[Modulation of umbilical cord blood mesenchymal stem cells on Treg cells in the patients with aplastic anemia].

Objective: To research the modulation of Umbilical cord blood mesenchymal stem cells on the number and function of Treg cells in the patients with aplastic anemia, as well as the expression of LFA-1 on Treg cells. Methods: A total of 20 newly diagnosed NSAA patients were collected from May 2015 to Jun 2016 in Department of Hematopathy, General Hospital of Jinan Military, and 10 healthy volunteers were recruited as controls. Separation of the patients and controls with peripheral blood mononuclear cells were divided into two groups, including PBMCs culture alone, PBMCs co-culture with UC-MSCs, application of flow cytometry detect respectively the proportion of the Treg cells and the expression of LFA-1 on Treg cells under different culture conditions. The Treg cells and CD4(+) CD25(-)T lymphocyte were separated by magnetic cell sorting (MACS) system, CFSE label CD4(+) CD25(-)T lymphocyte, comparing the inhibitive function of Treg cells on CD4(+) CD25(-)T lymphocyte with or without co-culture with UC-MSCs. Results: The intensity of fluorescence expression of LFA-1 on T lymphocyte in aplastic anemia increased obviously((71.4±10.1)vs(52.5±8.7) , P=0.002), but the LFA-1 expressed on Treg cells had no significant difference(P=0.199). After co-cultured with UC-MSCs, the proportion of LFA-1 on Treg cells in aplastic anemia reduced greatly ((20.96±1.76)% vs(44.26±1.19)%, P=0.012), at the same time, UC-MSCs increased the proportion of Treg cells obviously ((5.33±1.14)%vs(1.94±0.65)%, P=0.003), but the effect of Treg cells on the mean frquency of dividing CD4(+) CD25(-)T lymphocyte had no significant difference with or without co-culture with UC-MSCs(P=0.290). Conclusions: The intensity of fluorescence expression of LFA-1 on lymphocyte in aplastic anemia increases obviously, indicating the possible pathogenesis of AA. UC-MSCs inhibit the expression of LFA-1 on Treg cells and enhance the proportion of Treg cells, but UC-MSCs doesn't directly improve the immunosuppression of single Treg cells.