A comparison of CD105 and CD31 expression in tumor vessels of hepatocellular carcinoma by tissue microarray and flow cytometry.

Tumor endothelial cells (TECs) have been isolated from solid tumors by using immunological magnetic beads and magnetic active cell sorting, and lead to a more precise way to investigate tumor angiogenesis as well as screening of vascular targeting drugs. However, the question of which endothelial marker is a stable molecular signature in TECs and can be used for the isolation of TECs from tumor tissues remains unclear. In this study, we investigated the endothelial markers CD105 and CD31 in the tumor vessels from 90 patients with hepatocellular carcinoma (HCC) by tissue microarray, in addition to their expression in TECs isolated from fresh tissues resected from 11 patients with HCC by flow cytometry and confocal microscopy. The results revealed that among 90 cases of TMA, all tumor vessels were CD31 positive whereas 39 cases (43.3%) had little or no CD105 expression in tumors and their vessels but not peritumoral tissue spots, and that among these 39, 29 cases (74.4%) were poor-differentiated HCC. These findings were further verified by flow cytometry and confocal analysis of TECs isolated from HCC. Overall, the results suggested that CD105 may not be expressed in TECs derived from poor-differentiated HCC cases. In addition, combined with previous studies in which CD105 is not only expressed in TECs, but also in tumor cells, the results indicated a high risk of contamination with CD105 tumor cells. Thus, there is a limitation to the use CD105 as an endothelial marker for the isolation of TECs.