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| Fabrication and characterization of chitosan-gelatin blend nanofibers for skin tissue engineering.
June 5, 2010 at 6:49 AM
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| | Fabrication and characterization of chitosan-gelatin blend nanofibers for skin tissue engineering. J Biomed Mater Res B Appl Biomater. 2010 Jul;94(1):264-72 Authors: Dhandayuthapani B, Krishnan UM, Sethuraman S Tissue engineering scaffolds produced by electrospinning feature a structural similarity to the natural extracellular matrix. Polymer blending is one of the effective methods to provide new and desirable biocomposites for tissue engineering applications. In this study chitosan was blended with gelatin and the effect of processing parameters of electrospinning and the solution properties of the polymer on the morphology of the fibers obtained were investigated. The morphology of the electrospun chitosan, gelatin and the chitosan-gelatin blend were characterized using a scanning electron microscope (SEM). The miscibility of the blend was determined using a SEM, and differential scanning calorimetry (DSC) Fourier transform Infrared spectrometer (FTIR). Further the tensile properties of the blend nanofibers were studied and compared with chitosan and gelatin fibers. In this study we have been able to electrospin defect-free chitosan, gelatin and chitosan-gelatin blend nanofibers with smooth morphology and diameter ranging from 120 to 200 nm, 100 to 150 nm, and 120-220 nm, respectively by optimizing the process and solution parameters. Chitosan and gelatin formed completely miscible blends as evidenced from DSC and FTIR measurements. The tensile strength of the chitosan-gelatin blend nanofibers (37.91 +/- 4.42 MPa) was significantly higher than the gelatin nanofibers (7.23 +/- 1.15 MPa) (p < 0.05) and comparable with that of normal human skin. Thus the novel chitosan-gelatin blend nanofiber system has potential application in skin regeneration. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20524203 [PubMed - in process] | | |
| Acetaldehyde plasma polymer-coated PET fibers for endothelial cell patterning: Chemical, topographical, and biological analysis.
June 5, 2010 at 6:49 AM
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| | Acetaldehyde plasma polymer-coated PET fibers for endothelial cell patterning: Chemical, topographical, and biological analysis. J Biomed Mater Res B Appl Biomater. 2010 Jul;94(1):11-21 Authors: Hadjizadeh A The objective of this study was to produce fibrous biomaterials with cell adhesive and cell repulsive capabilities for biomedical applications. To this aim, the surface of 100-mum diameter polyethylene terephthalate fibers were functionalized with acetaldehyde plasma polymer deposition followed by carboxymethyl dextran grafting onto the aldehyde-coated surfaces via a polyethyleneimine interlayer. The performance of the surface modification steps were confirmed by surface chemical composition analysis using X-ray photoelectron spectroscopy, surface topography analysis by atomic force microscopy, and scanning electron microscopy. The acetaldehyde plasma polymer-coated and polyethyleneimine-grafted substrates promoted human umbilical vein endothelial cells attachment, spreading and actin filaments/focal adhesions formation. In contrast, carboxymethyl dextran-grafted substrates resisted cell adhesion. These observations demonstrate that the current surface-modified polymer fibers can be used in tissue engineering applications, such as cell patterning substrates or vascular prosthesis development. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20524180 [PubMed - in process] | | |
| Stimulus responsive peptide based materials.
June 5, 2010 at 6:49 AM
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| | Stimulus responsive peptide based materials. Chem Soc Rev. 2010 Jun 4; Authors: Löwik DW, Leunissen EH, van den Heuvel M, Hansen MB, van Hest JC In this tutorial review we give an introduction into the field of stimulus responsive peptide based materials illustrated by some recent and current developments. We have tried to categorize them according to the stimulus the materials are responsive to, being pH, temperature, metal ions, enzymes and light. Because we have focused on the structural changes that these stimuli effect we have further classified the topics according to the secondary structures that are involved. These changes in molecular structure in turn cause a change in the macroscopic properties of the material they constitute. It is believed that these materials, often referred to as smart materials, have a great potential being applicable in areas like drug delivery, tissue engineering and bio-sensors. PMID: 20523948 [PubMed - as supplied by publisher] | | |
| 3-dimensional structures to enhance cell therapy and engineer contractile tissue.
June 5, 2010 at 6:49 AM
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| | 3-dimensional structures to enhance cell therapy and engineer contractile tissue. Asian Cardiovasc Thorac Ann. 2010 Feb;18(2):188-98 Authors: Schussler O, Chachques JC, Mesana TG, Suuronen EJ, Lecarpentier Y, Ruel M Experimental studies in animals and recent human clinical trials have revealed the current limitations of cellular transplantation, which include poor cell survival, lack of cell engraftment, and poor differentiation. Evidence in animals suggests that use of a 3-dimensional scaffold may enhance cell therapy and engineer myocardial tissue by improving initial cell retention, survival, differentiation, and integration. Several scaffolds of synthetic or natural origin are under development. Until now, contractility has been demonstrated in vitro only in biological scaffolds prepared from decellularized organs or tissue, or in collagenic porous scaffold obtained by crosslinking collagen fibers. While contractility of a cellularized collagen construct is poor, it can be greatly enhanced by tumor basement membrane extract. Recent advances in biochemistry have shown improved cell-matrix interactions by coupling adhesion molecules to achieve an efficient and safe bioartificial myocardium with no tumoral component. Fixation of adhesion molecules may also be a way to enhance cell homing and/or differentiation to increase local angiogenesis. Whatever the clinically successful combination ultimately proves to be, it is likely that cell therapy will require providing a supportive biochemical, physical, and spatial environment that will allow the cells to optimally differentiate and integrate within the target myocardial tissue. PMID: 20304859 [PubMed - indexed for MEDLINE] | | |
| An in vitro model of biomaterial-augmented microfracture including chondrocyte-progenitor cell interaction.
June 5, 2010 at 6:49 AM
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| | An in vitro model of biomaterial-augmented microfracture including chondrocyte-progenitor cell interaction. Arch Orthop Trauma Surg. 2010 May;130(5):711-6 Authors: Vavken P, Arrich F, Pilz M, Dorotka R BACKGROUND: Biomaterials, acting as scaffolds for cell migration and differentiation, may be used to improve outcomes after microfracture. Three mechanisms determine the success of such procedures and are tested herein: the general capacity of adult femoral mesenchymal progenitor cells (MPC) to differentiate into cartilage, their capacity to do so in a biomaterial, and finally potential interactions between MPC and autologous chondrocytes. METHODS: Human adult chondrocytes and MPC were obtained with informed consent and cultured individually or in co-culture on a collagenous biomaterial. Differentiation potential of MPC was assessed using PCR and proliferation and biosynthesis were compared to test for differences between individual cultures and co-cultures. Finally, potential interaction between chondrocytes and MPC was assessed by comparing the observed levels of proliferation and biosynthesis with those expected in independent growth. RESULTS: We found that adult femoral marrow-derived MPC have the potential to differentiate into multiple lineages, and, seeded in a biomaterial, show similar differentiation when compared with autologous chondrocytes. Finally, there was a strong indication for an interaction between MPC and chondrocytes in biosynthetic activity, which was twice as high as would be expected in independent cell activity. Proliferation rates were unaffected. CONCLUSION: Our study showed that biomaterial-augmented microfracture is a viable option in cartilage repair from a biological perspective because adult femoral MPC have a strong capacity to differentiate into chondrocytes, which is further enhanced by the surrounding cartilage. Failure in in vivo studies must be explained by other factors of the intra-articular environment, such as cytokines or biomechanics. PMID: 20213450 [PubMed - indexed for MEDLINE] | | |
| Promotion of human adipose-derived stem cell proliferation mediated by exogenous nucleosides.
June 5, 2010 at 6:36 AM
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| | Promotion of human adipose-derived stem cell proliferation mediated by exogenous nucleosides. Cell Biol Int. 2010 Jun 3; Authors: RodrÃguez-Serrano F, Alvarez P, Caba O, Picón M, Marchal JA, Perán M, Prados J, Melguizo C, Rama AR, Boulaiz H, Aránega A Adult stem cells are becoming the best option for regenerative medicine because they have low tumorigenic potential and permit autologous transplantation, even without in vitro culture. Our objectives were to evaluate the effects of exogenous nucleosides on the proliferation of human adipose-derived stem cells (hASCs), with or without co-treatment with 5-azacytidine (5-aza), and to analyze the expression of lamin A/C during cardiomyocyte differentiation of these cells. We isolated hASCs from human lipoaspirates that were positive for mesenchymal stem cell markers. We found that 5-aza induces a dose-dependent inhibition of hASC proliferation (IC50: 5.37muM), whereas exogenous nucleosides significantly promote the proliferation of hASCs and partially revert the antiproliferative effect of the drug. Multipotentiality of isolated hASCs was confirmed by adipogenic, osteogenic, and cardiomyogenic induction. 5-aza-induced cells expressed cardiac troponins I and T and myosin light chain 2 myocardial markers that were directly correlated with lamin A/C expression. Our results support the importance of the nucleoside supplementation of media to improve conditions for the expansion and maintenance of hASCs in culture. In addition, the quantification of lamin A/C expression appears to be a good marker for the characterization of cardiomyocyte differentiation of stem cells that has rarely been used. PMID: 20522021 [PubMed - as supplied by publisher] | | |
| C-myc and N-myc in the developing brain.
June 5, 2010 at 6:10 AM
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| | C-myc and N-myc in the developing brain. Aging (Albany NY). 2010 May;2(5):261-2 Authors: Wey A, Knoepfler PS PMID: 20522921 [PubMed - in process] | | |
| IDENTIFICATION OF A NOVEL PUTATIVE PANCREATIC STEM/PROGENITOR CELL MARKER DCAMKL-1 IN NORMAL MOUSE PANCREAS.
June 5, 2010 at 6:10 AM
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| | IDENTIFICATION OF A NOVEL PUTATIVE PANCREATIC STEM/PROGENITOR CELL MARKER DCAMKL-1 IN NORMAL MOUSE PANCREAS. Am J Physiol Gastrointest Liver Physiol. 2010 Jun 3; Authors: May RJ, Sureban SM, Lightfoot SA, Hoskins AB, Brackett DJ, Postier RG, Ramanujam R, Rao CV, Wyche JH, Anant S, Houchen CW Stem cells are critical in maintaining adult homeostasis and have been proposed to be the origin of many solid tumors, including pancreatic cancer. Here we demonstrate the expression patterns of the putative intestinal stem cell marker DCAMKL-1 in the pancreas of uninjured C57BL/6 mice compared to other pancreatic stem/progenitor cell markers. We then determined the viability of isolated pancreatic stem/progenitor cells in isotransplantation assays following DCAMKL-1 antibody-based cell sorting. Sorted cells were grown in suspension culture and injected into the flanks of athymic nude mice. Here we report that DCAMKL-1 is expressed in the main pancreatic duct epithelia and islets, but not within acinar cells. Co-expression was observed with somatostatin, NGN3 and nestin, but not glucagon or insulin. Isolated DCAMKL-1+ cells formed spheroids in suspension culture and induced nodule formation in isotransplantation assays. Analysis of nodules demonstrated markers of early pancreatic development (PDX-1), glandular epithelium (cytokeratin-14 and Ep-CAM), and islet-like structures (somatostatin and secretin). These data taken together suggest that DCAMKL-1 is a novel putative stem/progenitor marker, can be used to isolate normal pancreatic stem/progenitors, and potentially regenerate pancreatic tissues. This may represent a novel tool for regenerative medicine and a target for anti-stem cell-based therapeutics in pancreatic cancer. PMID: 20522640 [PubMed - as supplied by publisher] | | |
| Promotion of human adipose-derived stem cell proliferation mediated by exogenous nucleosides.
June 5, 2010 at 6:10 AM
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| | Promotion of human adipose-derived stem cell proliferation mediated by exogenous nucleosides. Cell Biol Int. 2010 Jun 3; Authors: RodrÃguez-Serrano F, Alvarez P, Caba O, Picón M, Marchal JA, Perán M, Prados J, Melguizo C, Rama AR, Boulaiz H, Aránega A Adult stem cells are becoming the best option for regenerative medicine because they have low tumorigenic potential and permit autologous transplantation, even without in vitro culture. Our objectives were to evaluate the effects of exogenous nucleosides on the proliferation of human adipose-derived stem cells (hASCs), with or without co-treatment with 5-azacytidine (5-aza), and to analyze the expression of lamin A/C during cardiomyocyte differentiation of these cells. We isolated hASCs from human lipoaspirates that were positive for mesenchymal stem cell markers. We found that 5-aza induces a dose-dependent inhibition of hASC proliferation (IC50: 5.37muM), whereas exogenous nucleosides significantly promote the proliferation of hASCs and partially revert the antiproliferative effect of the drug. Multipotentiality of isolated hASCs was confirmed by adipogenic, osteogenic, and cardiomyogenic induction. 5-aza-induced cells expressed cardiac troponins I and T and myosin light chain 2 myocardial markers that were directly correlated with lamin A/C expression. Our results support the importance of the nucleoside supplementation of media to improve conditions for the expansion and maintenance of hASCs in culture. In addition, the quantification of lamin A/C expression appears to be a good marker for the characterization of cardiomyocyte differentiation of stem cells that has rarely been used. PMID: 20522021 [PubMed - as supplied by publisher] | | |
| Crystal Structure of the Apo Form of D-Alanine:D-Alanine Ligase (DDl) from Streptococcus mutans.
June 5, 2010 at 6:10 AM
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| | Crystal Structure of the Apo Form of D-Alanine:D-Alanine Ligase (DDl) from Streptococcus mutans. Protein Pept Lett. 2010 May 3; Authors: Lu Y, Xu H, Zhao X D-Alanine:D-Alanine ligase (DDl) catalyzes the formation of D-Alanine:D-Alanine dipeptide and is an essential enzyme in bacterial cell wall biosynthesis.. This enzyme does not have a human ortholog, making it an attractive target for developing new antibiotic drugs. We determined the crystal structure at 2.23 A resolution of DDl from Streptococcus mutans (SmDDl), the principal aetiological agent of human dental caries. This structure reveals that SmDDl is a dimer and has a disordered omega-loop region. PMID: 20522004 [PubMed - as supplied by publisher] | | | | 
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