RESUMO
@#【Objective】 To investigate whether the dedifferented human umbilical cord mesenchymal stem cells（hMSC）modified by IDO gene can get improved ability to survive oxidative stress as well as to induce regulatory T（Treg） lymphocytes.【Methods】The dedifferentiated hMSC（De- hMSC）were obtained by a transient adipogenic induction and subsequent recovery culture in normal medium. The IDO gene modified De-hMSC （IDO/De-hMSC）were prepared by retroviral infection using recombinant retrovirus harboring IDO gene. The De- hMSC infected by retrovirus containing ZsGreen1 gene，the non- infected De- hMSC and hMSC were set as controls. Exogenous expression of IDO protein was confirmed by Western blot. Flow cytometry analysis was performed to detect the immunophenotype of IDO/De- hMSC ， and their osteogenic/adipogenic differentiation abilities were also assessed. Cell survival rates under the oxidative stress of 300 μmol/L t- BHP were determined by Annexin V- FITC/PI double staining flow cytometry. Human peripheral blood mononuclear cells （PBMC） were isolated and treated with conditioned medium containing the culture supernatant of hMSC，De-hMSC，Mock/De-hMSC and IDO/De-hMSC，respectively. Changes in the proportion of CD4+ CD25+ CD127low Treg cells in PBMC were determined by triple fluorescent labeling flow cytometry.【Results】The De-hMSC modified by IDO gene still have the immunophenotype as well as the osteogenic/adipogenic differentiation abilities that are typical of mesenchymal stem cells. When challenged by 300 μmol/L t-BHP，the number of viable cells in De-hMSC significantly elevated compared with hMSC（P<0.05），and the survival advantage of De-hMSC was not obviously affected by IDO gene modification（P>0.05）. Conditioned medium containing the supernatant from IDO/De- hMSC dramatically up- regulated the percentage of CD4+CD25+CD127low Treg cells in PBMC in contrast to the control groups（P<0.05）.【Conclusions】IDO/ De- hMSC have the same immunophenotype and differentiation capacity as the native hMSC ，and can simultaneously enhance the ability of hMSC to survive against oxidative stress and to induce Treg cells ，which may be a potential modification strategy of mesenchymal stem cells for immunosuppressive therapy.