Abstract 19633: A Novel Stent Based Gene Delivery System for the Prevention of Restenosis
Introduction: In-stent restenosis (ISR) remains an important clinical problem in the era of drug-eluting stents. Gene therapy of ISR has not come into clinical translation, mostly due to the immunogenicity of applied vectors and inadequate gene delivery systems. Herein we describe a new versatile stent-based gene delivery platform adaptable to provide local arterial gene transfer with a range of viral and non-viral vectors. This system exploits a natural affinity of protein G (PrG) to Fc region of mammalian IgG, making PrG a universal adaptor for surface immobilization of vector-capturing antibodies (Ab).
Hypotheses: Our studies tested 1) whether reversible surface immobilization of AAV gene vectors is feasible using vector tethering by AAV-specific Ab appended to the stent surface through covalently attached PrG; and 2) whether a PrG/Ab-tethered AAV2, engineered to overexpress inducible nitric oxide synthase (AAV2-iNOS), attenuates restenosis in the rat model of stent angioplasty.
Methods: The surface of stents was rendered thiol-reactive by consecutive exposure to polyallylamine bisphosphonate with latent thiol groups, thiol deprotection, and conversion of thiols to pyridyldithiol (PDT) groups with PDT-grafted polyethyleneimine. PrG-thiol was then covalently attached to the surface, followed by anti-AAV2 Ab (clone A20) and AAV2 vector. PrG, A20 and AAV2 working concentrations were optimized using fluorescent Ab depletion and Pico Green assays. Stents formulated with AAV2-Luc (109 VG) were implanted in rat carotids. Gene expression was studied over time by optical imaging. BMS and AAV2-iNOS eluting stents (109 VG) deployed in rat carotids were explanted 2 weeks after surgery for morphometric analysis.
Results: AAV2 immobilization density with PrG/Ab tethering was dependent upon PrG and A20 concentration and amounted to 5x1010 VG/cm2 after optimization. Luciferase expression after AAV2-Luc stent deployment was detectable in stented arteries from day 3 to day 120 post-stenting. Stent-based AAV2-iNOS delivery resulted in a 34% decrease of ISR compared to BMS.
Conclusions: PrG/Ab-mediated AAV immobilization on the stent surface provides long-term transgene expression and can be a therapeutically relevant approach for ISR prevention.
Author Disclosures: I. Fishbein: None. I.S. Alferiev: None. J.B. Foster: None. D.T. Guerrero: None. A. Mas Monteys: None. M. Chorny: None. R.J. Levy: None.
- © 2016 by American Heart Association, Inc.