Angiogenesis is a complex sequential process involving endothelial activation, basement membrane degradation, endothelial sprouting from the parent vessel, invasion of the extracellular matrix, endothelial proliferation, vessel elongation, branching, anastomosis, increases in vessel diameter, basement membrane formation, pericyte acquisition, and remodelling. Mostin vitroangiogenesis assays are two-dimensional and measure only one facet of this process, generally endothelial proliferation, migration, or tube formation. The two-dimensional nature of the assays also ignores the differences in endothelial phenotype seen in three-dimensional models andin vivo. Thein vitroserum-free three-dimensional rat aortic model closely approximates the complexities of angiogenesisin vivo, from endothelial activation to pericyte acquisition and remodelling, and most of these can be quantified by image analysis, immunohistochemistry, and biochemical analysis. It is easily manipulated using molecular biological intervention or exogenous inhibitors and activators in a relatively controlled system.
