy was put forward to synthesize monodisperse rattle-type magnetic carbon (Fe3O4@C) hollow microspheres. During the synthesis procedure, monodisperse Fe2O3 microspheres were used as chemical template, which released Fe3+ ions in acidic solution and initiated the in-situ polymerization of pyrrole into polypyrrole (PPy) shell. With the continual acidic etching of Fe2O3 microspheres, rattle-type Fe2O3@PPy microspheres were generated with the cavity appearing between the PPy shell and left Fe2O3 core, which were then transformed into Fe3O4@C hollow microspheres through calcination in nitrogen atmosphere. Compared with traditional physical template, the shell and cavity of rattle-type hollow microspheres were generated in one step by using the chemical template method, which obviously saved the complex procedures including the coating and removal of middle shells. The experimental results exhibited that the rattle-type Fe3O4@C hollow microspheres with different parameters could be regulated through controlled synthesis of the intermediate Fe2O3@PPy product. Moreover, when the rattle-type Fe3O4@C hollow microspheres were investigated as drug carrier, they manifested sustained-release behaviour of doxorubicin, justifying their promising applications as carriers in drug delivery. Statement of Significance The aim of the present study was first to synthesize rattle-type Fe3O4@C hollow microspheres through a simple synthesis method as a drug carrier. Here a chemical template synthesis of rattle-type hollow microspheres were developed, which saved the complex procedures including the coating and removal of middle shells in traditional physical template. Second, all the influence factors in the reaction processs was systematically investigated to obtain rattle-type Fe3O4@C hollow microspheres with controlled parameters. Third, the rattle-type Fe3O4@C hollow microspheres with controlled parameters were used as durg carriers and investigated for the influence on drug loading and releasing performance.
      Graphical abstract image

      PubDate: 2017-06-09T04:30:10Z
      DOI: 10.1016/j.actbio.2017.06.007
       
  • Effects of Substrate Stiffness on the Tenoinduction of Human Mesenchymal
           Stem Cells
    • Authors: Anowarul Islam; Thomas Mbimba; Mousa Younesi; Ozan Akkus
      Abstract: Publication date: Available online 5 June 2017
      Source:Acta Biomaterialia
      Author(s): Anowarul Islam, Thomas Mbimba, Mousa Younesi, Ozan Akkus
      Extracellular matrix modulus plays an important role in regulating cell morphology, proliferation and differentiation during regular and diseased states. Although the effects of substrate topography and modulus on MSC differentiation are well known with respect to osteogenesis and adipogenesis, there has been relatively little investigation on the effects of this phenomenon on tenogenesis. Furthermore, relative roles of topographical factors (matrix alignment vs. matrix modulus) in inducing tenogenic differentiation is not well understood. In this study we investigated the effects of modulus and topographical alignment of type I collagen substrate on tendon differentiation. Type I collagen sheet substrates with random topographical alignment were fabricated with their moduli tuned in the range of 0.1, 1, 10 and 100 MPa by using electrocompaction and controlled crosslinking. In one of the groups, topographical alignment was introduced at 10 MPa stiffness, by controlled unidirectional stretching of the sheet. RT-PCR, immunohistochemistry and immunofluorescence results showed that mimicking the tendon topography, i.e. increasing the substrate modulus as well as alignment increased the tenogenic differentiation. Higher substrate modulus increased the expression of COLI, COLIII, COMP and TSP-4 about 2-3 fold and increased the production of COLI, COLIII and TSP-4 about 2-4 fold. Substrate alignment up regulated COLIII and COMP expression by 2 fold. Therefore, the tenoinductive collagen material model developed in this study can be used in the research and development of tissue engineering tendon repair constructs in future. Statement of Significance Although the effects of substrate topography and modulus on MSC differentiation are well known with respect to osteogenesis and adipogenesis, there has been relatively little investigation on the effects of this phenomenon on tenogenesis. Furthermore, a relative role of topographical factors (matrix alignment vs. matrix modulus) in inducing tenogenic differentiation is not well understood. We investigated the effects of modulus and topographical alignment of type I collagen substrate on tendon differentiation. This study showed mimicking the tendon topography, i.e. increasing the substrate modulus as well as alignment increased the tenogenic differentiation. Therefore, the tenoinductive collagen material model developed in this study can be used in the research and development of tissue engineering tendon repair constructs in future.
      Graphical abstract image

      PubDate: 2017-06-09T04:30:10Z
      DOI: 10.1016/j.actbio.2017.05.058
       
  • Highly efficient delivery of potent anticancer iminoquinone derivative by
           multilayer hydrogel cubes
    • Authors: Bing Xue; Wei Wang; Jiang-Jiang Qin; Bhavitavya Nijampatnam; Srinivasan Murugesan; Veronika Kozlovskaya; Ruiwen Zhang; Sadanandan E. Velu; Eugenia Kharlampieva
      Abstract: Publication date: Available online 3 June 2017
      Source:Acta Biomaterialia
      Author(s): Bing Xue, Wei Wang, Jiang-Jiang Qin, Bhavitavya Nijampatnam, Srinivasan Murugesan, Veronika Kozlovskaya, Ruiwen Zhang, Sadanandan E. Velu, Eugenia Kharlampieva
      We report a novel delivery platform for a highly potent anticancer drug, 7-(benzylamino)-3,4-dihydro-pyrrolo[4,3,2-de]quinolin-8(1H)-one (BA-TPQ), using pH- and redox-sensitive poly(methacrylic acid) (PMAA) hydrogel cubes of micrometer size as the encapsulating matrix. The hydrogels are obtained upon cross-linking PMAA with cystamine in PMAA/poly(N-vinylpyrrolidone) multilayers assembled within mesoporous sacrificial templates. The BA-TPQ-loaded hydrogels maintain their cubical shape and pH-sensitivity after lyophilization, which is advantageous for long-term storage. Conversely, the particles degrade in vitro in the presence of glutathione (5 mM) providing 80% drug release within 24 h. Encapsulating BA-TPQ into hydrogels significantly increases its transport via Caco-2 cell monolayers used as a model for oral delivery where the apparent permeability of BA-TPQ-hydrogel cubes was ∼2-fold higher than that of BA-TPQ. BA-TPQ-hydrogel cubes exhibit better anticancer activity against HepG2 (IC50=0.52 µg/mL) and Huh7 (IC50=0.29 µg/mL) hepatoma cells with a 40% decrease in the IC50 compared to the non-encapsulated drug. Remarkably, non-malignant liver cells have a lower sensitivity to BA-TPQ-hydrogel cubes with 2-fold increased IC50 values compared to those of cancer cells. In addition, encapsulating BA-TPQ in the hydrogels amplifies the potency of the drug via down-regulation of MDM2 oncogenic protein and upregulation of p53 (a tumor suppressor) and p21 (cell proliferation suppressor) expression in HepG2 liver cancer cells. Moreover, enhanced inhibition of MDM2 protein expression by BA-TPQ-hydrogel cubes is independent of p53-status in Huh7 cells. This drug delivery platform of non-spherical shape provides a facile method for encapsulation of hydrophobic drugs and can facilitate the enhanced efficacy of BA-TPQ for liver cancer therapy. Statement of Significance Many potent anticancer drugs are hydrophobic and lack tumor selectivity, which limits their application in cancer therapy. Although cubical hydrogels of poly(methacrylic acid) exhibit excellent biocompatibility and versatility, they have not been investigated for hydrophobic drug delivery due to poor mechanical stability and incompatibility between hydrophobic drugs and a hydrophilic hydrogel network. In this study, we provide a facile method to prepare a multilayer hydrogel-based platform with controlled nanostructure, cubical shape and redox-responsiveness for delivery of highly potent anticancer therapeutics, hydrophobic BA-TPQ. The BA-TPQ-hydrogel cubes have exceptional structural stability upon lyophilization which is advantageous for a long-term storage. The greatly enhanced trans-epithelial permeability and amplified anti-tumor activity of BA-TPQ are achieved by encapsulation in these hydrogel cubes. Furthermore, the anticancer BA-TPQ-hydrogel platform retains the selective activity of BA-TPQ to hepatocellular carcinoma cells. Overall, the produced BA-TPQ-hydrogel cubes demonstrate a high potential for clinical liver cancer therapy.
      Graphical abstract image

      PubDate: 2017-06-04T04:25:37Z
      DOI: 10.1016/j.actbio.2017.06.004
       
  • Interleukin-13 conjugated quantum dots for identification of glioma
           initiating cells and their extracellular vesicles
    • Authors: A.B. Madhankumar; Oliver Mrowczynski; Suhag Patel; Cody Weston; Brad Zacharia; Michael Glantz; Christopher Siedlecki; Lichong Xu; James R. Connor
      Abstract: Publication date: Available online 3 June 2017
      Source:Acta Biomaterialia
      Author(s): A.B. Madhankumar, Oliver Mrowczynski, Suhag Patel, Cody Weston, Brad Zacharia, Michael Glantz, Christopher Siedlecki, Lichong Xu, James R. Connor
      Cadmium selenide (CdSe) based quantum dots modified with polyethylene glycol and chemically linked to interleukin-13 (IL13) were prepared with the aim of identifying the high affinity receptor (IL13Rα2) which is expressed in glioma stem cells and exosomes secreted by these cancer stem cells. IL13 conjugated quantum dots (IL13QD) were thoroughly characterized for their physicochemical properties including particle size and surface morphology. Furthermore, the specific binding of the IL13QD to glioma cells and to glioma stem cells (GSC) was verified using a competitive binding study. The exosomes were isolated from the GSC conditioned medium and the expression of IL13Rα2 in the GSC and exosomes was verified. The binding property of IL13QD to the tumor associated exosomes was initially confirmed by transmission electron microscopy. The force of attraction between the quantum dots and U251 glioma cells and the exosomes was investigated by atomic force microscopy, which indicated a higher force of binding interaction between the IL13QD and IL13Rα2 expressing glioma cells and exosomes secreted by glioma stem cells. Flow cytometry of the IL13QD and exosomes from the culture media and cerebrospinal fluid (CSF) of patients with glioma tumors indicated a distinctly populated complex pattern different from that of non-targeted quantum dots and bovine serum albumin (BSA) conjugated quantum dots confirming specific binding potential of the IL13QD to the tumor associated exosomes. The results of this study demonstrate that IL13QD can serve as an ex vivo marker for glioma stem cells and exosomes that can inform diagnosis and prognosis of patients harboring malignant disease. Statement of significance Functionalized quantum dots are flexible semiconductor nanomaterials which have an immense application in biomedical research. In particular, when they are functionalized with biomolecules like proteins or antibodies, they have the specialized ability to detect the expression of receptors and antigens in cells and tissues. In this study we designed a cytokine (interleukin-13) functionalized quantum dot to detect a cancer associated receptor expressed in cancer stem cells and the extracellular vesicles (exosomes) secreted by the cancer cells themselves. The binding pattern of these cytokine modified quantum dots to the cancer stem cells and exosomes alters the physical properties of the complex in the fixed and suspended form. This altered binding pattern can be monitored by a variety of techniques, including transmission electron microscopy, atomic force microscopy and flow cytometry, and subsequent characterization of this quantum dot binding profile provides useful data that can be utilized as a fingerprint to detect cancer disease progression. This type of functionalized quantum dot fingerprint is especially useful for invasive cancers including brain and other metastatic cancers and may allow for earlier detection of disease progression or recurrence, thus saving the lives of patients suffering from this devastating disease.
      Graphical abstract image

      PubDate: 2017-06-04T04:25:37Z
      DOI: 10.1016/j.actbio.2017.06.002
       
  • pH-responsive unimolecular micelle-gold nanoparticles-drug nanohybrid
           system for cancer theranostics
    • Authors: Wenjing Lin; Na Yao; Long Qian; Xiaofang Zhang; Quan Chen; Jufang Wang; Lijuan Zhang
      Abstract: Publication date: Available online 3 June 2017
      Source:Acta Biomaterialia
      Author(s): Wenjing Lin, Na Yao, Long Qian, Xiaofang Zhang, Quan Chen, Jufang Wang, Lijuan Zhang
      The development of an in situ formed pH-responsive theranostic nanocomposite for anticancer drug delivery and computed tomography (CT) imaging was reported. β-cyclodextrin-{poly(lactide)-poly(2-(dimethylamino) ethyl methacrylate)-poly[oligo(2-ethyl-2-oxazoline)methacrylate]}21 [β-CD-(PLA-PDMAEMA-PEtOxMA)21] unimolecular micelles served as a template for the in situ formation of gold nanoparticles (GNPs) and the subsequent encapsulation of doxorubicin (DOX). The formation of unimolecular micelles, microstructures and the distributions of GNPs and DOX were investigated through the combination of experiments and dissipative particle dynamics (DPD) simulations. β-CD-(PLA-PDMAEMA-PEtOxMA)21 formed spherical unimolecular micelles in aqueous solution within a certain range of polymer concentrations. GNPs preferentially distributed in the PDMAEMA area. The maximum wavelength (λ max) and the size of GNPs increased with increasing concentration of HAuCl4. DOX preferentially distributed in the PDMAEMA mesosphere, but penetrated the inner PLA core with increasing DOX concentration. DOX-loaded micelles with 41-61% entrapment efficiency showed fast release (88% after 102 h) under acidic tumor conditions. Both in vitro and in vivo experiments revealed superior anticancer efficacy and effective CT imaging properties for β-CD-(PLA-PDMAEMA-PEtOxMA)21/Au/DOX. We conclude that the reported unimolecular micelles represent a class of versatile smart nanocarriers for theranostic application. Statement of Significance Developing polymeric nanoplatforms as integrated theranostic vehicles for improving cancer diagnostics and therapy is an emerging field of much importance. This article aims to develop an in situ formed pH-responsive theranostic nanocomposite for anticancer drug delivery and computed tomography (CT) imaging. Specific emphases is on structure-properties relationship. There is a sea of literature on polymeric drug nanocarriers, and a couple of polymer-stablized gold nanoparticles (GNPs) systems for cancer diagnosis are also known. However, to our knowledge, there has been no report on polymeric unimolecualr micelles capable of dual loading of GNPs without external reducing agents and anticancer drugs for cancer diagnosis and treatment. To this end, the target of the current work was to develop an in situ formed nanocarrier, which actively dual wrapped CT contrast agent GNPs and hydrophobic anticancer drug doxorubicin (DOX), achieving high CT imaging and antitumor efficacy under in vitro and in vivo acid tumor condition. Meanwhile, by taking advantage of dissipative particle dynamics (DPD) simulation, we further obtained the formation process and mechanism of unimolecular micelles, and detailed distributions and microstructures of GNPs and DOX on unimolecular micelles. Taken together, our results here provide insight and guidance for the design of more effective nanocarriers for cancer theranostic application.
      Graphical abstract image

      PubDate: 2017-06-04T04:25:37Z
      DOI: 10.1016/j.actbio.2017.06.003
       
  • Angle-Ply Biomaterial Scaffold for Annulus Fibrosus Repair Replicates
           Native Tissue Mechanical Properties, Restores Spinal Kinematics, and
           Supports Cell Viability
    • Authors: Ryan Borem; Allison Madeline; Joshua Walters; Henry Mayo; Sanjitpal Gill; Jeremy Mercuri
      Abstract: Publication date: Available online 3 June 2017
      Source:Acta Biomaterialia
      Author(s): Ryan Borem, Allison Madeline, Joshua Walters, Henry Mayo, Sanjitpal Gill, Jeremy Mercuri
      Annulus fibrosus (AF) damage commonly occurs due to intervertebral disc (IVD) degeneration/herniation. The dynamic mechanical role of the AF is essential for proper IVD function and thus it is imperative that biomaterials developed to repair the AF withstand the mechanical rigors of the native tissue. Furthermore, these biomaterials must resist accelerated degradation within the proteolytic environment of degenerate IVDs while supporting integration with host tissue. We have previously reported a novel approach for developing collagen-based, multi-laminate AF repair patches (AFRPs) that mimic the angle-ply architecture and basic tensile properties of the human AF. Herein, we further evaluate AFRPs for their: tensile fatigue and impact burst strength, IVD attachment strength, and contribution to functional spinal unit (FSU) kinematics following IVD repair. Additionally, AFRP resistance to collagenase degradation and cytocompatibility were assessed following chemical crosslinking. In summary, AFRPs demonstrated enhanced durability at high applied stress amplitudes compared to human AF and withstood radially-directed biaxial stresses commonly borne by the native tissue prior to failure/detachment from IVDs. Moreover, FSUs repaired with AFRPs and nucleus pulposus (NP) surrogates had their axial kinematic parameters restored to intact levels. Finally, carbodiimide crosslinked AFRPs resisted accelerated collagenase digestion without detrimentally effecting AFRP tensile properties or cytocompatibility. Taken together, AFRPs demonstrate the mechanical robustness and enzymatic stability required for implantation into the damaged/degenerate IVD while supporting AF cell infiltration and viability. Statement of significance The quality of life for millions of individuals globally is detrimentally impacted by IVD degeneration and herniation. These pathologies often result in the structural demise of IVD tissue, particularly the annulus fibrosus (AF). Biomaterials developed for AF repair have yet to demonstrate the mechanical strength and durability required for utilization in the spine. Herein, we demonstrate the development of an angle-ply AF repair patch (AFRP) that can resist the application of physiologically relevant stresses without failure and which contributes to the restoration of functional spinal unit axial kinematics following repair. Furthermore, we show that this biomaterial can resist accelerated degradation in a simulated degenerate environment and supports AF cell viability.
      Graphical abstract image

      PubDate: 2017-06-04T04:25:37Z
      DOI: 10.1016/j.actbio.2017.06.006
       
  • pH-responsive self-healing injectable hydrogel based on N-carboxyethyl
           chitosan for hepatocellular carcinoma therapy
    • Authors: Jin Qu; Xin Zhao; Peter X. Ma; Baolin Guo
      Abstract: Publication date: Available online 2 June 2017
      Source:Acta Biomaterialia
      Author(s): Jin Qu, Xin Zhao, Peter X. Ma, Baolin Guo
      Injectable hydrogels with pH-responsiveness and self-healing ability have great potential for anti-cancer drug delivery. Herein, we developed a series of polysaccharide-based self-healing hydrogels with pH-sensitivity as drug delivery vehicles for hepatocellular carcinoma therapy. The hydrogels were prepared by using N-carboxyethyl chitosan (CEC) synthesized via Michael reaction in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) (PEGDA). Doxorubicin (Dox), as a model of water-soluble small molecule anti-cancer drug was encapsulated into the hydrogel in situ. Self-healing behavior of the hydrogels was investigated at microscopic and macroscopic levels, and the hydrogels showed rapid self-healing performance without any external stimulus owing to the dynamic covalent Schiff-base linkage between amine groups from CEC and benzaldehyde groups from PEGDA. The chemical structures, rheological property, in vitro gel degradation, morphology, gelation time and in vitro Dox release behavior from the hydrogels were characterized. Injectability was verified by in vitro injection and in vivo subcutaneous injection in a rat. pH-responsive behavior was verified by in vitro Dox release from hydrogels in PBS solutions with different pH values. Furthermore, the activity of Dox released from hydrogel matrix was evaluated by employing human hepatocellular liver carcinoma (HepG2). Cytotoxicity test of the hydrogels using L929 cells confirmed their good cytocompatibility. Together, these pH-responsive self-healing injectable hydrogels are excellent candidates as drug delivery vehicles for liver cancer treatment. Statement of Significance pH-responsive drug delivery system could release drug efficiently in targeted acid environment and minimalize the amount of drug release in normal physiological environment. pH-sensitive injectable hydrogels as smart anti-cancer drug delivery carriers show great potential application for cancer therapy. The hydrogels with self-healing property could prolong their lifetime during implantation and provide the advantage of minimally invasive surgery and high drug-loading ratio. This work reported the design of a series of pH-responsive self-healing injectable hydrogels based on N-carboxyethyl chitosan synthesized in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) via a green approach, and demonstrated their potential as intelligent delivery vehicle of doxorubicin for hepatocellular carcinoma therapy via the pH-responsive nature of dynamic Schiff base.
      Graphical abstract image

      PubDate: 2017-06-04T04:25:37Z
      DOI: 10.1016/j.actbio.2017.06.001
       
 
 
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