The endothelial cells (EC), lining all blood vessels’ inner surfaces, are the unique interface between the blood and tissues. With an estimated 10^13 cells and covering 5,000 to 7,000 m2, one would consider the endothelium as a full-fledged organ. 

During embryology and homeostasis, EC are involved in a multitude of physiologic functions, including vasculogenesis, blood fluidity maintenance, vasomotor tone regulation, and substrate and cell trafficking. EC activation has been demonstrated in multiple clinical situations that are the leading causes of morbidity and mortality globally, such as cancer, cardiovascular disease, and sepsis. EC activation is nonetheless a double-edged sword, either protecting the affected organ or precipitating its failure, defining a continuum between appropriate activation and endothelial dysfunction. Although all ECs share common properties, they have distinct patterns according to their organ physiological function and the biochemical composition, cellular interactions, and shear stress in their microenvironment.

At present, the endothelium is already a target in pathologies such as cancer or retinopathy. Its polymorphism and involvement in countless diseases make it a high potential candidate for innovative therapeutic approaches. Therefore, understanding the basic mechanisms of EC functions under homeostasis and in pathology, their plasticity, and heterogeneity is an exciting challenge and a very dynamic research field.

This Collection aims to cover state-of-the-art methods to study the multiple facets of the endothelium, from cell preparation for ex-vivo/in-vitro studies under experimental conditions to in vivo assessment in live animal models or patients.