Three-dimensional ultrastructural study of Endothelial cells and pericytes interdigitation in angiogenesis

血管内皮细胞和周细胞通过血管生成素系统在血管生成中起关键作用。内皮细胞和周细胞交错(EPI)由周细胞的胞质突起和相应的内皮凹陷组成，常见于血管生成部位。大鼠皮下植入一种热可逆凝胶聚合物盘，在体外24-72小时内进行实验。毛细血管密度在48h达到高峰。观察到大量的EPI在72小时达到高峰。连续切片免疫组织化学分析显示，血管生成素-1定位于周细胞和外周细胞。定量RT-PCR分析显示，血管生成素-1水平在72小时后升高。本研究表明微血管成熟可能参与了EPI和Angiopoietin-1的表达。

Endothelial cells and pericytes play critical role in angiogenesis by the angiopoietin system. Endothelial cell and pericyte interdigitations (EPI), consisting of cytoplasmic projections of pericytes and corresponding endothelial indentations, are frequently present at angiogenic sites. Rats subcutaneous implantation of a thermoreversible gelation polymer discs were inqubated in vitro 24-72hr. The capillary density increased to a peak on 48hr. A number of EPI were observed to a peak on 72hr. Serial sectioning electron microscopy immunohistochemical analysis revealed that Angiopoietin-1 localized at Pericytes and EPI. Quantitative RT-PCR analysis revealed that the level of Angiopoietin-1 increased on 72hr. The present study showed that the microvesselmaturation might to be involved in the expression of EPI and Angiopoietin-1.