Highly efficient ex vivo gene transfer to the transplanted heart by means of hypothermic perfusion with a low dose of adenoviral vector

Background: Hypothermic conditions required for donor heart preservation may reduce gene-transfer efficiency Experiments were designed to determine whether a perfusion technique could improve the efficiency of gene transfer to donor hearts. Methods: An adenoviral vector encoding beta-galactosidase (3.5 x 10(8) plaque-forming units) was infused into explanted rat hearts under 4 conditions teach n = 6): (1) the virus was diluted in 350 mu L of University of Wisconsin solution and infused as a high-pressure bolus into the coronary arteries of donor hearts through the aortic root; (2) the virus was diluted in 5 mL of University of Wisconsin solution and circulated by means of a peristaltic pump (flow, 0.75 mL/min) through the vasculature of the donor heart for 30 minutes; (3) 5 mi of viral solution was circulated as for group 2 for 15 minutes; and (4) 5 mt of viral solution was circulated for 5 minutes at a flow rate of 2.4 mL/min, Transduced hearts were transplanted into the abdomen of syngeneic rats, and transgene expression was assessed by means of immunoassay 4 days later. Results: The median beta-galactosidase content was (1) 45.0 ng/mg protein (25th-75th percentile, 33-73 ng/mg), (2) 6 10 ng/mg protein (25th-75th percentile, 613-878 ng/mg), (3) 493.8 ng/mg protein (25th-75th percentile, 456-527 ng/mg), and (4) 503.3 ng/mg protein (25th-75th percentile, 475-562 ng/mg; P <.01 for group 2 vs group 1, and P <.05 for groups 3 and 4 vs group 1), Transgene expression was predominantly in myocytes and favored the subepicardial region of the right ventricle, Conclusion: Hypothermic perfusion of the donor heart with an adenoviral vector resulted in efficient transgene expression compared with that induced by a single bolus injection.