Abstract 200: Development and Proof of Concept Testing of an Ex Vivo Perfusion Chamber for Studying Platelet Adhesion to Coronary Stents Under Physiological Conditions
Background: Current-generation drug-eluting stents unblock atherosclerotic arteries, inhibit restenosis, but also render the artery prone to thrombosis by inhibiting endothelial cell function. Hence, there is strong clinical interest in developing stents that inhibit restenosis, yet are less thrombogenic. Goals of this study were to 1) develop an ex vivo method to measure platelet adhesion and aggregation on coronary stents under clinically-relevant conditions, and 2) test the hypothesis that treating metal stents with trimethylsilane (TMS) through a novel glow discharge process that coats stents with a nanoscale layer of hydrophobic plasma coating, with or without additional post-deposition glow discharge treatment with NH3 and O2 gas, generating elemental nitrogen and oxygen on the stent surface, inhibits platelet adhesion to stents.
Methods: Bare-metal stents (BMS) made of 316L stainless steel was deployed in Masterflex tubing by inflating an over-the-wire coronary balloon within the stent. Tubing containing stents was filled with porcine indium-labeled platelets in anticoagulated whole blood and the ends were connected to create a closed circuit, which was connected to a peristaltic pump to generate unidirectional flow with shear stress of 67 s-1, similar to that present in human coronary arteries. After 30 min of continuous flow at 37°C the tubing was disconnected and extensively rinsed to remove blood. Platelet adhesion to stents was measured with a gamma counter and by scanning electron microscopy (SEM).
Results: Platelet adhesion to metal stents treated with TMS followed by NH3 and O2 (DC-TMS+NH3/O2) was 56±8.2% reduced compared to BMS (n=12; P=0.003), whereas TMS treatment alone did not significantly inhibit platelet adhesion. SEM confirmed significantly decreased platelet deposition on DC-TMS+ NH3/O2 stents vs. BMS.
Conclusions: A novel glow discharge surface modification involving TMS, NH3, and O2 gas generates stents with a bioactive surface that resists platelet adhesion under physiological conditions. Our ex vivo perfusion circuit facilitates rapid and precise comparison of stent thrombogenicity under physiological conditions, which should prove useful to other investigators developing coronary stents for clinical use.
Author Disclosures: T. Strawn: None. H. Kelly: None. J.E. Jones: None. M. Chen: None. W.P. Fay: None.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.