人脐血间充质干细胞对T淋巴细胞旁分泌的免疫调节作用**☆

背景：相关研究表明脐血间充质干细胞具有一定的免疫调节作用，但具体机制不详。 目的：观察脐血源间充质干细胞通过旁分泌机制对T淋巴细胞增殖的影响。 方法：分离正常分娩产妇脐血间充质干细胞和健康志愿者外周血T淋巴细胞，按不同比例建立脐血间充质干细胞与T淋巴细胞非接触共培养体系，以单独培养T淋巴细胞作为对照组。 结果与结论：脐血间充质干细胞形态学呈现成纤维梭型细胞样，呈旋涡状团集生长。流式细胞仪检测脐血间充质干细胞表面标记物：CD29(+)，CD44(+)，CD34(-)，CD45(-)，HLA-DR(-)；与对照组相比，共培养组可明显抑制植物血凝素刺激T淋巴细胞的增殖作用(P < 0.05)，且呈剂量依赖性；ElISA法检测共培养组分泌的白细胞介素10水平较对照组明显升高(P < 0.05)；中和试验后脐血间充质干细胞对T淋巴细胞增殖的抑制作用明显减弱。结果说明脐血间充质干细胞可明显抑制异体外周血T淋巴细胞的增殖，可能是通过旁分泌白细胞介素10达到负向免疫调节作用。

Immunoregulatory effect of human umbilical cord blood mesenchymal stem cells on proliferation of T lymphocytes through paracrine mechanism

BACKGROUND: Studies have shown that umbilical cord blood mesenchymal stem cells (UCB-MSCs) have a certain role in immune regulation, but the exact mechanism is unknown. OBJECTIVE: To study the effect of UCB-MSCs on T lymphocytes by paracrine mechanism. METHODS: We isolated the UCB-MSCs and T lymphocytes from the umbilical cord blood and peripheral blood. Indirect coculture system of UCB-MSCs and T lymphocytes with different proportion was constructed. The group of coculture acted as experiment group, the group of monoculture T lymphocytes as control group. RESULTS AND CONCLUSION: UBC-MSCs presented a shuffle-type growth which liked the fibroblast in morphology; the flow cytometry showed the results of cellular surface marks: CD29(+), CD44(+), CD34(-), CD45(-), HLA-DR(-). Compared with the control group, the experiment group could dramatically inhibit the proliferation of peripheral blood T lymphocytes stimulated by phytohemagglutinin in a dose-dependent manner (P < 0.05); the concentration of interleukin-10 secreted by UCB-MSCs was significantly higher in the experiment group than the control group (P < 0.05). The ability of UBC-MSCs to inhibit the proliferation of T lymphocytes was sharply impaired by neutralization experiments. UCB-MSCs can dramatically inhibit the proliferation of peripheral blood T lymphocytes, which may depend on paracrine interleukin-10 to play an immunoregulatory role.