Experimental study on the in vitro induction of regulatory T cells by umbilical cord mesenchymal stem cells with positive human leukocyte antigen-G

  Objective  To explore the effect of umbilical cord mesenchymal stem cells with positive human leukocyte antigen (HLA)-G on inducing the production of regulatory T cells (Treg) in vitro.

  Methods  Umbilical cord mesenchymal stem cells were isolated from umbilical cord of neonates. PEGFP-N1-HLA-G plasmid was transfected into the human umbilical cord mesenchymal stem cells by liposome transfection, as PEGFP-N1-HLA-G group. PEGFP-N1 empty vector plasmid was transfected into the human umbilical cord mesenchymal stem cells, as PEGFP-N1 group. The human umbilical cord mesenchymal stem cells without empty vector under the same conditions were set as blank control group. Markers of the umbilical cord mesenchymal stem cells were detected using flow cytometry. The expression of HLA-G protein in each group of cells was identified by Western Blot. After mixed-culturing with CD4⁺T cells in peripheral blood of healthy subjects for 24 h and 48 h, the proportion of CD4⁺ CD25⁺ Foxp3⁺Treg in total T cells of each group was detected by flow cytometry.

  Results  CD45, CD34 and HLA-DR presented negative expression on umbilical cord mesenchymal stem cells, while CD29, CD44 and CD105 presented positive expression. HLA-G protein could be expressed in the PEGFP-N1-HLA-G group, which had statistically significant difference compared with the blank control group and PEGFP-N1 group (both P < 0.01). After PEGFP-N1-HLA-G group and CD4⁺T cells were mixed-cultured for 24 h and 48 h, CD4⁺ CD25⁺ Foxp3⁺Treg accounted for (15.3±1.9)% and (14.3±2.1)% of the total T cells respectively, both of which presented statistically significant difference compared with the blank control group and PEGFP-N1 group (all P < 0.05).

  Conclusions  Umbilical cord mesenchymal stem cells with HLA-G gene modified can effectively induce the production of CD4⁺ CD25⁺ Foxp3⁺Treg in vitro.