SummaryConnective tissue growth factor (CTGF) plays a role in the fibrotic process of systemic sclerosis (SSc). Because hypoxia is associated with fibrosis in several profibrogenic conditions, we investigated whether CTGF expression in SSc fibroblasts is regulated by hypoxia. Dermal fibroblasts from patients with SSc and healthy controls were cultured in the presence of hypoxia or cobalt chloride (CoCl2), a chemical inducer of hypoxia-inducible factor (HIF)-1a. Expression of CTGF was evaluated by Northern and Western blot analyses. Dermal fibroblasts exposed to hypoxia (1% O2) or CoCl2 (1-100 mM) enhanced expression of CTGF mRNA. Skin fibroblasts transfected with HIF-1a showed the increased levels of CTGF protein and mRNA, as well as nuclear staining of HIF-1a, which was enhanced further by treatment of CoCl2. Simultaneous treatment of CoCl2 and transforming growth factor (TGF)-b additively increased CTGF mRNA in dermal fibroblasts. Interferon-g inhibited the TGF-b-induced CTGF mRNA expression dose-dependently in dermal fibroblasts, but they failed to hamper the CoCl2-induced CTGF mRNA expression. In addition, CoCl2 treatment increased nuclear factor (NF)-kB binding activity for CTGF mRNA, while decreasing IkBa expression in dermal fibroblasts. Our data suggest that hypoxia, caused possibly by microvascular alterations, up-regulates CTGF expression through the activation of HIF-1a in dermal fibroblasts of SSc patients, and thereby contributes to the progression of skin fibrosis.

Purpose Increased bone regeneration has been achieved through the use of stem cells in combination with graft material. However, the survival of transplanted stem cells remains a major concern. The purpose of this study was to evaluate the viability of transplanted mesenchymal stem cells (MSCs) at an early time point (24 hours) based on the type and form of the scaffold used, including type I collagen membrane and synthetic bone. Methods The stem cells were obtained from the periosteum of the otherwise healthy dental patients. Four symmetrical circular defects measuring 6 mm in diameter were made in New Zealand white rabbits using a trephine drill. The defects were grafted with 1) synthetic bone (β-tricalcium phosphate/hydroxyapatite [β-TCP/HA]) and 1×10 5 MSCs, 2) collagen membrane and 1×10 5 MSCs, 3) β-TCP/HA+collagen membrane and 1×10 5 MSCs, or 4) β-TCP/HA, a chipped collagen membrane and 1×10 5 MSCs. Cellular viability and the cell migration rate were analyzed. Results Cells were easily separated from the collagen membrane, but not from synthetic bone. The number of stem cells attached to synthetic bone in groups 1, 3, and 4 seemed to be similar. Cellular viability in group 2 was significantly higher than in the other groups ( P <0.05). The cell migration rate was highest in group 2, but this difference was not statistically significant ( P >0.05). Conclusions This study showed that stem cells can be applied when a membrane is used as a scaffold under no or minimal pressure. When space maintenance is needed, stem cells can be loaded onto synthetic bone with a chipped membrane to enhance the survival rate.

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