ABSTRACT Background Ferroptosis in pathophysiological mechanisms in early brain injury after subarachnoid hemorrhage (SAH‐EBI) has been demonstrated. MicroRNAs (miRNAs) are involved in various aspects of neurological disorders. A growing number of studies suggest that intense inflammation mediated by M1 microglia after subarachnoid hemorrhage (SAH) may lead to neurological damage. According to our research and related reports, exosomal miR‐369‐3p is involved in the pathophysiological process of SAH, and miR‐369‐3p has a potentially central role in regulating inflammatory responses. Therefore, targeted delivery of miR‐369‐3p across the blood‐brain barrier (BBB) into the brain to alleviate SAH‐EBI is a promising therapeutic approach. Methods In this study, we extracted exosomes from RBCs and then modified RVG peptide onto the exosome surface using the click chemistry principle. Finally, miR‐369‐3p mimic was loaded into the RVG peptide‐modified exosomes to form RVG‐Exo/miR‐369‐3p (RVG‐Exo/miR) by electroporation. Tail vein injection of RVG‐Exo/miR was used to achieve delivery of miR‐369‐3p into the brain of SAH mice. The effect of miR‐369‐3p on SAH‐EBI was examined by neurobehavioral scores, brain water content, Fluoro‐Jade C (FJC) staining, and Nissl staining. MDA and GSH kits were used to assess the extent of ferroptosis occurrence. Western blotting analysis, immunofluorescence staining, and qRT‐PCR were used to detect the levels of each protein, mRNA, and miRNA. Results The exosome system (RVG‐Exo/miR) successfully delivered miR‐369‐3p to the mouse central nervous system across the blood‐brain barrierBBB. This exosomal system reduced the number of M1 microglia by enhancing their sensitivity to ferroptosis by inhibiting the expression of iNOS and GPX4. In addition, miR‐369‐3p treatment alleviated neurobehavioral disorders, brain edema, and neuronal damage after SAH‐EBI. Conclusions RVG‐Exo/miR promotes ferroptosis in M1 microglia by inhibiting the iNOS/GPX4 axis, which may be a new and effective therapeutic strategy for treating SAH‐EBI.
Fang et al. (2025) studied this question.