Increased proliferation activities of vascular endothelial cells and tumour cells in residual hepatocellular carcinoma following transcatheter arterial embolization

Abstract

AIMS: Transcatheter arterial embolization induces extensive ischaemic necrosis or hypoxia via the obstruction of the hepatic artery in hepatocellular carcinoma (HCC). Ischaemia is strongly correlated with an increased expression of angiogenic factor and stimulates an increase in angiogenesis, including endothelial cell proliferation. The aim of this study was to evaluate whether ischaemic necrosis induced by transcatheter arterial embolization could increase the proliferative activities of intratumoral endothelial cells or tumour cells in the residual HCC. METHODS AND RESULTS: Using a double immunohistochemical technique (Ki67 antibody to determine the proliferative activity and CD34 antibody to highlight the intratumoral endothelial cells), we performed immunohistochemical staining for 24 HCCs treated by transcatheter arterial embolization. Seven HCCs without any preoperative transcatheter arterial embolization and nine cirrhosis cases were also studied as the control cases. The residual tumour was then divided into five areas at 0.5 mm intervals, according to the distance from the necrotic margin induced by embolization. The Ki67 labelling indices of the intratumoral endothelial cells and tumour cells were counted in each area. The correlation between the indices and the corresponding distance from the ischaemic necrosis was analysed. The Ki67 labelling index of intratumoral vascular endothelial cells in the area less than 0.5 mm from the necrotic margin (area 1) was 10.60 +/- 3.64% (mean +/- SD), which was twofold greater than those of the other areas more than 0.5 mm from the margin (areas 2--5) and those of the control HCCs without preoperative transcatheter arterial embolization. In addition, the proliferation labelling index of the tumour cells was 35.77 +/- 11.45% (mean +/- SD) in area 1. This was higher than those of areas 2--5 and control HCCs without preoperative transcatheter arterial embolization. There was a positive correlation between the proliferation of both endothelial and tumour cells and ischaemic necrosis (P < 0.05). CONCLUSIONS: Our study suggests that the proliferative activity of intratumoral endothelial cells and tumour cells is increased by ischaemic necrosis induced by transcatheter arterial embolization, and its effect is maximal in the area adjacent to the necrosis (less than 0.5 mm from the necrotic margin).