Recombinant adenovirus-mediated cardiac gene transfer of superoxide dismutase and catalase attenuates postischemic contractile dysfunction

Background - Coronary revascularization entails obligatory myocardial ischemia followed by reperfusion with occasional resultant postischemic contractile dysfunction, a state associated with significant morbidity and mortality. This injury is attributed in part to oxygen free radicals and has been partially ameliorated with exogenous antioxidants, a strategy limited by agent instability, low titer, and inadequate cardiomyocyte uptake. Cardiac gene transfer with antioxidant encoding vectors may significantly enhance intracellular free radical scavenger activity. Methods and Results - C57/BL6 neonatal mice (age, 2 days; n = 131) underwent intrapericardial delivery of recombinant adenoviruses encoding superoxide dismutase (SOD) and catalase (Cat) (n=76) or β-galactosidase (LacZ) as a control (n=55). After 3 days, hearts were explanted, and SOD and Cat transgene expression was detected by Western blot analysis. Spectrophotometric enzyme assays demonstrated enhanced SOD activity 1.6-fold (P<0.0001) and Cat 3.6-fold (P<0.00001) in experimental versus LacZ hearts. Isolated perfused hearts were subjected to 5 minutes of warm ischemia, and at 5, 10, and 15 minutes after initiation of reperfusion, LacZ controls lost 24%, 33%, and 41% of peak systolic apicobasal force, respectively, whereas experimental hearts lost 5%, 12%, and 20% (P<0.001, each time point). In controls, rate of force generation diminished 8%, 17%, and 35%; in experimental hearts, it increased 1% at 5 minutes and decreased 5% and 15% at 10 and 15 minutes (P<0.01, P<0.05, P<0.05). LacZ hearts exhibited dysfunction similar to hearts from uninjected animals (P=NS, each time point). Conclusions - Adenovirus-mediated cardiac gene transfer and expression of SOD and Cat augment antioxidant enzyme activity and minimize contractile dysfunction after ischemic reperfusion in the isolated perfused neonatal mouse heart.