Aims

Restenosis has been the principal limitation of bare metal stents. Based upon the presumption that platelet and inflammatory cell recruitment initiate neointimal proliferation, we explored a novel polymer coating that reduces cell-stent interactions. The purpose of the present study was to investigate the effect of poly (L-lysine)-graft-poly (ethyleneglycol)(PLL-g-PEG) adsorbed to stent surfaces to reduce neointimal hyperplasia in the porcine restenosis model.

Methods and results

Seven animals were instrumented each with 2 stainless steel stents (15 mm length, 2.5-3.5 mm diameter), randomly implanted in 1 major epicardial coronary artery. One stent was dip-coated with PLL-g-PEG, whereas the other stent served as the uncoated control stent. All animals were sacrificed after 6 weeks for histological examination. Neointimal hyperplasia was significantly less (-51%) in the PLL-g-PEG-coated stents (1.15+/-0.59 mm2) than in the uncoated control stents (2.33+/-1.01 mm2; p< 0.001). Conversely, lumen size was larger in the PLL-g-PEG-coated stents (2.91+/-1.17 mm2) than in the uncoated stents (2.04+/-0.64 mm2; p< 0.001). High magnification histomorphologic examination revealed no signs of inflammation or thrombus formation in either stent group.

Conclusions

Polymeric steric stabilization of stents with PLL-g-PEG significantly reduces neointimal hyperplasia in the porcine restenosis model. Reduction of cell-stent interactions mediated by PLL-g-PEG appear to improve biocompatibility of stainless steel stents without evidence of adverse inflammatory or prothrombotic effects.