Biology of the Endothelium

Endothelial cell functions are critical for cardiovascular health, and endothelial cell dysfunction underlies the pathology of many cardiovascular diseases. This review summarises the major aspects of endothelial physiology, which together contribute importantly to vascular homeostasis. These include regulation of haemostasis and thrombosis, vascular tone and permeability, lipid transport into the vessel wall, and leukocyte traffic from blood to tissue. Key examples are presented illustrating where endothelial cell dysfunction drives pathology and disease. Signalling pathways that are targets for current or future drug treatments for cardiovascular disease are highlighted. Control of endothelial cell phenotype is described in relation to vasculogenesis, angiogenesis, and other aspects of endothelial cell plasticity. This provides an overall framework linking endothelial physiology and pathology. By virtue of its pan-organ localisation endothelial phenotype is differentiated in multiple ways between different vascular beds due to its responses to organ-specific stimuli, which can change in disease. By virtue of its exposure to blood, endothelial phenotype is further maintained or modulated by prevailing and changing physical and chemical signals.