Background.

We hypothesized that ex vivo donor allograft transfection with antisense oligodeoxynucleotide (AS ODN) would inhibit the expression of intercellular adhesion molecule (ICAM)-1, an important mediator of T-cell adhesion and costimulation, and therefore suppress acute cardiac rejection.

Methods.

Hearts were transfected ex vivo with AS, reverse AS ODN, or saline by applying 3 atm pressure for 45 min at 4 C. Grafts were then transplanted into allogenic recipients±treatment with leukocyte function-associated antigen (LFA)-1 monoclonal antibody (mAb)(1.5 mg/kg intravenously), cyclosporine (2.5 mg/kg/day po), or rapamycin (0.025 mg/kg/day intraperitoneally). Reperfusion injury was assessed in grafts harvested at early time points using the myeloperoxidase,% wet weight, and% contraction band necrosis assays; transfection efficiency was assessed using fluorescent microscopy; and efficacy of ICAM-1 blockade was assessed using immunohistochemistry. Other grafts were followed until rejection with donor/third-party skin grafting, adoptive transfer, and interleukin 2 infusion studies in selected recipients.

Results.

Transfection was highly efficient (fluorescein isothiocyanate-ODN in 48±5% of total myocardial nuclei), nontoxic, and reduced the ICAM-1-positive area to 53±14% versus having no effect on MHC class I expression (n= 4). The incidence of survival> 60 days after AS ODN+ LFA-1 monoclonal antibody was 75%, significantly higher than other regimens.

Conclusion.

AS ODN hyperbaric transfection proved highly efficient, effective at ICAM-1 blockade, and induced cardiac allograft tolerance when combined with LFA-1 monoclonal antibody. This highly targeted alteration of allograft immunogenicity may have an important role in future immunosuppressive strategies.