Ma Feng-xia, Ren Qian, Han Zhong-chao
State Key Laboratory of Experimental Hematology, Hospital of Blood Disease, Institute of Hematology, CAMS and PUMC, Tianjin 300020, China.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2007 Jun;29(3):336-41.
To investigate whether oxidized low-density lipoprotein (oxLDL) affects the survival and activity of endothelial progenitor cell (EPC) and whether the effects are mediated by lectin-like oxidized low-density lipoprotein receptor (LOX-1).
CD34+ cells isolated from human umbilical blood were cultured in endothelial cell growth medium-2 (EGM-2). After 14 days of culture, some EPCs were stimulated with 10, 25, 50 microg/ml of oxLDL for 48 hours; some were preincubated with LOX-1 mAb, a blocking antibody of LOX-1, for 24 hours, then exposed to 50 microg/ml oxLDL for 48 hours; others without any further treatment were used as control. The survival of EPC and the ability of adhesion, migration, and tube formation were examined. The levels of LOX-1 protein and mRNA expression were also assayed.
Incubation with oxLDL at concentrations of 25 microg/ml or higher resulted in a dose-dependent increase of EPC apoptosis [25 microg/ml: (15.8 +/- 1.1.0%, 50 microg/ml: (18.8 +/- 2.0)% versus control: (9.0 +/- 1.2)%; P < 0.05]. Treated with oxLDL led to a significantly reduced migratry rate [25 microg/ml: (5.7 +/- 1.0)%, 50 microg/ml: (5.1 +/- 0.8)% versus control: (9.5 +/- 0.8)%; P < 0.05]. EPC treated with oxLDL showed a dose-dependent reduction of adhesion to fibronectin (25 Kg/ml: 33 +/- 2, 50 microg/ml: 30 +/- 3 versus control: 37 +/- 5; P < 0.05). Treatment with oxLDL impaired the in vitro vasculogenesis ability of EPCs. The total length of the tube structures in each photograph was decreased [25 microg/ml: (2.9 +/- 0.5) mm, 50 microg/ml: (1.8 +/- 0.5) mm versus control: (5.0 +/- 0.6) mm; P < 0.05]. The tube structure was severely disrupted, resulting in an incomplete and sparse tube network. However, all the detrimental effects on EPC were attenuated by pretreatment of EPC with LOX-1 mAb. In addition, Western blot analysis revealed that oxLDL increased LOX-1 protein expression from 100% to (172 +/- 8)% at a dose of 50 microg/ml. Furthermore, oxLDL caused an increase in LOX-1 mRNA expression from 100% to (174 +/- 39)% at a dose of 50 microig/ml.
OxLDL can directly inhibit EPC survival and activity and these effects are mediated by its receptor, LOX-1.
研究氧化型低密度脂蛋白（oxLDL）是否影响内皮祖细胞（EPC）的存活及活性，以及这些作用是否由凝集素样氧化型低密度脂蛋白受体（LOX-1）介导。
从人脐血中分离出的CD34⁺细胞在内皮细胞生长培养基-2（EGM-2）中培养。培养14天后，部分EPC用10、25、50μg/ml的oxLDL刺激48小时；部分先用LOX-1单克隆抗体（LOX-1的阻断抗体）预孵育24小时，然后暴露于50μg/ml oxLDL中48小时；其他未作进一步处理的用作对照。检测EPC的存活情况以及黏附、迁移和形成管腔的能力。同时检测LOX-1蛋白和mRNA表达水平。
用25μg/ml及更高浓度的oxLDL孵育导致EPC凋亡呈剂量依赖性增加[25μg/ml：（15.8±1.1）%，50μg/ml：（18.8±2.0）%，而对照为：（9.0±1.2）%；P<0.05]。用oxLDL处理导致迁移率显著降低[25μg/ml：（5.7±1.0）%，50μg/ml：（5.1±0.8）%，而对照为：（9.5±0.8）%；P<0.05]。用oxLDL处理的EPC对纤连蛋白的黏附呈剂量依赖性降低（25μg/ml：33±2，50μg/ml：30±3，而对照为：37±5；P<0.05）。用oxLDL处理损害了EPC的体外血管生成能力。每张照片中管腔结构的总长度缩短[25μg/ml：（2.9±0.5）mm，50μg/ml：（1.8±0.5）mm，而对照为：（5.0±0.6）mm；P<0.05]。管腔结构严重破坏，导致管腔网络不完整且稀疏。然而，如果先用LOX-1单克隆抗体预处理EPC，则oxLDL对EPC的所有有害作用均减弱。此外，蛋白质印迹分析显示，在50μg/ml剂量时，oxLDL使LOX-1蛋白表达从100%增加至（172±8）%。此外，在50μg/ml剂量时，oxLDL使LOX-1 mRNA表达从100%增加至（174±39）%。
oxLDL可直接抑制EPC的存活及活性，且这些作用由其受体LOX-1介导。
