Abstract: Objective: To study placenta-derived mesenchymal stem cells with HLA-G (Human Leukocyte Antigen, HLA-G) positive expression induce Treg (regulatory T cell, Treg) in vitro. Methods: placenta-derived mesenchymal stem cells were separated from neonatal placenta; PEGFP - N1 -HLA-G plasmid was transfected in placenta-derived mesenchymal stem cells by liposome transfection.The cells were divided into 3 groups including control group, PEGFP-N1 group and PEGFP-N1-HLA-G group, 5 complex walls in each group. Expression of HLA-G protein was detected by Western Blotting; after identification of cells, healthy human peripheral blood CD4⁺ T lymphocytes were cultured with placenta-derived mesenchymal stem cells with HLA-G positive expression, and the ratio of CD4⁺CD25⁺Foxp3⁺Treg in T lymphocytes was accounted. Results: After transfection of PEGFP-N1-HLA-G, the placenta-derived mesenchymal stem cells can express HLA-G protein significantly, compared with the control group and PEGFP - N1 group (P<0.01). After HLA-G positive placenta-derived mesenchymal stem cells and CD4 + T lymphocytes were cultured for 24 h, the ratio of CD4⁺CD25⁺Foxp3⁺Treg in T lymphocytes was (16.41±0.94)%. After HLA - G positive placenta-derived mesenchymal stem cells and CD4⁺ T lymphocytes were cultured for 48 h, the ratio of CD4⁺CD25⁺Foxp3⁺Treg in T lymphocytes was (16.46±0.59)% significantly, compared with the control group and PEGFP - N1 group (P<0.01). Conclusion: Placenta-derived mesenchymal stem cells modified by HLA-G gene can effectively induce CD4⁺CD25⁺Foxp3⁺Treg in vitro.

Key words: human leucocyte antigen-G, placenta-derived mesenchymal stem cell, T lymphocyte, regulatory T lymphocyte