Optimization of ex vivo pressure mediated delivery of antisense oligodeoxynucleotides to ICAM-1 reduces reperfusion injury in rat cardiac allografts

Background. Our purpose was to optimize hyperbaric pressure as a vector for ex vivo transfection of antisense oligodeoxynucleotides (AS-ODN) to intercellular adhesion molecule-1 to limit reperfusion injury (RI) in cardiac allografts. We investigated the effects of increased pressure, incubation time, and AS-ODN concentrations on transfection efficiency and toxicity. Methods and results. PVG (RT1c) donor hearts were heterotopically transplanted to ACI (RT1a) recipients. Donor hearts were harvested and the various groups were treated at: (1) different pressure (1-9 atm) for 45 min with 80 μmol/liter AS-ODN; (2) different incubation times (15 min to 6 hr) at 5 atm with 80 μmol/liter AS-ODN; 3) different AS-ODN concentrations (80- 240 μmol/liter) at 5 atm for 45 min. Hearts were procured 24 or 72 hr after transplantation. Transfection efficiency was determined with flourescein- labeled ASODN. The degree of RI was determined with biochemical and histological analysis. Increasing pressure from ambient (1 atm) pressure to pressures as high as 9 atm leads to a increase in transfection efficiency from 1.7±.5 to 62±3.9% and a reduction in RI. Increased incubation time up to 45 min increased transfection efficiency and reduced RI, but longer incubation times induced significant toxicity to the allograft. Increased AS- ODN concentrations improved transfection and reduced RI. Conclusions. Hyperbaric pressure is a safe and effective vector for the ex vivo delivery of AS-ICAM-1-ODN to rodent cardiac allografts and results in a reduction in reperfusion injury.