Studying Angiogenesis in the Rabbit Corneal Pocket Assay

The rabbit corneal micropocket assay uses the avascular cornea as a substrate to study angiogenesis in vivo. The continuous monitoring of neovascular growth in the same animal allows for the evaluation of drugs acting as suppressors or stimulators of angiogenesis. Through the use of standardized slow-release pellets, a predictable angiogenic response can be quantified over the course of 1-2 weeks. Uniform slow-release pellets are prepared by mixing purified angiogenic growth factors such as basic fibroblast growth factor (FGF) or vascular endothelial growth factor (VEGF) and a synthetic polymer to allow for their slow release. A micropocket is surgically created in the cornea thickness under anesthesia and in sterile conditions. The angiogenesis stimulus (growth factor but also tissue fragment or cell suspension) is placed into the pocket in order to induce vascular outgrowth from the limbal capillaries where vessels are preexisting. On the following days, the neovascular development and progression are measured and qualified using a slit lamp, as well as the concomitant vascular phenotype or inflammatory features. The results of the assay allow to assess the ability of potential therapeutic molecules to modulate angiogenesis in vivo, both when released locally or given by ocular formulations or through systemic treatment. In this chapter the experimental details of the avascular rabbit cornea assay, the technical challenges, advantages, and limitations are discussed.