The Role And Mechanism Of Adipose Mesenchymal Stem Cells In The Repair Of Spinal Cord Injury By Regulating Notch Signaling Pathway

BackgroundSpinal cord injury(SCI)is a serious central traumatic disease,which often leads to the loss of motor and sensory function of nerve roots or myelinated nerve bundles below the injury section.The therapeutic effect of adipose-derived mesenchymal stem cell(ADSC)transplantation in central nervous system(CNS)injury model has been confirmed,which is generally believed to be related to the regulation of inflammatory response;however,the exact underlying molecular mechanism is not well understood.The activation of Jagged1/Notch signaling pathway is thought to be related to inflammation of the central nervous system and activation of glial cells.Here,we explore the effect of ADSC transplantation on inflammatory response after SCI and the possible mechanism mediated by inhibition of Jagged1/Notch signal pathway.ObjectiveIn this study,we first identified the survival of ADSC in SCI mice,and discussed the role of ADSC in the regulation of inflammatory response and the recovery of neurological function,and in vitro experiments,using the co-culture system established by ADSC and neurons in the environment of glucose and oxygen deprivation,to verify the regulatory effect of ADSC on neuronal inflammatory response,and to explore the specific effect of ADSC on neurons through Jagged1/Notch signal pathway.Finally,in vivo experiments,we deeply studied the role of ADSC in regulating neuroinflammatory response and neurofunctional recovery in SCI,in order to clarify the regulatory role and mechanism of ADSC on neuroinflammatory response and neuronal survival in SCI through Jaggedl/Notch signal pathway,deepen the understanding of ADSC transplantation therapy,and provide basic theoretical basis for clinical ADSC treatment of SCI.Methods1.The model is that mice were subjected to contusion spinal cord injury,GFP-labeled ADSC was injected into the injured site to observe the regulation of ADSC on the inflammatory response of SCI and the recovery of neurological function.The motor function,spinal cord morphology-related proteins and pro-inflammatory transcription factors in each group were compared by BMS score,RT-PCR,Westernblot,immunofluorescence double labeling and hue tissue staining.2.Primary ADSC was isolated,cultured and identified,and co-cultured directly and indirectly with neurons in different culture environments.The release levels of IL-6,IL-1 β and TNF-α in the culture medium of each group were detected by ELISA,and the apoptosis of neurons was detected by western blot.3.In order to explore the hypothesis that the therapeutic effect of ADSC may be the inhibition of Jagged1/Notch signal,Jagged1-siRNA was injected into SCI tissue to knock down the expression of Jaggedl/Notch signal pathway.Microglia/macrophage activation index(IBA1),macrophage infiltration marker(ED1)and Jagged1/Notch signal pathway related proteins were detected by immunofluorescence staining and western blot.Results1.This study demonstrated that ADSC could survive in the injured spinal cord for at least 28 days,and it did not differentiate into astrocytes or neurons,2.ADSC treatment of SCI can significantly inhibit the expression of pro-inflammatory factors,reduce neuroinflammatory response,inhibit the expression of IBA1 and ED1 in SCI,reduce neuronal apoptosis and promote the recovery of neurological function.3.ADSC transplantation can inhibit the activation of Jagged1/Notch signal pathway.When Jagged1-siRNA was used to knock down the expression of Jaggedl/Notch signal pathway,it could inhibit the expression of pro-inflammatory cytokines after SCI,reduce the infiltration of microglia/macrophages,and increase the survival rate of neurons,which was similar to that of ADSC transplantation.4.Jagged1-siRNA inhibits the activation of Jagged1/Notch signal pathway after spinal cord injury,which leads to the decrease of JAK/STAT3 phosphorylation in astrocytes.ConclusionADSC transplantation can inhibit the Jaggedl/Notch signal pathway after SCI,reduce the infiltration of inflammatory cells,thus reduce the neuroinflammatory response,and inhibit the phosphorylation of JAK/STAT3 in astrocytes,thus protecting neurons.