Experimental Study on Residual Tumor Angiogenesis after Cryoablation

Abstract

<br/><b>Objective</b>: To explore the mechanism and significance of tumor angiogenesis by observing changes of microvesseldensity (MVD) and expression of vascular endothelial growth factor (VEGF) in residual tumor tissuesafter cryoablation. Materials and <br/><b>Methods</b>: A total of 18 nude mice xenograft models with transplanted lungadenocarcinoma cell line A549 were established and randomly divided into 3 groups when the maximum diameterof tumor reached 1 cm: control, cisplatin (DDP) and cryoablation. The nude mice were sacrificed after 21-dcryoablation to obtain the tumor tissues. Then immunohistochemistry was applied to determine MVD and theexpression of VEGF in tumor tissues. <br/><b>Results</b>: The tumor volumes of control group, DDP group and cryoablationgroup were 1.48±0.14 cm3, 1.03±0.12 cm3 and 0.99±0.06 cm3 respectively and the differences were significant(P<0.01), whereas MVD values were 21.1±0.86, 24.7±0.72 and 29.2±0.96 (P<0.01) and the positive expressionrates of VEGF were 36.2±1.72%, 39.0±1.79% and 50.8±2.14% (P<0.01), respectively, showing that MVD wasproportional to the positive expression of VEGF (r=0.928, P<0.01). <br/><b>Conclusions</b>: Cryoablation can effectivelyinhibit tumor growth, but tumor angiogenesis significantly increases in residual tumors, with high expressionof VEGF playing an important role in the residual tumor angiogenesis.