Abstract 1161: AAV-2-mediated Nerve Growth Factor Gene Transfer Prevents the Development of Experimental Diabetic Cardiomyopathy in Mice
Diabetes mellitus (DM) can cause cardiac dysfunction and heart failure independently of other risk factors like hypertension and myocardial infarction. The neurotrophin nerve growth factor (NGF) exerts cardioprotective effects but is downregulated in the diabetic heart. The present study challenged the hypothesis that NGF gene transfer (GT) could prevent diabetes-induced cardiac dysfunction. Type-1 DM was induced in CD1 mice by streptozotocin (40 mg/Kg/day IP for five days). Two weeks later, GT with an adeno-associated vector serotype 2 carrying human NGF in the expression cassette (AAV-2-hNGF) or with an empty vector (AAV-2-βGal) was performed. Constructs were delivered to the left ventricle (LV) by 4 injections (total dose of 1×1011 pfu). Non diabetic mice injected with AAV-2-βGal were studied for reference. X-Gal staining confirmed successful GT of LV. Moreover, hNGF transgene expression was detected in plasma by ELISA at 12 weeks. Echocardiography (Visual Sonics) at 12 weeks after GT showed a deterioration of systolic function in diabetic mice (LV ejection fraction: 64.6±3.8 vs 73.1±6.9% in healthy controls; LV fractional shortening: 35.3±2.8 vs 42.5±6.3%; P<0.05 for both comparisons). In contrast, AAV-2-hNGF Improved both LVEF and LVFS (113% and 121% respectively) as compared to diabetic controls (P<0.05 for both comparisons; N.S. vs healthy). Moreover, AAV-2-hNGF improved LV systolic pressure (LVSP) and contractility (expressed as dP/dtmax and dP/dtmin) measured by Millar catheter (LVSP: 76±4 vs 61±5 mmHg in diabetic controls; dP/dtmax and dP/dtmin: 141% and 149% of diabetic controls, respectively; P<0.01 for all comparisons). In addition, AAV-2-hNGF prevented enlargement of end-diastolic LV chamber volume (74±11 vs 89.1±13 μl in diabetic controls; P<0.05) and maintained the end-diastolic LV internal diameter (4.1±0.3 vs 4.4±0.3 μl in diabetic controls; P<0.05). Finally, as measured by fluorescent microspheres, DM reduced LV blood flow (0.39±0.1 vs 0.59±0.1 mL/min/g of tissue in healthy controls; P=NS), which was prevented by AAV-2-hNGF (0.69±0.1 mL/min/g of tissue; P=0.05 vs diabetic controls). These results provide evidence that prolonged NGF overexpression prevents systolic dysfunction and heart failure in diabetic mice.