Pushing the donor limits: Deceased donor liver transplantation using organs from octogenarian donors

The Future Frontier of Liver Transplantation Exploring Young Donor Allocation Strategies for HCC Recipients

Background

The role of donor age in liver transplantation (LT) outcomes for hepatocellular carcinoma (HCC) is controversial. Given the significant risk of HCC recurrence post-LT, optimizing donor/recipient matching is crucial. This study reassesses the impact of young donors on LT outcomes in patients with HCC.

Methods

A retrospective review of 11 704 LT cases from the United Network for Organ Sharing database (2012-2021) was conducted. The study focused on the effect of donor age on recurrence-free survival, using hazard associated with LT for HCC (HALT-HCC) and Metroticket 2.0 scores to evaluate post-LT survival in patients with HCC.

Results

Of 4706 cases with young donors, 11.0% had HCC recurrence or death within 2 y, and 18.3% within 5 y. These outcomes were comparable with those of non-young donors. A significant correlation between donor age and post-LT recurrence or mortality (P = 0.04) was observed, which became statistically insignificant after tumor-related adjustments (P = 0.32). The Kaplan-Meier curve showed that recipients with lower HALT-HCC scores (<9) and Metroticket 2.0 scores (<2.2) significantly benefited from young donors, unlike those exceeding these score thresholds. Cox regression analysis showed that donor age significantly influenced outcomes in recipients below certain score thresholds but was less impactful for higher scores.

Conclusions

Young donors are particularly beneficial for LT recipients with less aggressive HCC, as indicated by their HALT-HCC and Metroticket 2.0 scores. These findings suggest strategically allocating young donors to recipients with less aggressive tumor profiles, which could foster more efficient use of the scarce donor supply and potentially enhance post-LT outcomes.

Mitochondrial bioenergetics boost macrophage activation, promoting liver regeneration in metabolically compromised animals

BACKGROUND AND AIMS

Hepatic ischemia-reperfusion injury (IRI) is the leading cause of early posttransplantation organ failure as mitochondrial respiration and ATP production are affected. A shortage of donors has extended liver donor criteria, including aged or steatotic livers, which are more susceptible to IRI. Given the lack of an effective treatment and the extensive transplantation waitlist, we aimed at characterizing the effects of an accelerated mitochondrial activity by silencing methylation-controlled J protein (MCJ) in three preclinical models of IRI and liver regeneration, focusing on metabolically compromised animal models.

APPROACH AND RESULTS

Wild-type (WT), MCJ knockout (KO), and Mcj silenced WT mice were subjected to 70% partial hepatectomy (Phx), prolonged IRI, and 70% Phx with IRI. Old and young mice with metabolic syndrome were also subjected to these procedures. Expression of MCJ, an endogenous negative regulator of mitochondrial respiration, increases in preclinical models of Phx with or without vascular occlusion and in donor livers. Mice lacking MCJ initiate liver regeneration 12 h faster than WT and show reduced ischemic injury and increased survival. MCJ knockdown enables a mitochondrial adaptation that restores the bioenergetic supply for enhanced regeneration and prevents cell death after IRI. Mechanistically, increased ATP secretion facilitates the early activation of Kupffer cells and production of TNF, IL-6, and heparin-binding EGF, accelerating the priming phase and the progression through G₁ /S transition during liver regeneration. Therapeutic silencing of MCJ in 15-month-old mice and in mice fed a high-fat/high-fructose diet for 12 weeks improves mitochondrial respiration, reduces steatosis, and overcomes regenerative limitations.

CONCLUSIONS

Boosting mitochondrial activity by silencing MCJ could pave the way for a protective approach after major liver resection or IRI, especially in metabolically compromised, IRI-susceptible organs.

Impact of donor age on liver transplant outcomes in patients with hepatocellular carcinoma: analysis of the SRTR database

Background

Donor age is an important predictor for liver transplant recipients. Studies have not fully explored its impact on transplant outcomes in hepatocellular carcinoma (HCC) patients as well as its involvement in tumor recurrence.

Methods

HCC patients who received liver transplants during 2010–2017 from the Scientific Registry of Transplant Recipients database were included. The recipients were divided into four groups based on donor age: I (≤ 34 years), II (35–49 years), III (50–64 years), and IV (≥ 65 years). Transplant outcomes, including the overall survival (OS), tumor recurrence, and risks, were evaluated.

Results

A total of 13,276 HCC recipients were included in this study. Statistical significant differences were observed in OS among the four groups. The best 5-year survival was 76.0% in group I, followed by 73.5% in group II, 72.8% in group III, and 69.2% in group IV (P < 0.001). However, the liver-specific survival did not differ among these groups (P = 0.260). Donor age was found to be the independent predictor of OS after adjusting for other variables (P < 0.001, ref. group I; 1.087 (0.979–1.208) for group II, P = 0.119; 1.124 (1.015–1.246) for group III, P = 0.025; 1.395 (1.215–1.602) for group IV, P < 0.001). In subgroup analysis, OS was significantly different in recipients with hepatitis C virus (HCV), but there was no significant difference for recipients with hepatitis B virus (HBV), alcoholic liver diseases and nonalcoholic steatohepatitis (NASH). The post-transplant cumulative tumor recurrence rates were similar among the four groups (P = 0.382).

Conclusions

Older donor age was associated with decreased OS but not liver-specific survival as well as post-transplant tumor recurrence in HCC recipients. Donor age also had different effects in patients with different underlying liver diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01786-6.

Changing Trends in Liver Transplantation: Challenges and Solutions

Despite improvements in postliver transplant outcomes through refinements in perioperative management and surgical techniques, several changing trends in liver transplantation have presented challenges. Mortality on the waitlist remains high. In the United States, Europe, and the United Kingdom, there is an increasing need for liver transplantation, primarily as a result of increased incidence of nonalcoholic steatohepatitis-related cirrhosis and cancer indications. Meanwhile, donor suitability has decreased, as donors are often older and have more comorbidities. Despite a mismatch between organ need and availability, many organs are discarded. Notwithstanding this, many solutions have been developed to overcome these challenges. Innovative techniques in allograft preservation, viability assessment, and reconditioning have allowed the use of suboptimal organs with adequate results. Refinements in surgical procedures, including live donor liver transplantations, have increased the organ pool and are decreasing the time and mortality on the waitlist. Despite many challenges, a similar number of solutions and prospects are on the horizon. This review seeks to explore the changing trends and challenges in liver transplantation and highlight possible solutions and future directions.

Ischemia-Reperfusion Injury in Marginal Liver Grafts and the Role of Hypothermic Machine Perfusion: Molecular Mechanisms and Clinical Implications

Ischemia-reperfusion injury (IRI) constitutes a significant source of morbidity and mortality after orthotopic liver transplantation (OLT). The allograft is metabolically impaired during warm and cold ischemia and is further damaged by a paradox reperfusion injury after revascularization and reoxygenation. Short-term and long-term complications including post-reperfusion syndrome, delayed graft function, and immune activation have been associated with IRI. Due to the current critical organ shortage, extended criteria grafts are increasingly considered for transplantation, however, with an elevated risk to develop significant features of IRI. In recent years, ex vivo machine perfusion (MP) of the donor liver has witnessed significant advancements. Here, we describe the concept of hypothermic (oxygenated) machine perfusion (HMP/HOPE) approaches and highlight which allografts may benefit from this technology. This review also summarizes clinical applications and the main aspects of ongoing randomized controlled trials on hypothermic perfusion. The mechanistic aspects of IRI and hypothermic MP-which include tissue energy replenishment, optimization of mitochondrial function, and the reduction of oxidative and inflammatory damage following reperfusion-will be comprehensively discussed within the context of current preclinical and clinical evidence. Finally, we highlight novel trends and future perspectives in the field of hypothermic MP in the context of recent findings of basic and translational research.

The aged liver: Beyond cellular senescence

The aging of the population, the increased prevalence of chronic liver diseases in elderly and the need to broaden the list of potential liver donors enjoin us to better understand what is an aged liver. In this review, we provide a brief introduction to cellular senescence, revisit the main morphological and functional modifications of the liver induced by aging, particularly concerning metabolism, immune response and regeneration, and try to elude some of the signalling pathways responsible for these modifications. Finally, we discuss the clinical consequences of aging on chronic liver diseases and the implications of older age for donors and recipients in liver transplantation.

Age and liver transplantation

The average age of liver transplant donors and recipients has increased over the years. Independent of the cause of liver disease, older candidates have more comorbidities, higher waitlist mortality and higher post-transplant mortality than younger patients. However, transplant benefit may be similar in older and younger recipients, provided older recipients are carefully selected. The cohort of elderly patients transplanted decades ago is also increasingly raising issues concerning long-term exposure to immunosuppression and aging of the transplanted liver. Excellent results can be achieved with elderly donors and there is virtually no upper age limit for donors after brain death liver transplantation. The issue is how to optimise selection, procurement and matching to ensure good results with elderly donors. The impact of old donor age is more pronounced in younger recipients and patients with a high model for end-stage liver disease score. Age matching between the donor and the recipient should be incorporated into allocation policies with a multistep approach. However, age matching may vary depending on the objectives of different allocation policies. In addition, age matching must be revisited in the era of direct-acting antivirals. More restrictive limits have been adopted in donation after circulatory death. Perfusion machines which are currently under investigation may help expand these limits. In living donor liver transplantation, donor age limit is essentially guided by morbidity related to procurement. In this review we summarise changing trends in recipient and donor age. We discuss the implications of older age donors and recipients. We also consider different options for age matching in liver transplantation that could improve outcomes.

Should organs from hepatitis C-positive donors be used in hepatitis C-negative recipients for liver transplantation?

Given the scarcity of donated organs and the frequency of death on the waiting list, strategies that could improve the available supply of high-quality liver grafts are much needed. Direct-acting antiviral agent (DAA) regimens have proved to be highly effective to treat hepatitis C virus (HCV), even in the setting of posttransplantation. The question arises as to whether transplant communities should consider the utilization of HCV-positive donors into HCV-negative recipients. This review summarizes risk of transmission, treatment options with success rate, and ethical considerations for usage of HCV-positive donors. Liver Transplantation 24 831-840 2018 AASLD.