中文摘要：

【目的】探讨体外流体切应力对内皮祖细胞（EPC）再内皮化能力的影响及可能的分子机制。【方法】入选10名排除心血管病危险因素、病史和临床证据的青年志愿者[（25.4±6.6）岁],抽取外周血20 m L,采用密度梯度离心法分离提取EPC。在体外采用生理范围（15 dyn/cm2）流体切应力处理培养的EPC不同时间（0,6,12,24 h）,观察EPC体外的迁移、黏附能力的变化。通过建立裸鼠颈动脉拉脱损伤模型,观察流体切应力对志愿者EPC颈动脉内皮损伤修复能力的影响。用Realtime RT-PCR和Western-blot检测EPC表面基因和蛋白的表达情况,探讨切应力影响内皮化的分子机制。【结果 】体外切应力干预明显提高志愿者EPC体外的迁移、黏附能力,上调其颈动脉内皮损伤再内皮化能力（干预前：34%±6%;干预后：51%±8%;P〈0.01）。而基因和蛋白水平检测显示干预后EPC表面的CXCR4信号通路明显上调（干预前：1.0;干预后：2.8±0.3;P〈0.01）。【结论 】体外流体切应力干预可能部分通过上调EPC表面CXCR4信号通路表达,提高其血管内皮损伤修复能力。

英文摘要：

[Objective] To investigate the effects of shear stress on the endothelial repair capacity of endothelial progenitor cells （EPC） and underlying molecular mechanism. [Methods]Young （25.4 ± 6.6 years old, n = 10） healthy male subjects without clinical evidence of cardiovascular risk factors and significant medical history were enrolled into the study. EPC were isolated from peripheral blood of 10 young subjects by density gradient centrifugation method. EPC migration and adhesion in vitro were investigated after exposure to 15 dyn/cm2 of shear stress for 6, 12 or 24 hours. To determine the effect of shear stress on EPC-mediated re- endothelialization in vivo, EPC were exposed to 15 dyn/cm^2 of shear stress for 12 hours and then intravenously injected （separately） into nude mice 3 hours after surgical carotid artery denudation. The expression of genes and proteins of interest on surface of EPC were analyzed by Realtime RT-PCR or Western-blot. [Results] Pretreatment with shear stress significantly increased EPC migration, adhesion function in vitro and enhanced the re-endothelialization capacity of EPC from young subjects （before shear stress treatment： 34%± 6%;after shear stress treatment：51% ± 8%; P 〈 0.01）. CXC chemokine receptor 4 （CXCR4） expression were markedly upregulated by shear stress pretreatment in vitro （before shear stress treatment： 1.0 ; after shear stress treatment： 2.8 ± 0.3 ; P 〈 0.01 ）. [ Conclusion ] Fluid shear stress improves endothelial repair capacity of endothelial progenitor cells, which may be partly related to CXCR4-induced signaling pathway.