Icariin, a flavonoid from the herb Epimedium enhances the osteogenic differentiation of rat primary bone marrow stromal cells.

The herb Epimedium has long been used in Traditional Chinese Medicine to treat bone fracture and prevent osteoporosis. Researchers believe that the flavonoids contained in the herb are the effective component for this activity. However, no single flavonoid has been studied for its effect on bone-related cells. In the present study, icariin, one of the major flavonoids of the herb, supplemented the primary culture medium of rat bone marrow stromal cells (rMSCs) at 0.1 microM , 1 microM and 10 microM respectively. It was found that icariin stimulated the proliferation of rMSCs and increased the number of CFU-F stained positive for alkaline phosphatase in a dose-dependent manner. Icariin also dose-dependently increased the alkaline phosphatase activity, osteoalcin secretion and calcium deposition level of rMSCs during osteogenic induction. The addition of 10 microM icariin caused four times more mineralized bone nodules to be formed by rMSCs than in the control. The results demonstrated that icariin should be an effective component for bone-strengthening activity, and one of the mechanisms is to stimulate the proliferation and enhance the osteogenic differentiation of MSCs.