Basic fibroblast growth factor regulates expression of growth factors in rat epiphyseal chondrocytes

Chondrocytes produce several local regulatory factors such as basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I). In this study, we examined the effect of bFGF on the expressions of both mRNA and protein of the growth factors synthesized by chondrocytes. Treatment of chondrocytes with bFGF (1-100 ng/ml) stimulated the mRNA expression of bFGF and TGF-beta up to 121-604% and 130-220% at 12 h compared with the controls, respectively. On the other hand, the treatment of chondrocytes with bFGF (1-100 ng/ml) suppressed IGF-I mRNA expression to 79-47% at 12 h compared with the controls. An enzyme-linked immunosorbent assay (ELISA) revealed that the treatment of chondrocytes with bFGF (1-100 ng/ml) also enhanced the production of TGF-beta proteins in the chondrocytes up to 299-508% at 24 h compared with controls. We conclude that bFGF influenced the local expression of growth factors by chondrocytes, suggesting autoregulation of growth factor expression during chondrogenesis.