血管紧张素Ⅱ对脐血CD34+细胞体外分化为巨核细胞的影响

为了探讨血管紧张素Ⅱ对脐血CD34^＋细胞诱导分化为巨核细胞的影响，采用免疫磁珠法（MACS）分选8例健康产妇足月顺产胎儿脐血中的CD34^＋细胞，在舍血小板生成素（TPO50ng／ml）、白介素-3（IL-310ng／ml）、干细胞刺激因子（SCF50ng／l）的无血清培养液中添加浓度分别为50、100、1000μg／ml的血管紧张素Ⅱ作为实验组；同时以未添加血管紧张素Ⅱ的基础培养液作为对照组，培养14天后观察结果。细胞计数仪计数单个核细胞数（MNC）；流式细胞仪计数培养体系中的CD41^＋细胞数、血小板数，及分析细胞周期；利用CD41单克隆抗体免疫荧光染色观察培养体系中的细胞情况。结果表明：与对照组比较，实验组单个核细胞数无明显改变（P〉0．05）；而CD41^＋细胞和血小板数量有明显的增加（P〈0.05）；细胞周期分析显示，实验组的4倍体细胞增加，并存在明显的凋亡（P〈0．05）；荧光显微镜下观察对照组和实验组均可见大小不一的CD41^＋细胞。结论：血管紧张素Ⅱ可以促进脐血中CD34^＋细胞诱导分化为巨核细胞，并能促进巨核细胞产生血小板。

Effect of Angiotensin Ⅱ on Differentiation of Umbilical Cord Blood CD34+ Cells into Megakaryocytes

This study was aimed to investigate the effect of angiotensin II on differentiation of cord blood CD34+ cells into megakaryocytes in vitro. The CD34+ cells from eight fresh umbilical cord blood samples sorted by a high-gradient magnetic cell sorting system (MACS) were cultured in serum-free culture medium containing thrombopoietin (TPO) 50 ng/ml, IL-3 10 ng/ml, stem cell factor (SCF) 50 ng/ml and different concentrations of angiotensin II (0, 50, 100, 1000 microg/ml) for 14 days. Mononuclear cells (MNC) were counted by automatic cell analyzer. Cultured CD41+ cell and platelet counts in cultured system, and cell cycle were analyzed by flow cytometry. CD41 specific monoclonal antibody staining was observed by immunofluorescence microscopy. The results showed that as compared with the control group, the number of MNC not increased significantly (P > 0.05), but the number of CD41+ cells and platelets increased significantly in treatment group (P < 0.05). Cell cycle analysis revealed that the amounts of 4N cells increased and apoptosis cells obviously existed in treatment group (P < 0.05). After fluorescence staining, more CD41+ cells of different sizes were observed by means of fluorescence microscopy in both groups. It is concluded that angiotensin II can induce the cord blood CD34+ cells to differentiate towards megakaryocyte, and enhance the function of megakaryocyte to produce platelet.