Tumor angiogenesis: methods to analyze tumor vasculature and vessel normalization in mouse models of cancer.

Angiogenesis, the formation of neo-vessels, is one of the most important hallmarks of cancer. Tumor vasculature presents structural abnormalities such as dilatation of vessel diameter and hyper-branched and twisted pattern. A promising strategy in anticancer therapy to overcome the resistance to certain antiangiogenic therapies is the tumor blood vessel normalization, which restores the physiological perfusion and oxygenation of tumor vasculature. Many studies showed how vessel normalization is able to counteract metastasis formation and to favor chemotherapeutic drugs delivery to tumors. Herein we describe different techniques and protocols that allow the study, in vivo the main features of tumor vessel normalization such as the reduction of vessel branching and diameter, the increase of pericyte coverage, the reduction of vessel permeability, and the improvement of vessel perfusion and drug delivery.