Combined effects of simvastatin and fibroblast growth factor-2 on the proliferation and differentiation of preosteoblasts

Abstract

Simvastatin reportedly promotes osteoblastic and inhibits osteoclastic activity. It increases bone formation when injected subcutaneously over the calvaria in mice. It also increases cancellous bone volume in rats following oral administration. Fibroblast growth factor-2 (FGF-2), a member of the FGF family, is expressed by cells of the osteoblastic lineage. FGF-2 promotes osteoblast proliferation and it is secreted during the healing process of fractures or at bone surgery sites. FGF-2 reportedly regulates bone formation and osteoblast differentiation. In this study, the combined effects of simvastatin and FGF-2 on the proliferation and differentiation of preosteoblasts were investigated and an alkaline phosphatase (ALP) activity test was performed to assess the differentiation. Moreover, the expression of proteins associated with bone formation were measured using western blot analysis. The results demonstrated that the protein content of the cultures grown in osteogenic differentiation media in the presence of FGF-2 at a concentration of 20 ng/ml was higher compared to that of the untreated control cultures. ALP activity was decreased when cells were treated with FGF-2 (2 and 20 ng/ml) and increased when cells were treated with simvastatin. The cultures grown in the presence of 1 μM of simvastatin and 2 ng/ml of FGF-2 exhibited increased ALP activity when compared to that in the 2 ng/ml FGF-2-only group. The combination of 1.0 μM simvastatin and 2 ng/ml FGF-2 achieved a higher estrogen receptor-α expression compared to the 2 ng/ml FGF-2-only group. Within the limits of this study, simvastatin enhanced osteoblast differentiation. However, the combined treatment with simvastatin and FGF-2 did not exert synergistic effects on osteoblast differentiation under the current experimental conditions. Future studies are required to evaluate divergent conditions and determine the selective timing and optimal dosage for the delivery of the agents.