|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Collagen-PCL Sheath-Core Bicomponent Electrospun Scaffolds Increase Osteogenic Differentiation and Calcium Accretion of Human Adipose-Derived Stem Cells. J Biomater Sci Polym Ed. 2010 Sep 10; Authors: Haslauer CM, Moghe AK, Osborne JA, Gupta BS, Loboa EG Human adipose-derived stem cells (hASCs) are an abundant cell source capable of osteogenic differentiation, and have been investigated as an autologous stem cell source for bone tissue engineering applications. The objective of this study was to determine if the addition of a type-I collagen sheath to the surface of poly(ɛ-caprolactone) (PCL) nanofibers would enhance viability, proliferation and osteogenesis of hASCs. This is the first study to examine the differentiation behavior of hASCs on collagen-PCL sheath-core bicomponent nanofiber scaffolds developed using a co-axial electrospinning technique. The use of a sheath-core configuration ensured a uniform coating of collagen on the PCL nanofibers. PCL nanofiber scaffolds prepared using a conventional electrospinning technique served as controls. hASCs were seeded at a density of 20 000 cells/cm(2) on 1 cm(2) electrospun nanofiber (pure PCL or collagen-PCL sheath-core) sheets. Confocal microscopy and hASC proliferation data confirmed the presence of viable cells after 2 weeks in culture on all scaffolds. Greater cell spreading occurred on bicomponent collagen-PCL scaffolds at earlier time points. hASCs were osteogenically differentiated by addition of soluble osteogenic inductive factors. Calcium quantification indicated cell-mediated calcium accretion was approx. 5-times higher on bicomponent collagen-PCL sheath-core scaffolds compared to PCL controls, indicating collagen-PCL bicomponent scaffolds promoted greater hASC osteogenesis after two weeks of culture in osteogenic medium. This is the first study to examine the effects of collagen-PCL sheath-core composite nanofibers on hASC viability, proliferation and osteogenesis. The sheath-core composite fibers significantly increased calcium accretion of hASCs, indicating that collagen-PCL sheath-core bicomponent structures have potential for bone tissue engineering applications using hASCs. PMID: 20836922 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem cell therapy doctor exploited desperate patients, GMC finds. BMJ. 2010;341:c5001 Authors: Dyer C PMID: 20837578 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Anti-inflammatory protein TSG-6 reduces inflammatory damage to the cornea following chemical and mechanical injury. Proc Natl Acad Sci U S A. 2010 Sep 13; Authors: Oh JY, Roddy GW, Choi H, Lee RH, Ylöstalo JH, Rosa RH, Prockop DJ Previous reports demonstrated that adult stem/progenitor cells from bone marrow (multipotent mesenchymal stem cells; MSCs) can repair injured tissues with little evidence of engraftment or differentiation. In exploring this phenomenon, our group has recently discovered that the therapeutic benefits of MSCs are in part explained by the cells being activated by signals from injured tissues to express an anti-inflammatory protein TNF-α-stimulated gene/protein 6 (TSG-6). Therefore, we elected to test the hypothesis that TSG-6 would have therapeutic effects in inflammatory but noninfectious diseases of the corneal surface. We produced a chemical and mechanical injury of the cornea in rats by brief application of 100% ethanol followed by mechanical debridement of corneal and limbal epithelium. Recombinant human TSG-6 or PBS solution was then injected into the anterior chamber of the eye. TSG-6 markedly decreased corneal opacity, neovascularization, and neutrophil infiltration. The levels of proinflammatory cytokines, chemokines, and matrix metalloproteinases were also decreased. The data indicated that TSG-6, a therapeutic protein produced by MSCs in response to injury signals, can protect the corneal surface from the excessive inflammatory response following injury. PMID: 20837529 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Tissue regeneration potential in human umbilical cord blood. Best Pract Res Clin Haematol. 2010 Jun;23(2):291-303 Authors: Arien-Zakay H, Lazarovici P, Nagler A Regenerative medicine is the process of creating functional tissue with the aid of stem cells, to repair loss of organ function. Possible targets for regenerative medicine include orthopaedic, cardiac, hepatic, pancreatic and central nervous system (CNS) applications. Umbilical cord blood (CB) has established itself as a legitimate source for haematopoietic stem cell transplantation. It is also considered an accessible and less immunogenic source for mesenchymal, unrestricted somatic and for other stem cells with pluri/multipotent properties. The latter are capable of differentiating into a wide variety of cell types including bone, cartilage, cardiomyocytes and neural. They also possess protective abilities that may contribute to tissue repair even if in vitro differentiation is excluded. In view of the absence of treatment for many devastating diseases, the elucidation of non-haematopoietic applications for CB will facilitate the development of pioneering relevant cell therapy approaches. This review focusses on current studies using human CB-derived cells for regenerative medicine. PMID: 20837341 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cellular trans/-differentiation and morphogenesis towards the lymphatic lineage in regenerative medicine. Stem Cells Dev. 2010 Sep 13; Authors: Laco F, Grant MH, Flint D, Black RA Lymphoedema is a medically irresolvable condition. The lack of therapies addressing lymphatic vessel dysfunction suggests that improved understanding of lymphatic cell differentiation and vessel maturation processes is key to the development of novel, regenerative medicine and tissue engineering approaches. In this review we provide an overview of lymphatic characterisation markers and morphology in development. Furthermore, we describe multiple differentiation processes of the lymphatic system during embryonic, post-natal and pathogenic development. Using the example of pathogenic Kaposi Sarcoma-associated Herpes infection we illustrate the involvement of the Notch and PI3K pathways for lymphatic trans-differentiation. We also discuss the plasticity of certain cell types and bio-factors which enable trans-differentiation towards the lymphatic lineage. Here we argue the importance of pathway-associated induction factors for lymphatic trans-differentiation including growth factors such as VEGF-C and interleukins, and the involvement of extracellular matrix characteristics and dynamics for morphological functionality. PMID: 20836656 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Fifth Annual Stem Cell Summit. IDrugs. 2010 Apr;13(4):235-8 Authors: Knowlton D The Fifth Annual Stem Cell Summit, held in New York, included topics covering new commercial developments in the research field of stem cell-based therapies. This conference report highlights selected presentations on embryonic and adult stem cells, stem cell-based therapies for the treatment of orthopedic and cardiovascular indications and inflammatory diseases, as well as technologies for processing and storing stem cells. Investigational therapies discussed include placental expanded (PLX) cells (Pluristem Therapeutics Inc), StemEx (Gamida-Teva Joint Venture/Teva Pharmaceutical Industries Ltd) and remestemcel-L (Osiris Therapeutics Inc/Genzyme Corp/JCR Pharmaceuticals Co Ltd/ Mochida Pharmaceutical Co Ltd). PMID: 20373251 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Combinatorial and High-Throughput Screening of Biomaterials. Adv Mater. 2010 Sep 13; Authors: Simon CG, Lin-Gibson S Combinatorial and high-throughput methods have been increasingly used to accelerate research and development of new biomaterials. These methods involve creating miniaturized libraries that contain many specimens in one sample in the form of gradients or arrays, followed by automated data collection and analysis. This article reviews recent advances in utilizing combinatorial and high-throughput methods to better understand cell-material interactions, particularly highlighting our efforts at the NIST Polymers Division. Specifically, fabrication techniques to generate controlled surfaces (2D) and 3D cell environments (tissue engineering scaffolds) as well as methods to characterize and analyze material properties and cell-material interactions are described. In conclusion, additional opportunities for combinatorial methods for biomaterials research are noted, including streamlined sample fabrication and characterization, appropriate and automated bioassays, and data analysis. PMID: 20839249 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Interconnectivity analysis of supercritical CO(2)-foamed scaffolds. Comput Methods Programs Biomed. 2010 Sep 11; Authors: Lemon G, Reinwald Y, White LJ, Howdle SM, Shakesheff KM, King JR This paper describes a computer algorithm for the determination of the interconnectivity of the pore space inside scaffolds used for tissue engineering. To validate the algorithm and its computer implementation, the algorithm was applied to a computer-generated scaffold consisting of a set of overlapping spherical pores, for which the interconnectivity was calculated exactly. The algorithm was then applied to micro-computed X-ray tomography images of supercritical CO(2)-foamed scaffolds made from poly(lactic-co-glycolic acid) (PLGA), whereby the effect of using different weight average molecular weight polymer on the interconnectivity was investigated. PMID: 20837373 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Collagen-PCL Sheath-Core Bicomponent Electrospun Scaffolds Increase Osteogenic Differentiation and Calcium Accretion of Human Adipose-Derived Stem Cells. J Biomater Sci Polym Ed. 2010 Sep 10; Authors: Haslauer CM, Moghe AK, Osborne JA, Gupta BS, Loboa EG Human adipose-derived stem cells (hASCs) are an abundant cell source capable of osteogenic differentiation, and have been investigated as an autologous stem cell source for bone tissue engineering applications. The objective of this study was to determine if the addition of a type-I collagen sheath to the surface of poly(ɛ-caprolactone) (PCL) nanofibers would enhance viability, proliferation and osteogenesis of hASCs. This is the first study to examine the differentiation behavior of hASCs on collagen-PCL sheath-core bicomponent nanofiber scaffolds developed using a co-axial electrospinning technique. The use of a sheath-core configuration ensured a uniform coating of collagen on the PCL nanofibers. PCL nanofiber scaffolds prepared using a conventional electrospinning technique served as controls. hASCs were seeded at a density of 20 000 cells/cm(2) on 1 cm(2) electrospun nanofiber (pure PCL or collagen-PCL sheath-core) sheets. Confocal microscopy and hASC proliferation data confirmed the presence of viable cells after 2 weeks in culture on all scaffolds. Greater cell spreading occurred on bicomponent collagen-PCL scaffolds at earlier time points. hASCs were osteogenically differentiated by addition of soluble osteogenic inductive factors. Calcium quantification indicated cell-mediated calcium accretion was approx. 5-times higher on bicomponent collagen-PCL sheath-core scaffolds compared to PCL controls, indicating collagen-PCL bicomponent scaffolds promoted greater hASC osteogenesis after two weeks of culture in osteogenic medium. This is the first study to examine the effects of collagen-PCL sheath-core composite nanofibers on hASC viability, proliferation and osteogenesis. The sheath-core composite fibers significantly increased calcium accretion of hASCs, indicating that collagen-PCL sheath-core bicomponent structures have potential for bone tissue engineering applications using hASCs. PMID: 20836922 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cellular trans/-differentiation and morphogenesis towards the lymphatic lineage in regenerative medicine. Stem Cells Dev. 2010 Sep 13; Authors: Laco F, Grant MH, Flint D, Black RA Lymphoedema is a medically irresolvable condition. The lack of therapies addressing lymphatic vessel dysfunction suggests that improved understanding of lymphatic cell differentiation and vessel maturation processes is key to the development of novel, regenerative medicine and tissue engineering approaches. In this review we provide an overview of lymphatic characterisation markers and morphology in development. Furthermore, we describe multiple differentiation processes of the lymphatic system during embryonic, post-natal and pathogenic development. Using the example of pathogenic Kaposi Sarcoma-associated Herpes infection we illustrate the involvement of the Notch and PI3K pathways for lymphatic trans-differentiation. We also discuss the plasticity of certain cell types and bio-factors which enable trans-differentiation towards the lymphatic lineage. Here we argue the importance of pathway-associated induction factors for lymphatic trans-differentiation including growth factors such as VEGF-C and interleukins, and the involvement of extracellular matrix characteristics and dynamics for morphological functionality. PMID: 20836656 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Degradable, Thermo-Sensitive Poly(N-isopropyl acrylamide)-Based Scaffolds with Controlled Porosity for Tissue Engineering Applications. Biomacromolecules. 2010 Sep 13; Authors: Galperin A, Long TJ, Ratner BD We have developed a thermoresponsive poly(N-isopropyl acrylamide)-based scaffold with degradability and controlled porosity. Biodegradable poly(N-isopropyl acrylamide) hydrogels were synthesized by photocopolymerization of N-isopropylacrylamide with 2-methylene-1,3-dioxepane and polycaprolactone dimethacrylate. The hydrogels' phase transition temperature, swelling, and viscoelastic properties, as well as hydrolytic degradability at 25 and 37 °C, were explored. A sphere-templating technique was applied to fabricate hydrogel scaffolds with controllable pore size and a highly interconnected porous structure. The scaffold pore diameter change as a function of temperature was evaluated and, as expected, pores decreased in diameter when the temperature was raised to 37 °C. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test results suggested neither the scaffolds nor their degradation products were cytotoxic to NIH3T3 cells. Scaffolds with 55 ± 5 μm pore diameter were loaded with NIH3T3 cells and then were warmed to 37 °C entrapping cells in pores approximately 39 μm in diameter, a size range we have found to be optimal for angiogenesis and biointegration. Cells showed uniform infiltration and an elongated morphology after 7 days of culture. Due to the controlled monodisperse pore diameter, highly interconnected architecture, fully degradable chemistry and thermoresponsive properties, the polyNIPAM-based scaffolds developed here are attractive for applications in tissue engineering. PMID: 20836521 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Trinity Evolution. Foot Ankle Spec. 2010 Jun;3(3):144-7 Authors: Rush SM Trinity Evolution Cryopreserved Cell Viable Bone Matrix is a minimally manipulated, human cellular, and tissue-based allograft containing adult mesenchymal stem cells, osteoprogenitor cells, and a demineralized cortical component. The cancellous bone used to produce Trinity Evolution is derived from freshly recovered donor tissue by Food and Drug Administration-registered facilities and processed under aseptic conditions. Preclinical in vivo and in vitro testing as well as strict donor screening has demonstrated the safety of Trinity Evolution as well as its osteoinductive and osteogenic potential contained within a natural osteoconductive matrix. PMID: 20508016 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Trinity Evolution: mesenchymal stem cell allografting in foot and ankle surgery. Foot Ankle Spec. 2010 Jun;3(3):140-3 Authors: Rush SM Biologic augmentation of orthopaedic procedures is a time-tested useful adjunct. The ability to predictably heal all fractures and arthrodesis procedures is still elusive because of multiple factors. The next frontier in musculoskeletal medicine and surgery will involve increasing biologic manipulation of the healing environment. Mesenchymal stem cell allograft is viable living biologic material that is capable of new bone formation and osteointegration at the implantation site. PMID: 20508015 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Soft substrates drive optimal differentiation of human healthy and dystrophic myotubes. Integr Biol (Camb). 2010 Apr 7;2(4):193-201 Authors: Serena E, Zatti S, Reghelin E, Pasut A, Cimetta E, Elvassore N The in vitro development of human myotubes carrying genetic diseases, such as Duchenne Muscular Dystrophy, will open new perspectives in the identification of innovative therapeutic strategies. Through the proper design of the substrate, we guided the differentiation of human healthy and dystrophic myoblasts into myotubes exhibiting marked functional differentiation and highly defined sarcomeric organization. A thin film of photo cross-linkable elastic poly-acrylamide hydrogel with physiological-like and tunable mechanical properties (elastic moduli, E: 12, 15, 18 and 21 kPa) was used as substrate. The functionalization of its surface by micro-patterning in parallel lanes (75 microm wide, 100 microm spaced) of three adhesion proteins (laminin, fibronectin and matrigel) was meant to maximize human myoblasts fusion. Myotubes formed onto the hydrogel showed a remarkable sarcomere formation, with the highest percentage (60.0% +/- 3.8) of myotubes exhibiting sarcomeric organization, of myosin heavy chain II and alpha-actinin, after 7 days of culture onto an elastic (15 kPa) hydrogel and a matrigel patterning. In addition, healthy myotubes cultured in these conditions showed a significant membrane-localized dystrophin expression. In this study, the culture substrate has been adapted to human myoblasts differentiation, through an easy and rapid methodology, and has led to the development of in vitro human functional skeletal muscle myotubes useful for clinical purposes and in vitro physiological study, where to carry out a broad range of studies on human muscle physiopathology. PMID: 20473399 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Corneal regeneration following implantation of a biomimetic tissue-engineered substitute. Clin Transl Sci. 2009 Apr;2(2):162-4 Authors: Fagerholm P, Lagali NS, Carlsson DJ, Merrett K, Griffith M PMID: 20443883 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Biomolecular surface engineering of pancreatic islets with thrombomodulin. Acta Biomater. 2010 Jun;6(6):1895-903 Authors: Wilson JT, Haller CA, Qu Z, Cui W, Urlam MK, Chaikof EL Islet transplantation has emerged as a promising treatment for Type 1 diabetes, but its clinical impact remains limited by early islet destruction mediated by prothrombotic and innate inflammatory responses elicited upon transplantation. Thrombomodulin (TM) acts as an important regulator of thrombosis and inflammation through its capacity to channel the catalytic activity of thrombin towards generation of activated protein C (APC), a potent anticoagulant and anti-inflammatory agent. We herein describe a novel biomolecular strategy for re-engineering the surface of pancreatic islets with TM. A biosynthetic approach was employed to generate recombinant human TM (rTM) bearing a C-terminal azide group, which facilitated site-specific biotinylation of rTM through Staudinger ligation. Murine pancreatic islets were covalently biotinylated through targeting of cell surface amines and aldehydes and both islet viability and the surface density of streptavidin were maximized through optimization of biotinylation conditions. rTM was immobilized on islet surfaces through streptavidin-biotin interactions, resulting in a nearly threefold increase in the catalytic capacity of islets to generate APC. PMID: 20102751 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of crystalline phase on the biological properties of collagen-hydroxyapatite composites. Acta Biomater. 2010 Jun;6(6):2189-99 Authors: Zhang L, Tang P, Xu M, Zhang W, Chai W, Wang Y The objective of this study was to investigate the effects of spatial structure and crystalline phase on the biological performance of collagen-hydroxyapatite (Col-HA) composite prepared by biomineralization crystallization. Two types of Col-HA composites were prepared using mineralization crystallization (MC composites) and pre-crystallization (PC composites), respectively. Structural characteristics were analyzed by scanning electron microscopy and transmission electron microscopy. Surface elemental compositions were measured by electron spectroscopy for chemical analysis (ESCA). These composites were used in in vivo repair of bone defects. The effects of the crystalline phase on the biological performance of Col-HA composites were investigated using radionuclide bone scan, histopathology and morphological observation. It was observed that in MC composites, HA was located on the surface of the collagen fibers and aggregated into crystal balls, whereas HA in PC composites was scattered among the collagen fibers. ESCA showed that phosphorus and calcium were 8.99% and 17.56% on MC composite surface, compared with 4.39% and 5.86% on the PC composite surface. In vivo bone defect repair experiments revealed that radionuclide uptake was significantly higher in the area implanted with the PC composite than in the contralateral area implanted with the MC composite. Throughout the whole repair process, the PC composite proved to be superior to the MC composite with regard to capillary-forming capacity and the amount of newly formed bone tissue. So it could be concluded that HA placement on collagen fibers affected the biological performance of Col-HA composites. Pre-crystallization made HA scattered among collagen fibers, creating a better structure for bone defect repair in comparison with MC Col-HA composites. PMID: 20040387 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Biodegradable microgrooved polymeric surfaces obtained by photolithography for skeletal muscle cell orientation and myotube development. Acta Biomater. 2010 Jun;6(6):1948-57 Authors: Altomare L, Gadegaard N, Visai L, Tanzi MC, Farè S During tissue formation, skeletal muscle precursor cells fuse together to form multinucleated myotubes. To understand this mechanism, in vitro systems promoting cell alignment need to be developed; for this purpose, micrometer-scale features obtained on substrate surfaces by photolithography can be used to control and affect cell behaviour. This work was aimed at investigating how differently microgrooved polymeric surfaces can affect myoblast alignment, fusion and myotube formation in vitro. Microgrooved polymeric films were obtained by solvent casting of a biodegradable poly-l-lactide/trimethylene carbonate copolymer (PLLA-TMC) onto microgrooved silicon wafers with different groove widths (5, 10, 25, 50, 100microm) and depths (0.5, 1, 2.5, 5microm), obtained by a standard photolithographic technique. The surface topography of wafers and films was evaluated by scanning electron microscopy. Cell assays were performed using C2C12 cells and myotube formation was analysed by immunofluorescence assays. Cell alignment and circularity were also evaluated using ImageJ software. The obtained results confirm the ability of microgrooved surfaces to influence myotube formation and alignment; in addition, they represent a novel further improvement to the comprehension of best features to be used. The most encouraging results were observed in the case of microstructured PLLA-TMC films with grooves of 2.5 and 1microm depth, presenting, in particular, a groove width of 50 and 25microm. PMID: 20040385 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Electrospun hyaluronate-collagen nanofibrous matrix and the effects of varying the concentration of hyaluronate on the characteristics of foreskin fibroblast cells. Acta Biomater. 2010 Jun;6(6):2140-7 Authors: Hsu FY, Hung YS, Liou HM, Shen CH In this study we propose a novel electrospinning fabrication process for the production of a nanofibrous matrix composed of collagen and hyaluronate. This procedure utilized 1,1,1,3,3,3-hexafluoro-2-propanol and formic acid as a mixed solvent. Fluorescence microscopy photographs revealed that the resulting electrospun nanofibers contained both collagen and hyaluronate. The mean diameter of the composite nanofibrous matrix (as observed using scanning electron micrographs) was approximately 200nm; this dimension is similar to that of native fibrous protein within the extracellular matrix. The expression of proteinases (e.g. matrix metalloproteinases, MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been implicated in epidermal repair during wound healing. Moreover, the characteristics of scarless wounds are known to be related to a decreased ratio of TIMP to MMP expression. In the present study the ratio of expression of TIMP1 to MMP1 was lower in foreskin fibroblast cells that were cultured on a hyaluronate-collagen composite nanofibrous matrix than in those cultured on an exclusively collagen nanofibrous matrix. This indicates that the hyaluronate-collagen composite nanofibrous matrix could potentially be used as a wound dressing for the regeneration of scarless skin. PMID: 20035907 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Porous biocompatible three-dimensional scaffolds of cellulose microfiber/gelatin composites for cell culture. Acta Biomater. 2010 Jun;6(6):2132-9 Authors: Xing Q, Zhao F, Chen S, McNamara J, Decoster MA, Lvov YM Physiological tissues, including brain and other organs, have three-dimensional (3-D) aspects that need to be supported to model them in vitro. Here we report the use of cellulose microfibers combined with cross-linked gelatin to make biocompatible porous microscaffolds for the sustained growth of brain cell and human mesenchymal stem cells (hMSCs) in 3-D structure. Live imaging using confocal microscopy indicated that 3-D microscaffolds composed of gelatin or cellulose fiber/gelatin both supported brain cell adhesion and growth for 16days in vitro. Cellulose microfiber/gelatin composites containing up to 75% cellulose fibers can withstand a higher mechanical load than gelatin alone, and composites also provided linear pathways along which brain cells could grow compared to more clumped cell growth in gelatin alone. Therefore, the bulk cellulose microfiber provides a novel skeleton in this new scaffold material. Cellulose fiber/gelatin scaffold supported hMSCs growth and extracellular matrix formation. hMSCs osteogenic and adipogenic assays indicated that hMSCs cultured in cellulose fiber/gelatin composite preserved the multilineage differentiation potential. As natural, biocompatible components, the combination of gelatin and cellulose microfibers, fabricated into 3-D matrices, may therefore provide optimal porosity and tensile strength for long-term maintenance and observation of cells. PMID: 20035906 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A one-step method to fabricate PLLA scaffolds with deposition of bioactive hydroxyapatite and collagen using ice-based microporogens. Acta Biomater. 2010 Jun;6(6):2013-9 Authors: Li J, Chen Y, Mak AF, Tuan RS, Li L, Li Y Porous poly(l-lactic acid) (PLLA) scaffolds with bioactive coatings were prepared by a novel one-step method. In this process, ice-based microporogens containing bioactive molecules, such as hydroxyapatite (HA) and collagen, served as both porogens to form the porous structure and vehicles to transfer the bioactive molecules to the inside of PLLA scaffolds in a single step. Based on scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy analysis, the bioactive components were found to be transferred successfully from the porogens to PLLA scaffolds evenly. Osteoblast cells were used to evaluate the cellular behaviors of the composite scaffolds. After culturing for 8days, MTT assay and alkaline phosphatase activity results suggested that HA/collagen could improve the interactions between osteoblast cells and the polymeric scaffold. PMID: 20004261 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Engineering surfaces for site-specific vascular differentiation of mouse embryonic stem cells. Acta Biomater. 2010 Jun;6(6):1904-16 Authors: Chiang CK, Chowdhury MF, Iyer RK, Stanford WL, Radisic M Differentiation of stem and progenitor cells routinely relies on the application of soluble growth factors, an approach that enables temporal control of cell fate but enables no spatial control of the differentiation process. Angiogenic progenitor cells derived from mouse embryonic stem cells (ESCs) were differentiated here according to the pattern of immobilized vascular endothelial growth factor-A (VEGF). Mouse ESCs engineered to express green fluorescent protein (eGFP) under control of promoter for the receptor tyrosine kinase Flk1 were used. The Flk1+ angiogenic progenitors were selected from day 3 differentiating embryoid bodies based on their expression of eGFP using fluorescence activated cell sorting. Mouse VEGF(165) was covalently immobilized onto collagen IV (ColIV) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) chemistry. A non-cell adhesive layer of photocrosslinkable chitosan was first created, after which VEGF-ColIV was stamped as 100mum wide lanes on top of the chitosan layer and the Flk1+ angiogenic progenitors were seeded for site-specific differentiation. Lanes stamped with only ColIV served as controls. The results presented here demonstrate that the cultivation of Flk1+ progenitors on surfaces with immobilized VEGF yielded primarily endothelial cells (53+/-13% CD31 positive and 17+/-2% smooth muscle actin positive), whereas surfaces without VEGF favored vascular smooth muscle-like cell differentiation (26+/-17% CD31 positive and 38+/-9% smooth muscle actin positive). PMID: 20004260 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Functionally graded hydroxyapatite coatings doped with antibacterial components. Acta Biomater. 2010 Jun;6(6):2264-73 Authors: Bai X, More K, Rouleau CM, Rabiei A A series of functionally graded hydroxyapatite (FGHA) coatings incorporated with various percentages of silver were deposited on titanium substrates using ion beam-assisted deposition. The analysis of the coating's cross-section using transmission electron microscopy (TEM) and scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy has shown a decreased crystallinity as well as a distribution of nanoscale (10-50nm) silver particles from the coating/substrate interface to top surface. Both X-ray diffraction and fast Fourier transforms on high-resolution TEM images revealed the presence of hydroxyapatite within the coatings. The amount of Ag (wt.%) on the outer surface of the FGHA, as determined from X-ray photoelectron spectroscopy, ranged from 1.09 to 6.59, which was about half of the average Ag wt.% incorporated in the entire coating. Average adhesion strengths evaluated by pull-off tests were in the range of 83+/-6 to 88+/-3MPa, which is comparable to 85MPa for FGHA without silver. Further optical observations of failed areas illustrated that the dominant failure mechanism was epoxy failure, and FGHA coating delamination was not observed. PMID: 19969112 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Surface engineering of titanium with potassium hydroxide and its effects on the growth behavior of mesenchymal stem cells. Acta Biomater. 2010 Jun;6(6):2314-21 Authors: Cai K, Lai M, Yang W, Hu R, Xin R, Liu Q, Sung KL To improve the corrosion resistance and biological performance of commercially pure titanium (cp-Ti) substrates, potassium hydroxide was employed to modify the surfaces of titanium substrates, followed by biomimetic deposition of apatite on the substrates in a simulated body fluid. The morphologies of native and treated titanium substrates were characterized by field emission scanning electron microscopy (FE-SEM). Treatment with potassium hydroxide led to the formation of intermediate layers of potassium titanate on the surfaces of titanium substrates, while apatite was subsequently deposited onto the intermediate layer. The formation of potassium titanate and apatite was confirmed by thin-film X-ray diffraction and FE-SEM equipped with energy dispersive spectroscopy, respectively. Electrochemical impedance spectroscopy showed that the formed potassium titanate layer improved the corrosion-resistance properties of titanium substrates. The influence of modified titanium substrates on the biological behavior of mesenchymal stem cells (MSCs), including osteogenic differentiation, was investigated in vitro. Compared with cp-Ti substrates, MSCs cultured onto alkali- and heat-treated titanium substrates and apatite-deposited titanium substrates displayed significantly higher (P<0.05 or P<0.01) proliferation and differentiation levels of alkaline phosphatase and osteocalcin in 7 and 14day cultures, respectively. More importantly, our results suggest that the modified titanium substrates have great potential for inducing MSCs to differentiate into osteoblasts. The approach presented here may be exploited to fabricate titanium-based implants. PMID: 19963080 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Direct laser processing of a tantalum coating on titanium for bone replacement structures. Acta Biomater. 2010 Jun;6(6):2329-34 Authors: Balla VK, Banerjee S, Bose S, Bandyopadhyay A Recently tantalum is gaining more attention as a new metallic biomaterial as it has been shown to be bioactive and biologically bonds to bone. However, the relatively high cost of manufacture and an inability to produce a modular all Ta implant has limited its widespread acceptance. In this study we have successfully deposited a Ta coating on Ti using laser engineered net shaping (LENS) to enhance the osseointegration properties. In vitro biocompatibility study, using human osteoblast cell line hFOB, showed excellent cellular adherence and growth with abundant extracellular matrix formation on the Ta coating surface compared with the Ti surface. A six times higher living cell density was observed on the Ta coating than on the Ti control surface by MMT assay. A high surface energy and wettability of the Ta surface were observed to contribute to its significantly better cell-material interactions. Also, these dense Ta coatings do not suffer from low fatigue resistance due to the absence of porosity and a sharp interface between the coating and the substrate, which is a major concern for porous coatings used for enhanced/early biological fixation. PMID: 19931654 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Three-dimensional visualization of in vitro cultivated chondrocytes inside porous gelatine scaffolds: A tomographic approach. Acta Biomater. 2010 Jun;6(6):2097-107 Authors: Zehbe R, Goebbels J, Ibold Y, Gross U, Schubert H Synchrotron radiation-based microcomputed tomography (SR-microCT) has become a valuable tool in the structural characterization of different types of materials, achieving volumetric details with micrometre resolution. Biomedical research dealing with porous polymeric biomaterials is one of the research fields which can benefit greatly from the use of SR-microCT. This study demonstrates that current experimental set-ups at synchrotron beamlines achieve a sufficiently high resolution in order to visualize the positions of individual cartilage cells cultivated on porous gelatine scaffolds made by a freeze-structuring technique. Depending on the processing parameters, the pore morphology of the scaffolds investigated was changed from large-pore sized but non-ordered structures to highly directional and fine pored. The cell-seeded scaffolds were stained with a combined Au/Ag stain to enhance the absorption contrast in SR-microCT. While only some cells showed enhanced absorption contrast, most cells did not show any difference in contrast to the surrounding scaffold and were consequently not detectable using conventional greyscale threshold methods. Therefore, using an image-based three-dimensional segmentation tool on the tomographic data revealed a multitude of non-stained cells. In addition, the SR-microCT data were compared with data obtained from scanning electron microscopy, energy dispersive X-ray spectroscopy and histology, while further linking the initial cell density measured via a MTT assay to the pore size as determined by SR-microCT. PMID: 19931653 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
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