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Extracellular Matrix Genes (extracellular + matrix_gene)
Selected AbstractsIdentifying a molecular phenotype for bone marrow stromal cells with in vivo bone-forming capacityJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2010Kenneth H Larsen Abstract The ability of bone marrow stromal cells (BMSCs) to differentiate into osteoblasts is being exploited in cell-based therapy for repair of bone defects. However, the phenotype of ex vivo cultured BMSCs predicting their bone-forming capacity is not known. Thus we employed DNA microarrays comparing two human bone marrow stromal cell (hBMSC) populations: One is capable of in vivo heterotopic bone formation (hBMSC-TERT+Bone), and the other is not (hBMSC-TERT,Bone). Compared with hBMSC-TERT,Bone, the hBMSC-TERT+Bone cells had an increased overrepresentation of extracellular matrix genes (17% versus 5%) and a larger percentage of genes with predicted SP3 transcription factor,binding sites in their promoter region (21% versus 8%). On the other hand, hBMSC-TERT,Bone cells expressed a larger number of immune-response-related genes (26% versus 8%). In order to test for the predictive value of these markers, we studied the correlation between their expression levels in six different hBMSC-derived clones and the ability to form bone in vivo. We found a significant correlation for decorin, lysyl oxidase-like 4, natriuretic peptide receptor C, and tetranectin. No significant positive correlation was found for canonical osteoblastic markers Runx2, alkaline phosphatase, collagen type I, osteopontin, and bone sialoprotein. Prospective isolation of four additional hBMSC clones based on their expression levels of the molecular markers correlated with their in vivo bone-formation ability. In conclusion, our data suggest an in vitro molecular signature predictive for hBMSCs' in vivo bone-formation ability. Identifying more of these predictive markers would be very useful in the quality control of osteoblastic cells before use in therapy. © 2010 American Society for Bone and Mineral Research [source] Enhanced Chondrogenesis and Wnt Signaling in PTH-Treated Fractures,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2007Sanjeev Kakar Abstract Studies have shown that systemic PTH treatment enhanced the rate of bone repair in rodent models. However, the mechanisms through which PTH affects bone repair have not been elucidated. In these studies we show that PTH primarily enhanced the earliest stages of endochondral bone repair by increasing chondrocyte recruitment and rate of differentiation. In coordination with these cellular events, we observed an increased level of canonical Wnt-signaling in PTH-treated bones at multiple time-points across the time-course of fracture repair, supporting the conclusion that PTH responses are at least in part mediated through Wnt signaling. Introduction: Since FDA approval of PTH [PTH(1,34); Forteo] as a treatment for osteoporosis, there has been interest in its use in other musculoskeletal conditions. Fracture repair is one area in which PTH may have a significant clinical impact. Multiple animal studies have shown that systemic PTH treatment of healing fractures increased both callus volume and return of mechanical competence in models of fracture healing. Whereas the potential for PTH has been established, the mechanism(s) by which PTH produces these effects remain elusive. Materials and Methods: Closed femoral fractures were generated in 8-wk-old male C57Bl/6 mice followed by daily systemic injections of either saline (control) or 30 ,g/kg PTH(1,34) for 14 days after fracture. Bones were harvested at days 2, 3, 5, 7, 10, 14, 21, and 28 after fracture and analyzed at the tissue level by radiography and histomorphometry and at the molecular and biochemical levels level by RNase protection assay (RPA), real-time PCR, and Western blot analysis. Results: Quantitative ,CT analysis showed that PTH treatment induced a larger callus cross-sectional area, length, and total volume compared with controls. Molecular analysis of the expression of extracellular matrix genes associated with chondrogenesis and osteogenesis showed that PTH treated fractures displayed a 3-fold greater increase in chondrogenesis relative to osteogenesis over the course of the repair process. In addition, chondrocyte hypertrophy occurred earlier in the PTH-treated callus tissues. Analysis of the expression of potential mediators of PTH actions showed that PTH treatment significantly induced the expression of Wnts 4, 5a, 5b, and 10b and increased levels of unphosphorylated, nuclear localized ,-catenin protein, a central feature of canonical Wnt signaling. Conclusions: These results showed that the PTH-mediated enhancement of fracture repair is primarily associated with an amplification of chondrocyte recruitment and maturation in the early fracture callus. Associated with these cellular effects, we observed an increase in canonical Wnt signaling supporting the conclusion that PTH effects on bone repair are mediated at least in part through the activation of Wnt-signaling pathways. [source] Expression of extracellular matrix genes in cultured hepatic oval cells: an origin of hepatic stellate cells through transforming growth factor beta?LIVER INTERNATIONAL, Issue 4 2009Ping Wang Abstract Background: Hepatic oval cells, progenitor cells in the liver, can differentiate into hepatocytes and bile duct cells both in vitro and in vivo. Although hepatic stellate cells are another important cell component in the liver, less attention has been focused on the relationship between hepatic oval cells and hepatic stellate cells. Methods: Hepatic oval cells were isolated from rats fed a choline-deficient diet supplemented with 0.1% ethionine for 6 weeks and characterized by electron microscopy, flow cytometry, reverse transcription polymerase chain reaction, Western blot and bi-direction differentiation. After treatment with transforming growth factor-,1 (TGF-,1), changes in cell viability, morphology, extracellular matrix (ECM) expression and immune phenotype were analysed in these cultured and adherent hepatic oval cells. Results: The primary cultured hepatic oval cells were positive for the oval cell-specific markers OV-6, BD-1/BD-2 and M2PK as well as the hepatocyte markers albumin and ,-foetoprotein. These hepatic oval cells differentiated bipotentially into hepatocytes or bile duct-like cells under appropriate conditions. It is noteworthy that these bipotential hepatic oval cells expressed ECM genes stably, including collagens, matrix metalloproteinases and tissue inhibitor of mellatoproteinase. Furthermore, except for growth inhibition and morphological changes in the hepatic oval cells after exposure to TGF-,1, there was an increased expression of ECM genes, the onset expression of snail and loss expression of E-cadherin. During this process, TGF-,1 treatment induced an upregulation of marker genes for hepatic stellate cells in hepatic oval cells, such as desmin and GFAP. Conclusion: Except for the expression of ECM, the cultured hepatic oval cells could induce an increased expression of hepatic stellate cell markers by TGF-,1 through an epithelial,mesenchymal transition process, which might indicate the contribution of hepatic oval cells to liver fibrosis. [source] SPARC, an upstream regulator of connective tissue growth factor in response to transforming growth factor , stimulationARTHRITIS & RHEUMATISM, Issue 12 2006X. D. Zhou Objective To differentiate the effects of inhibition of specific small interfering RNA (siRNA) of SPARC (secreted protein, acidic and rich in cysteine) and siRNA of connective tissue growth factor (CTGF) in cultured human fibroblasts, and to identify potential interrelationships between SPARC and CTGF. Methods Fibroblasts from skin biopsy specimens of 2 normal individuals were transfected with siRNA of SPARC and siRNA of CTGF. The fibroblasts were stimulated with or without transforming growth factor ,1 (TGF,1) and examined by real-time quantitative reverse transcription,polymerase chain reaction to determine the transcription levels of several extracellular matrix genes. Results After exogenous TGF,1 stimulation, both SPARC siRNA and CTGF siRNA showed a protective role against overexpression of collagen genes. Following TGF,1 stimulation, SPARC siRNA,transfected fibroblasts showed a greater reduction in expression of the collagen genes compared with CTGF siRNA,transfected fibroblasts, as well as a significantly decreased expression of CTGF (P < 0.05). Using linear structure equations to quantitatively model a genetic network based on expression levels of each gene, a positive regulatory role of SPARC on CTGF, COL1A2, COL3A1, COL11A1, and TIMP3 was observed. However, the regulatory role of CTGF on SPARC appeared to be negative and very small, while the positive regulatory effects of CTGF on COL1A2, COL3A1, COL11A1, and TIMP3 were less than those of SPARC. Conclusion The results of this quantitative comparison support the hypothesis that in these cultured fibroblasts, the regulatory effects of SPARC on some major extracellular matrix structural components are greater than those of CTGF. In addition, SPARC appears to regulate CTGF in a predominantly positive manner, while CTGF may act as a negative feedback control on SPARC following TGF, stimulation. [source] | ||||||||||