Study On Immune Mechanism of Human Marrow Mesenchymal Stem Cells Adjusting Dendritic Cells for Treatment of Aplastic Anemia

(1)To explore whether MSC has inhibiting effect on the proliferation ofAA patients' Tcell;(2)To discuss whether MSC affects T cell's proliferation via adjusting the growth of DCs.

(1) MSC were separated and cultured in vitro. Cell morphology was observed and the cell surface antigen was determined by flow cytometry.(2) Peripheral blood mononuclear cells were extracted from 20 patients suffered AA and then T lymphocytes were separated by nylon fiber column. Flow cytometry was applied to determine the surface antigen and subpopulation of T cell.(3)mononuclear cells were separated from normal human peripheral blood. DCs were prepared under the culture condition of recombination human granulocyte-macrophage colony stimulating factor (GM-CSF) and recombinant human interleukin-4 (IL-4). After acquiring the mature DCs induced by LPS, the phenotype analysis of DCs before and after culture was examined by flow cytometry, respectively.

(1) After co-culture of MSC and T lymphocytes from AA peripheral blood, flow cytometry showed that the ratio of D8+ in T cells reduced significantly from 38.7% to 29.7 % (p < 0.05), whereas the CD4+ ratio increased from 24.9% to 34.9% significantly (p < 0.05). Meanwhile, ELISA analysis indicated that the concentration of IL-2 and IFN-γ were significantly decreased from 38.9 and 38.5 ng/L to 6.8 and 6.6 ng/L, respectively (p < 0.05). However, IL-4 and IL-10 increased from 2.8 and 2.9 to 5.3 and 8.3 ng/L, respectively (p < 0.05).(2) After the induction of immature DCs by LPS, flow cytometry showed that the expression of CD1a increased from 2.4% to 68.4% in the treatment without MSC, while that of CD14+ decreased from 83.6% to 3.5% (p < 0.05).(3) After the co-culture of mature DCs and MSC, the expression of CD14+ increased from 5.8% to 62.8% when the expression of CD1a, CD83 and CD80 decreased from 48.6%, 60.8% and 50.2% to 30.7%,40.9% and 20.3%, respectively.

Our study shows that (1)MSC inhibits the proliferation of T lymphocytes from AA p-atients by regulating CD8+ and CD4+; (2)futher study indicates that MSC can inhibit the growth of DCs and reverse the status of DCs from matureness to immatureness; (3)thus suggests the possible mechanism of MSC's inhibiting effect as follows: MSC decreases the liveness by controlling the growth of DCs and further inhibits its proliferation.

No relevant conflicts of interest to declare.