Relationship between platelets and neutrophil adhesion and neointimal growth after repeated arterial wall injury induced by angioplasty in pigs

Platelet and neutrophil interactions with injured vascular wall may contribute to restenosis. Their importance was mainly examined following balloon injury of intact arteries. However, dilation of diseased arteries is clinically more relevant and may elicit different responses. We investigated the relationship between platelets and neutrophil adhesion, neointima formation and P-selectin expression on damaged arteries after repeated balloon injury. In an acute single-injury model, 8 pigs were subjected to bilateral carotid angioplasty and sacrificed 1 h later. In a chronic model, 19 pigs were subjected to similar procedures and allowed to recover for 4 weeks; then 18 arteries were redilated at the same previously injured sites (double injury) while the remaining arteries were not redilated and used to investigate the extent and the adhesive properties of the neointima. After single injury, Cr-51-platelet adhesion (x 10(6)/cm(2)) increased significantly from 3.8 +/- 0.6 to 45.9 +/- 6.5 (p < 0.05) on mildly and deeply injured segments, respectively, and were statistically similar after double injury. After single injury, (111)ln-neutrophil adhesion ( x 10(3)/cm(2)) increased from 226.6 +/- 45.5 to 512.5 +/- 70.3 (p < 0.05) on mildly and deeply injured segments, and were significantly higher (p< 0.05) after double injury (mild: 1,289.1 +/- 227.9 and deep: 2,417.8 +/- 333.9). As well, the neo-endothelium expresses P-selectin at 4 weeks and platelet and neutrophil adhesion was directly related to neointimal growth. These results, which indicate ongoing proinflammatory processes 1 month post-angioplasty, suggest that neutrophils may participate in the progression of restenosis. Copyright (C) 2001 S. Karger AG. Basel.