Abstract：Objective: To investigate the regulatory effects of BMSCs-derived exosomes (BMSCs-Exos) on osteogenic differentiation in vitro, to elucidate the mechanism by which miR-181 targets ERK5 to mediate this regulation, and to study the impact of BMSCs-Exos and overexpressed miR-181 on femoral fracture healing in mice.Methods: BMSCs-Exos were characterized using dynamic light scattering (DLS) and Western blot techniques. The expression levels of miR-181 and ERK5 were assessed via qRT-PCR and Western blot. Dual-luciferase reporter assays were performed to validate the targeting relationship between miR-181 and ERK5. Protein expression and ALP activity were analyzed using Western blot and ELISA. In a mouse femoral fracture model, miR-181 mimic or BMSCs-Exos were injected, and fracture healing was evaluated by measuring callus volume (CV), trabecular bone volume fraction (BV/TV), and relevant protein levels.Results: The particle size of BMSCs-Exos ranged from 50 to 150 nm, with a Zeta potential of -25.69±2.88 mV. Surface markers CD9, CD63, and CD81 were prominently expressed. In the BMSCs-Exos group, miR-181 expression was upregulated (P<0.05), while ERK5 expression was downregulated (P<0.05). The miR-181 mimic increased miR-181 expression and decreased ERK5 protein levels (P<0.05). BMSCs-Exos delivering miR-181 promoted osteogenic differentiation of BMSCs in vitro by targeting ERK5 (P<0.05). Both BMSCs-Exos and overexpressed miR-181 enhanced femoral fracture healing in mice (P<0.05).Conclusion: BMSCs-Exos facilitate osteogenic differentiation of BMSCs in vitro by transporting miR-181 and targeting ERK5, and they also aid in femoral fracture healing in mice.
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2024, Vol. 30 
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