A Translatable, Closed Recirculation System for AAV6 Vector-Mediated Myocardial Gene Delivery in the Large Animal

Current strategies for managing congestive heart failure are limited, validating the search for an alternative treatment modality. Gene therapy holds tremendous promise as both a practical and translatable technology platform. Its effectiveness is evidenced by the improvements in cardiac function observed in vector-mediated therapeutic transgene delivery to the murine myocardium. A large animal model validating these results is the likely segue into clinical application. However, controversy still exists regarding a suitable method of vector-mediated cardiac gene delivery that provides for efficient, global gene transfer to the large animal myocardium that is also clinically translatable and practical. Intramyocardial injection and catheter-based coronary delivery techniques are attractive alternatives with respect to their clinical applicability; yet, they are fraught with numerous challenges, including concerns regarding collateral gene expression in other organs, low efficiency of vector delivery to the myocardium, inhomogeneous expression, and untoward immune response secondary to gene delivery. Cardiopulmonary bypass (CPB) delivery with dual systemic and isolated cardiac circuitry precludes these drawbacks and has the added advantage of allowing for control of the pharmacological milieu, multiple pass recirculation through the coronary circulation, the selective addition of endothelial permeabilizing agents, and an increase in vector residence time. Collectively, these mechanics significantly improve the efficiency of global, vector-mediated cardiac gene delivery to the large animal myocardium, highlighting a potential therapeutic strategy to be extended to some heart failure patients.