Immunomodulatory decrease on T cell proliferation To analyse immunomodulatory effects on T cell proliferation, irradiated MSCs were added to mitogen-stimulated T cell proliferation reactions and mixed lymphocyte reactions (MLR). A previous study showed that MSCs from healthy volunteers could obviously inhibit the proliferation of T cells not only stimulated with mitogen

but also in MLR. Additionally, this inhibitory effect occurred in a dose-dependent manner. In mitogen-stimulated T cell proliferation assays, the proliferation of T cells at 1:2 ratio (MSCs to MNCs) was significantly inhibited to about 1% with normal MSCs, but proliferation selleck chemical at the same ratiowas inhibited only to about 37% with CML-derived MSCs (compared with co-culture system of normal MSCs, p < 0.05). Similarly, inhibitory rates were impaired at 1:10 ratio (MSCs to MNCs) in CML-derived MSCs (compared with co-culture system of normal MSCs, p < 0.05). Also the inhibitory effect was dose dependent in CML-derived MSCs. (Figure 2A). In MLR, a similar impaired inhibitory effect with MDS-derived MSCs was observed. (Figure 2B) Figure 2 The effects of Flk-1+CD31-CD34- MSCs on T lymphocyte proliferation. (A) The effects of Flk-1+CD31-CD34- MSCs on T lymphocyte proliferation in mitogen proliferative assays. There are three groups, including nonstimulated

T cells (none), PHA-stimulated T cells (Ts) and PHA-stimulated T cells cocultured with MSC at different ratios (MSC to T cell = 1:2, 1:10, :100). Data are shown as means ± S.D. of three independent experiments (*p < 0.05,**p < 0.005 vs. Ts). oxyclozanide (B) The effects Citarinostat price of Flk-1+CD31-CD34- MSCs on T lymphocyte proliferation in MLR. Flk-1+CD31-CD34- MSCs at 1:10 ratios (irradiated MSCs to T cells); there are four groups, including nonstimulated responder T cells (T0), irradiated stimulator cells plus responder T cells; normalMSC plusMLR (BMSC Ts), CML-derived MSC plus MLR (CML Ts). Data are shown as means ± S.D. of three independent experiments

(*p ≥ 0.05,**p = 0.001 vs. Ts) Immunomodulatory attenuation of MSCs on T cell cycle A previous study showed that MSCs could silence T cells in G0/G1 phase, which might be one of the possible mechanisms of MSC’s inhibitory effect on T cells. When the inhibitory effect of CML-derived MSC on T cell proliferation was impaired, the related inhibitory effect on cell cycle was analyzed. In a PHA-stimulating system without MSC co-culture, there were 67.3 ± 3.7% and 28.4 ± 2.9% T cells in G0/G1 phase and S phase, respectively. When normal MSCs were present in co-culture, the percentages of T cells in G0/G1 phase and S phase were 94.0 ± 1.9% and 3.1 ± 1.9%, respectively (compared with PHA stimulated T cells, p < 0.05). MSCs from healthy volunteers could have most of their T cells in G0/G1 phase with fewer cells entering S phase. However, T cells in G0/G1 phase and S phase remained 74.5 ± 1.2% and 22.1 ± 2.