Abstract
Mesenchymal stem cells (MSC) generated from human umbilical cord (UC‐MSC) and placenta (PLC‐MSC) were assessed and compared for their immunomodulatory function on T cells proliferation by analysis of the cell cycle. Mitogen stimulated or resting T cells were co‐cultured in the presence or absence of MSC. T‐cell proliferation was assessed by tritiated thymidine (3H‐TdR) assay and the mechanism of inhibition was examined bycell cycle and apoptosis assay. Both UC‐MSC and PLC‐MSC profoundly inhibited the proliferation of T‐cell, mainly via cell‐to‐cell contact. MSC‐mediated anti‐proliferation does not lead to apoptosis,but prevented T cells from entering S phase and they therefore accumulated in the G0/G1 phases. The anti‐proliferative activity of MSC was related to this cell cycle arrest of T‐cell. UC‐MSC produced a greater inhibition than PLC‐MSC in all measured parameters.