The Preliminary Study On The Suppression Of Human Umbilical Uord Mesenchymal Stem Cells On AGVHD In Murine Allogeneic Bone Marrow Transplantation

Objective: The purpose of this study was to investigate the therapeutic potential of human umbilical cord mesenchymal stem cells (HUCMSCs) for preventing aGVHD following murine allogeneic bone marrow transplantation (BMT).Methods: In this study, a new method of separating and culturing HUCMSCs was used. The human umbilical cord tissue was digested by collagenaseⅡfor 2h. And after passaged to P3, purer HUCMSCs could be obtained. CD4+CD25-T cells stained with CFSE were cocultured with HUCMSCs in vitro, using flow cytometry to measure the proliferation of CD4+CD25-T cells. Acute GVHD model of C57BL/6→DBA/2 was established, just as aGVHD group. Based on this aGVHD model, donor HUCMSCs were adoptive transferred, termed HUCMSCs-treated group. Then the survival, body weight, GVHD scoring, histopathological specimens, lymphocyte subgroups and serum cytokine analysis in the aGVHD group were compared with those in the HUCMSCs-treated group.Results: In vitro, IFN-γtreated HUCMSCs had a strong inhibitory effect on the proliferation of CD4+CD25-T cells, but untreated HUCMSCs can not obviously inhibit the proliferation of CD4+CD25-T cells. IDO is involved in the immunosuppression of HUCMSCs. The mice treated with HUCMSCs exhibited light symptoms of aGVHD and had survived longer. There were higher IFN-γand IL-12 levels by day 7 in serum of mice that received HUCMSCs compared to those without HUCMSCs-treatment, while the IL-4 levels showed no significant difference between the two groups. The proportion of CD3+NK1.1+NKT cells in splenocytes of HUCMSCs-treated group is higher in day 21 compared with that in day 7.Conclusion: In vitro, IFN-γcan promote the immunosuppressive capacity of HUCMSCs on the proliferation of CD4+CD25-T cells through the expression of IDO. After the xenogeneic transplantation of HUCMSCs to the aGVHD model of mice, HUCMSCs can alleviat aGVHD symptoms and prolonged the survival period. Our study gives a clue to the therapeutic potential of in vitro-expanded donor HUCMSCs in protection against aGVHD in allogeneic HSCT.