Efficient adventitial gene delivery to rabbit carotid artery with cationicpolymer-plasmid complexes

Different lipids and cationic polymers were tested in vitro for their abili ty to transfect rabbit aortic smooth muscle cells and human endothelial cel ls with lacZ marker gene. Toxicity of the complexes was evaluated with MTT assay Selected plasmid-polymer complexes with different charge ratios were then tested for in vivo gene transfer efficiency using adventitial gene tra nsfer by placing a silastic gene delivery reservoir (collar) around the car otid artery. Transfection efficiency was determined by X-gal staining 3 day s after the gene transfer. Based on in vitro experiments, fractured polyami doamine dendrimers and polyethylenimines (PEI) were selected for in vivo ex periments. Fractured dendrimers (generation 6, +/- charge ratio of 3) had t he highest in vivo gene transfer efficiency (4.4% +/- 1.7). PEI with molecu lar size of 25 kDa (+/- charge ratio 4) was also effective (2.8% +/- 1.8) i n this model. PEI of 800 kDa showed a constant but modest gene transfer eff iciency (1.8% +/- 0.1) with all charge ratios. A low level gene transfer wa s also detected with naked DNA (0.5% +/- 0.3). No signs of inflammation wer e seen in any of the study groups. We show here that in vitro cell culture experiments can be used to identify efficient in vivo gene transfer methods for arterial gene therapy, but the charge ratios for each complex must be optimized in vivo. it is concluded that fractured dendrimer and PEI are eff icient gene delivery vehicles and can be used for arterial gene therapy via adventitial gene delivery route.