The Rat Aortic Ring Assay for In Vitro Study of Angiogenesis

Angiogenesis is necessary for growth and metastasis of cancer. It is comprised of several distinct steps, including degradation of extracellular matrix, cell migration, proliferation, and structural reorganization (1 ). Inhibition of angiogenesis has been shown in pre-clinical studies to suppress tumor growth (2 –4 ). Currently, the use of anti-angiogenic therapy in cancer is under intensive investigation (5 ). Several in vitro and in vivo assays are available to study angiogenesis, each with its own advantages and limitations (6 ). In vivo assays simulate the natural process but are often complicated by inflammatory host responses that may interfere with angiogenesis. Variables are more likely to be controlled using in vitro assays. However, these assays are performed using undefined media supplemented with serum, which in itself is very much angiogenic (7 ). In addition, most in vitro assays are designed only to look at selective phases (endothelial cell migration and proliferation) of angiogenesis.