Long-term biocompatibility evaluation of a novel polymer-coated stent in a porcine coronary stent model.
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.
Huang
Yanming
Y
Department of Cardiology, University Hospitals Leuven, Belgium.
Liu
Xiaoshun
X
Wang
Lan
L
Li
Shengqiao
S
Verbeken
Eric
E
De Scheerder
Ivan
I
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
D020099:Coated Materials, Biocompatible; D009943:Organophosphorus Compounds; D011108:Polymers; C081660:poly(bis(trifluoroethoxy)phosphazene)