Osteogenic Potential of Human Mesenchymal Stem Cells During Serial Subculture / 대한정형외과연구학회지

PURPOSE: The purpose of this study was to evaluate the osteogenic differentiation potential of human mesenchymal stem cells during serial subculture. MATERIALS AND METHODS: Human bone marrow-derived MSCs were serially subcultured and then maintained in basal or osteogenic medium for 14 days. Then we performed FAC analysis, RT-PCR, alkaline phosphatase activity and stains. RESULTS: Human MSCs had different morphologies, immunophenotypes, and growth rates that were correlated with the length of serial subculture. The phenotype changed from small spindle-shaped cells at passage 1 into large cuboidal or flattened cells at passage 7. The osteogenic capacity of human MSCs decreased during serial subculture. Using RT-PCR, the mRNA levels of bone-specific genes, such as cbfa1/runx2 and osteocal-cin, decreased with increasing passage number. Strong positive staining was observed for ALP and Alizarin reds in osteogenic medium on day 14, but declined significantly with increasing passage number. CONCLUSION: We have shown that osteogenic potential of human MSCs decreased during serial subculture. This result can provide the helpful information to decide the timing of human MSC transplantation during in vitro culture expansion for treatment of bone defects and so on.

ERK1/2 Activation Modulates Matrix Metalloproteinase 2 Activity and Ezrin Expression in Osteosarcoma Cell Lines / 대한정형외과연구학회지

PURPOSE: In this study, we aimed to investigate the influence of mitogen-activated protein kinase (MAPK) signal pathway and related factors of metastatic property on the osteosarcoma cell lines. MATERIALS AND METHODS: Osteosarcoma cell lines, MG-63, HOS, U2OS, SAOS-2, and osteoblast-like cell line, MC3T3-E1 were used for evaluating the activation of MAPK signal pathway and the effect of ERK1/2 inhibiton by 15 micrometer U0126 for 6 days. Then we measured the activity of matrix metalloproteinases (MMP) by gelatin zymography analysis. RESULTS: ERK was strongly activated in three osteosarcoma cell lines, MG-63, HOS, U2OS, and was weakly activated in SAOS-2 cell line. MMP2 was strongly activated in MG-63, HOS, U2OS cell lines. However, SAOS-2 cell line, in which ERK1/2 was weakly activated, showed weak activation of MMP2. When the ERK1/2 was inhibited by U0126 for 6 days, the ezrin expression was remarkably suppressed in all osteosarcoma cell lines. These data showed that the suppression of ezrin expression might be dependent on the ERK1/2 activation in osteosarcoma cell lines. CONCLUSION: Our results suggested that the ERK1/2 activation might be related to the activity of MMP2 and the suppression of ezrin expression in osteosarcoma cell lines. We suggest that ERK1/2 activation might be closely related to the ezrin expression and the ezrin expression might play an important role in the activation of MMP2 which is known to involve in the activated MMP2 involves in early metastatic properties in osteosarcoma.

beta-Catenin Expression in Gastric Carcinogenesis

BACKGROUND: The molecular pathogenesis of gastric carcinoma is not yet well characterized. The purpose of this study is to assess the role of beta-catenin in gastric carcinogenesis. METHODS: We analyzed beta-catenin expression using immunohistochemistry on 68 gastric adenomas and 34 gastric adenocarcinomas, and compared the result with pathological and molecular types of tumors and E-cadherin expression. RESULTS: Nuclear expression of beta-catenin was noted more frequently in gastric adenomas than in carcinomas (40% vs. 21%, 0.05< or = P<1). There was no significant relationship between nuclear beta-catenin expression and histologic degree of adenoma, histologic type of carcinoma or microsatellite instability. E-cadherin expression showed significantly more frequent decrease in the membrane stainability of carcinomas compared to adenomas (P<0.01). CONCLUSIONS: The frequent nuclear beta-catenin expression in gastric adenomas suggests that the beta-catenin alteration might play an early role in gastric carcinogenesis.