Angiogenesis, or neovascularization, is the process that allows the generation of new blood vessels derived from an existing vasculature. The main cells involved in this process are the endothelial cells, which line all the blood vessels and constitute virtually all the capillaries.

Angiogenesis is composed of multiple stages: basement membrane disruption, cell migration, proliferation, tube formation.

There are in vivo tests to study these processes but these tests are very long to set up and require technical knowledge.

The simplest way to evaluate angiogenesis is to measure the ability of endothelial cells to form three-dimensional structures. This is called tube formation. Endothelial cells have the ability to form tubes in collagen or fibrin when cultured for days in petri dishes or plates. Tube formation by endothelial cells in a gel composed of in vivo mimicking extracellular matrix proteins (ECMs) can be used to test angiogenesis inhibitors prior to testing under in vivo conditions.