RESUMO
Objective:Immunoregulation study of umbilical mesenchymal stem cell (UCMSCs) on allogeneic umbilical cord blood(UCB) CD4+T lymphocytes,which proliferation,apoptosis and the differentiation to CD4+CD25+ regulatory T cell (Treg) in vitro. Methods:Establishing on direct contact or transwell co-culture system,adopt in different proportion of UCMCs with phytohaemag-glutinin (PHA)-activated UCB CD4+T lymphocytes were co-cultured. The proliferation of lymphocyte,percent of CD4+CD25+/CD4+and Foxp3 expression, regulatory T cell marker gene were measured. Apoptosis of CD4+T lymphocytes were observed in the direct contact or transwell coculture system of UCMSCs with desamethason( DXM)-stimulated UCB CD4+T lymphocytes. Results: The UCB CD4+T lymphocytes cocultured with UCMSCs with PHA-activating for 3 days,compared with the UCMSCs free control group,the amount of cells was reduced noticeably(P<0. 05) and the percent of CD4+CD25+in CD4+T lymphocytes and Foxp3 expression significantly in-creased(P<0. 01) in a dose dependent way(P<0. 05). The UCB CD4+T lymphocytes cocultured with UCMSCs with DXM-inducing for 7 days,the apoptosis rate was significantly lower than that of the control group without UCMSCs (P<0. 01). These effects were partially attenuated in transwell coculture but could not be eliminated. Conclusion: UCMSCs are negative effect on UCB CD4+T lymphocytes-mediated immunity effects,and mainly manifested in the regulation on cell proliferate ability and differentiation rather than promoting apoptosis.