In this study, we report a method of controlled pressure-mediated delivery of "naked" DNA that achieves efficient and safe arterial gene and oligonucleotide transfer. We demonstrated a pressure-dependent uptake of fluorescein-labeled (FITC) oligonucleotide (ODN) in rabbit carotid arteries with preexisting neointimal hyperplasia, using nondistending intravascular delivery pressures ranging from 0 to 760 mmHg. At an infusion pressure of 50 mmHg, 10.5 +/- 5% of neointimal cell nuclei were positive for nuclear uptake of FITC-ODN 4 days after transfection. With an infusion pressure of 760 mmHg, the transfection efficiency increased to 84.2 +/- 5.3% of neointimal cells, and to 64.5 +/- 11.6 and 92.4 +/- 5.5% of medial and adventitial cells, respectively. Similar patterns of FITC-ODN uptake were seen in atherosclerotic injured arteries. We also investigated the pressure-mediated delivery of plasmid DNA. Transfection of a luciferase expression plasmid, using an infusion pressure of 760 mmHg, yielded luciferase expression of 816.6 +/- 108.6 fg/mg protein in normal rabbit carotid arteries, as compared with 38.9 +/- 23.7 fg/mg protein at 100 mmHg. Luciferase expression was significantily higher in pressure-transfected injured atherosclerotic arteries (5467.3 +/- 1047.6 fg/mg protein at 760 mmHg). Transfection of beta-galactosidase indicated that significant transgene expression occurred in the neointima and media. These data indicate that this pressure-mediated transfection method yields efficient oligonucleotide delivery and enhances transduction with plasmid DNA in normal as well as injured nonatherosclerotic or atherosclerotic arteries.