Cardiac Gene Therapy With Phosphodiesterase 2A Limits Remodeling and Arrhythmias in Mouse Models of Heart Failure.

BACKGROUND: PDE2 (phosphodiesterase 2) is upregulated in human heart failure. Cardiac PDE2-transgenic mice are protected against contractile dysfunction and arrhythmias in heart failure but whether an acute elevation of PDE2 could be of therapeutic value remains elusive. This hypothesis was tested using cardiac PDE2 gene transfer in preclinical models of heart failure. METHODS AND RESULTS: C57BL/6 male mice were injected with serotype 9 adeno-associated viruses encoding for PDE2A. This led to a ≈10-fold rise of PDE2A protein levels that affected neither cardiac structure nor function in healthy mice. Two weeks after inoculation with serotype 9 adeno-associated viruses, mice were implanted with minipumps delivering either NaCl, isoproterenol (60 mg/kg per day), or isoproterenol and phenylephrine (30 mg/kg per day each) for 2 weeks. In mice injected with serotype 9 adeno-associated viruses encoding for LUC (luciferase), isoproterenol or isoproterenol+phenylephrine infusion induced left ventricular hypertrophy, decreased ejection fraction unveiled by echocardiography, and promoted fibrosis and apoptosis assessed by Masson's trichrome and Tunel, respectively. Furthermore, inotropic responses to isoproterenol of ventricular cardiomyocytes isolated from isoproterenol+phenylephrine-LUC mice loaded with 1 μmol/L Fura-2AM and stimulated at 1 Hz to record calcium transients and sarcomere shortening were dampened. Spontaneous calcium waves at the cellular level were promoted as well as ventricular arrhythmias evoked in vivo by catheter-mediated ventricular pacing after isoproterenol (1.5 mg/kg) and atropine (1 mg/kg) injection. However, increased PDE2A blunted these adverse outcomes evoked by sympathomimetic amines. CONCLUSIONS: Cardiac gene therapy with PDE2A limits left ventricle remodeling, dysfunction, and arrhythmias evoked by catecholamines, providing evidence that increasing PDE2A activity acutely could prevent progression toward heart failure.