Abstract:

BACKGROUND: Simvastatin can promote osteoblast differentiation of human or rat bone marrow stromal stem cells cultured in vitro. But the mechanism remains unclear.
OBJECTIVE: To investigate the effects of simvastain on expression of factors related to Wnt and bone morphogenetic protein 2 (BMP-2) signaling pathway during osteoblast differentiation of bone marrow stromal cells.
METHODS: Bilateral femur and tibia bone marrow was harvested from 6-week-old female Sprague-Dawley rats for in vitro culture of osteoblasts. In the SIM group, 10-7 mol/L simvastain was added, and in the control group, the same amount of dehydrated alcohol and PBS was added. After 14 days of culture, alkaline phosphatase staining was performed. At 28 days, von Kossa staining was applied to observe osteoblastic differentiation and mineralization. At 14 and 21 days, immunofluorescent cytochemical staining was used to detect β-catenin, Smad1/5, Cbfa1 expression and distribution in osteoblasts. 
RESULTS AND CONCLUSION: Cells in each group were differentiated into osteoblast lineage, as shown by alkaline phosphatase activity and extracellular matrix mineralization. Simvastatin can significantly upregulate alkaline phosphatase expression during the osteoblast differentiation of bone marrow stromal cells. The expression of β-catenin, Smad1/5, and Cbfa1 was significantly increased in the SIM group than in the control group. The above-mentioned expression in the SIM group accumulated in the nuclear more than in the cytoplasm. These results showed that the mechanism by which simvastatin promotes osteoblast differentiation of bone marrow stromal stem cells may be partially related to expression and distribution of factors regulating Wnt and BMP-2 signaling pathway.