Delivery of scAAV8 and scAAV6 to the canine heart via needle-tip injection catheter. GFP expression in representative cryosections of the heart 7–10 days following injection of either 5×1011 gc/kg of (a) scAAV8-CB-EGFP or (b) scAAV6-CB-EGFP. IVS, interventricular septum; LVFW, left ventricular free wall; Endo, endocardium; Epi, epicardium. Scale bar, 200 μm. Quantitative analysis of GFP expression reported as either (c) total area positive for GFP or (d) percent cardiomyocyte area positive for GFP. Note that scAAV6 is superior to the other serotypes examined (*p=0.0001). Error bars represent mean + SD.