Inhibition of ischemia/reperfusion injury and chronic graft deterioration by a single-donor treatment with cobalt-protoporphyrin for the induction of heme oxygenase-1.

Today, the major problem in organ transplantation is not acute graft rejection but chronic graft deterioration. In addition to alloantigen-specific events, alloantigen independent factors like donor age, previous diseases, consequences of brain death, and perioperative events of ischemia/reperfusion injury have a major impact on long-term graft function. The induction of the stress protein heme oxygenase-1 (HO-1) protects cells from injury and apoptosis. Here, we tested the protective effects of HO-1 induction in a clinically relevant kidney transplant model. Induction of HO-1 expression following cobalt-protoporphyrin (CoPP) treatment in organ donors prolonged graft survival and long-term function remarkably following extended periods of ischemia. Positive effects were observed with both optimal and marginal grafts from old donor animals. Structural changes characteristic for chronic rejection, as well as graft infiltration by monocytes/macrophages and CD8+ T cells, were substantially reduced following HO-1 induction. Up-regulation of HO-1 expression before organ transplantation was also associated with reduced levels for tumor necrosis factor (TNF)-alpha mRNA, increased levels for interferon (IFN)-gamma, and bcl-x, and insignificant differences for CD25, interleukin (IL)-2, IL-4, IL-6, and IL-10 mRNA levels. The significant improvement of long-term graft function following induction of HO-1 expression in donor organs suggests that this strategy may be a novel clinical treatment option with particular relevance for transplantation of marginal organs.