Optimization of adenoviral vector-mediated gene transfer to pulmonary arteries in newborn swine

Efficient pulmonary vascular gene transfer in neonates would aid in underst anding the pathophysiology of, and ultimately allow the development of spec ific therapies for, pulmonary vascular diseases. The purpose of this study was to optimize efficiency, and evaluate the duration, of catheter-based ad enoviral vector-mediated pulmonary artery gene transfer in newborn pigs. An adenovirus vector encoding LacZ was infused,ia percutaneously placed cathe ters that were advanced to segmental pulmonary arteries under fluoroscopic guidance. Optimal viral dose and duration of expression were determined by histochemical evaluation of gene transfer efficiency 72 hr, 2 weeks, and 1 month after gene delivery. The effect of protamine on the efficiency of gen e transfer was studied by assaying transgene protein in lung at 72 hr. The optimal viral dose was 2 x 10(10) plaque-forming units (PFU). Seventy-two h ours after infusion, expression predominated in medium-sized artery endothe lial cells, 40% of which expressed beta-galactosidase. At 2 weeks, the dist ribution of expression had changed such that the majority of transduced cel ls were seen not in arteries but in gas exchange units of lung. No histoche mical evidence of transgene expression was seen 1 month after virus infusio n. The addition of protamine to virus infusate resulted in a fivefold incre ase in transgene protein product in lung tissue assayed 72 hr after gene tr ansfer. Adenoviral vector-mediated gene transfer in neonatal swine results in high-efficiency transduction of arterial endothelial cells. However, the time course of gene transfer is not significantly prolonged compared with the adult. The addition of protamine results in a significant improvement i n transduction efficiency, permitting lower doses of virus.