BMSCs Alleviate Early Brain Injury Following Subarachnoid Hemorrhage In Rats And The Relevant Mechanism

Background:Activated microglia-mediated neuroinflammation has been regarded as an underlying key player in the pathogenesis of subarachnoid hemorrhage(SAH)induced early brain injury(EBI).The therapeutic potential of bone marrow mesenchymal stem cells(BMSCs)transplantation has been demonstrated in several brain injury models and is thought to involve modulation of the inflammatory response.The present study investigated the salutary effects of BMSCs on EBI after SAH and the potential mechanism mediated by Notchl signaling pathway inhibition.Methods:Sprague-Dawley rats SAH model was induced by endovascular perforation method.BMSCs(3 × 106 cells)were transplanted intravenously into rats,N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-Phenylglycine t-butyl ester(DAPT),a Notchl activation inhibitor,and Notchl small interfering RNA(siRNA)were injected intracerebroventricularly.The effects of BMSCs on EBI were assayed by neurological score,brain water content(BWC),blood-brain barrier(BBB)permeability,magnetic resonance imaging,hematoxylin and eosin staining and Fluoro-Jade C staining.Immunofluorescence and imunohistochemistry staining,western blot and quantitative real-time polymerase chain reaction were used to analyze various proteins and transcript levels.Pro-inflammatory cytokines were measured by enzyme-linked immunosorbent assay.Results:BMSCs treatment mitigated the neurobehavioral dysfunction,BWC and BBB disruption associated with EBI after SAH,reduced ionized calcium binding adapter molecule 1 and cluster of differentiation 68 staining and interleukin(IL)-1 beta,IL-6 and tumor necrosis factor alpha expression in the left hemisphere but concurrently increased IL-10 expression.DAPT or Notch1 siRNA administration reduced Notch1 signaling pathway activation following SAH,ameliorated neurobehavioral impairments,BBB disruption,increased BWC,and neuronal degeneration and inhibited activation of microglia and production of pro-inflammatory factors.The augmentation of Notch1 signal pathway agents and phosphorylation of nuclear factor-κB after SAH were suppressed by BMSCs but the levels of Botch were upregulated in the ipsilateral hemisphere.Botch knockdown in BMSCs abrogated the protective effects of BMSCs treatment on EBI and the suppressive effects of BMSCs on Notchl expression.Conclusions:BMSCs treatment alleviated neurobehavioral impairments and the inflammatory response in EBI after SAH;these effects may be attributed to Botch upregulation in brain tissue,which subsequently inhibited the Notchl signaling pathway.