Objective       To determine the effect of hepatocyte growth factor (HGF) combined with bone morphogenetic protein 9 (BMP9) on the induced osteogenic differentiation of mesenchymal stem cell (MSC) line C3H10 and investigate the possible underlying mechanism.       Methods       C3H10 cells were treated by recombinant adenovirus expressing Ad-BMP9 infection and HGF (20 ng/mL) induction. The expression of osteocalcin (OC) and osteopontin (OPN) at mRNA and protein levels were determined by real-time PCR and Western blot analysis respectively. The activity of alkaline phosphatase (ALP) was detected by ALP staining and activity assay. Calcium deposition was detected by Alizarin Red S staining. At last

the mRNA expression of Smad1/5/8 was analyzed by real-time PCR.       Results       BMP9 alone induced the osteogenic differentiation of C3H10 cells and increased the ALP activity. HGF alone slightly induced osteogenic differentiation

while significantly promoted the BMP9-induced OC and OPN expression (P0.05)

ALP activity

and calcium deposition. Furthermore

HGF induction resulted in significant increase in the transcription levels of Smad1/5/8 (P0.05).       Conclusion       HGF synergistically promotes the effect of BMP9 on induction of osteogenic differentiation of C3H10 cells

and this effect maybe due to the activation of Smad signaling pathways.