| Herba Epimedii is one of the most frequently used herbs prescribed for the treatment of osteoporosis in China, and may be used as a complementary and alternative therapy for postmenopausal osteoporosis. Icariin has been found to be the major flavonoids contained in the herb and be responsible for most of its pharmacological activities. However, little is known about the mechanism of this effect. The objective of this study is to investigate the effect of icariin on osteogenic differentiation of rat bone marrow stromal cells (rBMSCs), which are the only precursor cells of osteoblasts in bone marrow. Icariin was supplemented into the primary culture media of rBMSCs at 10μmol/l, 1μmol/l and 0.1μmol/l respectively. After 9 days (day 1 for osteogenic induction), the osteogenic induction supplements (100mmol/l L-ascorvic acid-z--phosphate, 10-8 mol/l dexamethasone and 10mmol/lβ-glycerophosphate) were added. The effect of icarrin on the proliferation of rBMSCs was assessed by MTT assay and flow cytometric analysis on day 9. The effect of icariin on the osteogenic differentiation of rBMSCs was evaluated by the assay of alkaline phosphatase (ALP) activity, osteocalcin secretion, calcium deposition, calcium nodules staining and the expression level of bone-related mark genes. The results showed that icariin dose-dependently promotes osteogenic differentiation of rBMSCs at each stage of culture, demonstrated by the increasing of ALP activity and the number of CFU-F stained positive for ALP at early stage, and the enhancement of osteocalcin secretion and the deposition of calcium level at late stage. The up-regulated mark genes for osteoblast were also found. The most effective concentration of icariin is 10μmol/l. In conclusion, icariin enhances the osteogenic differentiation of bone marrow stromal cells and therefore promotes bone formation, which is the basis of Herba Epimedii for its activities of prevention and treatment of osteoporosis. |
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