目的：观察人脐带源间充质干细胞（hUC-MSC）对异源性脐带血T淋巴细胞激活与增殖的影响，探讨其在免疫调控中的作用。方法： 建立分离、扩增hUC-MSC的方法，检测其MHC表型；实验分3组：(1)单纯脐带血组（阴性组）；（2)脐带血+丝裂原刺激组（对照组）；（3）脐带血+丝裂原刺激 +MSC共培养组（实验组）;流式细胞术检测各组脐带血T细胞及其CD4＋和CD8＋亚型细胞共培养8 h后早期激活标志CD69的表达, MTT法检测各组脐带血T细胞共培养5 d后增殖情况。 结果：成功建立分离、扩增hUC-MSC的方法，免疫表型分析显示hUC-MSC不表达HLA-Ⅱ抗原，低表达HLA-I抗原；流式细胞术检测示在hUC-MSC共培养情况下，经丝裂原刺激后，脐带血T淋巴细胞CD69表达与对照组\[(22. 6±5.2)%\]的阳性率相比较，下降至(7.8±3.5)%（P<0.01），而且这种抑制对不同亚型T细胞（CD4+/CD8+）均起作用；MTT检测显示在hUC-MSC共培养条件下，丝裂原刺激T细胞增殖受到抑制，抑制的程度与hUC-MSC的剂量呈依赖性。 结论： hUC-MSC对异源性脐带血T淋巴细胞激活和增殖具有抑制作用，而且这种作用为非选择性的，呈剂量依赖性。

Objective: To investigate the effects of human umbilical cord derived mesenchymal stem cells (hUC-MSCs) on the activation and proliferation of allogenic umbilical core blood T lymphocytes, so as to study the immunomodulatory capacity of hUC-MSC. Methods: hUC-MSCs were isolated, culture-expanded from human umbilical cord after enzyme digestion, and the major histocompatibility (MHC) phenotype features of hUC-MSC were detected. The experiment was divided into 3 groups: (1) Negative group: umbilical cord blood MNCs were cultured alone; (2) Control group: MNCs were cultured with nonspecific mitogenic stimuli; (3) Experimental group: MNCs were co-cultured with hUC-MSC and nonspecific mitogenic stimuli. FCM technique was used to detect the CD69 expression, an indicator of T-cell early activation, on T cells and CD4+, CD8+ subsets after 8 hours' co-culture. T-lymphocyte proliferation in each group was detected by MTT after 5 days' co-culture. Results: We successfully established a simple method to isolate and culture-expand abundant hUC-MSCs from human umbilical cord. The immunophenotypic analysis showed that hUC-MSCs expressed no HLA class Ⅱ and less HLA class Ⅰ. hUC-MSC inhibited CD69 expression in PHA and PMA activated T cells from (22.6±5.2)% to (7.8±3.5)%（P<0.01）after 8 hours' co-culture, which influenced both CD4+ and CD8+ T-cell subsets. MTT showed that hUC-MSC dose-dependently inhibited PHA-induced T-lymphocyte proliferation. Conclusion: hUC-MSC has a dose-dependent inhibitory effect on nonspecific mitogenic stimuli triggered activation and proliferation of allogeneic umbilical cord blood T lymphocytes, and the effect is not selective.

国家高新技术发展规划（“863”计划） (2003AA205060) ; 国家重点基础研究发展项目（“973”计划）(001CB5101); 国家自然科学基金 (30570905)