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| CIRM Director Azziz Looking to Move to Georgia
February 23, 2010 at 5:36 PM
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| If you are interested in serving on the board of directors of the $3 billion California stem cell agency, you might want to get your application in early to Gov. Arnold Schwarzenneger. But if you don't work for Cedars of Sinai Medical Center in Los Angeles, you may be out of luck.
It appears that Ricardo Azziz, one of the governor's appointees, will soon be leaving for the Peach State. Azziz | | |
| Stem cell and progenitor cell therapy in peripheral artery disease. A critical appraisal.
February 23, 2010 at 6:52 AM
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| | Stem cell and progenitor cell therapy in peripheral artery disease. A critical appraisal. Thromb Haemost. 2010 Feb 19;103(4) Authors: Lawall H, Bramlage P, Amann B Atherosclerotic peripheral artery disease (PAD) is a common manifestation of atherosclerosis. The occlusion of large limb arteries leads to ischaemia with claudication which can progress to critical limb ischaemia (CLI) with pain at rest, and to tissue loss. At present, common therapy for CLI is either surgical or endovascular revascularisation aimed at improving blood flow to the affected extremity. However, major amputation and death are still frequent complications. Exploring new strategies for revascularisation of ischaemic limbs is thus of major importance. Bone marrow (BM)-derived stem and progenitor cells have been identified as a potential new therapeutic option to induce therapeutic angiogenesis. Encouraging results of preclinical studies have rapidly led to several small clinical trials, in which BM-derived mononuclear cells were administered to patients with limb ischaemia. Clinical benefits were reported from these trials including improvement of ankle! -brachial index (ABI), transcutaneous partial pressure of oxygen (TcPO2), reduction of pain, and decreased need for amputation. Nonetheless, large randomised, placebo-controlled, double-blind studies are necessary and currently ongoing (BONMOT-CLI, JUVENTUS and NCT00498069). Further research relates to the optimal cell type and dosage, the isolation method, the role of colony-stimulating factors, administration route, and the supportive stimulation of cells with reduced functioning due to advanced PAD. Autologous stem cell therapy for ischaemic peripheral disease seems to be a promising new tool for the treatment of severe limb ischaemia. Preliminary evidence has established its safety, feasibility and effectiveness on several important endpoints. Several large endpoints studies are underway to further consolidate this evidence. PMID: 20174766 [PubMed - as supplied by publisher] | | |
| Stem cell therapy for type 1 diabetes mellitus.
February 23, 2010 at 6:52 AM
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| | Stem cell therapy for type 1 diabetes mellitus. Nat Rev Endocrinol. 2010 Mar;6(3):139-48 Authors: Aguayo-Mazzucato C, Bonner-Weir S The use of stem cells in regenerative medicine holds great promise for the cure of many diseases, including type 1 diabetes mellitus (T1DM). Any potential stem-cell-based cure for T1DM should address the need for beta-cell replacement, as well as control of the autoimmune response to cells which express insulin. The ex vivo generation of beta cells suitable for transplantation to reconstitute a functional beta-cell mass has used pluripotent cells from diverse sources, as well as organ-specific facultative progenitor cells from the liver and the pancreas. The most effective protocols to date have produced cells that express insulin and have molecular characteristics that closely resemble bona fide insulin-secreting cells; however, these cells are often unresponsive to glucose, a characteristic that should be addressed in future protocols. The use of mesenchymal stromal cells or umbilical cord blood to modulate the immune response is already in clinical trials; howe! ver, definitive results are still pending. This Review focuses on current strategies to obtain cells which express insulin from different progenitor sources and highlights the main pathways and genes involved, as well as the different approaches for the modulation of the immune response in patients with T1DM. PMID: 20173775 [PubMed - in process] | | |
| Toll-like receptor 2 mediates mesenchymal stem cell associated myocardial recovery and VEGF production following acute ischemia/reperfusion injury.
February 23, 2010 at 6:52 AM
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| | Toll-like receptor 2 mediates mesenchymal stem cell associated myocardial recovery and VEGF production following acute ischemia/reperfusion injury. Am J Physiol Heart Circ Physiol. 2010 Feb 19; Authors: Abarbanell AM, Wang Y, Herrmann JL, Weil BR, Poynter JA, Manukyan MC, Meldrum DR Toll-like receptor 2 (TLR2), a key component of the innate immune system, is linked to inflammation and myocardial dysfunction after ischemia/reperfusion injury (I/R). Treatment of the heart with mesenchymal stem cells (MSC) is known to improve myocardial recovery after I/R in part by paracrine factors such as VEGF. However, it is unknown whether TLR2 activation on the MSC affects MSC-mediated myocardial recovery and VEGF production. We hypothesized that knockout of TLR2 on the MSC (TLR2KO MSC) would: 1) improve MSC-mediated myocardial recovery and 2) increase myocardial and MSC VEGF release. Using the isolated heart perfusion system, Sprague-Dawley rat hearts were subjected to I/R and received one of three intracoronary treatments: vehicle, male wild-type MSC (MWT MSC) or TL2KO MSC. All treatments were performed immediately prior to ischemia, and heart function was measured continuously. Post-reperfusion, heart homogenates were analyzed for myocardial VEGF produc! tion. Contrary to our hypothesis, only MWT MSC treatment significantly improved recovery of left ventricular developed pressure (LVDP) and +/- dP/dt. In addition VEGF production was greatest in hearts treated with MWT MSC. To investigate MSC production of VEGF, MSC were activated with TNF in vitro, and the supernatants collected for ELISA. In vitro basal levels of MSC VEGF production were similar. However with TNF activation, MWT MSC produced significantly more VEGF, while activated TLR2KO MSC production of VEGF was unchanged. Finally, we observed that MWT MSC proliferated more rapidly than TLR2KO MSC. These data indicate that TLR2 may be essential to MSC mediated myocardial recovery and VEGF production. Key words: innate immunity, inflammation, stem cell therapy, paracrine signaling. PMID: 20173040 [PubMed - as supplied by publisher] | | |
| In vitro non-viral lipofectamine delivery of the gene for glial cell line-derived neurotrophic factor to human umbilical cord blood CD34+ cells.
February 23, 2010 at 6:52 AM
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| | In vitro non-viral lipofectamine delivery of the gene for glial cell line-derived neurotrophic factor to human umbilical cord blood CD34+ cells. Brain Res. 2010 Feb 17; Authors: Yu G, Borlongan CV, Ou Y, Stahl CE, Yu S, Bae E, Kaneko Y, Yang T, Yuan C, Fang L Using a lipofection technique, we explored a non-viral delivery of plasmid DNA encoding a rat pGDNF (glial cell line-derived neurotrophic factor) to CD34+ cells derived from human umbilical cord blood (HUCB) cells in order to obtain cells stably expressing the GDNF gene. The target gene GDNF was amplified from cortex cells of newborn Sprague Dawley rats by reverse-transcriptase polymerase chain reaction (RT-PCR) and inserted into vector pEGFP-N1 to construct the eukaryotic expression vector pEGFP/GDNF. The positive clones were identified by sequencing and endonuclease digestion. The expression of pEGFP/GDNF transfected HUCB cells CD34+ was examined by ELISA. Single fragment of 640bp was obtained after the rat GDNF cDNA was amplified by RT-PCR. Two fragments of about 4.3kb and 640pb were obtained after digestion of recombinant plasmid pEGFP/GDNF with XhoI/KpnI. The nucleic acid fragment of 640bp was confirmed to agree well with the sequence of GDNF gene published b! y GeneBank. The expression of GDNF mRNA and the level of GDNF from pEGFP/GDNF-transfected CD34+ cells were increased substantially, compared with pEGFP control plasmid transfected CD34+ cells (P<0.05). Moreover, co-culture of primary rat cells with the pEGFP/GDNF-transfected CD34+ cells promoted enhanced neuropotection against oxygen-glucose deprivation induced cell dysfunctions. The present results support the use of the non-viral plasmid liposome for therapeutic gene expression for stem cell therapy. PMID: 20171195 [PubMed - as supplied by publisher] | | |
| Functional testing of a tissue-engineered vocal fold cover replacement.
February 23, 2010 at 6:17 AM
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| | Functional testing of a tissue-engineered vocal fold cover replacement. Otolaryngol Head Neck Surg. 2010 Mar;142(3):438-440 Authors: Long JL, Neubauer J, Zhang Z, Zuk P, Berke GS, Chhetri DK OBJECTIVES: Tissue engineering may provide a treatment for severe vocal fold scars. This study quantifies mechanical properties and demonstrates vibration of a tissue-engineered vocal fold cover replacement. METHODS: Tissue-engineered constructs were produced from fibrin and adipose-derived stem cells. Optimized bilayered constructs contained epithelial and mesenchymal cell phenotypes in a stratified geometry. For comparison, homogeneous constructs did not have epithelial differentiation. Elastic modulus was determined using indentation. Immunohistochemical labeling for type I collagen was performed. A bilayered construct was also tested in phonation in an excised larynx model. RESULTS: Bilayered vocal fold cover replacements had indentation moduli similar to human vocal fold covers (mean construct modulus 6.8 kPa). Collagen deposition occurred in the middle of the construct. Homogeneous constructs had a mean modulus of 8.3 kPa, and collagen was concentrated at th! e surface. An excised larynx with unilateral vocal fold cover replacement phonated and exhibited mucosal waves at physiologic airflow. CONCLUSION: Bilayered tissue-engineered constructs were produced that exhibited indentation modulus, microstructure, and vibration similar to that exhibited by human vocal fold covers. PMID: 20172395 [PubMed - as supplied by publisher] | | |
| Use of Human Umbilical Cord Blood-Derived Progenitor Cells for Tissue-Engineered Heart Valves.
February 23, 2010 at 6:17 AM
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| | Use of Human Umbilical Cord Blood-Derived Progenitor Cells for Tissue-Engineered Heart Valves. Ann Thorac Surg. 2010 Mar;89(3):819-828 Authors: Sodian R, Schaefermeier P, Abegg-Zips S, Kuebler WM, Shakibaei M, Daebritz S, Ziegelmueller J, Schmitz C, Reichart B BACKGROUND: Tissue engineering of autologous heart valves with the potential to grow and to remodel represents a promising concept. Here we describe the use of cryopreserved umbilical cord blood-derived CD133(+) cells as a single cell source for the tissue engineering of heart valves. METHODS: After expansion and differentiation of CD133(+) cells, phenotypes were analyzed by immunohistochemistry and cryopreserved. Heart valve scaffolds fabricated from a biodegradable polymer (n = 8) were seeded with blood-derived myofibroblasts and subsequently coated with blood-derived endothelial cells. Afterward, the heart valve constructs were grown in a pulse duplicator system. Analysis of all heart valves, including histology, immunohistochemistry, electron microscopy, fluorescence imaging, and biochemical and biomechanical examination, was performed. RESULTS: The tissue-engineered heart valves showed endothelialized layered tissue formation including connective tissue betwe! en the inside and the outside of the scaffold. The notion of an intact endothelial phenotype was substantiated by fluorescence imaging studies of cellular nitric oxide production and Ca(2+) signaling. Electron microscopy showed that the cells had grown into the pores and formed a confluent tissue layer. Biochemical examination showed extracellular matrix formation (77% +/- 9% collagen of human pulmonary leaflet tissue [HPLT], 85% +/- 61% glycosaminoglycans of HPLT and 67% +/- 17% elastin of HPLT). CONCLUSIONS: Importantly, this study demonstrates in vitro generation of viable human heart valves based on CD133(+) cells derived from umbilical cord blood. These findings constitute a significant step forward in the development of new clinical strategies for the treatment of congenital defects. PMID: 20172137 [PubMed - as supplied by publisher] | | |
| Human immune responses to porcine xenogeneic matrices and their extracellular matrix constituents in vitro.
February 23, 2010 at 6:17 AM
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| | Human immune responses to porcine xenogeneic matrices and their extracellular matrix constituents in vitro. Biomaterials. 2010 Feb 18; Authors: Bayrak A, Tyralla M, Ladhoff J, Schleicher M, Stock UA, Volk HD, Seifert M Several tissue engineering approaches for the treatment of cardiovascular diseases are based on a xenogeneic extracellular matrix. However, the application of engineered heart valves has failed in some patients, causing severe signs of inflammation by so far undetermined processes. Therefore we investigated the immune-mediated responses to porcine valve matrices (native, decellularized and glutaraldehyde-fixed) and to purified xenogeneic extracellular matrix proteins (ECMp). The induction of human immune responses in vitro was evaluated by analyzing the co-stimulatory effects of matrices and ECMp collagen and elastin on the proliferation of immune cell sub-populations via CFSE-based proliferation assays. The pattern of cytokine release was also determined. In porcine matrix punches we demonstrated strong immune responses with the native as well as the decellularized type, in contrast to attenuated effects with glutaraldehyde-fixed matrices. Furthermore, our result! s indicate that collagen type I (porcine and human) and human elastin were able to elicit proliferation in co-stimulation with anti-CD3 antibody, accompanied by a strong release of Th1 cytokines (IFN-gamma, TNF-alpha). In contrast, porcine elastin did not elicit any response at all. This low immunogenic potential of porcine elastin suggests its suitability for the creation of new tissue engineering heart valve scaffolds in the future. PMID: 20171732 [PubMed - as supplied by publisher] | | |
| Island Osteoperiosteal Flap for Alveolar Bone Reconstruction.
February 23, 2010 at 6:17 AM
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| | Island Osteoperiosteal Flap for Alveolar Bone Reconstruction. J Oral Maxillofac Surg. 2010 Mar;68(3):539-546 Authors: Jensen OT, Mogyoros R, Owen Z, Cottam JR, Alterman M, Casap N The island osteoperiosteal flap (I-flap) is introduced as a modified alveolar split bone grafting technique used to gain width and modify the facial or buccal bone plate position. Three case examples are shown as well as animal histology indicating the possible development of this new surgical procedure as an adjunct for alveolar augmentation and implant therapy. PMID: 20171473 [PubMed - as supplied by publisher] | | |
| CRTAC1 homolog proteins are conserved from cyanobacteria to man and secreted by the teleost fish pituitary gland.
February 23, 2010 at 6:17 AM
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| | CRTAC1 homolog proteins are conserved from cyanobacteria to man and secreted by the teleost fish pituitary gland. Gene. 2010 Feb 17; Authors: Redruello B, Louro B, Anjos L, Silva N, Greenwell RS, Canario AV, Power DM Cartilage acidic protein 1 (CRTAC1) gene expression is used as a marker for chondrocyte differentiation in stem-cell based tissue engineering. It is also transcribed outside the skeleton where at least two different transcripts are expressed in lung and brain. In the pituitary gland of the teleost fish sea bream Sparus auratus we have found a transcript with a high degree of sequence identity to CRTAC1 family members but lacking the EGF-like calcium binding domain encoding sequence of CRTAC1 and designated it as CRTAC2. Database searches revealed many previously unidentified members of the CRTAC1 and CRTAC2 in phylogenetically distant organisms, such as cyanobacteria, bryophyta, lancelets and diverse representatives of vertebrates. Phylogenetic analyses showed that the genes encoding CRTAC1 and CRTAC2 proteins co-exist in teleost fish genomes. Structural prediction analysis identified the N-terminal region of the CRTAC1/CRTAC2 family members as a potential seven b! laded beta-propeller structure, closely related to those of integrin alpha chains and glycosylphosphatidylinositol specific phospholipase D1 protein families. This relationship is confirmed by phylogenetic analysis with the N-terminal domain of sea bream CRTAC2 as the most divergent sequence. Since teleost fishes are the only phylogenetic group where both CRTAC1 and CRTAC2 genes are present, they occupy a pivotal position in studies of the mechanisms governing the specific expression patterns of each gene/protein subfamily. This will be essential to elucidate their respective biological roles. PMID: 20171266 [PubMed - as supplied by publisher] | | |
| In vivo engineering of a functional tendon sheath in a hen model.
February 23, 2010 at 6:17 AM
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| | In vivo engineering of a functional tendon sheath in a hen model. Biomaterials. 2010 Feb 17; Authors: Xu L, Cao D, Liu W, Zhou G, Zhang WJ, Cao Y Repair of injured tendon sheath remains a major challenge and this study explored the possibility of in vivo reconstruction of a tendon sheath with tendon sheath derived cells and polyglycolic acid (PGA) fibers in a Leghorn hen model. Total 55 Leghorn hens with a 1cm tendon sheath defect created in the left middle toe of each animal were randomly assigned into: (1) experimental group (n=19) that received a cell-PGA construct; (2) scaffold control group (n=18) that received a cell-free PGA scaffold; (3) blank control group (n=18) with the defect untreated. Tendon sheath cells were isolated, in vitro expanded, and seeded onto PGA scaffolds. After in vitro culture for 7 days, the constructs were in vivo implanted to repair the sheath defects. Alcian blue staining confirmed the ability of cultured cells to produce specific matrices containing acidic carboxyl mucopolysaccharide (mainly hyaluronic acid). In addition, the engineered sheath formed a relatively mature stru! cture at 12 weeks post-surgery, which was similar to that of native counterpart, including a smooth inner surface, a well-developed sheath histological structure with a clear space between the tendon and the engineered sheath. More importantly, Work of Flexion assay revealed that the tendons needed less power consumption to glide inside the engineered sheath when compared to the tendons which were surrounded by scar-repaired tissues, indicating that the engineered sheaths had gained the function to a certain extent of preventing tendon adhesion. Taken together, these results suggest that tendon sheaths that are functionally and structurally similar to native sheaths are possible to be engineered in vivo using tendon sheath cells and PGA scaffolds. PMID: 20170958 [PubMed - as supplied by publisher] | | |
| Pre-vascularization of in vitro three-dimensional tissues created by cell sheet engineering.
February 23, 2010 at 6:17 AM
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| | Pre-vascularization of in vitro three-dimensional tissues created by cell sheet engineering. Biomaterials. 2010 Feb 17; Authors: Asakawa N, Shimizu T, Tsuda Y, Sekiya S, Sasagawa T, Yamato M, Fukai F, Okano T Reconstructing a vascular network is a common task for three-dimensional (3-D) tissue engineering. Three-dimensional stratified tissues were created by stacking cell sheets, and the co-culture with endothelial cells (ECs) in the tissues was found to lead to in vitro pre-vascular network formation and promoted in vivo neovascularization after their transplantation. In this study, to clarify the effect of tissue fabrication process on a pre-vascular network formation, human origin ECs were introduced into the stratified tissue in several different ways, and the behavior of ECs in various positions of the 3-D tissue were compared each other. Human umbilical vein endothelial cells (HUVECs), normal human dermal fibroblasts (NHDFs), and their mixture were harvested as an intact cell sheet from temperature-responsive culture dish at low-temperature (<20 degrees C). Single mono-culture EC sheet was stacked with two NHDF-sheets in different orders, and 3 co-cultured cel! l sheets were layered by a cell sheet collecting device. Morphological analyses revealed that pre-vascular networks composing of HUVECs were formed in all the triple layer constructs. Confocal microscope observation showed that the pre-vascular networks formed tube structures like a native microvasculature. These data indicate that the primary EC positioning in 3-D tissues may be critical for vascular formation. PMID: 20170957 [PubMed - as supplied by publisher] | | |
| Thermogelling chitosan and collagen composite hydrogels initiated with beta-glycerophosphate for bone tissue engineering.
February 23, 2010 at 6:17 AM
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| | Thermogelling chitosan and collagen composite hydrogels initiated with beta-glycerophosphate for bone tissue engineering. Biomaterials. 2010 Feb 17; Authors: Wang L, Stegemann JP Chitosan and collagen type I are naturally derived materials used as cell carriers because of their ability to mimic the extracellular environment and direct cell function. In this study beta-glycerophosphate (beta-GP), an osteogenic medium supplement and a weak base, was used to simultaneously initiate gelation of pure chitosan, pure collagen, and chitosan-collagen composite materials at physiological pH and temperature. Adult human bone marrow-derived stem cells (hBMSC) encapsulated in such hydrogels at chitosan/collagen ratios of 100/0, 65/35, 25/75, and 0/100wt% exhibited high viability at day 1 after encapsulation, but DNA content dropped by about half over 12 days in pure chitosan materials while it increased twofold in materials containing collagen. Collagen-containing materials compacted more strongly and were significantly stiffer than pure chitosan gels. In monolayer culture, exposure of hBMSC to beta-GP resulted in decreased cell metabolic activity that! varied with concentration and exposure time, but washing effectively removed excess beta-GP from hydrogels. The presence of chitosan in materials resulted in higher expression of osterix and bone sialoprotein genes in medium with and without osteogenic supplements. Chitosan also increased alkaline phosphatase activity and calcium deposition in osteogenic medium. Chitosan-collagen composite materials have potential as matrices for cell encapsulation and delivery, or as in situ gel-forming materials for tissue repair. PMID: 20170955 [PubMed - as supplied by publisher] | | |
| Intra-uterine tissue engineering of full-thickness skin defects in a fetal sheep model.
February 23, 2010 at 6:17 AM
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| | Intra-uterine tissue engineering of full-thickness skin defects in a fetal sheep model. Biomaterials. 2010 Feb 17; Authors: Hosper NA, Eggink AJ, Roelofs LA, Wijnen RM, van Luyn MJ, Bank RA, Harmsen MC, Geutjes PJ, Daamen WF, van Kuppevelt TH, Tiemessen DM, Oosterwijk E, Crevels JJ, Blokx WA, Lotgering FK, van den Berg PP, Feitz WF In spina bifida the neural tube fails to close during the embryonic period and it is thought that prolonged exposure of the unprotected spinal cord to the amniotic fluid during pregnancy causes additional neural damage. Intra-uterine repair might protect the neural tissue from exposure to amniotic fluid and might reduce additional neural damage. Biodegradable collagen scaffolds may be useful in case of fetal therapy for spina bifida, but biochemical properties need to be studied. The aim of this study was to investigate whether biodegradable collagen scaffolds can be used to treat full-thickness fetal skin defects. We hypothesized that the pro-angiogenic growth factors VEGF and FGF2 would enhance vascularization, epidermialization and lead to improved wound healing. To investigate the effect of these two growth factors, a fetal sheep model for skin defects was used. Compared to wounds treated with bare collagen scaffolds, wounds treated with growth factor-loaded s! caffolds showed excessive formation of capillaries and less myofibroblasts were present in these wounds, leading to less contraction. This study has demonstrated that collagen scaffolds can be used to treat fetal skin defects and that the combination of collagen scaffolds with VEGF and FGF2 had a beneficial effect on wound healing. PMID: 20170954 [PubMed - as supplied by publisher] | | |
| Enzymatically degradable poly(ethylene glycol) based hydrogels for adipose tissue engineering.
February 23, 2010 at 6:17 AM
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| | Enzymatically degradable poly(ethylene glycol) based hydrogels for adipose tissue engineering. Biomaterials. 2010 Feb 17; Authors: Brandl FP, Seitz AK, Teßmar JK, Blunk T, Göpferich AM Adipose tissue engineering requires biomaterials that promote the differentiation of seeded adipocytes. Here, we report on the development and characterization of in situ forming, poly(ethylene glycol) (PEG) based hydrogels for soft tissue augmentation. Branched PEG-amines were modified with collagenase-sensitive peptides and cross-linked with branched PEG-succinimidyl propionates without the use of free-radical initiators (enzymatically degradable hydrogels). Alanine-modified PEG-amines were used for the preparation of non-degradable gels. Depending on the used polymer concentration, the strength of degradable gels after swelling ranged from 1708 to 7412Pa; the strength of non-degradable hydrogels varied between 1496 and 7686Pa. Enzyme mediated gel degradation occurred within 10, 16, and 19 days (5%, 10%, and 15% initial polymer content). To evaluate their suitability as scaffold materials for adipose tissue engineering, the hydrogels were functionalized with the! laminin-derived adhesion peptide YIGSR, and seeded with 3T3-L1 preadipocytes. Compared to a standard two-dimensional cell culture model, the developed hydrogels significantly enhanced the intracellular triglyceride accumulation of encapsulated adipocytes. Functionalization with YIGSR further enhanced lipid synthesis within differentiating adipocytes. Long-term studies suggested that enzymatically degradable hydrogels furthermore promote the formation of coherent adipose tissue-like structures featuring many mature unilocular fat cells. PMID: 20170951 [PubMed - as supplied by publisher] | | |
| Influences of Tensile Load on in vitro Degradation of Electrospun Poly(L-Lactide-co-Glycolide) Scaffold.
February 23, 2010 at 6:17 AM
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| | Influences of Tensile Load on in vitro Degradation of Electrospun Poly(L-Lactide-co-Glycolide) Scaffold. Acta Biomater. 2010 Feb 16; Authors: Li P, Feng X, Jia X, Fan Y The scaffolds for tissue engineering, regenerative medicine and implantation are usually subjected to different mechanical loads during invitro or in vivo degradation. In this study, invitro degradation procedures of electrospun poly(L-lactide-co-glycolide) (PLGA) scaffolds were examined under continuous tensile load in comparison with that under no load. While PLGA degraded in phosphate buffered saline solution (pH, 7.4) at 37 degrees C over a 7-week period, the tensile elastic modulus and ultimate strength of loaded specimen increased dramatically, then followed by a decreasing tendency which was much faster than that of unloaded, whereas the break elongation of loaded ones declined quicker during the whole degradation time. Moreover, changes in molecular weight, thermal properties and lactic acid release showed a more remarkable degradation behavior under load. And the ruptured morphologies were more obvious after degradation under tensile load. The results dem! onstrated that the tensile load increased the degradation rate of electrospun PLGA and it may be highly necessary to consider the effect of mechanical load when designing or applying the biodegradable scaffold. Finally, some possible explanations to the faster degradation under load were given. PMID: 20170760 [PubMed - as supplied by publisher] | | |
| Development of a porcine bladder acellular matrix with well preserved extracellular bioactive factors for tissue engineering.
February 23, 2010 at 6:17 AM
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| | Development of a porcine bladder acellular matrix with well preserved extracellular bioactive factors for tissue engineering. Tissue Eng Part C Methods. 2010 Feb 22; Authors: Yang B, Zhang Y, Zhou LH, Sun ZY, Zheng JH, Chen Y, Dai YT In this study, we compared four decellularization protocols and finally developed an optimized one through which a porcine bladder acellular matrix (BAM) with well preserved extracellular bioactive factors had been prepared. In this protocol, the intact bladder was treated with trypsin/EDTA to remove the urothelium, then with hypotonic buffer and Triton X-100 in hypertonic buffer to remove the membranous and cytoplasmic materials and finally with nuclease to degrade the cellular nuclear components. Bladder distention and mechanical agitation were simultaneously used to facilitate cell removal. Meanwhile, several preservative techniques, including limitation of wash time, supplement with inhibitors of proteinase, control of the pH value and temperature of the wash buffer, ethylene oxide sterilization and lyophilization of the scaffold for storage, were used to protect the extracellular bioactive factors. This decellularization protocol had completely removed the ce! llular materials and well preserved the extracellular collagen, sulfated glycosaminoglycan (GAG) and bioactive factors. The preserved bioactive factors had a great potential of promoting the proliferation and migration of both human bladder smooth muscle cell and human umbilical vein endothelial cell. It was also found that the amount of two representative bioactive factors, platelet-derived growth factor BB (PDGF-BB) and vascular endothelial growth factor (VEGF), was positively correlated with the sulfated GAG content in the porcine BAM, implying that the amount of sulfated GAG might be a determinant for preservation of bioactive factors in the decellularized tissues. In conclusion, the porcine BAM with well preserved extracellular bioactive factors might be a favorable scaffold for tissue engineering applications. PMID: 20170425 [PubMed - as supplied by publisher] | | |
| Chimeric composite skin substitutes for delivery of autologous keratinocytes to promote tissue regeneration.
February 23, 2010 at 6:17 AM
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| | Chimeric composite skin substitutes for delivery of autologous keratinocytes to promote tissue regeneration. Ann Surg. 2010 Feb;251(2):368-76 Authors: Rasmussen CA, Gibson AL, Schlosser SJ, Schurr MJ, Allen-Hoffmann BL OBJECTIVE: We hypothesize that the pathogen-free NIKS human keratinocyte progenitor cell line cultured in a chimeric fashion with patient's primary keratinocytes would produce a fully stratified engineered skin substitute tissue and serve to deliver autologous keratinocytes to a cutaneous wound. SUMMARY OF BACKGROUND DATA: Chimeric autologous/allogeneic bioengineered skin substitutes offer an innovative regenerative medicine approach for providing wound coverage and restoring cutaneous barrier function while delivering autologous keratinocytes to the wound site. NIKS keratinocytes are an attractive allogeneic cell source for this application. METHODS: Mixed populations of green fluorescent protein (GFP)-labeled NIKS and unlabeled primary keratinocytes were used to model the allogeneic and autologous components in chimeric monolayer and organotypic cultures. RESULTS: In monolayer coculture, GFP-labeled NIKS had no effect on the growth rate of primary keratinocytes ! and cell-cell junction formation between labeled and unlabeled keratinocytes was observed. In organotypic culture employing dermal and epidermal compartments, chimeric composite skin substitutes generated using up to 90% GFP-labeled NIKS exhibited normal tissue architecture and possessed substantial regions attributable to the primary keratinocytes. Tissues expressed proteins essential for the structure and function of a contiguous, fully-stratified squamous epithelia and exhibited barrier function similar to that of native skin. Furthermore, chimeric human skin substitutes stably engrafted in an in vivo mouse model, with long-term retention of primary keratinocytes but loss of the GFP-labeled NIKS population by 28 days after surgical application. CONCLUSIONS: This study provides proof of concept for the use of NIKS keratinocytes as an allogeneic cell source for the formation of bioengineered chimeric skin substitute tissues, providing immediate formal wound coverage while ! simultaneously supplying autologous cells for tissue regenerat! ion. PMID: 20010085 [PubMed - indexed for MEDLINE] | | |
| The influence of rat mesenchymal stem cell CD44 surface markers on cell growth, fibronectin expression, and cardiomyogenic differentiation on silk fibroin - Hyaluronic acid cardiac patches.
February 23, 2010 at 6:17 AM
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| | The influence of rat mesenchymal stem cell CD44 surface markers on cell growth, fibronectin expression, and cardiomyogenic differentiation on silk fibroin - Hyaluronic acid cardiac patches. Biomaterials. 2010 Feb;31(5):854-62 Authors: Yang MC, Chi NH, Chou NK, Huang YY, Chung TW, Chang YL, Liu HC, Shieh MJ, Wang SS Since MSCs contain an abundant of CD44 surface markers, it is of interesting to investigate whether CD44 on rat MSC (rMSCs) influenced cell growth, fibronectin expression and cardiomyogenic differentiation on new SF/HA cardiac patches. For this investigation, we examined the influences of rMSCs with or without a CD44-blockage treatment on the aforementioned issues after they were cultivated, and further induced by 5-aza on SF and SF/HA patches. The results showed that the relative growth rates of rMSCs cultured on cultural wells, SF/HA patches without or with a CD44-blockage treatment were 100%, 208.9+/-7.1 (%) or 48.4+/-6.0 (%) (n=3, for all), respectively, after five days of cultivations. Moreover, rMSCs cultivated on SF/HA patches highly promoted fibronectin expressions (e.g., 1.8x10(5)/cell, in fluorescent intensity) while cells with a CD44-blockage treatment markedly diminished the expressions (e.g., 1.1x10(4)/cell, in fluorescent intensity) on same patches. ! For investigating possible influences of CD44 surface markers of rMSCs on their cardiomyogenic differentiation, the expressions of specific cardiac genes of cells were examined by using real-time PCR analysis. The results indicated that 5-aza inducing rMSCs significantly promoted the expressions of Gata4, Nkx2.5, Tnnt2 and Actc1 genes (all, P<0.01 or better, n=3) on SF/HA patches compared with those expressions on SF patches and for cells with a CD44-blockage treatment on SF/HA patches. Furthermore, the intensity of the expressions of cardiotin and connexin 43 of 5-aza inducing rMSCs were markedly higher than those of cells with a CD44-blockage treatment after they were cultured on SF/HA patches. Through this study, we reported that CD44 surface markers of rMSCs highly influenced the proliferations, fibronectin expressions and cardiomyogenic differentiation of rMSCs cultivated on cardiac SF/HA patches. PMID: 19857893 [PubMed - indexed for MEDLINE] | | |
| Non-haematological uses of cord blood stem cells.
February 23, 2010 at 6:17 AM
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| | Non-haematological uses of cord blood stem cells. Br J Haematol. 2009 Oct;147(2):177-84 Authors: Harris DT Embryonic stem (ES) cell therapies are often promoted as the optimal stem cell source for regenerative medicine applications because of their ability to develop into any tissue in the body. Unfortunately, ES cell applications are currently limited by ethical, political, biological and regulatory hurdles. However, multipotent non-ES cells are available in large numbers in umbilical cord blood (CB). CB stem cells are capable of giving rise to hematopoietic, epithelial, endothelial and neural tissues both in vitro and in vivo. Thus, CB stem cells are amenable to treat a wide variety of diseases including cardiovascular, ophthalmic, orthopaedic, neurological and endocrine diseases. In addition, the recent use of CB in several regenerative medicine clinical studies has demonstrated its pluripotent nature. Here we review the latest developments in the use of CB in regenerative medicine. Examples of these usages include cerebral palsy and type I diabetes. The numbers of ! individuals affected with each of these diseases are estimated at 10 000 infants diagnosed with cerebral palsy annually and 15 000 youths diagnosed with type 1 diabetes annually. A summary of the initial results from such clinical studies using autologous cord blood stem cells will be presented. PMID: 19796266 [PubMed - indexed for MEDLINE] | | | | 
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