title: Chronic platelet and neutrophil adhesion: a causal role for neointimal hyperplasia in in-stent restenosis.
abstract: OBJECTIVE
  To investigate the relationship between platelets and neutrophils and the progression of neointimal hyperplasia after angioplasty versus stenting of porcine coronary arteries.
  
  
  METHODS
  Balloon angioplasty or implantation of a balloon-expandable stent was randomly performed in the left and right coronary arteries of 16 Yorkshire swine; the animals were euthanized 1 hour (n=6), 24 hours (n=4), or 1 month (n=6) after the interventions. The adhesion of chromium 51-labeled platelets and indium 111-labeled neutrophils was quantified (per cm2), and histological and morphometric analyses were performed.
  
  
  RESULTS
  The acute adhesion of platelets and neutrophils observed on the injured segments 1 hour after the interventions was similar between the treated groups. However, at 24 hours, stenting was associated with 2-fold more platelets and 3-fold more neutrophils (p<0.05) than was dilation, and stented arteries remained more thrombogenic at 1 month (p<0.05). Neointimal formation was more intense after stent implantation (3.80+/-0.77 mm, p<0.05) than after dilation (0.81+/-0.21 mm), and it correlated positively with the adhesion of platelets (r=0.81, p<0.002) and neutrophils (r=0.69, p<0.01).
  
  
  CONCLUSIONS
  These results indicate that stent implantation is associated with a more intense acute and chronic, low-grade inflammatory response than is dilation. It appears that the chronic inflammatory response is, at least in part, platelet- and neutrophil-driven and contributes to the progression of neointimal proliferation after stenting.
authors.affiliation: Experimental Interventional Laboratory, Montreal Heart Institute and University of Montreal, Quebec, Canada. tanguay@icm.umontreal.ca
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Tanguay
authors.forename: Talal
authors.initials: T
authors.lastname: Hammoud
authors.forename: Pascale
authors.initials: P
authors.lastname: Geoffroy
authors.forename: Yahye
authors.initials: Y
authors.lastname: Merhi
mesh_terms: D000800:Angioplasty, Balloon; D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D002448:Cell Adhesion; D002908:Chronic Disease; D006083:Graft Occlusion, Vascular / Q000209:etiology* / Q000473:pathology; D006965:Hyperplasia / Q000209:etiology; D009504:Neutrophils / Q000502:physiology*; D011897:Random Allocation; D015607:Stents; D013552:Swine; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology*