Abstract
Mesenchymal stem cells (MSCs) and extracellular vesicles (EVs) are promising therapies for the treatment of spinal cord injury (SCI). This study sought to explore the epigenetic mechanism of miR-26b-5p-enriched MSCs-EVs in SCI. MSCs and MSCs-EVs were isolated and characterized. The SCI rat model was established, followed by Basso-Beattie-Bresnahan scoring and H&E staining. In vitro cell models were established in PC12 cells with lipopolysaccharide (LPS) treatment, followed by cell viability evaluation using CCK-8 assay. The levels of miR-26b-5p, lysine demethylase 6A (KDM6A), NADPH oxidase 4 (NOX4), reactive oxygen species (ROS), and inflammatory factors (TNF-α/IL-1β/IL-6) in tissues and cells were detected. The levels of cy3-lablled miR-26b-5p in tissues and cells were observed by confocal microscopy. The binding of miR-26b-5p to KDM6A 3'UTR and the enrichments of KDM6A and H3K27me3 at the NOX4 promoter were analyzed. MSCs-EVs attenuated motor dysfunction, inflammation, and oxidative stress in SCI rats. MSCs-EVs delivered miR-26b-5p into PC12 cells to reduce LPS-induced inflammation and ROS production and enhance cell viability. miR-26b-5p inhibited KDM6A, and KDM6A reduced H3K27me3 at the NOX4 promoter to promote NOX4. Overexpression of KDM6A or NOX4 reversed the alleviative role of MSCs-EVs in SCI or LPS-induced cell injury. Overall, MSCs-EVs delivered miR-26b-5p into cells to target the KDM6A/NOX4 axis and facilitate the recovery from SCI.