Huang Yu-Han, Sharifpanah Fatemeh, Becker Sven, Wartenberg Maria, Sauer Heinrich
Department of Physiology, Justus Liebig University, Giessen, Germany.
Cells Tissues Organs. 2016;201(5):319-32. doi: 10.1159/000445680. Epub 2016 May 21.
Embryonic stem (ES) cells can differentiate into various kinds of cells, such as endothelial and hematopoietic cells. In addition, some evidence suggests that inflammatory mediators such as leukotrienes (LTs), which include the 5-lipoxygenase (LOX) family, can regulate endothelial cell differentiation. In the present study, the eicosanoid precursor arachidonic acid (AA) stimulated vasculogenesis of ES cells by increasing the number of fetal liver kinase-1+ vascular progenitor cells as well as vascular structures positive for platelet endothelial cell adhesion protein-1 and vascular endothelial cadherin. The stimulation of vasculogenesis and expression of the rate-limiting enzyme in the LT signaling pathway, 5-LOX-activating protein (FLAP), was blunted upon treatment with the FLAP inhibitors AM643 and REV5901. Vasculogenesis was significantly restored upon exogenous addition of LTs. Downstream of FLAP, the LTB4 receptor (BLT1) blocker U75302, the BLT2 receptor blocker LY255283 as well as the cysteinyl LT blocker BAY-u9773 inhibited vasculogenesis of ES cells. AA treatment of differentiating ES cells increased reactive oxygen species (ROS) generation, which was not affected upon either FLAP or cyclooxygenase-2 inhibition. Prevention of ROS generation by either the free radical scavengers vitamin E and N-(2-mercaptopropionyl)glycine or the NADPH oxidase inhibitor VAS2870 downregulated vasculogenesis of ES cells and blunted the provasculogenic effect of AA. In summary, our data demonstrate that proinflammatory AA stimulates vasculogenesis of ES cells via the LT pathway by mechanisms involving ROS generation.
胚胎干细胞（ES细胞）可分化为各种类型的细胞，如内皮细胞和造血细胞。此外，一些证据表明，炎症介质如白三烯（LTs），包括5-脂氧合酶（LOX）家族，可调节内皮细胞分化。在本研究中，类二十烷酸前体花生四烯酸（AA）通过增加胎肝激酶-1+血管祖细胞的数量以及血小板内皮细胞黏附蛋白-1和血管内皮钙黏蛋白阳性的血管结构，刺激了ES细胞的血管生成。在用FLAP抑制剂AM643和REV5901处理后，LT信号通路中限速酶5-LOX激活蛋白（FLAP）的血管生成刺激作用和表达受到抑制。外源性添加LTs后，血管生成明显恢复。在FLAP的下游，LTB4受体（BLT1）阻滞剂U75302、BLT2受体阻滞剂LY255283以及半胱氨酰LT阻滞剂BAY-u9773均抑制了ES细胞的血管生成。用AA处理分化中的ES细胞会增加活性氧（ROS）的生成，而FLAP或环氧合酶-2抑制对此均无影响。用自由基清除剂维生素E和N-（2-巯基丙酰基）甘氨酸或NADPH氧化酶抑制剂VAS2870预防ROS生成，可下调ES细胞的血管生成，并减弱AA的促血管生成作用。总之，我们的数据表明，促炎的AA通过涉及ROS生成的机制，经由LT途径刺激ES细胞的血管生成。
