Exosomes from Bone Marrow Mesenchymal Stem Cells Can Alleviate Early Brain Injury After Subarachnoid Hemorrhage Through miRNA129-5p-HMGB1 Pathway

In this study, the roles of exosomes (Exo) from bone marrow mesenchymal stem cells (BMSCs) in attenuating early brain injury (EBI) in rat brain after subarachnoid hemorrhage (SAH) had been investigated. The male Sprague-Dawley rats (300-350 g) were used to establish the SAH model using endovascular perforation method. The animals were randomly divided into three groups: sham ( n  = 25), SAH+PBS ( n  = 42), and SAH+Exo groups ( n  = 33). At 1 h after SAH, Exo or phosphate-buffered saline (PBS) was administered by femoral vein injection. The effects of Exo on the mortality, neurological function, brain water content, and blood-brain barrier (BBB) were explored. Furthermore, the expressions of miRNA129-5p and high-mobility group box 1 protein (HMGB1) after Exo treatment were also detected. In addition, immunohistochemistry and western blot were applied to investigate the mechanism of Exo's effects. The results indicated that Exo could improve the neurological functions, reduce brain water content and maintain BBB integrity after SAH. After Exo treatment, the expression of miRNA129-5p was significantly increased, whereas the RNA level of HMGB1 was decreased. The protein levels of proinflammatory and proapoptosis factors, such as HMGB1, Toll-like receptor-4 (TLR4), tumor necrosis factor-α, and p53, were increased after SAH, which were significantly declined after Exo application. The results indicated that Exo from BMSCs could alleviate EBI after SAH through miRNA129-5p's anti-inflammation and antiapoptosis effects through quenching the activity of HMGB1-TLR4 pathway.