1Department of Biology, Islamic Azad University, Fars Science and Research Branch
2Autoimmune Diseases Research Center and Immunology Department, Shiraz University of Medical Sciences
3Transplant Research Center, Shiraz University of Medical Sciences, Shiraz
4Department of Biology, Islamic Azad University, Kazerun branch, Kazerun, Iran
Background: Mesenchymal stem cells (MSCs) possess a wide range of immunomodulatory functions mostly in immune cells including dendritic cells (DCs). DCs are the key cells in the immune response and play an important role in initiating cell-mediated immunity. Objective: To evaluate the immunomodulatory effects of MSCs supernatant on maturation and function of DCs. Methods: Bone marrow derived mice MSCs were isolated and cultured. Twenty-four, forty-eight and seventy-two hours after passage 6, supernatants were collected and MSCs were assessed by cytometric analysis for the expression of CD34, CD44, CD45 and SCA-1. Splenic DCs were isolated using MACS and then co-cultured with MSCs supernatant. Expression of CD86, CD40 and MHC-II on DCs were also evaluated by cytometry. H 3-thymidine incorporation by proliferating T cells was determined in two separate MLR assay settings. In one setting, DCs were co-cultured with T cells in the presence of MSCs supernatant, and in the other setting DCs were treated with MSCs supernatant and then were co-cultured with T cells. Production of IL-12, IL-6 and IL-10 cytokines was measured in the supernatant of DCs treated with MSCs supernatant. We also measured IFN- γ and IL-4 levels in MLR supernatant. Results: The results showed that 72h MSCs supernatant could decrease the expression of MHC-II and CD86. The T cell proliferation was inhibited in the presence of MSCs supernatant and MSCs supernatant treated DCs as demonstrated by MLR assay. A significant increase in IL-4 level and a non significant decrease in IFN- γ level in MLR supernatant were observed. However, IL-6, IL-10 and IL-12 production did not change significantly. Conclusion: MSCs supernatant has a time dependent effect on the maturation of DCs. Also, it could alter cytokine production from responding T cells toward Th2. Generally, the findings of this study supported the immunomodulatory effect of MSCs supernatant on DCs maturation and function.