Salvia miltiorrhiza Bunge promotes osteogenesis and angiogenesis by activating HIF-1α/VEGF and Slit3 pathways.

BACKGROUND: Osteogenesis and angiogenesis are closely coupled during bone modeling and remodeling, providing a potential direction for treating osteoporosis. Salvia miltiorrhiza Bunge (SM) has been preclinically and clinically used to treat skeletal and cardiovascular diseases in traditional Chinese medicine, but its mechanisms in bone formation and vascularization remain poorly understood.

PURPOSE: To elucidate the actions and mechanisms of SM against osteoporosis.

METHODS: Osteoporotic mice established by bilateral ovariectomy were orally administered SM aqueous extracts for 14 weeks. Bone quality was evaluated by micro-CT, histomorphometry, and three-point bending assay. Immunofluorescence staining was performed to quantify the proportions of type H vessels (CD31hiEMCNhi) in the femurs. In vitro, SM medicated serum was applied to MC3T3-E1 preosteoblasts and EA.hy926 endothelial cells to evaluate osteogenic and angiogenic capacities. Mechanistic studies involved HIF-1α inhibition and Slit3 knockdown in both cell lines. Moreover, the ingredients of SM aqueous extracts and SM medicated serum were characterized by an UPLC-MS/MS.

RESULTS: SM treatment improved bone mass and strength, promoted bone formation and type H vessels formation, and upregulated the expressions of HIF-1α, VEGF and Slit3 in the bones of ovariectomized mice. In vitro, SM enhanced osteogenic and angiogenic activities in MC3T3-E1 and EA.hy926 cells. These actions were dependent on HIF-1α/VEGF and Slit3 pathways, as their inhibition abolished the beneficial outcomes. Additionally, salvianolic acid B (Sal B) was identified as a key bioactive component contributing to these processes.

CONCLUSION: SM improves bone quality in osteoporosis by concurrently stimulating osteogenesis and angiogenesis through the HIF-1α/VEGF and Slit3 signaling pathways. These results provide a mechanistic basis for the application of SM in osteoporosis treatment and highlight its potential as a multi-target therapy.