Nanovesicles Synergistically Regulate Ferroptosis Characteristic Macrophage-Induced Angiogenesis via Ferritin Heavy Chain 1/Glutathione Peroxidase 4 Pathway to Promote Peripheral Nerve Regeneration

Peripheral nerves can regenerate following injury; however, this ability is imperfect, causing incomplete functional recovery. Macrophage-induced angiogenesis guiding Schwann cell (SCs) migration played an essential role in reconnecting severed nerves and promoting regeneration. However, macrophages engulfing myelin debris (MD) will undergo ferroptosis and diminish its protective effect. It is still lacking effective strategies for synergistically regulating macrophage-induced angiogenesis. Plant-derived extracellular vesicles (PDEVs) have raised more and more attention in treating diseases due to their low immunogenicity, good biocompatibility, high yield, and low cost. However, the application of the treatment of peripheral nerve injury (PNI) is still rare. In this study, we prepared and characterized Salvia miltiorrhiza-derived extracellular vesicles (SM^EVs). We identified that macrophages experienced lipid peroxidation and elevated ferroptosis after engulfing myelin debris at the injury site. SM^EVs can significantly upregulate the expression levels of ferroptosis-protective factors Ferritin Heavy Chain 1 (Fth1) and glutathione peroxidase 4 (GPX4), while downregulating the expression levels of Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), resulting in a significant reduction in lipid peroxidation and ferroptosis in macrophages. Interestingly, we found that SM^EVs can also reverse the downregulation of vascular endothelial growth factor A (VEGFA) levels following macrophage ferroptosis, thereby promoting angiogenesis after nerve injury. Our study reveals that SM^EVs can promote nerve regeneration and functional recovery by reducing macrophage ferroptosis and enhancing angiogenesis following PNI.