Bushenhuoxue formula promotes osteogenic differentiation of growth plate chondrocytes through β-catenin-dependent manner during osteoporosis

Abstract Background Bushenhuoxue formula (BSHXF) has shown excellent clinical effects on the treatment of osteoporosis in China. The aim of this study is to determine the anti-osteoporosis effects and precise molecular mechanisms of BSHXF on mouse models. Methods Ten-week-old female C57BL/6 J mice were subjected to ovariectomy and provided a daily treatment of BSHXF. At 8 weeks post-surgery, the femurs were harvested for tissue analyses including μCT, histology, qRT-PCR and immunohistochemical (IHC) staining of β-catenin, ALP and FABP4. To investigate the role of β-catenin in the anti-osteoporosis effects of BSHXF, relative experiments mentioned above were performed in β-catenin conditional knockout mice. Results Ovariectomized (OVX) mice presented severe bone loss and excessive fat accumulation in the chondro-osseous junction underneath the growth plate, with decreased expression of ALP and increased expression of FABP4. BSHXF significantly recovered the OVX-induced abnormal osteogenesis and adipogenesis with the activation of β-catenin in growth plate chondrocytes. Further, we generated growth plate chondrocyte-specific β-catenin knockout (β-cateninGli1ER) mice that exhibited bone loss and fat accumulation in the chondro-osseous junction, similar to the OVX mice. However, BSHXF failed to rescue the osteoporosis-like phenotype in β-cateninGli1ER mice, indicating the anti-osteoporosis effects of BSHXF act mainly through β-catenin signaling. No significant restoration of ALP and FABP4 was observed in β-cateninGli1ER mice after the treatment of BSHXF. Conclusions BSHXF attenuates osteoporosis by promoting osteogenic differentiation of growth plate chondrocytes mainly in β-catenin-dependent manner. BSHXF is considered as a new candidate for the treatment of osteoporosis.