Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Attenuate Secondary Brain Injury After Intracerebral Hemorrhage in Rats by Modulating the SIRT6/Notch1/NF-κB Signaling

This study aimed to investigate the effects and potential mechanisms of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) on secondary brain injury (SBI) after intracerebral hemorrhage (ICH) in rats. BMSC-Exos were isolated and characterized by transmission electron microscopy and Western blot analysis of exosomal markers (CD9, CD63, and TSG101). A rat model of ICH was established by intracerebral injection of Type IV collagenase, and a PC12 cell model of ICH was induced by hemin exposure. Neurological deficits was evaluated using the modified neurological severity score (mNSS). Histopathological changes in the brain of rats were observed by H&E, Nissl, and TUNEL staining. Inflammatory cytokines (TNF-α, IL-1β) and oxidative stress indicators (ROS) were measured by ELISA and fluorescence assays. PC12 cells were co-cultured with BMSC-Exos, and cell viability, Apoptosis, and oxidative stress were assessed using CCK-8, LDH release, EdU assay, and flow cytometry. Expression of SIRT6/Notch1/NF-κB pathway proteins were analyzed by Western blot. BMSC-Exos treatment significantly improved neurological function, reducing mNSS scores by approximately 44% at 72 h after ICH (P < 0.001), and decreased brain water content by about 8.7% (P < 0.05). Histopathological analysis showed a 45% reduction in neuronal Apoptosis and 41% increase in surviving neurons compared with untreated ICH rats (P < 0.05). Inflammatory cytokines TNF-α and IL-1β were reduced by 33% and 39%, respectively, and ROS production declined by ~ 40% (P < 0.05). In vitro, BMSC-Exos enhanced PC12 cell viability by 49%, reduced LDH release by 30%, and decreased apoptotic cell ratio by 46% following hemin injury (P < 0.05). Mechanistically, BMSC-Exos upregulated SIRT6 expression and suppressed Notch1 and NF-κB p65 phosphorylation, whereas SIRT6 knockdown reversed these protective effects. BMSC-Exos alleviate SBI after ICH by enhancing SIRT6 expression, thereby suppressing Notch1/NF-κB activation and mitigating neuronal Apoptosis, oxidative stress, and inflammation.