|  |  |  | | | | | TERMSC | | | | | | | | | | | | | | | | | | | Stem cell therapy doctor exploited desperate patients, GMC finds. BMJ. 2010;341:c5001 Authors: Dyer C PMID: 20837578 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | Keratinocyte growth factor phage model peptides can promote epidermal cell proliferation without tumorigenic effect. Chin Med J (Engl). 2010 May;123(9):1195-200 Authors: Zong XL, Jiang DY, Wang JC, Liu JL, Liu ZZ, Cai JL BACKGROUND: Keratinocyte growth factor (KGF) significantly influences epithelial wound healing. The aim of this study was to isolate KGF phage model peptides from a phage display 7-mer peptide library to evaluate their effect on promoting epidermal cell proliferation. METHODS: A phage display 7-mer peptide library was screened using monoclonal anti-human KGF antibody as the target. Enzyme linked immunosorbent assay (ELISA) was performed to select monoclonal phages with good binding activity. DNA sequencing was done to find the similarities of model peptides. Three-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, immunofluorescence assay and quantitative real-time PCR analysis were employed to evaluate the effect of the phage model peptides on epidermal cells. RESULTS: Thirty-three out of fifty-eight (56.9%) of the isolated monoclonal phages exhibited high binding activity by ELISA. Ten of fifteen obtained phage model peptides were similar to KGF or epidermal growth factor (EGF). MTT assay data showed that four (No. 1 - 4) of the ten phage model peptides could promote epidermal cell proliferation. The expression of keratinocyte growth factor receptor (KGFR) mRNA in the KGF control group and the two phage model peptide groups (No. 1 and No. 2) increased. Expression of c-Fos mRNA and c-Jun mRNA in the KGF control group increased, but did not increase in the four phage model peptide groups (No.1 - 4). CONCLUSION: Four phage model peptides isolated from the phage display 7-mer peptide library can safely promote epidermal cell proliferation without tumorigenic effect. PMID: 20529562 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | Material properties and osteogenic differentiation of marrow stromal cells on fiber-reinforced laminated hydrogel nanocomposites. Acta Biomater. 2010 Jun;6(6):1992-2002 Authors: Xu W, Ma J, Jabbari E The fibrils in the bone matrix are glued together by extracellular matrix proteins to form laminated structures (osteons) to provide elasticity and a supportive substrate for osteogenesis. The objective of this work was to investigate material properties and osteogenic differentiation of bone marrow stromal (BMS) cells seeded on osteon-mimetic fiber-reinforced hydrogel/apatite composites. Layers of electrospun poly(l-lactide) fiber mesh coated with a poly(lactide-co-ethylene oxide fumarate) (PLEOF) hydrogel precursor solution were stacked and pressed together, and crosslinked to produce a laminated fiber-reinforced composite. Hydroxyapatite (HA) nanocrystals were added to the precursor solution to produce an osteoconductive matrix for BMS cells. Acrylamide-terminated Arg-Gly-Asp (RGD) peptide (Ac-GRGD) was conjugated to the PLEOF/HA hydrogel phase to promote focal point adhesion of BMS cells. Laminates were characterized with respect to the Young's modulus, degradation kinetics and osteogenic differentiation of BMS cells. The moduli of the laminates under dry and wet conditions were significantly higher than those of the fiber mesh and PLEOF/HA hydrogel, and within the range of values reported for wet human cancellous bone. At days 14 and 21, alkaline phosphatase (ALPase) activity of the laminates was significantly higher than those of the fiber mesh and hydrogel. Lamination significantly increased the extent of mineralization of BMS cells and laminates with HA and conjugated with RGD (Lam-RGD-HA) had 2.7-, 3.5- and 2.8-fold higher calcium content (compared to laminates without HA or RGD) after 7, 14 and 21days, respectively. The Lam-RGD-HA group had significantly higher expression of osteopontin and osteocalcin compared to the hydrogel or laminates without HA or RGD, consistent with the higher ALPase activity and calcium content of Lam-RGD-HA. Laminated osteon-mimetic structures have the potential to provide mechanical strength to the regenerating region as well as supporting the differentiation of progenitor cells to the osteogenic lineage. PMID: 19995620 [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] | | | | | | | | | | | | | | | | | | | | | | | | | Biomimetic apatite formation on calcium phosphate-coated titanium in Dulbecco's phosphate-buffered saline solution containing CaCl(2) with and without fibronectin. Acta Biomater. 2010 Jun;6(6):2274-81 Authors: Chen C, Lee IS, Zhang SM, Yang HC Calcium phosphate (CaP) thin films with different degrees of crystallinity were coated on the surfaces of commercially pure titanium by electron beam evaporation. The details of apatite nucleation and growth on the coating layer were investigated in Dulbecco's phosphate-buffered saline solutions containing calcium chloride (DPBS) or DPBS with fibronectin (DPBSF). The surfaces of the samples were examined by field emission scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The concentrations of fibronectin and calcium ions (Ca(2+)) were monitored by the bicinchoninic acid method (BCA) and use of a calcium assay kit (DICA-500), respectively. Apatite initially formed at the fastest rate on the CaP-coated samples with the lowest degree of crystallinity and reached the maximum Ca(2+) concentration after immersion in DPBS solution for 15min. After 15min the concentration of Ca(2+) decreased with the growth of apatite on the coating layers. For all the samples the maximum Ca(2+) concentration in the DPBS solutions decreased with increasing crystallinity and immersion time to reach the maximum concentration increased. The presence of fibronectin in the DPBS solutions delayed the formation and affected the morphology of the apatite. Fibronectin incorporated into apatite deposited on the surface of titanium did not affect its biological activity in terms of promoting osteoblast adhesion. PMID: 19962459 [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] | | | | | | | | | | | | | | | | | | | | | | | | | The pivotal role of the alternative NF-kappaB pathway in maintenance of basal bone homeostasis and osteoclastogenesis. J Bone Miner Res. 2010 Apr;25(4):809-18 Authors: Soysa NS, Alles N, Weih D, Lovas A, Mian AH, Shimokawa H, Yasuda H, Weih F, Jimi E, Ohya K, Aoki K The alternative NF-kappaB pathway consists predominantly of NF-kappaB-inducing kinase (NIK), IkappaB kinase alpha (IKKalpha), p100/p52, and RelB. The hallmark of the alternative NF-kappaB signaling is the processing of p100 into p52 through NIK, thus allowing the binding of p52 and RelB. The physiologic relevance of alternative NF-kappaB activation in bone biology, however, is not well understood. To elucidate the role of the alternative pathway in bone homeostasis, we first analyzed alymphoplasic (aly/aly) mice, which have a defective NIK and are unable to process p100, resulting in the absence of p52. We observed increased bone mineral density (BMD) and bone volume, indicating an osteopetrotic phenotype. These mice also have a significant defect in RANKL-induced osteoclastogenesis in vitro and in vivo. NF-kappaB DNA-binding assays revealed reduced activity of RelA, RelB, and p50 and no binding activity of p52 in aly/aly osteoclast nuclear extracts after RANKL stimulation. To determine the role of p100 itself without the influence of a concomitant lack of p52, we used p100(-/-) mice, which specifically lack the p100 inhibitor but still express p52. p100(-/-) mice have an osteopenic phenotype owing to the increased osteoclast and decreased osteoblast numbers that was rescued by the deletion of one allele of the relB gene. Deletion of both allele of relB resulted in a significantly increased bone mass owing to decreased osteoclast activity and increased osteoblast numbers compared with wild-type (WT) controls, revealing a hitherto unknown role for RelB in bone formation. Our data suggest a pivotal role of the alternative NF-kappaB pathway, especially of the inhibitory role of p100, in both basal and stimulated osteoclastogenesis and the importance of RelB in both bone formation and resorption. PMID: 19839765 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Nanogel engineering for new nanobiomaterials: from chaperoning engineering to biomedical applications. Chem Rec. 2010 Sep 10; Authors: Sasaki Y, Akiyoshi K Nanosize hydrogels (nanogels) are polymer nanoparticles with three-dimensional networks, formed by chemical and/or physical cross-linking of polymer chains. Recently, various nanogels have been designed, with a particular focus on biomedical applications. In this review, we describe recent progress in the synthesis of nanogels and nanogel-integrated hydrogels (nanogel cross-linked gels) for drug-delivery systems (DDS), regenerative medicine, and bioimaging. We also discuss chaperone-like functions of physical cross-linking nanogel (chaperoning engineering) and organic-inorganic hybrid nanogels. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.201000008. PMID: 20836092 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biophysics and dynamics of natural and engineered stem cell microenvironments. Wiley Interdiscip Rev Syst Biol Med. 2010 Jan;2(1):49-64 Authors: Keung AJ, Healy KE, Kumar S, Schaffer DV Stem cells are defined by their ability to self-renew and to differentiate into one or more mature lineages, and they reside within natural niches in many types of adult and embryonic tissues that present them with complex signals to regulate these two hallmark properties. The diverse nature of these in vivo microenvironments raises important questions about the microenvironmental cues regulating stem cell plasticity, and the stem cell field has built a strong foundation of knowledge on the biochemical identities and regulatory effects of the soluble, cellular, and extracellular matrix factors surrounding stem cells through the isolation and culture of stem cells in vitro within microenvironments that, in effect, emulate the properties of the natural niche. Recent work, however, has expanded the field's perspective to include biophysical and dynamic characteristics of the microenvironment. These include biomechanical characteristics such as elastic modulus, shear force, and cyclic strain; architectural properties such as geometry, topography, and dimensionality; and dynamic structures and ligand profiles. We will review how these microenvironmental characteristics have been shown to regulate stem cell fate and discuss future research directions that may help expand our current understanding of stem cell biology and aid its application to regenerative medicine. Copyright © 2009 John Wiley & Sons, Inc.For further resources related to this article, please visit the WIREs website. PMID: 20836010 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Synthetic Adipose Tissue Models for Studying Mammary Gland Development and Breast Tissue Engineering. J Mammary Gland Biol Neoplasia. 2010 Sep 12; Authors: Wang X, Reagan MR, Kaplan DL The mammary gland is a dynamic organ that continually changes its architecture and function. Reciprocal interactions between epithelium and adipocyte-containing stroma exert profound effects on all stages of its development, even though the details of these events are not fully understood. To address this issue, enormous potential exists in the utilization of synthetic adipose tissue model systems to uncover the properties and functions of adipocytes in the mammary gland. The first part of this review focuses on mammary adipose tissue (or adipocyte)-related model systems developed in recent years and their utility in investigating adipose-epithelial interactions, mammary gland morphogenesis, development and tumorigenesis. The second part shifts to the field of adipose-based breast tissue engineering, focusing on how these synthetic adipose tissue models are being constructed in vitro or in vivo for regeneration of the mammary gland, and their potentials in adipose tissue engineering also are discussed. PMID: 20835885 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A novel composition for the culture of human adipose stem cells which includes complement C3. Cytotechnology. 2010 Sep 11; Authors: Hareendran S, Sathishkumar S, Abbas S, Mackay AM, Rajan P Adipose tissue is an easily accessible and abundant source of stem cells. Adipose stem cells (ASCs) are currently being researched as treatment options for repair and regeneration of damaged tissues. The standard culture conditions used for expansion of ASCs contain fetal bovine serum (FBS) which is undefined, could transmit known and unknown adventitious agents, and may cause adverse immune reactions. We have described a novel culture condition which excludes the use of FBS and characterised the resulting culture. Human ASCs were cultured in the novel culture medium, which included complement protein C3. These cultures, called C-ASCs, were compared with ASCs cultured in medium supplemented with FBS. Analysis of ASCs for surface marker profile, proliferation characteristics and differentiation potential indicated that the C-ASCs were similar to ASCs cultured in medium containing FBS. Using a specific inhibitor, we show that C3 is required for the survival of C-ASCs. This novel composition lends itself to being developed into a defined condition for the routine culture of ASCs for basic and clinical applications. PMID: 20835846 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | High-mobility group box 1 (HMGB1) as a master regulator of innate immunity. Cell Tissue Res. 2010 Sep 11; Authors: Castiglioni A, Canti V, Rovere-Querini P, Manfredi AA Damage-associated molecular patterns (DAMPs) comprise intracellular molecules characterized by the ability to reach the extracellular environment, where they prompt inflammation and tissue repair. The high-mobility box group 1 (HMGB1) protein is a prototypic DAMP and is highly conserved in evolution. HMGB1 is released upon cell and tissue necrosis and is actively produced by immune cells. Evidence suggests that HMGB1 acts as a key molecule of innate immunity, downstream of persistent tissue injury, orchestrating inflammation, stem cell recruitment/activation, and eventual tissue remodeling. PMID: 20835834 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Sex differences in the benefits of rehabilitative training during adolescence following neonatal hypoxia-ischemia in rats. Exp Neurol. 2010 Sep 9; Authors: Tsuji M, Mishima K, Harada K, Fujiwara M, Ikeda T Much effort and many resources are being devoted to rehabilitative programs for children with disabilities caused by neonatal hypoxic-ischemic encephalopathy without clear evidence of the efficacy of such programs. We recently reported that rehabilitative training tasks during adolescence improve spatial learning impairment following neonatal hypoxic-ischemic injury in rats without histological improvement. In the present study we focused on sex differences. Wister rat pups were exposed to a unilateral hypoxic-ischemic insult at 7days of age. Six weeks after hypoxia-ischemia, rehabilitative training tasks were started. The tasks consisted of the plus maze, the eight-arm radial maze, and the choice reaction time task. Sixteen weeks after the insult, the water maze task was performed to evaluate spatial learning ability. Afterwards, we morphologically examined brain injury. Our rehabilitative training significantly improved swimming time and length in females (P<0.01) but not in males. Likewise, the training ameliorated infarct areas in the injured cerebral hemisphere in females but not in males (P < 0.01). These results suggest that it may be important to develop and evaluate cognitive rehabilitation programs for children with brain injury on the basis of gender. PMID: 20833167 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Streptozotocin-induced diabetic rat-derived bone marrow mesenchymal stem cells have impaired abilities in proliferation, paracrine, antiapoptosis, and myogenic differentiation. Transplant Proc. 2010 Sep;42(7):2745-52 Authors: Jin P, Zhang X, Wu Y, Li L, Yin Q, Zheng L, Zhang H, Sun C BACKGROUND: Diabetes has been widely recognized as a major risk factor for cardiovascular disease. With the development of the regenerative medicine, autologous bone marrow-derived mesenchymal stem cells (BMSCs), transplantation can effectively improve cardiac function after myocardial infarction. However, the BMSCs used in most previous studies are derived from young or normal donors. Little is know about the biological characters change of BMSCs in diabetes mellitus. METHODS: BMSCs were taken from the streptozotocin (STZ)-induced diabetic rats and normal control rats. Cell proliferation was evaluated by CCK-8 assay. Production of vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF)-1 were measured by enzyme-linked immunosorbent assay. Apoptosis under hypoxia and serum deprivation culture conditions were detected by Hoechst 33342 stain and flow cytometry. Myogenic differentiation, induced by 5-azacytidine was assessed by using immunocytochemical staining for the expression of sarcomeric α-actin and desmin. RESULTS: Diabetic rat models were successfully induced by intraperitoneal injection of STZ. The proliferative abilities of BMSCs derived from diabetic rats decreased significantly compared with that from normal rats (P < .05). Similar results were also presented in the cytokines (VEGF and IGF-1) release (P = .02 and P < .01, respectively) that the ability of antiapoptosis and myogenic differentiation decreased obviously between diabetes group and the normal control group (P < .01). CONCLUSION: BMSCs from STZ-induced diabetic rats could be successfully harvested and expanded in vitro culture condition; their morphology was very similar to normal control group, with minor changes. However, the proliferative and differentiation properties of diabetic BMSCs, as well as cytokine release and antiapoptosis ability, were significantly impaired. PMID: 20832580 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | An in situ formed biodegradable hydrogel for reconstruction of the corneal endothelium. Colloids Surf B Biointerfaces. 2010 Jul 30; Authors: Liang Y, Liu W, Han B, Yang C, Ma Q, Song F, Bi Q Biodegradable hydrogels are important biomaterials for tissue engineering and drug delivery. For the purpose of corneal regenerative medicine, we describe an in situ formed hydrogel based on a water-soluble derivative of chitosan, hydroxypropyl chitosan (HPCTS), and sodium alginate dialdehyde (SAD). Periodate oxidized alginate rapidly cross-links HPCTS due to Schiff's base formation between the available aldehyde and amino groups. Hydrogel cytotoxicity, degradability and histocompatibility in vivo were examined. The potential of the composite hydrogel for corneal endothelium reconstruction was demonstrated by encapsulating corneal endothelial cells (CECs) to grow on Descemet's membranes. The results demonstrate that the composite hydrogel was both non-toxic and biodegradable and that CECs transplanted by the composite hydrogel could survive and retain normal morphology. These results provide an opportunity for corneal endothelium reconstruction based on tissue engineering by the in situ formed composite hydrogel. PMID: 20832263 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Nanowastes and the environment: Potential new waste management paradigm. Environ Int. 2010 Sep 8; Authors: Musee N Recent exponential growth in the development of nanomaterials (NMs) and nanoproducts is premised on the provision of novel benefits to the society-through the exploitation of their unique industrial and biomedical applications like medical imaging, fabrics in textiles, tissue engineering, nanocomposites, bioremediation, and biomedicine. These NMs and nanoproducts have increased in quantity and volume from few kilograms to thousands of tonnes over the last fifteen to twenty years, and their uncontrolled release into the environment is anticipated to grow dramatically in future. However, their potential impacts to the biological systems are unknown. Among the key present challenges in the waste management sector include the emergence of nanowastes; however, the effectiveness and the capability of the current systems to handle them are yet to be established. Because of limited studies on nanowastes management, in this paper, three-fold objectives are pursued, namely; (i) to raise concerns related to the alarming increases of uncontrolled releases of NMs into the environment through nanowastes, (ii) examine the unique challenges nanowastes pose to the waste management systems-both from technological and legislative perspectives, and (iii) summarize results of the first nanowastes classification formalism in order to elucidate the potential challenges of waste streams containing nanoscale dimension materials to the present waste management paradigm. Finally, the article closes by summarizing several proactive steps of enhancing effective long-term and responsible management of nanowastes. PMID: 20832119 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cell behavior on extracellular matrix mimic materials based on mussel adhesive protein fused with functional peptides. Biomaterials. 2010 Sep 8; Authors: Choi BH, Choi YS, Kang DG, Kim BJ, Song YH, Cha HJ Adhesion of cells to surfaces is a basic and important requirement in cell culture and tissue engineering. Here, we designed artificial extracellular matrix (ECM) mimics for efficient cellular attachment, based on mussel adhesive protein (MAP) fusion with biofunctional peptides originating from ECM materials, including fibronectin, laminin, and collagen. Cellular behaviors, including attachment, proliferation, spreading, viability, and differentiation, were investigated with the artificial ECM material-coated surfaces, using three mammalian cell lines (pre-osteoblast, chondrocyte, and pre-adipocyte). All cell lines examined displayed superior attachment, proliferation, spreading, and survival properties on the MAP-based ECM mimics, compared to other commercially available cell adhesion materials, such as poly-l-lysine and the naturally extracted MAP mixture. Additionally, the degree of differentiation of pre-osteoblast cells on MAP-based ECM mimics was increased. These results collectively demonstrate that the artificial ECM mimics developed in the present work are effective cell adhesion materials. Moreover, we expect that the MAP peptide fusion approach can be extended to other functional tissue-specific motifs. PMID: 20832110 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Rapid cellular internalization of multifunctional star polymers prepared by atom transfer radical polymerization. Biomacromolecules. 2010 Sep 13;11(9):2199-203 Authors: Cho HY, Gao H, Srinivasan A, Hong J, Bencherif SA, Siegwart DJ, Paik HJ, Hollinger JO, Matyjaszewski K Poly(ethylene glycol) (PEG) star polymers containing GRGDS (Gly-Arg-Gly-Asp-Ser) peptide sequences on the star periphery were synthesized by atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA), GRGDS modified poly(ethylene glycol) acrylate (GRGDS-PEG-Acryl), fluorescein o-methacrylate (FMA), and ethylene glycol dimethacrylate (EGDMA) via an "arm-first" method. Star polymers were approximately 20 nm in diameter, as measured by dynamic light scattering and atomic force microscopy. Conjugation of FMA to the stars was confirmed by fluorescence microscopy, and successful attachment of GRGDS segments to the star periphery was confirmed by (1)H NMR spectroscopy. Both fluorescent PEG star polymers with and without peripheral GRGDS peptide segments were cultured with MC3T3-E1.4 cells. These star polymers were biocompatible with ≥90% cell viability after 24 h of incubation. Cellular uptake of PEG star polymers in MC3T3-E1.4 cells was observed by confocal microscopy. Rapid uptake of PEG star polymers with GRGDS peptides (∼100% of FITC-positive cells in 15 min measured by flow cytometry) was observed, suggesting enhanced delivery potential of these functional star polymers. PMID: 20831270 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Surface Modification of Polyimide Sheets for Regenerative Medicine Applications. Biomacromolecules. 2010 Sep 10; Authors: Van Vlierberghe S, Sirova M, Rossmann P, Thielecke H, Boterberg V, Rihova B, Schacht E, Dubruel P In the present work, two strategies were elaborated to surface-functionalize implantable polyimide sheets. In the first methodology, cross-linkable vinyl groups were introduced on the polyimide surface using aminopropylmethacrylamide. In the second approach, a reactive succinimidyl ester was introduced on the surface of PI. Using the former approach, the aim is to apply a vinyl functionalized biopolymer coating. In the latter approach, any amine containing biopolymer can be immobilized. The foils developed were characterized in depth using a variety of characterization techniques including atomic force microscopy, static contact angle measurements, and X-ray photoelectron spectroscopy. The results indicated that both modification strategies were successful. The subcutaneous implantation in mice indicated that both modification strategies resulted in biocompatible materials, inducing only limited cellular infiltration to the surrounding tissue. PMID: 20831199 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Exploring atypical locations of mammalian neural stem cells: the human filum terminale. Arch Ital Biol. 2010 Jun;148(2):85-94 Authors: Varghese M, Olstorn H, Murrell W, Langmoen IA Neurogenesis is a multifactorial event determined by local environmental cues, inherent cellular program as well as cellular milieu and may not necessarily be restricted to the SVZ and SGZ. NSCs have been isolated from or neurogenesis has been demonstrated in traditionally non neurogenic regions. This more permissive view of neurogenesis, however, is not widely accepted due to concerns regarding the methodologies used. Furthermore, it is compounded by the fact that the basal levels of increased neurogenesis in such regions has not been completely confirmed and thus precludes a paradigm shift. Were this non limited view of neurogenesis to be generally accepted after thorough investigation, it would open new avenues for regenerative medicine and stem cell therapy. PMID: 20830971 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Neurogenesis in the enteric nervous system. Arch Ital Biol. 2010 Jun;148(2):73-83 Authors: Metzger M The enteric nervous system (ENS) represents the highly organized intrinsic innervation of the gastrointestinal tract and plays a critical role for all stages of postnatal life. Severe disturbances of ENS function can significantly influence life quality or, in severe cases, can have acute life-threatening effects. Recent in vitro and in vivo studies demonstrated the persistence of neural stem cells in postnatal gut and there seem to be many interesting parallels to the more extensively studied neural stem cells in the brain. Enteric stem cells have been proposed as an appropriate cell source to provide an alternative therapeutic option for a number of neurogastrointestinal diseases, however a better understanding of these cells would be crucial for the translation of cell-based therapies into clinic. This review tries to highlight the recent findings in the field of enteric neurogenesis and additionally gives a brief overview about the development, structure and function of the ENS and about the developmental or age-related disturbances affecting the ENS. PMID: 20830970 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | ADAM13 induces cranial neural crest by cleaving class B Ephrins and regulating Wnt signaling. Dev Cell. 2010 Aug 17;19(2):345-52 Authors: Wei S, Xu G, Bridges LC, Williams P, White JM, DeSimone DW The cranial neural crest (CNC) consists of multipotent embryonic cells that contribute to craniofacial structures and other cells and tissues of the vertebrate head. During embryogenesis, CNC is induced at the neural plate boundary through the interplay of several major signaling pathways. Here, we report that the metalloproteinase activity of ADAM13 is required for early induction of CNC in Xenopus. In both cultured cells and X. tropicalis embryos, membrane-bound Ephrins (Efns) B1 and B2 were identified as substrates for ADAM13. ADAM13 upregulates canonical Wnt signaling and early expression of the transcription factor snail2, whereas EfnB1 inhibits the canonical Wnt pathway and snail2 expression. We propose that by cleaving class B Efns, ADAM13 promotes canonical Wnt signaling and early CNC induction. PMID: 20708595 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Burgeoning stem cell product market lures major suppliers. Nat Biotechnol. 2010 Jun;28(6):535-6 Authors: Webb S PMID: 20531315 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Surface-initiated assembly of protein nanofabrics. Nano Lett. 2010 Jun 9;10(6):2184-91 Authors: Feinberg AW, Parker KK Cells and tissues are self-organized within an extracellular matrix (ECM) composed of multifunctional, nano- to micrometer scale protein fibrils. We have developed a cell-free, surface-initiated assembly technique to rebuild this ECM structure in vitro. The matrix proteins fibronectin, laminin, fibrinogen, collagen type I, and collagen type IV are micropatterned onto thermosensitive surfaces as 1 to 10 nm thick, micrometer to centimeter wide networks, and released as flexible, free-standing nanofabrics. Independent control of microstructure and protein composition enables us to engineer the mechanical and chemical anisotropy. Fibronectin nanofabrics are highly extensible (>4-fold) and serve as scaffolds for engineering synchronously contracting, cardiac muscle; demonstrating biofunctionality comparable to cell-generated ECM. PMID: 20486679 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Effect of matrix composition on differentiation of nestin-positive neural progenitors from circulation into neurons. J Neural Eng. 2010 Jun;7(3):036009 Authors: Jose A, Krishnan LK The human peripheral blood mononuclear cell has a mixture of progenitor cells with potential to differentiate into a wide range of lineages. The ability of hematopoietic tissue-derived adult stem cells to differentiate into neural progenitor cells offers an alternative to embryonic stem cells as a viable source for cell transplantation therapies to cure neurodegenerative diseases. This approach could lead to the use of autologous progenitors from blood circulation; however, due to the limited numbers available, in vitro cell expansion may be indispensable. In addition, for successful transplantation there is the requirement of a delivery matrix on which cells can survive and differentiate. In this context we carried out this study to identify a suitable biodegradable matrix on which progenitor cells can home, multiply and differentiate. We designed different compositions of the biomimetic matrix containing fibrin, fibronectin, gelatin, growth factors, laminin and hyaluronic acid. The attached cells expressed proliferation markers in initial periods of culture and between days 6 and 9 in culture they differentiated into neurons and/or astrocytes. The differentiation of progenitors into neurons and asterocyte on the composed matrix was established by morphological and immunochemical analysis. Flow cytometric analysis of cells in culture was employed to track development of neurons which expressed an early marker beta-tubulin3 and a terminal marker microtubule-associated protein-2 at a later culture period. In vitro experiments indicate that a highly specific niche consisting of various components of the extracellular matrix, including hyaluronic acid, promote cell homing, survival and differentiation. PMID: 20479522 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Stimulation of functional vessel growth by gene therapy. Integr Biol (Camb). 2010 Mar;2(2-3):102-12 Authors: Korpisalo P, Ylä-Herttuala S The process of growing new blood vessels through gene therapy may be difficult but is certainly possible. This review will discuss the most important factors determining the efficacy of angiogenic gene therapy. PMID: 20473388 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Fusion of concentrically layered tubular tissue constructs increases burst strength. Ann Biomed Eng. 2010 Jun;38(6):2226-36 Authors: Huynh TN, Tranquillo RT Tubular tissue constructs prepared from neonatal human dermal fibroblasts entrapped in fibrin gel were incubated on a mandrel for three weeks to allow for initial fibrin remodeling into tissue before being concentrically layered and incubated for an additional three weeks on the mandrel. Upon harvest, double layer constructs were not statistically different from single layer control constructs in terms of length, collagen density, cell density, tensile modulus, or ultimate tensile strength. However, the thickness and burst pressure were both approximately twice the single layer control values. Metabolically active cells were detected at the interface, and scanning electron microscopy revealed fiber structures bridging the two layers, co-localizing with the cells, which exhibited minimal migration across the layers. In contrast, double layer constructs where tissue fusion was prohibited by mechanical distraction of the layers showed no increase in burst pressure despite having increased thickness and the same collagen and cell densities of the single layer control constructs; moreover, the burst failure occurred sequentially in the layers in contrast to simultaneous failure for the fused double layer constructs. This study provides insight into the nature of the interface and the role of cell behavior when tissue fusion occurs between two layers of bioartificial tissue in vitro. It also suggests a method for improving the burst strength of fibrin-based tubular tissue constructs by increasing the construct thickness via concentrically layering and fusing two constructs. PMID: 20431952 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Therapeutic cell delivery for in situ regenerative medicine. Adv Drug Deliv Rev. 2010 Jun 15;62(7-8):669-70 Authors: Wang DA, Mahato RI PMID: 20420868 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Bioactive stratified polymer ceramic-hydrogel scaffold for integrative osteochondral repair. Ann Biomed Eng. 2010 Jun;38(6):2183-96 Authors: Jiang J, Tang A, Ateshian GA, Guo XE, Hung CT, Lu HH Due to the intrinsically poor repair potential of articular cartilage, injuries to this soft tissue do not heal and require clinical intervention. Tissue engineered osteochondral grafts offer a promising alternative for cartilage repair. The functionality and integration potential of these grafts can be further improved by the regeneration of a stable calcified cartilage interface. This study focuses on the design and optimization of a stratified osteochondral graft with biomimetic multi-tissue regions, including a pre-designed and pre-integrated interface region. Specifically, the scaffold based on agarose hydrogel and composite microspheres of polylactide-co-glycolide (PLGA) and 45S5 bioactive glass (BG) was fabricated and optimized for chondrocyte density and microsphere composition. It was observed that the stratified scaffold supported the region-specific co-culture of chondrocytes and osteoblasts which can lead to the production of three distinct yet continuous regions of cartilage, calcified cartilage and bone-like matrices. Moreover, higher cell density enhanced chondrogenesis and improved graft mechanical property over time. The PLGA-BG phase promoted chondrocyte mineralization potential and is required for the formation of a calcified interface and bone regions on the osteochondral graft. These results demonstrate the potential of the stratified scaffold for integrative cartilage repair and future studies will focus on scaffold optimization and in vivo evaluations. PMID: 20411332 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Cell-delivery therapeutics for adipose tissue regeneration. Adv Drug Deliv Rev. 2010 Jun 15;62(7-8):798-813 Authors: Bauer-Kreisel P, Goepferich A, Blunk T In reconstructive surgery, there is a tremendous clinical need for adequate implants to repair soft tissue defects resulting from traumatic injury, tumor resection, or congenital anomalies. Adipose tissue engineering holds the promise to provide answers to this still increasing demand. The current approaches to adipose tissue engineering are comprehensively reviewed detailing the different cell carriers under investigation. A special focus is put on the applied cells. The delivered mesenchymal stem cells act in a dual role as building block of the new tissue and modulators of the host response. The conditioning of the cells in vitro prior to implantation decisively influences the tissue development and long-term survival in vivo. The special role of vascularization in adipose engineering is discussed. In all parts, key messages are defined providing the base for future advances in the generation of fat substitutes. PMID: 20394786 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Different properties of electrospun fibrous scaffolds of separated heavy-chain and light-chain fibroins of Bombyx mori. Int J Biol Macromol. 2010 Jun;46(5):493-501 Authors: Wadbua P, Promdonkoy B, Maensiri S, Siri S This study is the first to report on the fabrication and properties of electrospun scaffolds derived from separated light-chain fibroin and heavy-chain fibroin, two major proteins of silk fibroin. Among seven different extraction conditions, which were commonly used to extract fibroin from cocoons of Bombyx mori, only Ajisawa's reagent and 9 M lithium thiocyanate could extract both heavy-chain fibroin and light-chain fibroin, while the other conditions could yield only the light-chain fibroin. Mixed fibroin, light-chain fibroin, and heavy-chain fibroin were fabricated using electrospinning methods. Average diameters of the fibers were 658+/-208, 517+/-162, and 518+/-171 nm, respectively and their sizes after treatment with 50% methanol for 60 min were slightly increased to 747+/-244, 556+/-164 and 521+/-201 nm, respectively. FTIR spectra showed similar predominant beta-sheet conformation of mixed fibroin and heavy-chain fibroin scaffolds after treated with methanol, whereas the predominant structure of light-chain fibroin was random coil conformation. Although, scaffolds derived from mixed fibroin and heavy-chain fibroin showed similar properties, the light-chain fibroin scaffold clearly exhibited different properties, including more hydrophilic character, water uptake ability, degradation rate, and cell adhesion capability. PMID: 20338193 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Hydroxyapatite nanorods/poly(vinyl pyrolidone) composite nanofibers, arrays and three-dimensional fabrics: electrospun preparation and transformation to hydroxyapatite nanostructures. Acta Biomater. 2010 Aug;6(8):3013-20 Authors: Chen F, Tang QL, Zhu YJ, Wang KW, Zhang ML, Zhai WY, Chang J Electrospinning has been recognized as an efficient technique for fabricating polymer nanofibrous biomaterials. However, the study of electrospun inorganic biomaterials with well-designed three-dimensional (3-D) structures is still limited and little reported. In this study hydroxyapatite (HAp) nanorods with an average diameter of approximately 7 nm and length of approximately 27 nm were synthesized through a simple precipitation method and used for the fabrication of inorganic/organic [poly(vinyl pyrolidone) (PVP)] composite nanofibers by electrospinning in ethanol solution. 3-D fabrics and aligned nanofiber arrays of the HAp nanorods/PVP composite were obtained as precursors. Thereafter, 3-D single phase HAp fabrics, tubular structures and aligned nanofiber arrays were obtained after thermal treatment of the corresponding composite precursors. Cytotoxicity experiments indicated that the HAp fabric scaffold had good biocompatibility. In vitro experiments showed that mesenchymal stem cells could attach to the HAp fabric scaffold after culture for 24h. PMID: 20167294 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Varying the diameter of aligned electrospun fibers alters neurite outgrowth and Schwann cell migration. Acta Biomater. 2010 Aug;6(8):2970-8 Authors: Wang HB, Mullins ME, Cregg JM, McCarthy CW, Gilbert RJ Aligned, electrospun fibers have shown great promise in facilitating directed neurite outgrowth within cell and animal models. While electrospun fiber diameter does influence cellular behavior, it is not known how aligned, electrospun fiber scaffolds of differing diameter influence neurite outgrowth and Schwann cell (SC) migration. Thus, the goal of this study was to first create highly aligned, electrospun fiber scaffolds of varying diameter and then assess neurite and SC behavior from dorsal root ganglia (DRG) explants. Three groups of highly aligned, electrospun poly-l-lactic acid (PLLA) fibers were created (1325+383 nm, large diameter fibers; 759+179 nm, intermediate diameter fibers; and 293+65 nm, small diameter fibers). Embryonic stage nine (E9) chick DRG were cultured on fiber substrates for 5 days and then the explants were stained against neurofilament and S100. DAPI stain was used to assess SC migration. Neurite length and SC migration distance were determined. In general, the direction of neurite extension and SC migration were guided along the aligned fibers. On the small diameter fiber substrate, the neurite length was 42% and 36% shorter than those on the intermediate and large fiber substrates, respectively. Interestingly, SC migration did not correlate with that of neurite extension in all situations. SCs migrated equivalently with extending neurites in both the small and large diameter scaffolds, but lagged behind neurites on the intermediate diameter scaffolds. Thus, in some situations, topography alone is sufficient to guide neurites without the leading support of SCs. Scanning electron microscopy images show that neurites cover the fibers and do not reside exclusively between fibers. Further, at the interface between fibers and neurites, filopodial extensions grab and attach to nearby fibers as they extend down the fiber substrate. Overall, the results and observations suggest that fiber diameter is an important parameter to consider when constructing aligned, electrospun fibers for nerve regeneration applications. PMID: 20167292 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Patterned transgene expression in multiple-channel bridges after spinal cord injury. Acta Biomater. 2010 Aug;6(8):2889-97 Authors: De Laporte L, Huang A, Ducommun MM, Zelivyanska ML, Aviles MO, Adler AF, Shea LD Patterning of gene delivery on sub-millimeter length scales within tissue engineering scaffolds is fundamental to recreating the complex architectures of tissues. Surface-mediated delivery of lipoplexes mixed with fibronectin was investigated to pattern vectors within 250 microm channels in poly(lactide-co-glycolide) (PLG) bridges. Initial studies performed in vitro on PLG surfaces indicated that a DNA density of 0.07 microg mm(-2) inside each channel with a weight ratio of DNA to fibronectin of 1:20 maximized the number of transfected cells and the levels of transgene expression. Patterned vectors encoding for nerve growth factor (NGF) resulted in localized neurite extension within the channel. Translation to three-dimensional multiple-channel bridges enabled patterned transfection of different vectors throughout the channels for DNA:fibronectin ratios of 1:4 and multiple DNA depositions, with a large increase of neural cell bodies and neurite extension for delivery of DNA encoding for NGF. In vivo, the immobilization of non-viral vectors within the channels resulted in localized transfection within the pore structure of the bridge immediately around the channels of the bridge containing DNA. This surface immobilization strategy enables patterned gene delivery in vitro and in vivo on length scales of hundreds of microns and may find utility in strategies aimed at regenerating tissues with complex architectures. PMID: 20167291 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Nanomaterials for in situ cell delivery and tissue regeneration. Adv Drug Deliv Rev. 2010 Jun 15;62(7-8):731-40 Authors: Wan AC, Ying JY Nanomaterials can be defined as materials that possess clearly defined features of less than 100nm, and whose nanostructured features confer characteristics crucial to the material's bulk property. The nanostructured features can be an intermediate or final state of the material in its synthesis process. The field of nanomaterials as applied to in situ cell delivery and tissue engineering is rapidly expanding. Nanomaterials that include peptide amphiphiles, self-assembling peptides, electrospun scaffolds, layer-by-layer complexes, nanotubes and nanocomposites have been applied to cell culture, encapsulation and delivery with promising results. As compared to scaffold-free cell delivery, nanomaterials are advantageous in terms of providing a means to control the biochemical and mechanical microenvironment of the cells. Nanomaterials are amenable to a bottom-up approach in functionalization and mechanical tuning, as illustrated in the examples presented in this review. Furthermore, nanomaterials such as DNA polyplexes and carbon nanotubes can also be incorporated into the cell delivery vehicle to improve the regenerative outcome. Lastly, while nanomaterials harbor much potential for cell delivery and tissue regeneration, further characterization is required in terms of clinical safety before these materials can be employed towards therapeutic applications. PMID: 20156499 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Microcapsules and microcarriers for in situ cell delivery. Adv Drug Deliv Rev. 2010 Jun 15;62(7-8):711-30 Authors: Hernández RM, Orive G, Murua A, Pedraz JL In recent years, the use of transplanted living cells pumping out active factors directly at the site has proven to be an emergent technology. However a recurring impediment to rapid development in the field is the immune rejection of transplanted allo- or xenogeneic cells. Immunosuppression is used clinically to prevent rejection of organ and cell transplants in humans, but prolonged usage can make the recipient vulnerable to infections, and increase the likelihood of tumorigenesis of the transplanted cells. Cell microencapsulation is a promising tool to overcome these drawbacks. It consists of surrounding cells with a semipermeable polymeric membrane. The latter permits the entry of nutrients and the exit of therapeutic protein products, obtaining in this way a sustained delivery of the desirable molecule. The membrane isolates the enclosed cells from the host immune system, preventing the recognition of the immobilization cells as foreign. This review paper intends to overview the current situation in the cell encapsulation field and discusses the main events that have occurred along the way. The technical advances together with the ever increasing knowledge and experience in the field will undoubtedly lead to the realization of the full potential of cell encapsulation in the future. PMID: 20153388 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Scaffold-free cell delivery for use in regenerative medicine. Adv Drug Deliv Rev. 2010 Jun 15;62(7-8):753-64 Authors: Kelm JM, Fussenegger M The development of cell-based therapies for diseased tissues is one of the most promising research directions in regenerative medicine. Cell-delivery methods are an essential part of cell therapy concepts. Therapies with the potential to become clinical routine will only be possible if these methods ensure efficient engraftment and therapeutically-relevant number of cells survive. Here we provide an overview of three different scaffold-free cell-delivery concepts: (i) single cell delivery, (ii) cell sheet engineering and (iii) microtissue technology. PMID: 20153387 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Hydrogel/calcium phosphate composites require specific properties for three-dimensional culture of human bone mesenchymal cells. Acta Biomater. 2010 Aug;6(8):2932-9 Authors: Sohier J, Corre P, Weiss P, Layrolle P To provide multipotent cells with a three-dimensional environment closer to bone matrix, an engineered construct mimicking bone components has been designed and evaluated. A biocompatible hydrogel (silated hydroxypropylmethyl cellulose) was used as an extra-cellular matrix while biphasic calcium phosphate ceramic particles were used to replace mineralized matrix. Finally, human bone mesenchymal cells were cultured in three dimensions in the resulting constructs to study their cell viability, proliferation, interactions within the composites, and maintenance of their osteogenic potential. This approach resulted in homogeneous structures in which cells were viable and retained their osteoblastic differentiation potential. However, the cells did not proliferate nor colonize the constructs, possibly because of a lack of suitable interactions with their micro-environment. PMID: 20152947 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Sol-gel silica-based biomaterials and bone tissue regeneration. Acta Biomater. 2010 Aug;6(8):2874-88 Authors: Arcos D, Vallet-Regà M The impact of bone diseases and trauma in developed and developing countries has increased significantly in the last decades. Bioactive glasses, especially silica-based materials, are called to play a fundamental role in this field due to their osteoconductive, osteoproductive and osteoinductive properties. In the last years, sol-gel processes and supramolecular chemistry of surfactants have been incorporated to the bioceramics field, allowing the porosity of bioglasses to be controlled at the nanometric scale. This advance has promoted a new generation of sol-gel bioactive glasses with applications such as drug delivery systems, as well as regenerative grafts with improved bioactive behaviour. Besides, the combination of silica-based glasses with organic components led to new organic-inorganic hybrid materials with improved mechanical properties. Finally, an effort has been made to organize at the macroscopic level the sol-gel glass preparation. This effort has resulted in new three-dimensional macroporous scaffolds, suitable to be used in tissue engineering techniques or as porous pieces to be implanted in situ. This review collects the most important advances in the field of silica glasses occurring in the last decade, which are called to play a lead role in the future of bone regenerative therapies. PMID: 20152946 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Essential modification of the Sircol Collagen Assay for the accurate quantification of collagen content in complex protein solutions. Acta Biomater. 2010 Aug;6(8):3146-51 Authors: Lareu RR, Zeugolis DI, Abu-Rub M, Pandit A, Raghunath M Collagen contains the unique imino acid hydroxyproline (HyPro), which is involved in the stabilization of this triple helical molecule. The concentration of HyPro is customarily used to calculate the total collagen content in a cell culture environment and in acid hydrolysates of normal and pathophysiological tissues. Radiolabelling, chromatographic and calorimetric assays have been developed over the years for the accurate determination of collagen content through HyPro estimation. Recently, the Sircol Collagen Assay (SCA) has been almost exclusively adopted as the fastest and simplest colorimetric method for the determination of collagen concentration in complex protein solutions. We show here that the colorimetric SCA, which is based on the binding of Sirius red (SR) to collagen, is flawed by interference of non-collagenous proteins (e.g. serum). In fact, we demonstrate that SCA in cell culture systems and tissue hydrolysates results in a dramatic overestimation of collagen content ranging from 3- to 24-fold. In order to rescue this otherwise very practical assay, we introduce a simple purification procedure that allows the removal of interfering non-collagenous proteins from culture media and tissue samples so that accurate measurements with SCA are now possible. PMID: 20144751 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Bioengineering the skin-implant interface: the use of regenerative therapies in implanted devices. Ann Biomed Eng. 2010 Jun;38(6):2013-31 Authors: Peramo A, Marcelo CL This discussion and review article focuses on the possible use of regenerative techniques applied to the interfaces between skin and medical implants. As is widely known, the area of contact between an implant and the skin--the skin-implant interface--is prone to recurrent and persistent problems originated from the lack of integration between the material of the implant and the skin. Producing a long-term successful biointerface between skin and the implanted device is still an unsolved problem. These complications have prevented the development of advanced prosthetics and the evolution of biointegrated devices with new technologies. While previous techniques addressing these issues have relied mostly on the coating of the implants or the modification of the topology of the devices, recent in vitro developed techniques have shown that is possible to introduce biocompatible and possibly regenerative materials at the skin-device interface. These techniques have also shown that the process of delivering the materials has biological effects on the skin surrounding the implant, thus converting bioinert into bioactive, dynamic interfaces. Given that the best clinical outcome is the long-term stabilization and integration of the soft tissue around the implant, this article presents the basis for the selection of regenerative materials and therapies for long-term use at the skin-device interface, with focus on the use of natural biopolymers and skin cell transplantation. PMID: 20140520 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Therapeutic cell delivery and fate control in hydrogels and hydrogel hybrids. Adv Drug Deliv Rev. 2010 Jun 15;62(7-8):699-710 Authors: Wang C, Varshney RR, Wang DA Hydrogels are synthetic or natural polymer networks that closely mimic native extracellular matrices. As hydrogel-based vehicles are being increasingly employed in therapeutic cell delivery, two inherent traits of most common hydrogels, namely low cell affinity and high cell constraint, have significantly drawn the attention of biomedical community. These two properties lead to the unfavourable settlement of anchorage-dependent cells (ADCs) and unsatisfactory cell delivery or tissue formation in hydrogel matrices. Tissue engineers have correspondingly made many efforts involving chemical modification or physical hybridisation to facilitate ADC settlement and promote tissue formation. On the other hand, these two 'bio-inert' characteristics have particularly favoured oncological cell therapists, who expect to utilize hydrogels to provide sufficiently high confinement of the delivered cells for anti-cancer purposes. In general, control of cell fate and behaviours in these three-dimensional (3D) microenvironments has become the central aim for hydrogel-mediated cell delivery, towards which various models based on hydrogels and their hybrids have emerged. In this paper, we will first review the development of strategies aiming to overcome the aforementioned two 'shortcomings' by (i) establishing ADC survival and (ii) creating space for tissue formation respectively, and then introduce how people take advantage of these 'disadvantages' of hydrogel encapsulation for (iii) an enhanced confinement of cell motion. PMID: 20138940 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Porous tantalum structures for bone implants: fabrication, mechanical and in vitro biological properties. Acta Biomater. 2010 Aug;6(8):3349-59 Authors: Balla VK, Bodhak S, Bose S, Bandyopadhyay A The relatively high cost of manufacturing and the inability to produce modular implants have limited the acceptance of tantalum, in spite of its excellent in vitro and in vivo biocompatibility. In this article, we report how to process Ta to create net-shape porous structures with varying porosity using Laser Engineered Net Shaping (LENS) for the first time. Porous Ta samples with relative densities between 45% and 73% have been successfully fabricated and characterized for their mechanical properties. In vitro cell materials interactions, using a human fetal osteoblast cell line, have been assessed on these porous Ta structures and compared with porous Ti control samples. The results show that the Young's modulus of porous Ta can be tailored between 1.5 and 20 GPa by changing the pore volume fraction between 27% and 55%. In vitro biocompatibility in terms of MTT assay and immunochemistry study showed excellent cellular adherence, growth and differentiation with abundant extracellular matrix formation on porous Ta structures compared to porous Ti control. These results indicate that porous Ta structures can promote enhanced/early biological fixation. The enhanced in vitro cell-material interactions on the porous Ta surface are attributed to its chemistry, its high wettability and its greater surface energy relative to porous Ti. Our results show that these laser-processed porous Ta structures can find numerous applications, particularly among older patients, for metallic implants because of their excellent bioactivity. PMID: 20132912 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | New processing approaches in calcium phosphate cements and their applications in regenerative medicine. Acta Biomater. 2010 Aug;6(8):2863-73 Authors: Ginebra MP, Espanol M, Montufar EB, Perez RA, Mestres G The key feature of calcium phosphate cements (CPCs) lies in the setting reaction triggered by mixing one or more solid calcium phosphate salts with an aqueous solution. Upon mixture, the reaction takes place through a dissolution-precipitation process which is macroscopically observed by a gradual hardening of the cement paste. The precipitation of hydroxyapatite nanocrystals at body or room temperature, and the fact that those materials can be used as self-setting pastes, have for many years been the most attractive features of CPCs. However, the need to develop materials able to sustain bone tissue ingrowth and be capable of delivering drugs and bioactive molecules, together with the continuous requirement from surgeons to develop more easily handling cements, has pushed the development of new processing routes that can accommodate all these requirements, taking advantage of the possibility of manipulating the self-setting CPC paste. It is the goal of this paper to provide a brief overview of the new processing developments in the area of CPCs and to identify the most significant achievements. PMID: 20123046 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Electrospun fibrous scaffolds with multiscale and photopatterned porosity. Macromol Biosci. 2010 Mar 10;10(3):265-70 Authors: Sundararaghavan HG, Metter RB, Burdick JA The structural and mechanical properties of tissue engineered environments are crucial for successful cellular growth and tissue repair. Electrospinning is gaining wide attention for the fabrication of tissue engineered scaffolds, but the small pore sizes of these scaffolds limit cell infiltration and construct vascularization. To address this problem, we have combined electrospinning with photopatterning to create multiscale porous scaffolds. This process retains the fibrous nature of the scaffolds and permits enhanced cellular infiltration and vascularization when compared to unpatterned scaffolds. This is the first time that photopatterning has been utilized with electrospun scaffolds and is only now possible with the electrospinning of reactive macromers. PMID: 20014198 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A decade of mammalian retinal stem cell research. Arch Ital Biol. 2010 Jun;148(2):59-72 Authors: Locker M, El Yakoubi W, Mazurier N, Dullin JP, Perron M Ten years have now passed since the discovery of quiescent neural stem cells within the mammalian retina. Beside the fascinating aspect of stem cell biology in basic science, these cells have also offered hope for the treatment of incurable retinal diseases. The field has thus rapidly evolved, fluctuating between major advances and recurring doubts. In this review, we will retrace the efforts of scientists during this last decade to characterize these cells and to use them in regenerative medicine. We will also highlight advances made in animal models capable of stem cell-mediated retinal regeneration. PMID: 20830969 [PubMed - in process] | | | | | | | | | |  | |  | |  |
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