title: Neointima formation after stent implantation in an experimental model of restenosis: polytetrafluoroethylene-covered versus uncovered stainless steel stents.
abstract: The aim of the study was to assess whether stents covered with a membrane of polytetrafluoroethylene spanned over the mashes of a sandwich-configured double stent (n = 15) prevent migration of smooth muscle cells through stent spaces, leading to less neointima formation compared with uncovered stainless steel stents (n = 14) in iliac arteries of male Chinchilla Bastard rabbits (n = 18). Lumen stenosis was assessed by quantitative angiography immediately before the animals were killed 5 weeks after stent deployment. Neointima formation was quantified by histomorphometric analysis. There were large regional and individual differences in neointima formation, leading locally to a significantly higher degree of stenosis in covered stents (histologically, 76.0 +/- 13.7 vs. 62.9 +/- 12.9%; angiographically, 33.5 +/- 21.1 vs. 7.8 +/- 8.8%) compared with uncovered stents, though mean neointimal and lumen area values were not significantly different. In conclusion, polytetrafluoroethylene-covered stents do not prevent neointima formation compared with uncovered stents. Although the membrane reduces local smooth muscle cell migration, the neointima hyperplasia at the proximal and distal ends of a covered stent stimulates migration along its longitudinal axis. In this stent-restenosis model, regional and individual proliferation processes and not the membrane-covering strut-to-strut distances determine lumen restenosis.
authors.affiliation: Heart Center, Department for Internal Medicine/Cardiology, University of Leipzig, Germany. sickp@medizin.uni-leipzig.de
authors.forename: Peter B
authors.initials: PB
authors.lastname: Sick
authors.forename: Oana
authors.initials: O
authors.lastname: Brosteanu
authors.forename: Josef
authors.initials: J
authors.lastname: Niebauer
authors.forename: Christoph
authors.initials: C
authors.lastname: Hehrlein
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schuler
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D017023:Coronary Angiography; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D023921:Coronary Stenosis / Q000628:therapy*; D003331:Coronary Vessels; D004195:Disease Models, Animal; D004869:Equipment Safety; D007150:Immunohistochemistry; D008422:Materials Testing; D008670:Metals; D011138:Polytetrafluoroethylene / Q000737:chemistry; D011336:Probability; D011817:Rabbits; D012016:Reference Values; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D015607:Stents / Q000009:adverse effects*; D017539:Tunica Intima / Q000473:pathology*
chemical_list: D001672:Biocompatible Materials; D008670:Metals; D011138:Polytetrafluoroethylene