immunomodulatory effects of mice mesenchymal stem cells on maturation and activation of dendritic cells

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.