Mesenchymal stem cells (MSCs) inhibit the proliferation of CD4+ T cells in vitro by induction of nitric oxide and prostaglandin E
). (a) CD4+ T cells, in the presence of accessory cells, were stimulated with 3 μg/ml anti-CD3 for 48 hours. Interleukin-17 (IL-17) and interferon-gamma (IFN-γ) levels in the supernatant of these cultures were analyzed by Bio-Plex protein array system. Bars represent averages of three values ± standard error of the mean. (b-d) Wild-type MSCs were stimulated with IL-17 (20 ng/mL) or IFN-γ (100 U/mL) or both for 48 hours. cDNA samples were prepared and subjected to quantitative polymerase chain reaction analysis. The relative quantity of target mRNA levels was normalized for 18S RNA. Relative levels of programmed death ligand-1 (PD-L1) (b), inducible nitric oxide (iNOS) (c), and cyclo-oxigenase-2 (COX-2) (d) are shown. Bars represent averages of two values. ND, not detectable. (e) CD4+ T cells (5 × 104 cells) and accessory cells (5 × 104 cells) were incubated with 3 μg/ml anti-CD3 antibody and the indicated number of mitomycin c-treated wild-type MSCs for 72 hours and pulsed for the last 16 hours with 1 μCi of [3H]TdR. Co-cultures were grown in the absence (control) or presence of 200 μM 1-methyl-DL-tryptophan, 10 μM indomethacin, or 10 μM GW274150. The percentage inhibition (100 × [(radioactivity in cultures without MSCs -- radioactivity in cultures with MSCs)/radioactivity in cultures without MSCs]) by increasing numbers of MSCs is shown.