Cardiovascular homeostasis is highly dependent on endothelial cells that are important constituents of blood vessels. They play critical roles in the regulation of blood fluidity and fibrinolysis, vascular tone, angiogenesis, monocyte/leukocyte adhesion, and platelet aggregation.

The quantification of circulating endothelial cells (CEC) in blood samples is a rather novel and reliable method of assessing endothelial damage and endothelial dysfunction. It is assumend that CEC are mature cells that have detached from the inner most cell layer of blood vessels in response to endothelial injury.

Increased numbers of CECs in cardiovascular disease and its risk factors, such as unstable angina, acute myocardial infarction, stroke, diabetes mellitus, and critical limb ischemia have been reported. The enumeration of CEC after acute myocardial infarction has been shown to be an accurate predictor of major adverse coronary events and death.