Icariin promotes the repair of bone marrow mesenchymal stem cells in rabbit knee cartilage defects via the BMP/Smad pathway

BACKGROUND: Icariin (ICA) has been widely used in the treatment of osteoporosis. However, the potential mechanism of its critical role in repairing knee cartilage damage still needs to be further clarified. METHODS: First, rabbit bone marrow mesenchymal stem cells (BMSCs) were isolated, cultured, and identified. Subsequently, BMSCs were treated with different concentrations of ICA. Cell Counting Kit 8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) were used to evaluate the cell proliferation in each group. Alcian Blue staining, immunofluorescence, and western blotting were used to evaluate the ability of BMSCs to differentiate cartilage. In addition, a rabbit knee cartilage injury model was established. Evaluation of cartilage defects in each group was performed according to the classification system outlined by the International Cartilage Repair Society (ICRS). Hematoxylin and eosin (HE), Alcian Blue, and immunohistochemistry were used to analyze the pathological status of knee cartilage. RESULTS: In vitro, the results showed that ICA promoted the cartilage differentiation of BMSCs as well as cell proliferation. In addition, ICA promoted the expression of type II collagen (COL2A1), aggrecan, and bone morphogenetic protein 2 (BMP2) in BMSCs, while BMP-Smad inhibitor (Noggin) reversed the repair effect of ICA on BMSCs. In vivo, our results showed that the ICRS score of the BMSC and ICA treatment group was higher. Moreover, BMSC and ICA treatment promoted the proliferation of chondrocytes and repaired the cartilage-like tissue on the surface of cartilage defect. CONCLUSIONS: The combined application of ICA and BMSCs can repair rabbit knee cartilage injury by regulating the BMP/Smads pathway, indicating that ICA and BMSCs may be a viable clinical treatment strategy for knee cartilage damage.