Ex Vivo Adenovirus-Mediated Gene Transfer To The Adult Rat Heart

Objective: The ability to transfer genes to adult myocardium may have therapeutic implications for cardiac transplantation. We investigated the feasibility of adenovirus-mediated transfer of marker genes LacZ and Luciferase, as well as the potentially therapeutic gene of the human β 2-adrenergic receptor in a rat heterotopic heart transplant model. Methods: Donor hearts were flushed with 10 12 total viral particles of one of three transgenes. Hearts were harvested at various time points after transplantation. LacZ-treated hearts were assessed by histologic staining and Luciferase-treated hearts were assayed for specific luminescence activity. Hearts treated with β 2-adrenergic receptor underwent radioligand binding assays and immunohistochemistry with the use of an antibody specific for the human β 2-adrenergic receptor. Results: LacZ hearts revealed diffuse myocyte staining as opposed to none within controls at 5 days. Luciferase hearts demonstrated a mean activity of 970,000 ± 220,000 arbitrary light units versus 500 ± 200 for the controls ( p = 0.001). Total β 2-adrenergic receptor densities (fmol/mg membrane protein) for hearts that received the β 2-adrenergic receptor transgene at 3, 5, 7, 10, and 14 days after infection were as follows: right ventricle, 488.5 ± 126.8, 519.4 ± 81.8,* 477.1 ± 51.8,* 183.0 ± 6.5,* and 82.7 ± 19.1; left ventricle, 511.0 ± 167.6, 1206.4 ± 321.8,* 525.3 ± 188.7, 183.5 ± 18.6,* and 75.9 ± 15.2 (* p < 0.05 vs control value of 75.6 ± 6.4). Immunohistochemical analysis revealed diffuse staining of varying intensity within myocardial sarcolemmal membranes. Conclusions: We conclude that global overexpression of different transgenes is possible during cardiac transplantation and, ultimately, adenovirus-mediated gene transfer may provide a unique opportunity for genetic manipulation of the donor organ, potentially enhancing its function. (J Thorac Cardiovasc Surg 1998;115:623-30)