Gene therapy in lung transplantation: effective gene transfer via the airways

Gene therapy may provide a means of modifying factors that contribute to the development of pathologic processes in transplanted lungs. Experiments were designed to study the feasibility of adenovirus-mediated gene transfer by way of the airways to the transplanted lung.

Orthotopic left lung transplantation (Lewis to Lewis rats) was performed on four groups of animals. 300 microl of adenovirus solution encoding for beta-galactosidase was infused into the left bronchus of donor rats at viral concentrations of 10(8) pfu/ml (n = 5), 10(9) pfu/ml (n = 6), and 10(10) pfu/ml (n = 6), and the lung was ventilated for 5 minutes. Controls (n = 6) received medium only. Seven days after transplantation, native and transduced, transplanted lungs were harvested. Sections of lung were fixed and stained with a solution of X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside) and staining was evaluated for distribution by cell type and intensity.

Beta-galactosidase expression was absent in the control group and in the native lungs. Two of five lungs in the 10(8) group expressed beta-galactosidase, but in a limited distribution and intensity. All six lungs in the 10(9) group and five of six lungs in the 10(10) group expressed beta-galactosidase. The distribution and intensity of beta-galactosidase expression ranged from only a few cells staining per slide to up to 75%. Pneumocytes were the most frequently stained cell type followed by alveolar macrophages.

Gene transfer to the transplanted lung via the bronchial route is feasible and offers a novel technique to modify pathologic processes in the transplanted lung.