Exposure of donor liver grafts to prolonged periods of warm ischemia before procurement causes injuries including intrahepatic cholangiopathy, which may lead to graft loss. Due to unavoidable prolonged ischemic time before procurement in donation after cardiac death (DCD) donation in 1 participating center, each liver graft of this center was pretreated with the new machine perfusion "Hypothermic Oxygenated PErfusion" (HOPE) in an attempt to improve graft quality before implantation. HOPE-treated DCD livers (n = 25) were matched and compared with normally preserved (static cold preservation) DCD liver grafts (n = 50) from 2 well-established European programs. Criteria for matching included duration of warm ischemia and key confounders summarized in the balance of risk score. In a second step, perfused and unperfused DCD livers were compared with liver grafts from standard brain dead donors (n = 50), also matched to the balance of risk score, serving as baseline controls. HOPE treatment of DCD livers significantly decreased graft injury compared with matched cold-stored DCD livers regarding peak alanine-aminotransferase (1239 vs 2065 U/L, P = 0.02), intrahepatic cholangiopathy (0% vs 22%, P = 0.015), biliary complications (20% vs 46%, P = 0.042), and 1-year graft survival (90% vs 69%, P = 0.035). No graft failure due to intrahepatic cholangiopathy or nonfunction occurred in HOPE-treated livers, whereas 18% of unperfused DCD livers needed retransplantation. In addition, HOPE-perfused DCD livers achieved similar results as control donation after brain death livers in all investigated endpoints. HOPE seems to offer important benefits in preserving higher-risk DCD liver grafts.

Machine perfusion is a novel method intended to optimize livers before transplantation. However, its effect on morbidity within a 1-year period after transplantation has remained unclear. In this multicenter controlled trial, we randomly assigned livers donated after brain death (DBD) for liver transplantation (LT). Livers were either conventionally cold stored (control group), or cold stored and subsequently treated by 1-2 h hypothermic oxygenated perfusion (HOPE) before implantation (HOPE group). The primary endpoint was the occurrence of at least one post-transplant complication per patient, graded by the Clavien score of ≥III, within 1-year after LT. The comprehensive complication index (CCI), laboratory parameters, as well as duration of hospital and intensive care unit stay, graft survival, patient survival, and biliary complications served as secondary endpoints. Between April 2015 and August 2019, we randomized 177 livers, resulting in 170 liver transplantations (85 in the HOPE group and 85 in the control group). The number of patients with at least one Clavien ≥III complication was 46/85 (54.1%) in the control group and 44/85 (51.8%) in the HOPE group (odds ratio 0.91; 95% CI 0.50-1.66; p = 0.76). Secondary endpoints were also not significantly different between groups. A post hoc analysis revealed that liver-related Clavien ≥IIIb complications occurred less frequently in the HOPE group compared to the control group (risk ratio 0.26; 95% CI 0.07-0.77; p = 0.027). Likewise, graft failure due to liver-related complications did not occur in the HOPE group, but occurred in 7% (6 of 85) of the control group (log-rank test, p = 0.004, Gray test, p = 0.015). HOPE after cold storage of DBD livers resulted in similar proportions of patients with at least one Clavien ≥III complication compared to controls. Exploratory findings suggest that HOPE decreases the risk of severe liver graft-related events. This randomized controlled phase III trial is the first to investigate the impact of hypothermic oxygenated perfusion (HOPE) on cumulative complications within a 12-month period after liver transplantation. Compared to conventional cold storage, HOPE did not have a significant effect on the number of patients with at least one Clavien ≥III complication. However, we believe that HOPE may have a beneficial effect on the quantity of complications per patient, based on its application leading to fewer severe liver graft-related complications, and to a lower risk of liver-related graft loss. The HOPE approach can be applied easily after organ transport during recipient hepatectomy. This appears fundamental for wide acceptance since concurring perfusion technologies need either perfusion at donor sites or continuous perfusion during organ transport, which are much costlier and more laborious. We conclude therefore that the post hoc findings of this trial should be further validated in future studies.

To evaluate the impact of a novel oxygenated perfusion approach on rejection after orthotopic liver transplantation (OLT). Hypothermic oxygenated perfusion (HOPE) was designed to prevent graft failure after OLT. One of the mechanisms is downregulation of Kupffer cells (in situ macrophages). We, therefore, designed experiments to test the effects of HOPE on the immune response in an allogeneic rodent model of nonarterialized OLT. Livers from Lewis rats were transplanted into Brown Norway rats to induce liver rejection in untreated recipients within 4 weeks. Next, Brown Norway recipients were treated with tacrolimus (1 mg/kg), whereas in a third group, liver grafts from Lewis rats underwent HOPE or deoxygenated machine perfusion for 1 hour before implantation, but recipients received no immunosuppression. In a last step, low-dose tacrolimus treatment (0.3 mg/kg) was assessed with and without HOPE. Allogeneic OLT without immunosuppression led to death within 3 weeks after nonarterialized OLT due to severe acute rejection. Full-dose tacrolimus prevented rejection, whereas low-dose tacrolimus led to graft fibrosis within 4 weeks. HOPE treatment without immunosuppression also protected from lethal rejection. The combination of low-dose tacrolimus and 1-hour HOPE resulted in 100% survival within 4 weeks without any signs of rejection. We demonstrate that allograft treatment by HOPE not only protects against preservation injury but also impressively downregulates the immune system, blunting the alloimmune response. Therefore, HOPE may offer many beneficial effects, not only to rescue marginal grafts but also by preventing rejection and the need for immunosuppression.