Abstract 15042: Cardiac-Enhanced Adeno-Associated Viral Vector Achieves Long-Term Transgene Expression in Transplanted Porcine Hearts When Administered During Ex Vivo Perfusion

Introduction: Use of gene therapy for cardiac transplantation is limited by the lack of an effective recombinant Adeno-associated viral vector (rAAV) gene delivery strategy. Ex vivo normothermic perfusion has been increasingly used in clinical practice and is an effective platform for achieving robust global gene delivery to a donor heart. Here we utilized a rationally designed cardiac-enhanced AAV3b variant, SASTG, to deliver the gene firefly luciferase to porcine hearts and evaluated transgene expression 30-days post-transplantation. Methods: Heterotopic heart transplantation was performed using blood-type and MHC matched Yucatan pigs (n=4). Donor hearts underwent ex vivo perfusion for 2-hours with perfusate containing the rAAV SASTG-Luciferase. Three different doses of rAAV were used: 2x10 13 , 8x10 13 , 1x10 14 viral genome copies (VGC). Recipients were survived for 30 days at which time they were euthanized and donor and recipient hearts were examined for overall levels of luciferase activity, luciferase DNA copy number, and histology for luciferase expression on immunostaining and evidence of inflammation. Results: There was a dose-dependent response in luciferase activity observed in the donor heart ventricles with the lowest activity detected at the 2x10 13 VGC dose (1.5-9.9x10 3 RLU/mg) mid-level activity at the 8x10 13 VGC dose (32.7-71.2x10 3 RLU/mg) and highest activity at the 1x10 14 VGC dose (27.6-278.1x10 3 RLU/mg). Luciferase DNA was detectable in a dose-dependent manner in the donor heart ventricles (0.02-131.1x10 3 VGC/pg of DNA), but undetectable in all native hearts. Finally, immunostaining demonstrated diffuse luciferase expression in the donor heart but none in the recipient hearts. There was also no evidence of inflammation in any of the donor hearts. Conclusions: The cardiac-enhanced AAV3b variant, SASTG, is associated with robust, global transgene expression in porcine cardiac allografts when administered during ex vivo perfusion.