Effect of MSCs on naive and memory T cells and phenotype of T cells and MSCs under different culture conditions. (A) CD3⁺ T cells were separated into CD45RA⁺ and CD45RO⁺ subsets and stimulated with allogeneic DCs or PHA in the presence or absence of MSCs. Proliferation was analyzed by [³H]thymidine incorporation. Bars illustrate the mean proliferation from 2 different normal donors, and error bars show SEM. (B) Percentage of CD25^highFoxp3⁺ cells in CD4⁺ T cells after stimulation with pp65 peptides or allogeneic PBMCs for 5 days in the presence or absence of MSCs (n = 6). The difference in expression of CD25 and Foxp3 between the different culture conditions was analyzed by Friedman test followed by Dunn multiple-comparison tests. (C) IFN-γ and IL-10 levels measured in supernatants from PBMCs cultured with indicated stimulation with or without MSCs for 5 days (n = 6). (D) mRNA expression in MSCs cultured in a transwell system with PBMCs stimulated with pp65 peptides or allogeneic PBMCs or with 100 U/mL IFN-γ for 3 days, analyzed with real-time quantitative PCR (n = 2).