Abstract 3809: Cardiac-Specific Overexpression of EcSOD Using an AAV9 Vector in Combination with the Cardiac Troponin-T Promoter Inhibits LV Remodeling after Myocardial Infarction
Introduction: The wide tissue tropism exhibited by AAV provides for efficient gene transfer throughout the body, but targeting gene expression to cardiomyocytes is desirable for cardiac gene therapy. We hypothesized that targeted overexpression of extracellular superoxide dismutase (EcSOD) via the cardiac Troponin-T (cTnT) promoter would suffice to minimize left ventricular (LV) remodeling after myocardial infarction (MI).
Methods: An AAV9 vector expressing EcSOD from the cTnT promoter (AcTnTEcSOD) was injected into 5 wk-old C57 mice via jugular vein (3x1011 vp/mouse). Western blots, immunohistochemistry & in vitro SOD assays were used to measure EcSOD expression, distribution and activity. Cardiac magnetic resonance (CMR) imaging was performed at baseline (5 wks post-vector injection) and at days 1, 7 & 28 after MI to assess LV volumes (vol) & ejection fraction (EF) as compared to WT mice (n=4). Infarct (IF) sizes were also compared by DE on D1.
Results: Systemic injection of the vector (AcTnTEcSOD) provided uniform EcSOD overexpression within cardiomyocytes (Panels A&B) and elevated total cardiac SOD activity by 5.6 fold (p<0.05). On D1 post-MI, IF sizes were similar in vector & WT groups (p=ns). The vector group had significantly lower end-diastolic vol at D7, D28 and lower end-systolic vol at D28 (all p<0.05 by ANOVA, Panels C&D), resulting in improved D28 EF over controls (p=0.02).
Conclusions: Cardiac-specific overexpression of therapeutic genes can be achieved by combining highly-efficient AAV9 vectors with cardiac-specific promoters. AAV-mediated, cardiac-restricted overexpression of EcSOD from the cTnT promoter significantly reduces post-MI LV remodeling.