Icariin stimulates hFOB 1.19 osteoblast proliferation and differentiation via OPG/RANKL mediated by the estrogen receptor.

Icariin (ICA), is one of the main effective components isolated from the traditional Chinese herb Epimedium brevicornu Maxim, has been reported to possess extensive pharmacological actions, including enhanced sexual function, immune regulation, anti-inflammation, and anti-osteoporosis. Our study was designed to investigate the effect of ICA on cell proliferation and differentiation and the molecular mechanism of OPG/RANKL mediated by the estrogen receptor (ER) in hFOB1.19 human osteoblast cells. The experimental results show that ICA can stimulate cell proliferation and increase the activity of alkaline phosphatase (ALP), osteocalcin (BGP) and I collagen (Col I) and the amount of calcified nodules. Furthermore the mRNA and protein expression of OPG and RANKL and the OPG/RANKL mRNA and protein expression ratios were upregulated by ICA. The above mentioned results indicated that the optimal concentration of ICA for stimulating osteogenesis was 50 ng/mL. Subsequent mechanistic studies comparing 50 ng/mL ICA with an estrogen receptor antagonist demonstrated that the effect of upregulated expression is connected with the estrogen receptor. In conclusions, ICA can regulate bone formation by promoting cell proliferation and differentiation and upregulating the OPG/RANKL expression ratio by the ER in hFOB1.19 human osteoblast cells.