Effects of basic fibroblast growth factor on osteoblast-related gene expression in the process of medullary bone formation induced in rat femur

The effects of basic fibroblast growth factor (bFGF) on osteogenic differentiation in-vivo were investigated using a rat bone marrow ablation model. bFGF was infused directly into rat femora for 6 days after bone marrow ablation. The contralateral femur was infused with vehicle only and used as control. Bone formation was induced in the rat femoral cavity, and the gene expression of osteoblast markers was examined. Treatment with bFGF at 50 and 100ng/day significantly enhanced the mRNA levels of osteopontin compared with the levels in the control leg, with increases of 25% and 24%, respectively. In contrast, bFGF infusion at 50 ng/day provoked a significant (nearly 20%) inhibition of expression for type I collagen. Infusion of bFGF at a higher dose exhibited an inhibitory tendency for bFGF action on gene expression. There were no significant changes in alkaline phosphatase and osteocalcin mRNA levels in response to any dose of bFGF. The findings presented here suggest that bFGF modulates osteogenic differentiation in-vivo and may play an important role in the process of bone remodeling.