Tube Formation In Vitro Angiogenesis Assay-Laboratory Methods in Cell Biology

Endothelial cell (EC) differentiation on basement membrane matrix is a highly specific process, which recapitulates many steps in blood vessel formation, including cell adhesion, migration, alignment, protease secretion and tubule formation. For this reason, it is presently considered as a reliable in vitro tool to identify factors with potential anti- or proangiogenic properties. Examples include pharmacological trials, as well as studies focused on the identification of endogenous factors involved in the modulation of the angiogenic process. The EC tube formation on basement membrane matrix is generally used as a first screen that is followed by additional in vitro and ex vivo or in vivo assays. Being quite easy to perform and not focused on a single specific step of the angiogenic process, as a first screen assay, it has many advantages over other in vitro tests. Moreover, the results provided by the tube formation on basement membrane assay can be accurately quantified by morphometric techniques and/or image analysis. Methodological issues concerning the assay and the quantitative evaluation of the results it provides are the focus of this chapter.