Flavonoids of Herba Epimedii stimulate osteogenic differentiation and suppress adipogenic differentiation of primary mesenchymal stem cells via estrogen receptor pathway

Context: Accumulating evidence indicates that Herba Epimedii [Epimedii folium (Berberidaceae)] has anti-osteoporotic effect by stimulating osteoblastic bone formation and reducing osteoclastic bone resorption. However, the effect of Herba Epimedii in regulating the cross-talk between osteogenic and adipogenic differentiation of mesenchymal stem cells (MSCs) remains unclear. Objective: The present study investigates the effect of total flavonoids of Herba Epimedii (HETF) on the osteogenesis and adipogenesis of primary MSCs. Materials and methods: HETF were prepared and identified by HPLC-fingerprinting, primary mouse MSCs in the presence of 0.006-6 mu g/mL HETF for 2-10 d were subject to morphological, biochemical, and quantitative real-time PCR analysis. Results: Sixteen chemical components were identified in HETF by HPLC-fingerprinting and account for over 95% of the total area of HPLC peaks. During osteogenesis of MSCs, 0.006-6 mu g/mL HETF promoted the proliferation of MSCs from 17% to 22%, increased alkaline phosphatase activity up to 3.7-fold (0.6 mu g/mL), and extracellular calcium deposits from 1.2- to 1.4-folds by up-regulating the expression of runt-related transcription factor-2 (Runx-2) and bone morphogenetic protein-2 (BMP-2). Meanwhile, HETF suppressed the adipogenesis of MSCs by reducing the formation of adipocyte-like cells and accumulation of fat droplets by down-regulating the expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma). The above biological activities of HETF were mainly through estrogen receptor-mediated pathway, which were blocked by estrogen receptor antagonist, ICI 182,780. Conclusion: HETF could regulate Runx-2-mediated osteogenesis and PPAR-gamma-mediated adipogenesis in MSCs and thus exhibit beneficial effects to bone health, which suggests a new strategy for treating patients with osteoporosis and obesity.