Exosomal miR-214-3p reprograms BMSC fate: A novel intercellular mechanism linking vascular insufficiency to impaired bone regeneration in nontraumatic ONFH

Background: Nontraumatic osteonecrosis of the femoral head (NONFH) is a debilitating bone disorder of unclear etiology, characterized by impaired bone regeneration and reduced vascularization. However, the influence of NONFH-derived exosomes on bone marrow stromal cell (BMSC) differentiation and angiogenesis remains poorly understood.

Methods: Exosomes were isolated from femoral head tissues of NONFH patients and fracture controls (femoral neck fractures). Their characteristics were confirmed by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot. BMSCs were treated with different exosomes (control exosomes, NONFH exosomes, or NONFH exosomes + miR-214-3p inhibitor), and osteogenic/adipogenic differentiation was assessed by Alkaline Phosphatase activity, calcium deposition, osteogenic/adipogenic marker expression, and Oil Red O staining. Human umbilical vein endothelial cells (HUVECs) were similarly treated, and angiogenesis was evaluated via tube formation assays. In vivo, exosomes were injected into rats, and femoral changes were analyzed by Western blot, hematoxylin-eosin (HE) staining, and immunohistochemistry.

Results: Exosomes from both groups exhibited typical morphology, size, and marker expression. NONFH exosomes suppressed BMSC osteogenesis, enhanced adipogenesis, and impaired HUVEC angiogenesis, with miR-214-3p as a critical mediator. Inhibiting miR-214-3p partially restored osteogenic and angiogenic capacities. In rats, NONFH exosomes reduced osteogenic protein expression, expanded marrow cavities, and disrupted trabecular bone structure, while miR-214-3p inhibition ameliorated these effects.

Conclusion: NONFH-derived exosomes contribute to disease progression by delivering miR-214-3p, which inhibits BMSC osteogenesis and HUVEC angiogenesis. Targeting this pathway may offer novel therapeutic strategies for NONFH.

Angiogenesis; Bone Marrow Stromal Cells; Exosomes; MiR-214–3p; Nontraumatic Osteonecrosis of the Femoral Head; Osteogenic Differentiation.