Safety and efficacy of high-dose adeno-associated virus 9 encoding sarcoplasmic reticulum Ca2+ adenosine triphosphatase delivered by molecular cardiac surgery with recirculating delivery in ovine ischemic cardiomyopathy

Objective: Therapeutic safety and efficacy are the basic prerequisites for clinical gene therapy. We investigated the effect of high-dose molecular cardiac surgery with recirculating delivery (MCARD)-mediated adeno-associated virus 9 (AAV9)/sarcoplasmic reticulum Ca2+ adenosine triphosphatase (SERCA2a) gene delivery on clinical parameters, oxidative stress, humoral and cellular immune responses, and cardiac remodeling. Methods: Ischemic cardiomyopathy was generated in a sheep model. The sheep were assigned to 1 of 2 groups: control (n = 10) and study (MCARD, n = 6). The control group underwent no intervention and the study group received 10(14) genome copies of AAV9/SERCA2a 4 weeks after infarction. Results: Our ischemic model produced reliable infarcts leading to heart failure. The baseline ejection fraction in the MCARD group was 57.6% +/- 1.6% versus 61.2% +/- 1.9% in the control group (P > .05). At 12 weeks after infarction, the MCARD group had superior left ventricular function compared with the control group: stroke volume index, 46.6 +/- 1.8 versus 35.8 +/- 2.5 mL/m(2) (P < .05); ejection fraction, 46.2% +/- 1.9% versus 38.7% +/- 2.5% (P < .05); and left ventricular end-systolic and end-diastolic dimensions, 41.3 +/- 1.7 versus 48.2 +/- 1.4 mm and 51.2 +/- 1.5 versus 57.6 +/- 1.7 mm, respectively (P < .05). The markers of oxidative stress were significantly reduced in the infarct zone in the MCARD group. No positive T-cell-mediated immune response was seen in the MCARD group at any point. Myocyte hypertrophy was also significantly attenuated in the MCARD group compared with the control group. Conclusions: Cardiac overexpression of the SERCA2a gene by way of MCARD is a safe therapeutic intervention. It significantly improves left ventricular function, decreases markers of oxidative stress, abrogates myocyte hypertrophy, arrests remodeling, and does not induce a T-cell-mediated immune response.