Intracoronary adenovirus-mediated transfer of immunosuppressive cytokine genes prolongs allograft survival

Abstract

Background: Intracoronary transfer and expression of recombinant genes in the intact heart is now feasible. In the transplant setting, local modulation of host immune responses by a genetically modified allograft may offer an attractive alternative to systemic immunosuppression.

Methods: We tested the efficacy and in vivo effect of intracoronary transfer of two immunosuppressive cytokine genes. First-generation E1-deleted adenoviral vectors expressing the Epstein-Barr virus interleukin-10 (AdSvIL10) or human transforming growth factor--beta 1 (AdCMVTGF-beta) were used. Rabbit cardiac allografts were transduced during cold preservation by slow (1 ml/min) intracoronary infusion of 10(10) pfu/gm diluted viral vectors and then implanted heterotopically. Controls included E1-deleted adenovirus (Ad5dI434) and AdCMVLacZ. Beating allografts were collected on day 4 for analysis of gene transfer efficacy and distribution. Additional grafts were used for evaluation of alloreactivity (n = 34).

Results: Mean allograft viral uptake was 81% (up to 91%). Polymerase chain reactions and reverse transcription-polymerase chain reactions confirmed the presence and expression of both genes in the grafts. beta-Galactosidase staining in AdCMVLacZ-infected grafts demonstrated efficient gene expression, which was highest (100%) in subepicardial regions. More homogeneous transmyocardial distribution of the transgene (in 25% to 40% of cells) could be achieved by pulsatile slow delivery. Allograft survival was 6.9 +/- 0.9 days in controls (n = 12), 11.1 +/- 1.7 days in AdCMVTGF-beta-infected grafts (n = 11, p < 10(-4)), and 11.2 +/- 3 days in AdSvIL10-infected grafts (n = 11, p < 10(-4)). Histologic scores (blinded) showed significantly (p < 0.005) higher regression coefficients for rejection in controls compared with both cytokine-transduced groups. Perioperative administration of cyclosporine A (INN: ciclosporin) to recipients had no effect on survival of AdCMVTGF-beta-infected grafts but reduced survival of AdSvIL10-infected grafts.

Conclusions: Intracoronary gene transfer of immunosuppressive cytokines to cardiac allografts is efficient and effectively prolongs graft survival. Vectors that would induce long-term expression of such genes may make this approach clinically applicable.