Abstract 716: Superior Cardiac Transduction Efficacy Using a Pseudotyped AAV2/6 Vector Compared to a Heparin-Binding Site Deleted AAV2
Cornerstone for an efficient cardiac gene therapy is the need for a vector system which enables selective and long-term expression of the gene of interest. In rodent animal models pseudotyped adeno-associated viral vectors like AAV2/6 have been shown to be superior in the transduction of cardiomyocytes compared to other AAV serotypes. However, since significant species dependent differences in transduction characteristics exist, and large animal models are of imminent need for pre-clinical evaluations, we compared the gene transfer efficiency of an AAV2/6 and a heparin-binding site deleted AAV2 (AAV2/dHep) in a porcine model.
Methods: Viral vectors were produced using a pseudotyping strategy. All vectors did express the reporter gene luciferase under control of a cardiac specific promoter (MLC2v). Vectors were delivered via percutaneous pressure-regulated retroinfusion into the coronary vein (3.5 x 10e10 genome copies/animal; n = 5 animals/group). Expression levels were evaluated 4 weeks after gene transfer determining luciferase activity. Leakage into other organs was determined by screening for vector genomes with PCR and luciferase assay.
Results: AAV2/dHep vectors did enable moderate transgene expression, which could be further increased with co-administration of recombinant VEGF (rhVEGF, 100ug). Gene transfer with AAV2/6 did permit a far superior cardiac transgene expression with levels up to 20-fold higher than with AAV2/dHep or 2-fold higher than with AAV2/dHep+ VEGF. There was no significant luciferase expression detectable in other organs like lung or liver, though there was evidence for marginal amounts of AAV vector genomes.
Conclusion: This report reveals for the first time, that AAV2/6 is the preferred vector system in pigs for selective and efficient cardiac gene transfer.