The aortic ring model of angiogenesis.

Angiogenesis is regulated by a complex cascade of cellular and molecular events. The entire process can be reproduced in vitro by culturing rat or mouse aortic explants in three-dimensional biomatrices under chemically defined conditions. Angiogenesis in this system is driven by endogenous growth factors released by the aorta and its outgrowth. Sprouting endothelial cells closely interact with pericytes, macrophages, and fibroblasts in an orderly sequence of morphogenetic events that recapitulates all stages of angiogenesis. This model can be used to study the basic mechanisms of the angiogenic process and to test the efficacy of proangiogenic or antiangiogenic compounds. Aortic cultures can be evaluated with a range of morphologic and molecular techniques for the study of gene expression. In this chapter we describe basic protocols currently used in our laboratory to prepare, quantify, and analyze this assay.