Potential usage of endothelial progenitor cells (EPC) in neovascularization

本课题旨在研究内皮祖细胞（EPC）在新生血管形成中的潜在作用，特别是支持其与成熟血管内皮粘附的分子机制。在项目的第一年，我们建立了EPC的体外培养体系。此外，我们使用EPC在生理流动条件下进行粘附测定。我们发现，与未活化的内皮细胞相比，血管内皮细胞的细胞因子活化显著上调EPC的粘附。当我们用抗E-选择素、ICAM-1和VCAM-1的粘附阻断抗体预处理这些血管内皮时，抗E-选择素抗体而不是其他抗体阻断EPC与内皮的粘附，表明E-选择素在EPC粘附中起重要作用。在第二年，我们开发了一个新的血管模型，使用缺血后肢在裸鼠。如前所述，向这些小鼠注射EPC显著改善了其后肢的新血管形成。当内皮祖细胞数量减少到最佳数量的1/5时，血流恢复明显减弱。然而，当含有E-选择素cDNA的腺病毒被引入以表达E-选择素时，新血管形成显著恢复。这些数据表明，E-选择素在新生血管形成中的潜在功效。

In this project, we investigated potential usage of endothelial progenitor cells (EPC) in neovascularization especially molecular mechanisms that support their adhesion to mature vascular endothelium. In the first year of the project, we were able to establish culture system of EPC in vitro. Moreover, we conducted an adhesion assay under physiological flow condition using EPC. We found that cytokine activation of vascular endothelium significantly upregulated adhesion of EPC when compared to unactivated endothelium. When we pretreated these vascular endothelium with adhesion blocking antibodies against E-selectin, ICAM 1, and VCAM-1, anti-E-selectin antibody but not other antibodies blocked adhesion of EPC to endothelium, suggesting an important role for E-selectin in EPC adhesion. In the second year, we developed a neovascularization model using ischemic hindlimb in nude mice. Injection of EPC to these mice significantly improved their neovascularization in the hindlimb as previously reported. When amount of EPC was reduced to one-fifth of the optimal number, the recovery of blood flow was significantly attenuated. However, when adenovirus containing E-selectin cDNA was introduced to express E-selectin, neovascularization was significantly restored. These data suggested that potential efficacy of E-selectin in neovascularization.