Abstract 15777: Viral Gene Transfer is Able to Revert Phenotypical Manifestation of Recessive Catecholaminergic Polymorphic Ventricular Tachycardia in Highly Symptomatic Adult Knock-In Mice
Introduction: We previously demonstrated that viral gene transfer of WT-CASQ2 in neonates CASQ2-R33Q-knock-in mice is able to prevent development of recessive Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), a life threatening arrhythmogenic disease.
Hypothesis: We investigated whether the WT-CASQ2-gene delivery is able to revert the arrhythmic phenotype in adult CASQ2-R33Q transgenic mice with a fully blown form of the disease.
Methods: Adult CASQ2-R33Q mice were instrumented with ECG telemetry to test arrhythmias susceptibility in vivo after β-adrenergic stimulation. Thereafter, mice were divided in two groups: 1) mice infected with adeno-associated-viral-vector-9 (AAV9) containing the coding sequence of WT-CASQ2 co-expressed with GFP gene, and 2) negative control mice injected with sterile saline (PBS). Two months later we evaluated the effects of the infection by in vivo ECG recording, in vitro electrophysiological and molecular assays.
Results: ECG was recorded in adult CASQ2-R33Q mice after epinephrine (2mg/kg) administration: 20/23 mice (87%, p<0.05) developed sustained ventricular tachycardia (VTs). All mice were randomized to AAV9-infection or PBS administration. Two months later, epinephrine test was repeated and we observed a major reduction of VTs in AAV9-infected mice (15%, n= 2/13) versus PBS-treated group (90%, n= 9/10, p< 0.001). Electrophysiological analysis of single myocytes showed that isoproterenol induced delayed after depolarizations (DADs) and triggered activity (TA) were significantly reduced in infected cardiomyocytes versus control cells (DADs: from 79%, n= 15/19, to 18%, n= 3/17, p<0.001; TA: from 63%, n= 12/19, to 12%, n= 2/17, p<0.005). Western-blot analysis showed that AAV9-infected hearts presented normalization of levels of calsequestrin, triadin and junctin.
Conclusions: We demonstrate that viral gene transfer of WT-CASQ2 reverts severe arrhythmic manifestations of the disease in vitro and in vivo and restores physiological concentrations of calsequestrin, triadin and junctin. Overall, viral gene-therapy is able to cure CPVT not only by preventing disease onset in neonates but also reverting phenotypical manifestations in adults.
- © 2013 by American Heart Association, Inc.