Arterial Gene Transfer Using Pure DNA Applied Directly to a Hydrogel-Coated Angioplasty Balloon

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Abstract
Direct arterial gene transfer has been previously achieved using double-balloon catheters and perforated balloons, in most cases facilitated by the use of cationic liposomes or viral vectors. These gene delivery systems, however, have been compromised by issues relating to efficacy and/or safety, and furthermore require that angioplasty be performed independent of gene transfer. We investigated the possibility that arterial gene transfer might be performed during balloon angioplasty by delivery of naked genetic material from a thin coat of hydrogel polymer applied to a standard angioplasty balloon. Transfections with luciferase DNA applied to a hydrogel balloon were performed in rabbit arteries. Luciferase expression 3 days after transfection was tested in three different models: (i) an organ culture model (n = 10); (ii) surgically exposed carotid arteries (n = 14); and (iii) external iliac arteries using a percutaneous approach (n = 13). Supplementary transfections (n = 3), intended to identify the site of arterial transfection, were performed using the gene encoding for nuclear-specific β-galactosidase (β-gal). All rabbit arteries transfected with the luciferase gene (37/37; 100%) expressed luciferase activity. Gene expression achieved in vivo, either in the surgically exposed carotid arteries or in the external iliac arteries transfected percutaneously, was quantitatively similar to that achieved in the organ culture model. Reduction in the duration of inflation from 30 min to 1 min had no statistically significant impact on transfection efficiency. Gene expression was documented to persist up to 14 days post percutaneous transfection. Analysis of arteries transfected with nuclear-specific β-gal showed the presence of the transgene in intimal and subintimal sites. These results demonstrate that vascular gene transfer can be performed successfully without liposomes or viral vectors using DNA applied to a standard angioplasty catheter balloon coated with hydrogel. Percutaneous transfection with a hydrogel-coated balloon permits gene transfer coincident with the angioplasty procedure itself, even with inflations as short as 1 min. Successful arterial gene transfer was performed directly, without the use of liposomes or viral vectors, during angioplasty with a hydrogel-coated balloon catheter. Plasmids containing the luciferase gene or the gene for nuclear-specific β-gal were applied to the coated balloon surface. All 37 rabbit arteries transfected with the luciferase gene expressed luciferase activity. Gene expression achieved in vivo, in surgically exposed as well as percutaneously transfected arteries, was quantitatively similar to that achieved under optimized conditions in an organ culture model. Reducing the duration of balloon inflation to as short as 1 min had no significant impact on transfection efficiency. Analysis of nuclear-specific β-gal transfectants demonstrated presence of the gene product in intimal and subintimal sites. Thus, percutaneous gene transfer is feasible using a standard angioplasty catheter coated with hydrogel, even in the absence of liposome, viral, or other delivery vectors.