The Immunosuppressive Effect And Mechanism Of Exosomes In Mice Allograft Heart Transplantation

Objectives:Mesenchymal Stem Cells(MSCs)have high research and application value in the field of transplantation immunity due to their low immunogenicity and immunosuppressive effect.In addition,studies have shown that IFN-y promotes the immunosuppressive effects of MSCs.It is currently believed that MSCs affect tissue repair primarily through their paracrine factors and host cell stimulation,rather than through cell replacement.Because MSCs secrete a large number of bioactive proteins,including exosomes secreted in the form of microvesicles,with bioactive components.Based on this,we exogenously added cytokines stimulated with IFN-γ or without IFN-γ stimulation(under natural conditions)and co-cultured with MSCs for 48h,then collected the culture medium of MSCs,and then obtained corresponding exosomes to study the effects of exosomes through different treatment on immune rejection in mice.Methods:Isolated from the umbilical cord,cultured the human umbilical cord MSCs,and its cell immune phenotype and differentiation function were identified.MSCs were cultured under the condition of adding/without IFN-y.The exosomes were obtained from the MSCs medium,and the particle size and morphology were identified.The inhibition effect of differently treated exosomes on lymphocyte proliferation in vitro was detected by the experiments of lymphocyte proliferation stimulated by anti-CD3/CD28.Allogeneic heart transplantation model from BALB/C to C57BL/6 was established by the neck casing method,and the effect of exosomes on immune rejection in mice was studied in vivo.Results:A large number of MSCs were easily isolated and cultured from the human umbilical cord.The cells had high purity,uniform morphology,and possessed the morphological and surface marker characteristics and differentiation ability.The corresponding exosomes can be stably obtained from the culture medium of MSCs with or without cytokine IFN-y stimulation.The results of lymphocyte proliferation experiments in vitro showed that exosomes produced by IFN-y stimulated MSCs had a stronger inhibitory effect on lymphocyte proliferation.In vivo experiments,exosomes attenuate immune response by reducing the infiltration of inflammatory cells and the expression of inflammatory factors in the heart transplants,reducing the proportion of CD4+T cells in the spleen,and the content IFN-y in the serum.Conclusions:Our study shows that IFN-y-stimulated MSCs-Exo has low immunogenicity,which weakens allogeneic immune rejection by inhibiting lymphocytes and has the potential to protect heart grafts.