Background: Icariin (ICA), 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 antiosteoporosis.
Methods: 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.
Results: 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 a number 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 50ng/mL. Subsequent
mechanistic studies comparing 50ng/mL ICA with an estrogen receptor antagonist demonstrated that
the effect of the upregulated expression is connected with the estrogen receptor. In conclusion, 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.