Abstract: Objective To investigate the effect of human adipose derived mesenchymal stems cells (haMSC) on T lymphocytes of aplastic anemia patients (AA) and explore its possible mechanism. Methods HaMSCs were extracted from human adipose tissues．T lymphocytes were isolated from peripheral blood of patients with AA by density gradient centrifμgation．HaMSCs were co-cultured with T-lymphocytes. Inhibitory effect of haMSCs on AA-TLCs was measured by MTT assay, T-bet and GATA-3 levels were examined by realtime PCR and Western blot. The levels of INF-γ, IL-2, IL-4 and IL-10 were detected by ELASA. Results HaMSCs showed inhibitory effect on lymphocyte proliferation of aplastic anemia patients in a time dependent manner: After 3,5 and 7 days’ co-culturing, their inhibitory rates were (34.94±10.11)%，(53.44±6.16)%，(68.13±15.24)%, respectively(p<0.05). The T-bet mRNA and protein levels in MSCs+AA-TLCs group were significantly lower than that in AA-TLCs group, while the GATA-3 mRNA and protein levels were significantly higher than that in AA-TLCs group. The concentrations of Th1 type cytokins INF-γ and IL-2 in MSCs+AA-TLCs group [(8.7±2.7) ng/L and (7.3±1.3) ng/L, respectively] were significantly lower than those in AA-TLCs group [(41.5±3.7)ng/L and (61.5±8.7) ng/L, respectively (p<0.05)]. But the concentrations of Th2 type cytokins IL-4 and IL-10 in MSCs+AA-TLCs group [(88.6±15.2) ng/L and (38.3±11.8) ng/L, respectively] were significantly higher than those in AA-TLCs group [(1.4±0.6) ng/L and (1.3±0.2) ng/L, respectively (p<0.05)]. Conclusion HaMSCs can mediate an immunoregulation effect on T lymphocytes of aplastic anemia patients in vitro，which was related with the depression of Th1-dominant response due to the disorder of T-bet and GATA-3 gene expression.

Key words: mesenchymal stem cells (MSCs), aplastic anemia (AA), Immune-modulatory , T-bet, GATA-3