Icaritin promotes the osteogenesis of bone marrow mesenchymal stem cells via the regulation of sclerostin expression

Icaritin, a metabolite of icariin, is a potent promoter of bone marrowderived mesenchymal stem cells (BMSCs) osteogenesis, but the underlying mechanisms remain unclear. To examine the effects of icaritin on osteogenic differentiation, BMSCs were exposed to osteogenic induction medium with or without icaritin pretreatment in the present study. It was identified that icaritin (0.011 microM) exhibited no cytotoxicity on the proliferative abilities of the BMSCs. Icaritin at 1 microM increased alkaline phosphatase activity, mineral deposition and osteoblastspecific gene expression. Treatment with 1 microM Icaritin upregulated osteocalcin, RUNX family transcription factor 2, tissuenonspecific alkaline phosphatase and betacatenin, and suppressed sclerostin (SOST) gene expression in different stages of osteogenic differentiation. It was also demonstrated that SOST overexpression inhibited icaritininduced osteogenesis. The western blot analysis data suggested that ICI 182780, which causes estrogen receptor alpha (ERalpha) degradation, reversed the icaritininduced decrease in SOST expression, which was inconsistent with the results of immunofluorescence analysis. In conclusion, icaritin was demonstrated to promote the osteogenesis of hBMSCs by downregulating SOST expression, and icaritininduced suppression of SOST was regulated in part via the Wnt/betacatenin/ERalpha axis.