Evaluation of a porcine model for pulmonary gene transfer using a novel synthetic vector.

Background: The pig lung, given its gross anatomical, histological and physiological similarities to the human lung, may be useful as a large animal model, in addition to rodents, in which to assess the potential of vectors for pulmonary airway gene transfer. The aim of this study was to assess the utility of the pig lung as a model of gene transfer to the human lung with a synthetic vector system.

Methods: The LID vector system consists of a complex of lipofectin (L), integrin-binding peptide (I) and plasmid DNA (D). LID complexes containing a beta-galactosidase reporter gene under a CMV promoter or a control plasmid at1 mg/3 ml PBS, or 3 ml buffer, was administered to the right lower lobe of the pig lung through a bronchoscope. Pigs were culled at 48 h and lung sections prepared for immunohistochemical and histological analysis. Bronchoalveolar lavage fluid was collected and analysed for TNF-alpha by ELISA.

Results: Immunohistochemical staining for the beta-galactosidase reporter gene indicated high efficiency of gene transfer by the LID vector to pig bronchial epithelium with 46% of large bronchi staining positively. There was no evidence for vector-specific inflammation assessed by leukocytosis and cytokine production.

Conclusions: This study demonstrates the use of the pig for studies of gene transfer in the lung and confirms in a second species the potential of the LID vector for gene therapy of pulmonary diseases such as cystic fibrosis.