Immunomodulatory properties of wharton jelly-derived mesenchymal stem sells (iWJ-MSCs)

Objective: The aim of this thesis is to transfect mature miRNA-181a involved in immunoregulation to increase the immunosuppressive efficacy of iWJ-MSCs, which have come to the forefront with both their potency and allogeneic use, and to analyze the effect of transfection in the human pan T cell model, an in vitro immune system model. Methods: In this thesis, T cell response after co-culture with miRNA transfected iWJ-MKCs; viability and proliferation (CCK8), apoptosis (AnnexinV-PI method) and cell cycle change (flow cytometric cell cycle analysis), anti- and pro-inflammatory cytokines (TGF-beta1, IL-6, TLR-4 and STAT1), regulatory T-cell (Treg) (CD4+CD25+Foxp3+), T-bet and T-cell marker/gene expressions (CD3, CD4, CD45, CD4+CD8 and CD69) were analyzed.. Results: PHA-M activated T lymphocytes were shown to be capable of forming distinct and highly viable colonies by phase-constrate microscopy. Both miRNA-transfected and non-miRNA-transfected iWJ-MSCs did not show apoptotic effect on day 4 and apoptosis was decreased. In cell cycle analysis, proliferation and apoptosis were decreased in T cells co-cultured with CCPs and proliferation was decreased and apoptosis was increased (*p<0.05) in those co-cultured with miRNA transfected CCPs compared to T cells alone on day 4. The percentage of T cells expressing T cell markers decreased in both co-culture groups. While TGF-beta gene expression was decreased, its secretion from both MSCs and Tregs in coculture medium increased and IFN-gamma secretion decreased despite the increase in Tbet cell population. It was observed that miRNA transfection increased T cell proliferation, apoptosis and Treg and T-bet populations in CRCs. Conclusion: It was concluded that miR-181a transfection regulates the immunosuppressive effects of CCPs through IL-6, STAT-1 and DUSP5 genes and TGF-beta and IFN-gamma cytokines. This study was financially supported by grants (YL A2 31858) Turkish Institutes of Health (TÜSEB