Mechanism of Icariin regulation of the effect of miR-122-5p in osteoblast-derived exosomes on osteogenesis and migration of bone marrow mesenchymal stem cells

Abstract: Background Avascular necrosis of the femoral head (ANFH) is a common orthopaedic disease due to bone defects. However, few clear methods to treat ANFH in clinical practice are known. Many findings suggest that promoting the osteogenic differentiation and directional migration of stem cells may be a key method for bone regeneration. Over time, an increasing number of researchers have begun to focus on Chinese medicine and Chinese medicinal extracts; Epimedium is the Chinese herbal medicine studied in the most detail in the field of bone regeneration, and Icariin (ICA) is one of the main active ingredients in Epimedium. Objective This study aimed to explore the effects of ICA on the osteogenic differentiation and migration of bone marrow mesenchymal stem cells (BMSCs) and reveal its mechanism to provide a theoretical basis for the treatment of ANFH. Methods After primary BMSCs were freshly isolated from a normal rabbit and treated with various concentrations of ICA, the activity and proliferation of BMSCs were detected by CCK-8 assay, and the mineralized nodules was detected by Alizarin Red staining, to determine the optimal concentration of ICA. qPCR and western blot were used to demostrate the effects of ICA on the osteogenic differentiation and migration of BMSCs. Osteoblasts-derived exosomes (OB-exos) were extracted and analysed by high-throughput sequencing. Effect of ICA combined with OB-exos were analysed. And miRNA mimic and an miRNA inhibitor were synthetised to verify the osteogenic differentiation and migration of BMSCs alone or co-cultured with ICA. Results The CCK-8 assay and Alizarin Red staining showed that the optimal concentration of ICA is 1×10^− 7 M. ICA could effectively promote the osteogenic differentiation and migration of BMSCs, and this could be enhanced after co-culturing with OB-exos. The four miRNAs with the greatest concentrations in the OB-exos were let-7a-5p, miR-100-5p, miR-21-5p and miR-122-5p. qPCR and western blot showed that miR-122-5p mimic has positive effects on the osteogensis and migration, and its inhitiotr has negative effects. Simliarly, they could enhance or inhitor the effects of ICA, which means miR-122-5p may be the target of ICA. Conclusion Like the OB-exos, ICA could obviously promote the osteogenic differentiation and migration of BMSCs. The combination of ICA and OB-exos enhanced these effects, in which miR-122-5p plays a pivotal role.