Transition from two‐dimensional to three‐dimensional models of endothelial cell cultures

In two-dimensional culture, endothelial cells grow as a monolayer on a flat surface, as a monolayer monoculture or as co-culture. This type of culture has the disadvantage that it lacks resemblance to the physiological conditions of an organism and the absence of a complex biological microenvironment. Moreover, studies on in vitro two-dimensional monolayer cell cultures are not capable of mimicking the nutrient and oxygen gradient. Two-dimensional assays are sufficient to induce endothelial cell cord formation, but they cannot reproduce the necessary cues for lumen formation. Three-dimensional assays have as their endpoint the formation of capillary-like cords or tubes by endothelial cells cultured either on the surface of (planar models) or within extracellular matrix. More recent applications include endothelial cell spheroids, embryoid bodies assay, and organoids.