IN-VIVO GENE DELIVERY TO THE PULMONARY CIRCULATION IN RATS - TRANSGENE DISTRIBUTION AND VASCULAR INFLAMMATORY RESPONSE

Although gene delivery to the pulmonary circulation has both experimen tal and therapeutic potential, the delivery methods, distribution of t ransgene, and subsequent inflammatory response have been poorly charac terized to date. To address these issues, we utilized a 0.76-mm OD (ou tside diameter) end hole catheter inserted into the internal jugular v ein of adult Sprague-Dawley rats, directing the tip into a pulmonary c apillary wedge position. We then compared infusion of polycationic lip id:DNA complexes to replication/defective adenovirus with respect to m agnitude and distribution of transgene expression using either chloram phenicol acetyltransferase (CAT) or human placental alkaline phosphata se (hpAP) reporter genes. Both lipid:DNA and adenovirus resulted in de tectable transgene expression, though maximum lung CAT activity using lipid (gamma AP-DLRIE/DOPE) was approximately 2% of maximum activity u sing adenovirus (Ad-CAT). Further characterization of expression after transfection with 10(8) (plaque forming units) of Ad-CAT demonstrated persistence of transgene for at least 14 days (lung CAT activity 27% of maximum). Alkaline phosphatase staining demonstrated that both larg e and small pulmonary arteries as Hell as the alveolar wall expressed transgene. Although little inflammatory response was detected in condu it arteries, a predominantly mononuclear cell infiltrate surrounded sm all pulmonary arteries as well as the alveolar spaces in transfected a reas of lung. We conclude that percutaneous catheter-mediated gene del ivery to the pulmonary circulation in rats using non-viral and viral v ectors is feasible. Although an inflammatory response to first generat ion replication-defective adenovirus was detected, it appeared to he l argely restricted to the distal pulmonary circulation and airspace. Th is technique should prove useful for investigations requiring overexpr ession of novel genes in the pulmonary artery wall, and could ultimate ly be used to develop gene-based therapies for pulmonary vascular dise ases.