Endothelial progenitor cells: markers of vascular reparative capacity

Assessment of the propensity for vascular events has been based on measurement of risk factors predisposing one to vascular injury. These assessments are based on the strong associations between risk factors such as hypertension, cholesterol levels, smoking, and diabetes which were first described almost a half century ago. The more recent discovery of the relationship between ongoing inflammation and clinical outcomes has led to a variety of blood-based assays which may impart additional knowledge about an individual's propensity for future cardiovascular events. Vascular health is now better represented as a balance between ongoing injury and resultant vascular repair, mediated at least in part by circulating endothelial progenitor cells. To date, one's risk for vascular events has focused exclusively on assessing propensity for vascular damage, either by assessing conventional risk factors which were initially identified over half a century ago, or more recently by assessing markers of inflammation and other circulating factors which area related to subsequent clinical events. Circulating endothelial progenitor cells play important roles in accelerating endothelialization at areas of vascular damage, and EPC enumeration is a viable strategy for assessing reparative capacity. To date, EPC numbers have been correlated with the numbers of cardiovascular risk factors, extent of coronary disease, and future cardiovascular events. Given that EPC enumeration and functional characterization represent the only assessment of the reparative side of the balance between damage and renovation, this technique may offer independent and different assessment of propensity to cardiovascular injury, greatly improving risk stratification of patients.