Background: Allograft deterioration is the major obstacle to organ transplantation as a long-term treatment of end-stage heart failure. In this study, we transduced the antioxidant gene, heme oxygenase-1 (HO-1), to heart grafts using a recombinant adeno-associated viral vector (rAAV) in a rat heart transplantation model and investigated its potentiality in prevention of chronic graft deterioration.
Methods and results: rAAV/HO-1 was administered to heart grafts through the coronary arteries during cold preservation. We investigated the expression patterns and activities of transgene, graft survival, graft histomorphology, and relevance of HO-1 expression on graft survival and chronic graft deterioration by itself. Long-term allograft survival can be achieved by rAAV/HO-1-mediated stable transgene expression. The development of graft arteriosclerosis and interstitial fibrosis was prevented in rAAV/HO-1-transduced allografts on day 100. rAAV/HO-1-mediated long-term graft protection was accompanied by remarkable downregulation of the intragraft mRNA level of macrophage migration inhibitory factor, tumor necrosis factor-alpha, and transforming growth factor-beta1. Blockage of HO activities by zinc protoporphyrin IX at different posttransplant phases showed that the stable expression of HO-1 is a prerequisite for both survival of grafts and prevention of graft arteriosclerosis.
Conclusions: rAAV/HO-1 gene transfer represents a novel therapeutic approach to prevent chronic allograft deterioration in clinical heart transplantation.