Differential responses of human umbilical and coronary artery endothelial cells to apoptosis

Apoptosis, or programmed cell death, plays an important role not only in normal homeostasis but is increasingly implicated in a number of pathological processes. The contribution of apoptosis in the pathophysiology of coronary artery disease has been suggested. In this study, the authors compared the effects of inductive and suppressive signals as well as the two combined apoptotic signals during the early stages of apoptosis using two types of human endothelial cells isolated from the umbilical vein (HUVECs) and from the coronary artery (HCAECs) vascular beds as study targets. The authors demonstrated that HUVECs were more susceptible than HCAECs to apoptosis, as measured by a 2.5-fold increase in caspase-3 activity, which in turn may suggest a different pattern in association to the apoptotic mechanism within each cell type. Under inducing conditions of apoptosis, a significant increase in tissue factor (TF) expression at both the mRNA and protein level in HUVECs compared to the level of TF expression in HCAECs was observed. These different responses of endothelial cell types potentially indicate unequal susceptibility to apoptosis, depending on their vascular bed origins, and emphasize the importance of cell-type and -origin considerations when selecting a study model of apoptosis and pathophysiology.