Direct evidence of endothelial injury during cardiopulmonary bypass by demonstration of circulating endothelial cells

Endothelial activation is considered a key process in the development of a whole body inflammatory response secondary to cardiopulmonary bypass (CPB). Increased levels of a multitude of soluble mediators have been described as being released during and after cardiac surgery. Circulating endothelial cells have recently been established as a novel marker of endothelial damage in a variety of vascular disorders. Blood samples from 20 patients undergoing elective coronary artery bypass surgery were obtained preoperatively and 1, 6, 12, 24, and 48 h after termination of CPB. Control samples were obtained from ten healthy volunteers. Circulating endothelial cells (CEC) were isolated with immunomagnetic anti-CD146-coated Dynabeads, and counted in a Nageotte chamber. Low numbers of CEC were observed in healthy control volunteers (12±6 cells/mL; median: 9 cells/mL). CEC numbers were already significantly elevated in all patients before CPB, and there was a further significant increase after weaning from CPB (maximum increase at 6 h after CPB: 73±30 cells/mL; range: 30-153 cells/mL, p < 0.001). The number of CEC provides further and direct evidence that CPB is associated with a pronounced endothelial injury and/or damage. CEC appear to be most useful markers for vascular endothelial activation because they are specific, stable, and circulating components of injured vessel wall.