title: Long-term biocompatibility evaluation of a novel polymer-coated stent in a porcine coronary stent model.
abstract: BACKGROUND
  Polymer coatings have been used to modify the surface of stents and to serve as a matrix for local drug delivery.
  
  
  METHODS
  Bare stainless steel stents or poly-bis-trifluorethoxy phosphazene (PTFEP) dip-coated stents (Coroflex, Germany) were randomly implanted into porcine coronary arteries with a balloon-to-artery ratio of 1.1-1.2 : 1. Scanning electron microscopy (SEM), repeat quantitative coronary angiography (QCA) and histomorphometric analysis were performed at 5 days, 6 weeks and 6 months.
  
  
  RESULTS
  At 5 days, complete endothelial cell coverage with fibrin strands was detected in both the bare and the coated stents with SEM. Late loss, determined by QCA, of coated and bare stents was identical at all time points. Histomorphometric analysis showed that coated and bare stents elicited a similar tissue response at 5 days. At 6 weeks, the coated stents showed a moderate peri-strut inflammatory response, resulting in increased neointimal hyperplasia. Compared to the bare stents, however, no significant differences were observed. At 6 months, peri-strut inflammation was minimal and similar in the coated and the bare stent groups. Neointimal hyperplasia of the coated and bare stent groups was also comparable (1.37+/-0.44 compared with 1.15+/-0.40 mm2, P=0.213) and decreased compared to the 6-week response.
  
  
  CONCLUSIONS
  This PTFEP stent coating showed a long-term biocompatibility in a porcine coronary stent model. Because no increased proliferative response was observed up to 6 months, this phosphazene coating may serve as a vehicle for local drug delivery.
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Belgium.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiaoshun
authors.initials: X
authors.lastname: Liu
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.forename: Shengqiao
authors.initials: S
authors.lastname: Li
authors.forename: Eric
authors.initials: E
authors.lastname: Verbeken
authors.forename: Ivan
authors.initials: I
authors.lastname: De Scheerder
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible; D017023:Coronary Angiography; D003331:Coronary Vessels; D005260:Female; D008297:Male; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D009943:Organophosphorus Compounds; D011108:Polymers; D011897:Random Allocation; D013552:Swine
chemical_list: D020099:Coated Materials, Biocompatible; D009943:Organophosphorus Compounds; D011108:Polymers; C081660:poly(bis(trifluoroethoxy)phosphazene)