Human umbilical cord mesenchymal stem cell-derived exosomes ameliorate muscle atrophy via the miR-132-3p/FoxO3 axis.

Background: Muscle atrophy or sarcopenia is the loss of muscle mass and strength and leads to an increased risk of disability and death including osteoporotic fractures. Currently, there are no available clinical biologic agents for the treatment of sarcopenia. Since exosomes have become increasingly attractive as a novel therapeutic approach due to their ability to facilitate cell-cell transfer of proteins and RNAs, promoting cell repair and function recovery, we hypothesized that human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Exos) might benefit muscle atrophy in age-related and dexamethasone-induced sarcopenia animal models. Methods: HucMSC-Exos were harvested by ultrafast centrifugation and identified by transmission electron microscopy, particle size analysis, and Western blot analysis. The effects of hucMSC-Exos on muscle atrophy were evaluated using age-related and dexamethasone-induced muscle atrophy mice models. Body weight, grip strength, muscle weight, and muscle histology of these mice were assessed. The expression levels of muscle RING finger 1 (MuRF1) and muscle atrophy F-box (atrogin-1) were measured by Western blot. Dexamethasone-induced C2C12 myotube atrophy was used to establish the cell model of muscle atrophy. Myotube diameter was evaluated by immunofluorescence staining. Bioinformatic analysis, RNA sequencing analysis, and Western blot analysis were performed to explore the underlying mechanisms. Results: In vivo experiments, hucMSC-Exos demonstrated a remarkable capacity to improve grip strength, increase muscle mass, and muscle fiber cross-sectional area, while concurrently reducing the expression of MuRF1 and atrogin-1 in age-related and dexamethasone-induced muscle atrophy mice. In vitro experiments, hucMSC-Exos can promote the proliferation of C2C12 cells, and rescue the dexamethasone-induced decline in the viability of C2C12 myotubes. In addition, hucMSC-Exos can increase the diameter of C2C12 myotubes, and reduce dexamethasone-induced upregulation of MuRF1 and atrogin-1. Combined with bioinformatics analysis and RNA sequencing analysis, we further showed that miR-132-3p was one of the essential miRNAs in hucMSC-Exos and played an important role by targeting FoxO3. Conclusion: Our findings suggested that hucMSC-Exos can improve age-related and dexamethasone-induced muscle atrophy in mice models. This study first demonstrated that hucMSC-Exos may ameliorate muscle atrophy via the miR-132-3p/FoxO3 axis. These data may provide novel and valuable insights into the clinical transformation of hucMSC-Exos for the treatment of sarcopenia. The translational potential of this article: HucMSC-Exos are easily available for clinical application, this study further consolidates the evidence for the clinical transformation potential of hucMSC-Exos for sarcopenia and provides its new target pathway.