Methods: The cells were cultured with 0, 10-8, 10-6 or 10-4 M BA for up to 12 days. Mineralized nodule formation was detected by alizarin red staining, and the calcium content in mineralized nodules was determined using a calcium assay kit. The gene and protein expression levels for type I collagen, bone sialoprotein (BSP), osteopontin (OPN), M-CSF, and OPG were examined using real-time PCR and ELISA, respectively.
Results: Mineralized nodule formation and the calcium content of mineralized nodules were increased by BA in a dose-dependent manner. Cell proliferation and ALPase activity were not affected by the addition of BA. Following the addition of 10-4 M BA, the expression levels of BSP, OPN, and OPG increased, whereas the expression levels of type I collagen and M-CSF were not markedly affected.
Conclusion: These results suggest that BA stimulates bone formation by increasing the production of BSP and OPN, whereas it suppresses osteoclast differentiation by increasing the production of OPG by human osteoblasts.