UP-REGULATION OF ANGIOTENSIN-CONVERTING ENZYME DURING THE HEALING-PROCESS AFTER INJURY AT THE SITE OF PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY IN HUMANS

Background Balloon injury models in rat have shown enhanced expression of ACE in the developing neointima. However, neointimal lesions in hu man coronary arteries are complex due to atherosclerosis and different types of wall laceration. This study was designed to investigate whet her ACE is present in the neointima of humans, including patients with restenosis after percutaneous transluminal coronary angioplasty (PTCA ). Methods and Results Thirty-seven sites with angioplasty injury, obt ained at autopsy, were studied using immunocytochemical techniques. Si tes with injury limited to a fibrous plaque and those with injury exte nding into the media (< 2 months after PTCA) showed fibrocellular repa ir tissue composed mainly of smooth muscle cells that were distinctly positive for ACE. In cellular reactions at the site of injury limited to the atheromatous plaque (< 2 months after PTCA), the expression of ACE appeared first in accumulated macrophages; once smooth muscle cell s appeared in the repair tissue, they also expressed ACE. At a later s tage (3 months after PTCA), the number of cells with ACE expression de creased markedly; from 7 months on, ACE was no longer expressed within the repair tissue, Basically, there were no differences with regard t o ACE expression during the healing process after PTCA between segment s with and those without angiographic evidence of restenosis. Conclusi ons These results show that PTCA. injury in humans results in upregula tion of ACE at sites of active repair and, therefore, ACE could play a n important role as one of the mediators of the healing process after PTCA.