Combination of simvastatin and bone morphogenetic protein-2 enhances the differentiation of osteoblasts by regulating the expression of phospho-Smad1/5/8.

Statins inhibit 3-hydroxy-3-methylglutarylcoen zyme A reductase, which catalyzes the conversion of 3-hydroxy-3-methylglutaryl-coenzyme A to mevalonate, a rate-limiting step in cholesterol synthesis. A number of studies have demonstrated bone-promoting effects when simvastatin is applied locally with different carriers in various animal models. In the prsent study, the dose-dependent impact of simvastatin and bone morphogenetic protein-2 (BMP-2) on the cellular proliferation and differentiation of osteopre-cursor cells was evaluated. The alkaline phosphatase activity (ALP) test was performed to assess differentiation, and protein expression related to bone formation, including that of phospho-Smad1/5/8 (pSmad1/5/8), was measured using western blot analysis to evaluate the underlying mechanism(s). Cultures grown in the presence of 0.1 μM simvastatin with 60 ng/ml BMP-2 exhibited the highest value for ALP activity. The results of the western blot analysis indicated that the addition of simvastatin upregulated pSmad1/5/8 expression and the combination of 0.1 μM simvastatin and 60 ng/ml BMP-2 produced a significant increase in protein expression. Based on these findings, it was concluded that the combination of simvastatin and BMP-2 produced positive effects on the differentiation of osteoprecursor cells. The results also suggest that the combination of simvastatin and BMP-2 has synergistic effects that are achieved through the BMP pathway by enhancing the expression of pSmad1/5/8 expression.