Therapeutic Effects of Mechanical Stress-Induced C2C12-Derived Exosomes on Glucocorticoid-Induced Osteoporosis Through miR-92a-3p/PTEN/AKT Signaling Pathway.

Introduction: Osteoporosis is a common bone disease in which the bone loses density and strength and is prone to fracture. Bone marrow mesenchymal stem cells (BMSCs) are important in bone-related diseases. Exosomes, as mediators of cell communication, have potential in cell processes. Previous studies have focused on muscle factors' regulation of bone remodeling, but research on exosomes is lacking. Methods: In order to confirm the therapeutic effect of mechanically stimulated myocytes (C2C12) derived exosomes (Exosome-MS) on the Glucocorticoid-induced osteoporosis(GIOP) compared with unmechanically stimulated myocytes (C2C12) derived exosomes (Exosomes), we established a dexamethasone-induced osteoporosis model in vivo and in vitro. Cell viability and proliferation were assessed using CCK8 and EDU assays. Osteogenic potential was evaluated through Western blotting, real-time PCR, alkaline phosphatase activity assay, and alizarin red staining. Differential expression of miRNAs was determined by high-throughput sequencing. The regulatory mechanism of miR-92a-3p on cell proliferation and osteogenic differentiation via the PTEN/AKT pathway was investigated using real-time PCR, luciferase reporter gene assay, Western blotting, and immunofluorescence. The therapeutic effects of exosomes were evaluated in vivo using microCT, HE staining, Masson staining, and immunohistochemistry. Results: In this study, we found that exosomes derived from mechanical stress had a positive impact on the proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs). Importantly, we demonstrated that miR-92a-3p mimics could reverse dexamethasone-induced osteoporosis in vitro and in vivo, indicating that mechanical stress-induced mouse myoblast-derived exosomes could promote osteogenesis and prevent the occurrence and progression of osteoporosis in mice through miR-92a-3p/PTEN/AKT signaling pathway. Conclusion: Exosomes derived from mechanical stress-induced myoblasts can promote the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells through miR-92a-3p/PTEN/AKT signaling pathway, and can have a therapeutic effect on glucocorticoid-induced osteoporosis in mice in vivo.