The Immunoregulation effects of bone marrow mesenchymal stem cells on the lymphocytes of rats with type 1 diabetes mellitus in vitro

Objective To observe the effects of bone marrow mesenchymal stem cells (MSCs) on the lymphocytes of rats with type 1 diabetes mellitus (T1DM) in vitro, and investigate the inhibitory effect of MSCs on lymphocytes proliferation and the underlying mechanism. Methods MSCs were isolated from SD rats, cultured in vitro, purified and then identified by testing the phenotypes with flow cytometry (FCM). The third-generation MSCs were planted in 24-well plates. After treated with mitomycin C, MSCs were co-cultured for 72 h with the T1 DM rat's lymphocytes activated by phytohemagglutinin (PHA). The proliferation of lymphocyte was measured by methyl thiazol tetrazolium (MTT) method. FCM analysis was done to investigate the apoptosis, cell cycle and the proportion of CD4+ CD25+ regulatory T cells of the T1 DM rat's lymphocytes after co-cultivation. Results The phenotypes of MSCs from normal SD rats were CD29 + , CD90 +, CD106 + , CD34-, CD45 -. MSCs obviously inhibited the lymphocyte proliferation stimco-culture system, most of the lymphocytes were arrested at G0/G1 phase. The apoptosis rate of lymphocytes (58.05 ± 0. 89)% in group C was increased significantly as compared with the control group (43.35± 0.86 ) % ( P ＜ 0. 05 ) as well as the proportion of CD4 + CD25 + regulatory T cells (22.76 ± 1.15 ) % vs (5.80 ± 0. 68) %. Conclusion In vitro, MSCs can obviously inhibit the T1 DM rat' s lymphocytes proliferation stimulated with PHA via increasing the proportion of CD4 + CD25 + regulatory T cells. Key words: Diabetes mellitus;  Bone marrow mesenchymal stem cells;  T cells;  Immunoregulation