The aim of this study was to investigate the effect of human bone marrow mesenchymal stem cells on human T-cell proliferation resulted from stimulation with PHA and possible immunomodulating mechanism. T cells were positively selected by CD3(+) magnetic beads, and were then co-cultured with irradiated MSCs overnight before the addition of PHA. T-cell proliferation was measured by BrdU assay and the degree of apoptosis was assessed by flow cytometry with Annexin V/PI. T cells co-cultured with or without MSCs were treated with PHA for 72 hours, then harvested. They were labeled with anti-CD4, anti-CD8, anti-CD25 antibodies and analyzed by flow cytometry. The results showed that MSCs inhibited T-cell proliferation, but did not induce T cell apoptosis. There were no significant changes in the ratio of CD4(+) and CD8(+) T cells of MSC-treated group, as compared with the control group. After stimulation with PHA, there was an increase in CD4(+) T cells and decrease of CD4(+)CD25(+) cells in MSC co-cultured group. It is concluded that the MSCs inhibit T-cell proliferation after stimulation with PHA, and show more inhibitive effects on CD8(+) and CD4(+) T cells, but CD25(+) regulatory T cells may not be involved in this process.
Bone Marrow Cells CD4-CD8 Ratio