Passivation of metallic stents after arterial gene transfer of phVEGF165 inhibits thrombus formation and intimal thickening

Abstract

Objectives: This study sought to test the hypothesis that direct gene transfer of an endothelial cell mitogen could passivate metallic stents by accelerating endothelialization of the prosthesis.

Background: Thrombosis and restenosis comprise the principal clinical manifestations of compromised biocompatibility of endovascular stents. Previous studies have demonstrated that endothelial recovery at sites of balloon injury is a critical determinant of consequent intimal thickening and mural thrombus. We therefore investigated the potential for an endothelial cell mitogen delivered as plasmid DNA to optimize stent biocompatibility.

Methods: Naked plasmid DNA encoding vascular endothelial growth factor (VEGF)/vascular permeability factor (VPF) (phVEGF165) was delivered locally using a hydrogel-coated balloon angioplasty catheter to 16 rabbit iliac arteries in which metallic stents had been placed at the site of balloon injury; the contralateral iliac artery of each rabbit was balloon injured and stented but not transfected.

Results: Stent endothelialization was accelerated by phVEGF165 gene transfer (87.38 +/- 5.06% vs. 33.13 +/- 9.73% [mean +/- SEM] of the planimetered stent surface in the treated vs. contralateral limb, p = 0.005). This was associated with a significant reduction in mural thrombus (3.7 +/- 2.4% vs. 32.7 +/- 9.7%, p = 0.01) at day 7 and intimal thickening (maximal intimal area 0.61 +/- 0.09 vs. 1.44 +/- 0.12 mm2, p < 0.0001) at day 28. No benefit was observed from pCMV-luciferase in 14 similarly instrumented control rabbits.

Conclusions: These findings indicate that arterial gene transfer of naked plasmid DNA encoding for an endothelial cell mitogen may successfully passivate endovascular stents by accelerating stent endothelialization, thereby reducing in-stent thrombus and obstruction due to intimal thickening.