Figure 6. The effects of mesenchymal stem cells (MSCs) on apoptosis of phytohemagglutinin-CD3+ T cells based on annexin V-PI. Representative analysis of annexin V-PI-labeled stimulated T cells by flow cytometry in direct [mixed lymphocyte reactions (MLR)] (A) and indirect (transwell) (B) co-cultures with human MSCs on days 1 and 4 (n=3, mean ± standard deviation). The graphical representation of the data (C) points out the highest apoptotic levels of induced T cells in the co-culture with hBM-MSCs. Noticeable apoptotic levels were detected in both direct (MLR) (Ω p<0.01-1^st day; Δ p<0.001-4^th day) and indirect (transwell) (Δ p<0.001-1^st and 4^th days) co-cultures. Interestingly, the most promising results were obtained in the co-culture allowing cell-to-cell contact in both cell lines on the 4^th day. Weak but significant apoptotic effect was observed in indirect co-culture also in both cell lines (# p<0.05 and Ω p<0.01). hBM: Human bone marrow, hAT: human adipose tissue, hWJ: human Wharton’s jelly.