Icariin, the main effective component of Herba Epimedii, has been identified to regulate the osteogenic differentiation of rat bone marrow stromal cells (rBMSCs) and have potential application in preventing bone loss and promoting bone regeneration. However, the underlying signaling pathway of its osteogenic effect remains unclear. Here, we investigated whether icariin could promote osteogenesis of rBMSCs through modulating the estrogen receptor alpha (ER alpha) and Wnt/beta-catenin signaling pathways, which implicated in rBMSCs osteogenesis. rBMSCs were cultured in osteogenic induction medium and treated with icariin or together with ICI 182780 or DKK1, the effects on the expression of osteogenic genes and Wnt/beta-catenin signaling were detected. Results indicated that icariin (0.1 mu M) markedly enhanced the proliferation of rBMSCs and alkaline phosphatase ( ALP) activity. Additionally, icariin ( 0.1 mM) significantly up-regulated the expression of osteogenic genes (Runx2, osteopotin, DLX5, osteocalcin, collagen type I, and ER alpha) and Wnt signal members (beta-catenin, Lef1, TCF7, c-jun, c-myc, and cyclin D). Furthermore, icariin stimulated the activation of beta-catenin as evidenced by increased total beta-catenin protein and nuclear translocation. These osteogenesis-potentiating effects of icariin were blocked by ICI 182780 or DKK1. Taken together, these results suggest that the osteogenic effects of icariin on rBMSCs involves the ER alpha-Wnt/beta-catenin signaling pathway. (C) 2016 Elsevier Masson SAS. All rights reserved.