PLATELET ATTACHMENT STIMULATES ENDOTHELIAL-CELL REGENERATION AFTER ARTERIAL INJURY

Background. Arterial injury is associated with endothelial disruption and attachment of platelets to an exposed subintimal layer. A variety of factors released by platelets mall affect the ability of endothelia l cells bordering an injury to regenerate. In this study an organ cult ure model of arterial injury was used to investigate the relationship between attachment of platelets to a superficial arterial injury and e ndothelial regeneration. Methods. A defined superficial endothelial in jury was made in whole vessel wall explants of rabbit thoracic aorta. Injured explants were treated with either fresh whole platelets, the s upernatant of platelets aggregated by collagen, or basic fibroblast gr owth factor. Four days after injury and treatment, the average distanc e of endothelial regeneration was determined. Results. A dramatic incr ease in the rate of endothelial cell regeneration was observed when in jured vessels were exposed to fresh whole platelets (p = 0.003). This increase in regeneration was comparable to that observed with fibrobla st growth factor. No increase in the regenerative rate was found after exposure of explants to the supernatant of aggregated platelets (p = 0.69). Conclusions. Platelets stimulate endothelial regeneration at a rate equal to that observed with the potent endothelial mitogen basic fibroblast growth factor. Because this effect was not demonstrated wit h the supernatant of aggregated platelets, endothelial regeneration ma y be dependent on attachment of the platelets to the area of injury.