Comparing hypothermic oxygenated and normothermic liver machine perfusion: Translation matters

Hypothermic oxygenated machine perfusion influences the immunogenicity of donor livers in humans

Hypothermic oxygenated machine perfusion (HOPE) is an organ preservation strategy shown to reduce ischemia-reperfusion injury (IRI)-related complications following liver transplantation. In animal models, HOPE can also decrease alloimmune responses after transplantation, but this remains to be evaluated in humans. Our study, involving 27 patients undergoing liver transplantation enrolled in 2 randomized controlled trials comparing static cold storage with HOPE (14 HOPE-treated and 13 static cold storage-treated), delves into the impact of HOPE on the molecular profile of liver allografts and on the immune responses elicited after transplantation. Following HOPE treatment, fewer intrahepatic immune cells were observed in liver perfusates compared to static cold storage. Analysis of liver tissue transcriptome at reperfusion revealed an effect of HOPE on the reactive oxygen species pathway. Two weeks after transplantation, HOPE recipients exhibited increased circulating CD4+FOXP3+CD127lo regulatory T cells ( p < 0.01), which corresponded to a higher frequency of donor-specific regulatory T cells ( p < 0.01) and was followed by reduced alloreactivity index of CD8+ T cells 3 months after transplant. Our study provides novel mechanistic insight into the capacity of HOPE to influence liver ischemia-reperfusion injury and to modulate effector and regulatory donor-specific T-cell responses after transplantation. These findings, which confirm observations made in animal models, help explain the decreased rejection rates reported in patients receiving HOPE-treated allografts.

Beyond the icebox: modern strategies in organ preservation for transplantation

Organ transplantation, a critical treatment for end-stage organ failure, has witnessed significant advancements due to the integration of improved surgical techniques, immunosuppressive therapies, and donor-recipient matching. This review explores the progress of organ preservation, focusing on the shift from static cold storage (SCS) to advanced machine perfusion techniques such as hypothermic (HMP) and normothermic machine perfusion (NMP). Although SCS has been the standard approach, its limitations in preserving marginal organs and preventing ischemia-reperfusion injury (IRI) have led to the adoption of HMP and NMP. HMP, which is now the gold standard for high-risk donor kidneys, reduces metabolic activity and improves posttransplant outcomes. NMP allows real-time organ viability assessment and reconditioning, especially for liver transplants. Controlled oxygenated rewarming further minimizes IRI by addressing mitochondrial dysfunction. The review also highlights the potential of cryopreservation for long-term organ storage, despite challenges with ice formation. These advances are crucial for expanding the donor pool, improving transplant success rates, and addressing organ shortages. Continued innovation is necessary to meet the growing demands of transplantation and save more lives.