Figure 4: Immunosuppressive potential of MSCs harvested at high cell density. (a) The intensity of CFSE in PHA-induced proliferating CD3-positive T-cells was measured by flow cytometry. The proliferation of CD3-positive T-cell decreased in the coculture with high density MSCs. Immunoblot analysis of MSCs treated with PTGES (b) or ULBP1 (c) siRNA. (d) The effect of high density MSCs transfected with PTGES or ULBP1 siRNA on the response of T-cells to PHA was determined by the BrdU incorporation assay. MSCs at passage 3 or 4 were used to validate the correlation between the immunosuppressive effects of MSCs and the expression of specific genes. Each experiment was independently performed using different passage MSCs. Data are shown as the mean ± SD from three separate experiments. * .