Comparison of characteristics of MSC-induced osteoblast-like cells after different inductive intervals

Objective To compare the characteristics of MSC-derived osteoblast-like cells in different inductive time period. Methods Mononuclear cells (MNC) were isolated from adult bone marrow and cultured, mesenchymal stem cell (MSC) were obtained from the adherent cells. Dexamethasone(DEX), sodium-β-glycerophosphate and ascorbic acid were added into the culture of the fourth passage cells to induce osteogenic differentiation. After induction for 7 and 14 days MSC-derived ostebblast-like cells and normal osteoblast from adult tibia were treated with different concentrations of BMP-2 and DEX. Fourty-eight hours later, cell proliferation (MTT method), ALP (alkaline phosphatase) activity and osteocalcin (OCN) content were measured. Results Proliferation and ALP activity significantly increased in the 7 d inductive osteoblast-like cells after 48 h administrated with BMP-2 and DEX. However, for the 14 d osteoblast-like cells, Neither proliferation nor ALP activity increased OCN content could be induced by BMP-2 and DEX. The reactions of normal osteoblast to the BMP-2 and DEX treatment were similar to those of 14 d osteoblast-like cells. The OCN level of normal os-teoblast was much higher than those of MSC-derived osteoblast-like cells. Conclusion The results suggested that the characteristics of 7 and 14 d MSC-derived osteoblast-like cells were different and the length of inductive period was a key factor for MSC osteogenic differentiation. Further study is needed to optimize the period and to explore the mechanism. The osteogenic potentiality of MSC-derived osteoblast-like cells was lower as compared to normal osteoblast.