Study On Immunoregulatory Effects Of Mesenchymal Stem Cells On Lymphocytes

Backgroud:Mesenchymal stem cells(MSCs)are nonhematopoietic progenitor cells of the bone marrow stromal cells.Studies show that MSCs can also regulate allogeneic stem-cell transplantation and the function of T and B lymphocytes.However,the mechanisms of the immunosuppression are still obscure.Objective:To investigate the immunoregulatory effects and potential mechanism of murine MSCs and MSCs combined with rapamycin on Splenic lymphocytes and human MSCs on peripheral blood T-lymphocytes of normal human and systemic lupus erythematosus(SLE)paitients.It maybe useful for clinical application in future.Methods:(1)Murine MSCs on Splenic lymphocytes:MSCs were isolated and cultured from BALB/c mice routinely.The purity was detected through surface markers by flow cytometry(FCM).MSCs were collected and irradiated at 15 Gy by the linear accelerator for experiment.Under ConA or LPS stimulating,Splenic lymphocytes were treated with MSCs(MSCs accorded to different proportion)and MSCs combined with rapamycin(final concentration was 80ng/ml).the proliferation was assessed by MTT coloremetry.FCM was used to analyze the apoptosis and surface markers-CD69,CD28andCD86.the mRNA expression of interferon-γ, (IFN-γ)and interleukin-10(IL-10)were detected by real-time quantitative PCR.(2)Human MSCs on T-lymphocytes of SLE patients: human MSCs were isolated and cultivated from the bone marrow of normal human.MSCs were collected and irradiated with the linear accelerator for experiment.Under PHA stimulating,peripheral blood T-lymphocytes of normal human and SLE patients were treated with MSCs(MSCs accorded to different proportion),the proliferation was assessed by MTT coloremetry. FCM was used to analyze the surface markers-CD152 and CD28.the mRNA expression of IFN-γand IL-10 were detected by real-time quantitative PCR.Results:(1)Murine MSCs cound inhibit the lymphocytes proliferation and T cells apoptosis significantly with increase interferon(IFN)-γbut decrease interleukin(IL)-10 at mRNA expression(P＜0.01),and such effect exhibited MSCs volume dependent.(2)Rapamycin could enhence the immunoregulatory effect of Murine MSCs on Splenic lymphocytes obviously(P＜0.05).No difference of CD69,CD28 andCD86 expression was observed among all groups.(3)Human MSCs cound inhibit the lymphocytes proliferation and CD3~+CD28~+ expression of SLE significantly with decrease IFN-γ,and IL-6 at mRNA expression,and such effect exhibited MSCs volume dependent.Conclusion:MSCs could down-modulate function of T and B lymphocytes,and the potional mechanism maybe related with the effect on the proliferation,apoptosis and the mRNA expression of T cell differentiation-related cytokine.The mechanism was very complicated and also related with diffent source and object of MSCs.