Regrowth of arterial endothelium. Denudation with minimal trauma leads to complete endothelial cell regrowth.

Endothelial regeneration in the rat carotid artery was investigated using two different techniques of denudation. With balloon catheter denudation, medial cell death occurred, and endothelial regrowth stopped after several weeks, leaving a large area devoid of endothelium. After denudation with a new technique that removed the endothelium without damaging the media complete endothelial regrowth was achieved. Acutely after this denudation, large platelet thrombi were present on the subendothelial surface of vessels denuded with the filament loop. In contrast, balloon catheter denuded arteries showed only a platelet monolayer on their luminal surface. Within the first few weeks after denudation with either technique the regenerating endothelial cells stained strongly for basic fibroblast growth factor. At later times when replication of endothelium had stopped, the balloon catheter denuded vessels did not stain with this antibody. After filament denudation endothelial cell replication remained high until regrowth was complete and intensive staining was observed in the regenerating endothelial cells at all times. No differences were seen in staining of smooth muscle cells for transforming growth factor-beta and fibronectin in either set of denuded vessels. Both groups showed transforming growth factor-beta to be located in the developing intima and especially on the apical surface of luminal smooth muscle cells. The surface of these luminal smooth muscle cells also stained with antibody to fibronectin. These data demonstrate that total regrowth of endothelium can occur over large denuded areas despite the presence of transforming growth factor-beta and fibronectin on these surfaces. Furthermore the ability of these endothelial cells to proliferate would appear to be dependent on the presence of basic fibroblast growth factor and on the severity of the trauma induced by denudation.