| Effects of mechanical loading on collagen propeptides processing in cartilage repair.
October 21, 2009 at 10:05 am
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| | Effects of mechanical loading on collagen propeptides processing in cartilage repair. J Tissue Eng Regen Med. 2009 Oct 19; Authors: Hardmeier R, Redl H, Marlovits S Injured articular cartilage has poor reparative capabilities and if left untreated may develop into osteoarthritis. Unsatisfactory results with conventional treatment methods have brought as an alternative treatment the development of matrix autologous chondrocyte transplants (MACTs). Recent evidence proposes that the maintenance of the original phenotype by isolated chondrocytes grown in a scaffold transplant is linked to mechanical compression, because macromolecules, particularly collagen, of the extracellular matrix have the ability to 'self-assemble'. In load-bearing tissues, collagen is abundantly present and mechanical properties depend on the collagen fibre architecture. Study of the active changes in collagen architecture is the focus of diverse fields of research, including developmental biology, biomechanics and tissue engineering. In this review, the structural model of collagen assembly is presented in order to understand how scaffold geometry plays a critical role in collagen propeptide processing and chondrocyte development. When physical forces are applied to different cell-based scaffolds, the resulting specific twist of the scaffolds might be accompanied by changes in the fibril pattern synthesis of the new collagen. The alteration in the scaffolds due to mechanical stress is associated with cellular signalling communication and the preservation of N-terminus procollagen moieties, which would regulate both the collagen synthesis and the diameter of the fibre. The structural difference would also affect actin stabilization, cytoskeleton remodelling and proteoglycan assembly. These effects seemed to be dependent on the magnitude and duration of the physical stress. This review will contribute to the understanding of mechanisms for collagen assembly in both a natural and an artificial environment. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19842116 [PubMed - as supplied by publisher] |
| Human cell culture process capability: a comparison of manual and automated production.
October 21, 2009 at 10:05 am
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| | Human cell culture process capability: a comparison of manual and automated production. J Tissue Eng Regen Med. 2009 Oct 19; Authors: Liu Y, Hourd P, Chandra A, Williams DJ Cell culture is one of the critical bioprocessing steps required to generate sufficient human-derived cellular material for most cell-based therapeutic applications in regenerative medicine. Automated cell expansion is fundamental to the development of scaled, robust and cost effective commercial production processes for cell-based therapeutic products. This paper describes the first application of process capability analysis to establish and compare the short-term process capability of manual and automated processes for the in vitro expansion of a selected anchorage-dependent cell line. Estimates of the process capability indices (Cp, Cpk) have been used to assess the ability of both processes to consistently meet the requirements for a selected productivity output and to direct process improvement activities. Point estimates of Cp and Cpk show that the manual process has poor capability (Cp = 0.55, Cpk = 0.26) compared to the automated process (Cp = 1.32, Cpk = 0.25), resulting from excess variability. Comparison of point estimates, which shows that Cpk < Cp, indicates that the automated process mean was off-centre and that intervention is required to adjust the location of the process mean. A process improvement strategy involving an adjustment to the automated process settings has demonstrated in principle that the process mean can be shifted closer to the centre of the specification to achieve an estimated seven-fold improvement in process performance. In practice, the 90% confidence bound estimate of Cp (Cp = 0.90) indicates that that once the process is centred within the specification, a further reduction of process variation is required to attain an automated process with the desired minimum capability requirement. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19842115 [PubMed - as supplied by publisher] |
| A tissue-like construct of human bone marrow MSCs composite scaffold support in vivo ectopic bone formation.
October 21, 2009 at 10:05 am
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| | A tissue-like construct of human bone marrow MSCs composite scaffold support in vivo ectopic bone formation. J Tissue Eng Regen Med. 2009 Oct 19; Authors: Ben-David D, Kizhner T, Livne E, Srouji S Biocompatible and osteoconductive cell-scaffold constructs comprise the first and most important step towards successful in vivo bone repair. This study reports on a new cell-scaffold construct composed of gelatin-based hydrogel and ceramic (CaCO(3)/beta-TCP) particles loaded with human MSCs producing a tissue-like construct applied as a transplant for in vivo bone formation. Bone marrow-derived human MSCs were cultured in osteogenic induction medium. 5 x 10(5) (P(2)) cells were loaded on a mixture of hydrogel microspheres and ceramic particles, cultured in a rotating dynamic culture for up to 3 weeks. Both hydrogel microspheres and ceramic particles coalesced together to form a tissue-like construct, shown by histology to contain elongated spindle-like cells forming the new tissue between the individual particles. Cell proliferation and cell viability were confirmed by Alamar blue assay and by staining with CFDA, respectively. FACS analysis conducted before loading the cells, and after formation of the construct, revealed that the profile of cell surface markers remained unchanged throughout the dynamic culture. The osteogenic potential of the cells composing the tissue-like construct was further validated by subcutaneous transplants in athymic nude mice. After 8 weeks a substantial amount of new bone formation was observed in the cell-construct transplants, whereas no bone formation was observed in transplants containing no cells. This new cell construct provides a system for in vivo bone transplants. It can be tailored for a specific size and shape as needed for various transplant sites and for all aspects of regenerative medicine and biomaterial science. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19842114 [PubMed - as supplied by publisher] |
| Expansion of human mesenchymal stromal cells on microcarriers: growth and metabolism.
October 21, 2009 at 10:05 am
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| | Expansion of human mesenchymal stromal cells on microcarriers: growth and metabolism. J Tissue Eng Regen Med. 2009 Oct 19; Authors: Schop D, van Dijkhuizen-Radersma R, Borgart E, Janssen FW, Rozemuller H, Prins HJ, de Bruijn JD Adult stem cells, or mesenchymal stromal cells (MSCs), are of great potential for cell therapy and tissue-engineering applications. However, for therapeutic use, these cells need to be isolated from tissue or a biopsy and efficiently expanded, as they cannot be harvested in sufficient quantities from the body. In our opinion, efficient expansion of MSCs can be achieved in a microcarrier-based cultivation system. This study selected a suitable microcarrier for human bone marrow-derived stromal cells (HBMSCs), optimized cell-seeding strategies by varying serum concentrations, and optimized dynamic expansion of the HBMSCs in a microcarrier-based spinner flask cultivation system by applying various feeding regimes. Cytodex 1 microcarriers in combination with a low-serum concentration (0-5%) in the medium resulted in the highest seeding efficiency for the HBMSCs. Subsequently, significant expansion of the HBMSCs on these carriers has been observed. The highest number of HBMSCs population doublings (4.8 doublings) was obtained by a combination of 50% medium refreshment combined with addition of 30% medium containing microcarriers every 3 days. Exponential cell growth was observed for at least 9 days after seeding, provided that sufficient nutrients (such as glucose) were present, metabolite concentrations (such as ammonia) were kept below growth-inhibitory concentrations and adequate surface area was present for the cells. After dynamic expansion of the HBMSCs, the cells retained their differentiation potential and their cell surface markers, indicating that HBMSCs expansion on Cytodex 1 microcarriers did not alter the phenotypic properties of the cells. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19842106 [PubMed - as supplied by publisher] |
| Supercritical phase inversion of starch-poly(epsilon-caprolactone) for tissue engineering applications.
October 21, 2009 at 10:05 am
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| | Supercritical phase inversion of starch-poly(epsilon-caprolactone) for tissue engineering applications. J Mater Sci Mater Med. 2009 Oct 20; Authors: Duarte AR, Mano JF, Reis RL In this work, a starch-based polymer, namely a blend of starch-poly(epsilon-caprolactone) was processed by supercritical assisted phase inversion process. This processing technique has been proposed for the development of 3D structures with potential applications in tissue engineering applications, as scaffolds. The use of carbon dioxide as non-solvent in the phase inversion process leads to the formation of a porous and interconnected structure, dry and free of any residual solvent. Different processing conditions such as pressure (from 80 up to 150 bar) and temperature (45 and 55 degrees C) were studied and the effect on the morphological features of the scaffolds was evaluated by scanning electron microscopy and micro-computed tomography. The mechanical properties of the SPCL scaffolds prepared were also studied. Additionally, in this work, the in vitro biological performance of the scaffolds was studied. Cell adhesion and morphology, viability and proliferation was assessed and the results suggest that the materials prepared are allow cell attachment and promote cell proliferation having thus potential to be used in some for biomedical applications. PMID: 19842016 [PubMed - as supplied by publisher] |
| In sickness and in health: Corneal epithelial stem cell biology, pathology and therapy.
October 21, 2009 at 10:05 am
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| | In sickness and in health: Corneal epithelial stem cell biology, pathology and therapy. Exp Eye Res. 2009 Oct 16; Authors: Notara M, Alatza A, Gilfillan J, Harris A, Levis H, Schrader S, Vernon A, Daniels J Our window to the world is provided by the cornea on the front surface of the eye. The integrity and functionality of the outermost corneal epithelium is essential for vision. A population of limbal epithelial stem cells (LESCs) are responsible for maintaining the epithelium throughout life by providing a constant supply of daughter cells that replenish those constantly lost from the ocular surface during normal wear and tear and following injury. LESC deficiency leads to corneal opacification, inflammation, vascularisation and discomfort (Daniels et al., 2001; Daniels et al., 2007). Cultured LESC delivery is one of several examples of successful adult stem cell therapy in patients. The clinical precedence for use of stem cell therapy and the accessibility of the transparent stem cell niche make the cornea a unique model for the study of adult stem cells in physiological conditions as well as in disease. PMID: 19840786 [PubMed - as supplied by publisher] |
| Galanin is highly expressed in bone marrow mesenchymal stem cells and facilitates migration of cells both in vitro and in vivo.
October 21, 2009 at 10:05 am
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| | Galanin is highly expressed in bone marrow mesenchymal stem cells and facilitates migration of cells both in vitro and in vivo. Biochem Biophys Res Commun. 2009 Oct 16; Authors: Louridas M, Letourneau S, Lautatzis ME, Vrontakis M Galanin peptide has recently been found to be highly abundant in early embryonic mouse mesenhyme, while galanin and its receptors are expressed in embryonic mouse stem cells. Bone marrow mesenchymal stem cells (BMMSCs) represent the primary source for adult stem cell therapy. In the present study we examined the abundance of galanin and its receptors in BMMSCs and evaluated its possible function. Galanin mRNA and protein were highly expressed in BMMSCs cultures up to four passages, while among the three galanin receptor subtypes (GalR1, GalR2, and GalR3) only GalR2 and to a lesser extent GalR3 were expressed. Using chemotaxis and wound assays we found that galanin protein increased the migration of BMMSCs. Furthermore, increased serum galanin levels in a galanin transgenic model enhanced the mobilization (homing) of injected BMMSCs in vivo. These data suggest a role for galanin in BMMSC migration, probably through activation of the GalR2 receptor. PMID: 19840773 [PubMed - as supplied by publisher] |
| Effect of age and extrinsic microenvironment on the proliferation and osteogenic differentiation of rat dental pulp stem cells in vitro.
October 21, 2009 at 10:05 am
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| | Effect of age and extrinsic microenvironment on the proliferation and osteogenic differentiation of rat dental pulp stem cells in vitro. J Endod. 2009 Nov;35(11):1546-53 Authors: Ma D, Ma Z, Zhang X, Wang W, Yang Z, Zhang M, Wu G, Lu W, Deng Z, Jin Y INTRODUCTION: It is suggested that dental pulp stem cells (DPSCs) possess pluripotent differentiation and self-renewal capacity and play a crucial role in maintaining dental pulp homeostasis. However, little is known about the age-related changes of DPSCs, and whether aging and its microenvironment are associated with DPSCs remains a question. In this study, age-related changes in proliferation and osteogenic differentiation ability of rat DPSCs were assessed. METHODS: To examine the influence of microenvironment factors on different ages of DPSCs, we exposed adult rat DPSCs to juvenile rat dental pulp cell-conditioned medium (DPC-CM), and juvenile DPSCs were exposed to adult DPC-CM. Morphologic appearance, colony-forming assay, cell cycle analysis, 3-(4,5-dimethyl-thyazol-2-yl)-2,5-diphenyltetrazolium, gene expression, and mineralization assay after osteogenic induction of DPSCs were evaluated. RESULTS: DPSCs isolated from the juvenile donors displayed increased proliferation and decreased osteogenic differentiation ability compared with the adult DPSCs. Interestingly, adult DPSCs induced by juvenile DPC-CM demonstrated enhanced proliferation but decreased osteogenic differentiation ability, whereas DPSCs from juvenile donors induced by adult DPC-CM showed decreased proliferation but enhanced osteogenic differentiation ability. CONCLUSIONS: Our data suggest that age-related changes of DPSCs should be taken into account when DPSCs are intended to be used for investigations and application. Furthermore, the activity of DPSCs can be modulated by the extrinsic microenvironment. PMID: 19840645 [PubMed - in process] |
| Stem Cell Proliferation Pathways Comparison between Human Exfoliated Deciduous Teeth and Dental Pulp Stem Cells by Gene Expression Profile from Promising Dental Pulp.
October 21, 2009 at 10:05 am
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| | Stem Cell Proliferation Pathways Comparison between Human Exfoliated Deciduous Teeth and Dental Pulp Stem Cells by Gene Expression Profile from Promising Dental Pulp. J Endod. 2009 Nov;35(11):1536-42 Authors: Nakamura S, Yamada Y, Katagiri W, Sugito T, Ito K, Ueda M INTRODUCTION: Mesenchymal stem cells (MSCs) have been used for clinical application in tissue engineering and regenerative medicine (TERM). To date, the most common source of MSCs has been bone marrow. However, the bone marrow aspirate is an invasive and painful procedure for the donor. Thus, the identification and characterization of alternative sources of MSCs are of great importance. This study focused on the characterization of stem cells from human exfoliated deciduous teeth (SHED) compared with dental pulp stem cells (DPSCs) and bone marrow-derived mesenchymal stem cells (BMMSCs). METHODS: We have compared "stemness" such as the proliferation rate and the expression of stem cell marker of DPSCs, SHED, and BMMSCs. In addition, gene expression profile of DPSCs and SHED were analyzed by using DNA microarray. RESULTS: All cells isolated from the three sources exhibited MSC characteristics including a fibroblastic morphology, and the expression of mesenchymal stem-cell markers. The proliferation rate of SHED was significantly higher than that of DPSCs and BMMSCs (P < 0.05). The comparison of the gene expression profiles indicated 4386 genes with a changed expression between DPSCs and SHED by 2.0-fold or more. Higher expression in SHED was observed for genes that participate in pathways related to cell proliferation and extracellular matrix, including several cytokines such as fibroblast growth factor and tumor growth factor beta. CONCLUSIONS: Because of its advantages of a higher proliferation capability, abundant cell supply, and painless stem cell collection with minimal invasion, SHED could be a desirable option as a cell source for potential therapeutic applications. PMID: 19840643 [PubMed - in process] |
| [Structural Feature and Biological Function of PPP2R5C Gene.]
October 21, 2009 at 10:05 am
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| | [Structural Feature and Biological Function of PPP2R5C Gene.] Zhongguo Shi Yan Xue Ye Xue Za Zhi. 2009 Oct;17(5):1127-9 Authors: Li YQ, Zhou YB, Yang LJ PPP2R5C is one of the members of regulatory subunits of protein phosphatase 2A (PP2A), which plays a critical role in cell proliferation, differentiation and transformatiom, based on its induction of dephosphorylation of P53 at various residues. Recently, it was characterized that the alteration of expression pattern of PPP2R5C is associated with cell malignant transformation, thus PPP2R5C was thought as a marker for progressive disease in B-CLL. In this article the gene structure and biological function of PPP2R5C as well as relation of PPP2R5C with genesis and development of cancer were discussed. PMID: 19840435 [PubMed - in process] |
| Glomerular parietal epithelial cells of adult murine kidney undergo EMT to generate cells with traits of renal progenitors.
October 21, 2009 at 10:05 am
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| | Glomerular parietal epithelial cells of adult murine kidney undergo EMT to generate cells with traits of renal progenitors. J Cell Mol Med. 2009 Oct 16; Authors: Chandra V, Phadnis S, Bhonde R ABSTRACT Glomerular parietal epithelial cells (GPECs) are known to revert to embryonic phenotype in response to renal injury. However, the mechanism of de-differentiation in GPECs and the underlying cellular processes are not fully understood. In the present study, we show that cultured GPECs of adult murine kidney undergo epithelial-mesenchymal transition (EMT) to generate cells, which express CD24, CD44 and CD29 surface antigens. Characterization by qRT-PCR and immunostaining of these clonogenic cells demonstrate that they exhibit metastable phenotype with co-expression of both epithelial (cytokeratin-18) and mesenchymal (vimentin) markers. Transcript analysis by qRT-PCR revealed high expression of metanephric mesenchymal (Pax2, WT-1, SIX-1, EYA-1, GDNF) and uteric bud (Hoxb-7, C-RET) genes in these cells, indicating their bipotent progenitor status. Incubation of GPECs with EMT blocker Prostaglandin E2, resulted in low expression of renal progenitor markers reflecting the correlation between EMT and acquired stemness in these cells. Additional in vitro renal commitment assays confirmed their functional staminality. When injected into E13.5 kidney rudiments, the cells incorporated into the developing kidney primordia and co-culture with E13.5 spinal-cord resulted in branching and tubulogenesis in these cells. When implanted under renal capsule of unilaterally nephrectomised mice, these cells differentiated into immature glomeruli and vascular ducts. Our study demonstrates that EMT plays a major role in imparting plasticity to terminally differentiated GPECs by producing metastable cells with traits of kidney progenitors. The present study would improve our understanding on epithelial cell plasticity, furthering our knowledge of its role in renal repair and regeneration. PMID: 19840197 [PubMed - as supplied by publisher] |
| Growth Factor-Rich Plasma Increases Tendon Cell Proliferation and Matrix Synthesis on a Synthetic Scaffold: An In Vitro Study.
October 21, 2009 at 10:05 am
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| | Growth Factor-Rich Plasma Increases Tendon Cell Proliferation and Matrix Synthesis on a Synthetic Scaffold: An In Vitro Study. Tissue Eng Part A. 2009 Oct 20; Authors: Visser LC, Arnoczky SP, Caballero O, Kern A, Ratcliffe A, Gardner KL Numerous scaffolds have been proposed for use in connective tissue engineering. Although these scaffolds direct cell migration and attachment, many are biologically inert and thus lack the physiological stimulus to attract cells and induce mitogenesis and matrix synthesis. In the current study, a bioactive scaffold was created by combining a synthetic scaffold with growth factor-rich plasma (GFRP), an autologous concentration of growth factors derived from a platelet-rich plasma preparation. In vitro tendon cell proliferation and matrix synthesis on autologous GFRP-enriched scaffolds, autologous serum-enriched scaffolds, and scaffolds alone were compared. The GFRP preparation was found to have a 4.7-fold greater concentration of a sentinel growth factor (TGF-beta1) compared to serum. When combined with media containing calcium, the GFRP produced a thin fibrin matrix over and within the GFRP-enriched scaffolds. Cell proliferation assays demonstrated that GFRP-enriched scaffolds significantly enhanced cell proliferation over autologous serum and control groups at both 48 and 72 hours. Analysis of the scaffolds at 14, 21, and 28 days revealed that GFRP-enriched scaffolds significantly increased the deposition of a collagen-rich extracellular matrix when compared to the other groups. These results indicate that GFRP can be used to enhance in vitro cellular population and matrix deposition of tissue-engineered scaffolds. PMID: 19839921 [PubMed - as supplied by publisher] |
| Potential application of adult stem cells in retinal repair-challenge for regenerative medicine.
October 21, 2009 at 10:05 am
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| | Potential application of adult stem cells in retinal repair-challenge for regenerative medicine. Curr Eye Res. 2009 Sep;34(9):748-60 Authors: Machalińska A, Baumert B, Kuprjanowicz L, Wiszniewska B, Karczewicz D, Machaliński B Stem cells (SCs) maintain the balance among somatic cell populations in various tissues and are responsible for organ regeneration. The remarkable progress of regenerative medicine in the last few years indicates promise for the use of SCs in ophthalmic disorder treatment. This review describes the current view on hierarchy in the SC compartment and presents the latest attempts to use adult SCs in the regeneration of the retina. Research performed primarily in animal models gives hope for using similar strategies in humans. However, the search for the optimal source of SCs for cell therapy continues. We briefly discuss various potential sources of adult SCs that could be employed in regenerative medicine, particularly focusing on recently identified, very small embryonic-like SCs (VSEL-SCs). These cells are even present in the bone marrow and adult tissues of older patients and could be harvested from cord blood. We believe that VSEL-SCs, after the establishment of ex vivo expansion and differentiation protocols, could be harnessed for retina regeneration. PMID: 19839868 [PubMed - in process] |
| Magnetically modulated nanosystems: a unique drug-delivery platform.
October 21, 2009 at 10:05 am
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| | Magnetically modulated nanosystems: a unique drug-delivery platform. Nanomed. 2009 Oct;4(7):799-812 Authors: Barakat NS Magnetic nanoparticles are attractive targets owing to their unique characteristics that are not shared by bulk materials. Magnetic particles, ranging from nanometer-sized to 1 microm in size, are being used in an increasing number of medical applications. The important properties of magnetic particles for medical applications are nontoxicity, biocompatiblilty, injectability and high-level accumulation in the target tissue or organ. Magnetic nanoparticles modified with organic molecules have been widely used for biotechnological and biomedical applications as their properties can be magnetically controlled by applying an external magnetic field. They offer high potential for numerous biomedical applications, such as cell separation, automated DNA extraction, gene targeting, drug delivery, MRI and hyperthermia. When coated with, for example, an antibody, they can be applied in highly sensitive immunoassays or small substance recoveries. Furthermore, a novel application of magnetic nanoparticles and magnetic forces for tissue engineering, termed 'magnetic force-based tissue engineering' has been proposed. Particular attention had been paid to the preparation methods that allow the synthesis of particles of nearly uniform size and shape. PMID: 19839815 [PubMed - in process] |
| Conference Scene: Innovative medical devices and nanotechnology: 1-day interactive workshop.
October 21, 2009 at 10:05 am
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| | Conference Scene: Innovative medical devices and nanotechnology: 1-day interactive workshop. Nanomed. 2009 Oct;4(7):709-12 Authors: Moore R, Battaglia G The Institute of Nanotechnology, in collaboration with the University of Sheffield, organized this 1-day interactive workshop held at the Kroto Institute, Sheffield University North Campus, Sheffield, UK. The workshop provided a showcase of innovative and exciting new medical nanotechnologies. The topics addressed included diagnostics and imaging, tissue engineering, polymer therapeutics and drug delivery, and drug discovery and screening. The workshop was attended by clinicians, medical researchers, industry experts, healthcare managers, academics and students. The workshop was divided into four sessions: regenerative medicine and smart materials; innovations in medical diagnostics and sensing; new techniques for drug discovery and drug delivery; and novel therapeutics. A concluding talk was given by Richard Moore from the Institute of Nanotechnology on the importance of nanoscale hazard identification and risk management for medical nanotechnologies. PMID: 19839807 [PubMed - in process] |
| Distinctive Degradation Behaviors of Electrospun Polyglycolide, Poly(dl-Lactide-co-Glycolide), and Poly(l-Lactide-co-varepsilon-Caprolactone) Nanofibers Cultured With/Without Porcine Smooth Muscle Cells.
October 21, 2009 at 10:05 am
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| | Distinctive Degradation Behaviors of Electrospun Polyglycolide, Poly(dl-Lactide-co-Glycolide), and Poly(l-Lactide-co-varepsilon-Caprolactone) Nanofibers Cultured With/Without Porcine Smooth Muscle Cells. Tissue Eng Part A. 2009 Oct 19; Authors: Dong Y, Yong T, Liao S, Chan CK, Stevens MM, Ramakrishna S Biodegradable nanofibers have become a popular candidate for tissue engineering scaffolds because of their biomimetic structure that physically resembles the extracellular matrix. For certain tissue regeneration applications, prolonged in vitro culture time for cellular reorganization and tissue remodeling may be required. Therefore, extensive understanding of cellular effects on scaffold degradation is needed. There are only few studies on the degradation of nanofibers, and also the studies on degradation throughout cell culture are rare. In this study, polyglycolide (PGA), poly(dl-lactide-co-glycolide) (PLGA) and poly(l-lactide-co-varepsilon-caprolactone) [P(LLA-CL)] were electrospun into nanofibrous meshes. The nanofibers were cultured with porcine smooth muscle cells for up to 3 months to evaluate their degradation behavior and cellular response. The results showed that the degradation rates are in the order of PGA >> PLGA > P(LLA-CL). PGA nanofibers degraded in 3 weeks and supported cell growth only in the first few days. PLGA nanofiber scaffolds facilitated cell growth during the first 30 days after seeding, but cell growth was slow thereafter. P(LLA-CL) nanofibers facilitated long-term (1-3 months) cell growth. mRNA quantification using real-time polymerase chain reaction revealed that some smooth muscle cell markers (alpha-actinin and calponin) and extracellular matrix genes (collagen and integrin) seemed to be downregulated with increased cell culture time. Cell culture significantly increased the degradation rate of PGA nanofibers, whereas the effect on PLGA and P(LLA-CL) nanofibers was limited. We found that the molecular weight of P(LLA-CL) and PLGA nanofibers decreased linearly for up to 100 days. Half lives of PLGA and P(LLA-CL) nanofibers were shown to be 80 and 110 days, respectively. In summary, this is the first study to our knowledge to evaluate long-term polymeric nanofiber degradation in vitro with cell culture. Cell culture accelerated the nanofibrous scaffold degradation to a limited extent. P(LLA-CL) nanofibers could be a good choice as scaffolds for long-term smooth muscle cell culture. PMID: 19839726 [PubMed - as supplied by publisher] |
| In vitro and in vivo evaluation of osteogenesis of human umbilical cord blood derived mesenchymal stem cells on partially demineralized bone matrix.
October 21, 2009 at 10:05 am
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| | In vitro and in vivo evaluation of osteogenesis of human umbilical cord blood derived mesenchymal stem cells on partially demineralized bone matrix. Tissue Eng Part A. 2009 Oct 19; Authors: Liu G, Li Y, Sun J, Zhou H, Zhang W, Cui L, Cao Y The osteogenic differentiation potential of umbilical cord blood derived mesenchymal stem cells (UCB-MSCs) has been documented previously, and partially demineralized bone matrix (pDBM) represents a promising candidate for bone tissue engineering scaffolds. In this study, pDBM scaffolds derived from porcine cancellous bone were evaluated for their ability to support human UCB-MSCs osteogenic differentiation in vitro and bone-forming capacity in vivo in order to assess the potential use of UCB-MSCs in bone tissue-engineering applications. MSCs were isolated from full-term human UCB and expanded, and their cell surface antigen markers and multilineage capability to differentiate into osteoblasts, chondrocytes and adipocytes were analyzed. The in vitro proliferation and osteogenic differentiation of UCB-MSCs loaded onto the three-dimensional pDBM scaffolds were determined. Critical-sized full-thickness circular defects (5mm in diameter) created bilaterally in the parietal bones of athymic rats were treated with one of the following: osteogenically induced UCB-MSC/pDBM composites (Group A, n=8), non-induced UCB-MSC/pDBM composites (Group B, n=8), pDBM alone (Group C, n=8), or left untreated (Group D, n=8). Micro-CT analysis showed that new bone was formed in Group A at 6 weeks post-implantation, and greater bone volume and density were found after 12 weeks. In other groups, new bone formation was not evident after 6 weeks, and no bone union was found at 12 weeks. Histological examination revealed that the defect was repaired by tissue-engineered bone in Group A at 12 weeks, and fibrous union was observed in Groups B, C and D. These results demonstrate that pDBM can support osteogenic differentiation of human UCB-MSCs in vitro and in vivo, and UCB-MSCs may serve as an alternative cell source for bone tissue engineering and regeneration. PMID: 19839720 [PubMed - as supplied by publisher] |
| In vitro enhancement of SAOS-2 cell calcified matrix deposition onto r.f. magnetron sputtered bioglass-coated titanium scaffolds.
October 21, 2009 at 10:05 am
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| | In vitro enhancement of SAOS-2 cell calcified matrix deposition onto r.f. magnetron sputtered bioglass-coated titanium scaffolds. Tissue Eng Part A. 2009 Oct 19; Authors: Saino E, Maliardi V, Quartarone E, Fassina L, Benedetti L, Cusella De Angelis MG, Mustarelli P, Facchini A, Visai L In bone tissue engineering, bioglass coating of titanium scaffolds has drawn attention as a method to improve osteointegration and implant fixation. In this in vitro study, bioactive glass layers with an approximate thickness of 1 microm were deposited at 200 degrees C onto a three-dimensional Ti-6Al-4V (3D Ti alloy) scaffold using a r.f. magnetron sputtering system. After incubation with SAOS-2 human osteoblasts, in comparison with uncoated scaffolds, the bioglass-coated scaffolds showed a 2-fold increase in cell proliferation (p<0.05) up to 68.4x10e6, and enhanced deposition of extracellular matrix (ECM) components such as decorin, fibronectin, osteocalcin, osteonectin, osteopontin, type-I and -III collagens (p<0.05). Calcium deposition was 2-fold greater on bioglass coated scaffolds (p<0.05). The immunofluorescence related to the preceding bone matrix proteins and calcium showed their co-localization to cell-rich areas. Alkaline phosphatase (ALP) activity increased 2-fold (p<0.001) and its protein content was 3-fold higher with respect to the uncoated sample. Quantitative RT-PCR (qRT-PCR) analysis revealed up-regulated transcription specific for type-I collagen and osteopontin (p<0.001). All together, these results demonstrate that bioglass-coating of 3D Ti scaffolds by the r.f. magnetron sputtering technique determines an in vitro increase of bone matrix elaboration and may potentially have a clinical benefit. PMID: 19839719 [PubMed - as supplied by publisher] |
| Collagen-based matrices improve the delivery of transplanted circulating progenitor cells: development and demonstration by ex vivo radionuclide cell labeling and in vivo tracking with positron-emission tomography.
October 21, 2009 at 10:05 am
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| | Collagen-based matrices improve the delivery of transplanted circulating progenitor cells: development and demonstration by ex vivo radionuclide cell labeling and in vivo tracking with positron-emission tomography. Circ Cardiovasc Imaging. 2008 Nov;1(3):197-204 Authors: Zhang Y, Thorn S, DaSilva JN, Lamoureux M, DeKemp RA, Beanlands RS, Ruel M, Suuronen EJ BACKGROUND: Collagen delivery matrices have been reported to improve the results of cell therapy, but knowledge of their mechanisms of action is limited. To evaluate whether a collagen matrix improves early engraftment posttransplantation, 2-[(18)F]fluoro-2-deoxy-d-glucose ((18)F-FDG) was used to label transplanted circulating progenitor cells (CPCs) and track them in vivo with positron-emission tomography. METHODS AND RESULTS: Efficiency of (18)F-FDG cell labeling was CPC-concentration dependent (r=0.61, P<0.001) but not (18)F-FDG-dose dependent. Labeled human CPCs (2x10(6)) were injected with or without a collagen-based matrix in the ischemic hind limb of rats (n=12 per group) 2 weeks after femoral artery ligation. Imaging of labeled cells, acquired by small animal positron-emission tomography at 150 minutes postinjection, revealed greater CPC retention in the ischemic hind limb and less nonspecific leakage to other tissues (retention ratio, 0.44+/-0.08) when CPCs were delivered within the matrix, compared with cells injected alone (0.22+/-0.13, P=0.040) and with (18)F-FDG injected with or without the matrix (0.10+/-0.05 and 0.11+/-0.05, respectively, P<0.005). Tissue radionuclide biodistribution was performed after completion of positron-emission tomography imaging. When (18)F-FDG-labeled cells were injected with the collagen matrix, accumulation was significantly increased (by 69.6%, P=0.021) in the target ischemic hind limb muscle and significantly reduced (by 14.8% to 31.4%, P<0.05) in nonspecific tissues, compared with cells injected alone. Histology confirmed the increased retention in target tissue associated with the matrix. CONCLUSIONS: Early posttransplantation, a collagen matrix enhances progenitor cell retention and limits distribution to nonspecific tissues, as measured by the use of (18)F-FDG labeled cells and positron-emission tomography imaging and confirmed by biodistribution and histology. PMID: 19808543 [PubMed - indexed for MEDLINE] | | | 
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