Utilization of livers donated after circulatory death for transplantation - An international comparison

Post-reperfusion syndrome in liver transplant recipients: What is new in prevention and management?

Post-reperfusion syndrome (PRS) in liver transplant recipients remains one of the most dreaded complications in liver transplant surgery. PRS can impact the short-term and long-term patient and graft outcomes. The definition of PRS has evolved over the years, from changes in arterial blood pressures and heart and/or decreases in the systemic vascular resistance and cardiac output to including the fibrinolysis and grading the severity of PRS. However, all that did not reflect on the management of PRS or its impact on the outcomes. In recent years, new scientific techniques and new technology have been in the pipeline to better understand, manage and maybe prevent PRS. These new methods and techniques are still in the infancy, and they have to be proven not in prevention and management of PRS but their effects in the patient and graft outcomes. In this article, we will review the long history of PRS, its definition, etiology, management and most importantly the new advances in science and technology to prevent and properly manage PRS.

Normothermic regional perfusion and liver transplant: expanding the donation after circulatory death donor pool

PURPOSE OF REVIEW

Normothermic regional perfusion (NRP) is a novel technique developed to improve organ utilization and recipient outcomes following donation after circulatory death (DCD). NRP has revolutionized DCD liver transplant by extending donor criteria and reducing the incidence of ischemic cholangiopathy (IC) and other complications in recipients. However, there is significant geographic and center-specific variation in NRP use and practices. This review collates practices from pioneering NRP centers across the globe regarding donor selection criteria, NRP techniques, organ viability monitoring, and other key areas to help guide the continued growth of NRP liver transplantation.

RECENT FINDINGS

DCD livers recovered using NRP have consistently demonstrated excellent outcomes, with IC and patient and graft survival rates approaching those seen with grafts from donation after brain death donors. Recently, transplant centers have been working to increase the DCD donor pool by relaxing limits on donor quality, reconsidering organ viability markers, and combining NRP with ex situ machine perfusion technologies.

SUMMARY

NRP is a powerful organ recovery technology transforming the practice of DCD liver transplantation. Current evidence suggests that organ utilization could be further expanded using NRP recovery, with excellent clinical outcomes reported by centers using less stringent donor and organ viability criteria.

Comparisons of liver transplant from DCD outcomes in high-utilization centers versus low-utilization centers in the US: a systematic review and meta-analysis

Purpose/Objective

Donation after Cardiac Death (DCD) grafts are considered to be inferiors compared to Donation after Brain Death (DBD) grafts. Consequently, many transplant centers employ highly selective criteria for utilizing DCD, while others use them more liberally, potentially gaining greater expertise with this procedure. This disparity in approach raises questions about the impact of organ selection versus the benefits of increased experience with DCD organs. We performed a systematic review and meta-analysis to evaluate various outcomes in centers with high and low utilization rates of DCD.

Materials/Methods

Electronic databases PubMed, Embase, and Cochrane Library were systematically searched up to May 24th, 2023, for studies related to liver transplantation (LT). This search was conducted in accordance with PRISMA guidelines. The inclusion criteria focused on studies involving controlled DCD published within the last five years, and reporting on at least one of the outcomes of interest. Data was extracted and analyzed using a random-effects generalized linear mixed model with a 95% confidence interval (CI). The primary outcomes assessed were patient survival and graft survival. Heterogeneity among the included studies was evaluated using the I2 test, with I2>40% considered significant, and further explored through influence analysis. Subgroup meta-analysis by DCD utilization rate was done for each outcome. An analysis of the Organ Procurement & Transplantation Network (OPTN) database was performed on October 30th to determine the DCD rates and percentiles.

Results

Seven studies encompassing 898 patients were analyzed. In parallel, data from 151 centers were examined using the OPTN database, determining the rates of DCD utilization in each center over the past five years. Centers from the seven studies were divided into five high-utilization centers (HUC) and two low-utilization centers (LUC), with the 80th percentile (13.33% DCDs/Total LT) used as the threshold for high-utilization. Overall, the 1-year patient survival rate was 94.5% (95%CI: 92.4-96.1; I2 = 0%). HUCs had a rate of 94.6% (95%CI: 92.4-96.1; I2 = 0%), and LUCs had 93.7% (95%CI: 79.1-99.2; I2 = 0%), with a p=0.84. The overall 1-year graft survival rate was 90.6% (95% CI: 88.4-92.4; I2 = 0%). HUCs showed a 1-year graft survival of 90.9% (95%CI: 88.4-92.9; I2 = 0%), and LUCs showed 89.4% (95%CI: 83.8-93.2; I2 = 0%), p=0.54. The overall incidence of ischemic cholangiopathy was 10.3% (95% CI:7.9-13.3; I2 = 0%). The total rate of primary nonfunction was 1.5% (95% CI: 0.7-3.1%; I2 = 46%).

Conclusion

Our findings indicate no statistical difference in outcomes between high and low-utilization centers for DCD liver transplants, possibly suggesting that the higher selection in low-utilization centers is compensated by a greater experience in high-utilization centers.

Dynamic Preservation of Donation After Circulatory Death Liver Grafts From Donors Aged 60 y and Older

BACKGROUND

Donor livers from older donation after circulatory death (DCD) donors are frequently discarded for transplantation because of the high risk of graft failure. It is unknown whether DCD livers from older donors benefit from dynamic preservation.

METHODS

In a multicenter study, we retrospectively compared graft and patient outcomes after transplantation of livers from DCD donors older than 60 y, preserved with either static cold storage (SCS), ex situ sequential dual hypothermic perfusion, controlled oxygenated rewarming, and normothermic perfusion (DHOPE-COR-NMP), or in situ abdominal normothermic regional perfusion (aNRP).

RESULTS

Fifty-six liver transplants were included in the SCS cohort, 33 in the DHOPE-COR-NMP cohort, and 27 in the aNRP cohort. Donor warm ischemia time was significantly shorter in the SCS group than in DHOPE-COR-NMP ( P  < 0.001) and aNRP ( P  < 0.001) groups. Cold ischemia times were similar. One-year incidence of nonanastomotic biliary strictures was lower after DHOPE-COR-NMP (3%, P  = 0.03) or aNRP (7%, P  = 0.13), compared with SCS alone (21%). Anastomotic strictures were less frequent in aNRP (19%) compared with DHOPE-COR-NMP (52%; P  = 0.015). One-year graft and patient survival were similar.

CONCLUSIONS

Dynamic preservation allows safe transplantation of livers from DCD donors aged 60 y or older. The risk of nonanastomotic strictures was significantly lower after DHOPE-COR-NMP than after SCS, despite longer donor warm ischemia times.

Precision surgery for hepatocellular carcinoma

Hepatocellular carcinoma arises in the setting of cirrhosis in most cases, requiring multidisciplinary input to define resectability. In this regard, more precise surgical management considers patient factors and anatomical states, including resection margins, tumour biology, and perioperative therapy. Together with advances in surgical techniques, this integrated approach has resulted in considerable improvements in patient morbidity and oncological outcomes. Despite this, recurrence rates in hepatocellular carcinoma remain high. As the systemic treatment landscape in hepatocellular carcinoma continues to evolve and locoregional options are increasingly used, we review current and future opportunities to individualise the surgical management of patients with hepatocellular carcinoma.

Comprehensive Evaluation of Human Donor Liver Viability with Polarization-Sensitive Optical Coherence Tomography

Human liver transplantation is severely constrained by a critical shortage of donor livers, with approximately one quarter of patients on the waiting list dying due to the scarcity of viable organs. Current liver viability assessments, which rely on invasive pathological methods, are hampered by limited sampling from biopsies, particularly in marginal livers from extended criteria donors (ECD) intended to expand the donor pool. Consequently, there is a pressing need for more comprehensive and non-invasive evaluation techniques to meet the escalating demand for liver transplants. In this study, we propose the use of polarization-sensitive optical coherence tomography (PS-OCT) to perform a thorough viability evaluation across the entire surface of donor livers. PS-OCT imaging was conducted on multiple regions, achieving near-complete coverage of the liver surface, and the findings were cross-validated with histopathological evaluations. The analysis of hepatic parameters derived from pathology highlighted tissue heterogeneity. Leveraging machine learning and texture analysis, we quantified hepatic steatosis, fibrosis, inflammation, and necrosis, and established strong correlations (≥ 80%) between PS-OCT quantifications and pathological assessments. PS-OCT offers a non-invasive assessment of liver viability by quantifying hepatic parenchymal parameters across the entire donor liver, significantly complementing current pathological analysis. These results suggest that PS-OCT provides a robust, non-invasive approach to assessing donor liver viability, which could potentially decrease the discard rate of higher risk livers, thereby expanding the donor pool and reducing the inadvertent use of those livers unsuitable for transplantation.

Living Donor Liver Transplant Programs in the United States Need to Be Carefully Nurtured Amidst Expanding Use of Perfusion Technology

Living donor transplantation constitutes a small portion of total transplants in the United States as compared Southeast Asia and Middle East. Recent consensus meeting has identified reluctance on the part of transplant providers and donor financial concerns as the major hindrance in increasing the Living donor liver transplants in US. There is a need to carefully analyze the recent outcome data from across the globe and from large volume North American centers that clearly establishes the benefit of Living donor transplants for both adults and children and reducing wait list mortality. LDLT also provides an opportunity for expanding the indications to offer transplant for indications like colorectal metastasis and intrahepatic cholangiocarcinoma without reducing the number of livers available for traditional indications. Recent expansion of perfusion technology has demonstrated significant increase in utilization of Non heart beating donor livers over the last few years. However, with simultaneous increase in patients being added to the wait list, the wait list mortality and dropouts have been persistently high. In this opinion piece, the authors have looked at the transplant trends in the US in the last few years and advocate for adopting a complementary rather than a singular approach for expansion of LDLT along with new perfusion technologies for increasing the number of liver transplants in the US.

Global transplantation: Lessons from organ transplantation organizations worldwide

Although national transplant organizations share common visions and goals, the creation of a unified global organization remains impractical. Differences in ethnicity, culture, religion, and education shape local practices and infrastructure, making the establishment of a single global entity unfeasible. Even with these social disparities aside, logistical factors such as time and distance between organ procurement and transplantation sites pose significant challenges. While technological advancements have extended organ preservation times, they have yet to support the demands of transcontinental transplantations effectively. This review presents a comparative analysis of the structures, operational frameworks, policies, and legislation governing various transplant organizations around the world. Key differences pertain to the administration of these organizations, trends in organ donation, and organ allocation policies, which reflect the financial, cultural, and religious diversity across different regions. While a global transplant organization may be out of reach, agreeing on best practices for the benefit of patients is essential.

Core outcome sets and benchmarking complications: Defining best practices for standardized outcome reporting in liver transplantation

The comparison of outcomes in liver transplantation (LT) is hampered by using clinically nonrelevant surrogate endpoints and considerable variability in reported relevant posttransplant outcomes. Such variability stems from nonstandard outcome measures across studies, variable definitions of the same complication, and different timing of reporting. The Clavien-Dindo classification was established to improve the rigor of outcome reporting but is nonspecific to an intervention, and there are unsolved dilemmas specifically related to LT. Core outcome sets (COSs) have been used in other specialties to standardize outcomes research, but have not been defined for LT. Thus, we use the 5 major benchmarking studies published to date to define a 10-measure COS for LT using previously validated metrics. We further provide standard definitions for each of the 10 measures that may be used in international research on the topic. These definitions also include standard time points for recording to facilitate between-study comparisons and future meta-analysis. These 10 outcomes are paired with 3 validated, procedure-independent metrics, including the Clavien-Dindo Classification and the Comprehensive Complications Index. The Clavien scale and Comprehensive Complications Index are specifically reviewed to enhance their utility in LT, and their use, along with the COS, is explored. We encourage future studies to employ this COS along with the Clavien-Dindo grading system and Comprehensive Complications Index to improve the reproducibility and generalizability of research concerning LT.

Normothermic Machine Perfusion Improves Outcomes for Donation After Cardiac Death Allografts With Extended Donor Warm Ischemia Time

INTRODUCTION

Donation after circulatory death (DCD) allografts are underutilized in liver transplantation (LT) due to increased risk of complications. These risks stem from ischemic injury sustained during the total donor warm ischemia time (tDWIT), historically limited to 30 min. Normothermic machine perfusion (NMP) can mitigate these risks and facilitate LT of DCD grafts with extended tDWIT. We aimed to compare outcomes of DCD allografts with extended tDWIT preserved on NMP versus static cold storage (SCS).

METHODS

This single-center study included adult DCD LT with tDWIT ≥ 30 from 2019 to 2023. Outcomes of NMP and SCS were compared including EAD, IC, graft survival, and patient survival.

RESULTS

Among 68 DCD LT with tDWIT ≥ 30, 64.7% (n = 44) were preserved with NMP and 35.3% (n = 24) with SCS. No differences in donor or recipient demographics were observed. The median tDWIT was 33 min for NMP and 30.5 min for SCS (p < 0.01). Despite longer tDWIT, the NMP group had lower rates of EAD (4.5% vs. 66.7%, p < 0.01) and IC (2.3% vs. 29.2%, p < 0.01). One-year graft survival was higher in NMP (p < 0.01), and 1-year patient survival was comparable between groups (p = 0.18).

CONCLUSION

NMP challenges traditional tDWIT constraints and can increase the pool of viable DCD allografts for transplantation.

Thoracoabdominal Normothermic Regional Perfusion: Real-world Experience and Outcomes of DCD Liver Transplantation

Background

Donation after circulatory death liver transplantation (DCD LT) is underused given historical outcomes fraught with ischemic cholangiopathy (IC). We aimed to assess 6-mo IC in LT from DCD via normothermic regional perfusion (NRP) compared with DCD via static cold storage (SCS).

Methods

A retrospective review of adult Maastricht-III DCD liver donors and recipients at the University of Colorado Hospital from January 1, 2017, to August 27, 2024, was performed. The 6-mo IC rate was compared between NRP and SCS. Secondary outcomes included biochemical assessments of accepted versus declined NRP liver allografts and allograft and patient survival for NRP and SCS groups.

Results

One hundred sixty-two DCD LTs (SCS = 79; NRP = 97) were performed and 150 recipients (SCS = 74; NRP = 86) reached 6-mo follow-up. Six-month IC was lower for NRP compared with SCS (1.2% versus 9.5%, P = 0.03). The Donor Risk Index (2.44 [2.02-2.82] versus 2.17 [1.97-2.30], P = 0.002) and UK DCD Risk Score (4.2 ± 2.9 versus 3.2 ± 2.3, P = 0.008) were higher for NRP versus SCS. The Liver Graft assessment Following Transplantation score was less for NRP compared with SCS (-3.3 versus -3.1, P < 0.05). There were several differences in median biochemical parameters during NRP between accepted and declined livers, including higher terminal biliary bicarbonate (22.7 [20.9-29.1] versus 10.8 [7.6-13.1] mEq/L, P = 0.004). There were no significant differences in 12-mo allograft or patient survival for NRP versus SCS.

Conclusions

NRP is a disruptive innovation that improves the utilization of DCD livers. Despite higher-risk donor-recipient pairing for NRP compared with SCS, we demonstrate a decrease in IC for NRP. These data facilitate benchmarking of thoracoabdominal NRP DCD LT and support further protocol development.

Assessment of liver graft quality during hypothermic oxygenated perfusion: The first international validation study

BACKGROUND & AIMS

While it is currently assumed that liver assessment is only possible during normothermic machine perfusion, there is uncertainty regarding a reliable and quick prediction of graft injury during ex situ hypothermic oxygenated perfusion (HOPE). We therefore intended to test, in an international liver transplant cohort, recently described mitochondrial injury biomarkers measured during HOPE before liver transplantation.

METHODS

Perfusate samples of human livers from ten centers in seven countries with HOPE experience were analyzed for released mitochondrial compounds, i.e. flavin mononucleotide (FMN), NADH, purine derivatives and inflammatory markers. Livers deemed unsuitable for transplantation served as negative controls.

RESULTS

We collected 473 perfusate samples of human donation after cardiac death (n = 315) and donation after brain death (n = 158) livers. Fluorometric assessment of FMN in perfusate was validated by mass spectrometry (R = 0.7011, p <0.0001). Graft loss due to primary non-function or cholangiopathy was predicted by perfusate FMN values (c-statistic mass spectrometry 0.8418, 95% CI 0.7466-0.9370, p <0.0001; c-statistic fluorometry 0.7733, 95% CI 0.7006-0.8461, p <0.0001). Perfusate FMN values were also significantly correlated with symptomatic non-anastomotic strictures and kidney failure, and superior for the prediction of graft loss than conventional scores derived from donor and recipient parameters, such as the donor risk index and the balance of risk score. Mitochondrial FMN values in liver tissues of non-utilized livers were low, and inversely correlated to high perfusate FMN values and purine metabolite release.

CONCLUSIONS

This first international study validates the predictive value of the mitochondrial cofactor FMN, released from complex I during HOPE, and may therefore contribute to a better risk stratification of injured livers before implantation.

IMPACT AND IMPLICATIONS

Analysis of 473 perfusates, collected from ten international centers during HOPE (hypothermic oxygenated perfusion), revealed that mitochondria-derived flavin mononucleotide values in perfusate are predictive of graft loss, cholangiopathy, and kidney failure after liver transplantation. This result is of high clinical relevance, as recognition of graft quality is urgently needed to improve the safe utilization of marginal livers. Ex situ machine perfusion approaches, such as HOPE, are therefore likely to increase the number of useable liver grafts.

Liver transplant program utilization of donation after circulatory death liver grafts by procurement technique and storage modality: a survey of US liver transplant surgical directors

Introduction

Donation after circulatory death (DCD) increased in the US over the past decade. However, 30% of DCD liver grafts procured for transplantation are not utilized. Barriers to DCD liver utilization include quality concerns, particularly the risk of ischemic cholangiopathy and retransplantation, and costs associated with DCD organ acquisition. This study investigated the attitudes of the liver transplantation community in the US toward DCD and identified barriers to DCD liver utilization.

Methods

RedCap survey of liver transplantation surgical directors in the US.

Results

Of 101 liver transplantation surgical directors, 24 responded to the survey, and 96% of respondents accepted DCD donors. Most programs accepted livers from thoracoabdominal normothermic regional perfusion with cold storage (96%), while substantially fewer accepted liver grafts from rapid recovery DCD donors with cold storage (67%). Sixty-five percent of transplant centers' functional warm ischemic time started when oxygen saturation or systolic blood pressure was <80%/mm Hg; 13% started at extubation, 17.4% started at systolic blood pressure <80 mm Hg, and 4.3% used a systolic blood pressure <50 mm Hg.

Conclusion

We found variability among transplant programs in DCD liver graft acceptance based on procuring surgeon, procurement technique, and storage modality. Quality and cost are two main barriers to DCD liver utilization, with the main tradeoffs being between rapid recovery with static cold storage (lower cost, lower quality) and machine perfusion/normothermic regional perfusion (higher cost, better quality).

Challenges and opportunities in organ donation after circulatory death

In recent years, there has been resurgence in donation after circulatory death (DCD). Despite that, the number of organs transplanted from these donors remains low due to concerns about their function and a lack of an objective assessment at the time of donation. This overview examines the current DCD practices and the classification modifications to accommodate regional perspectives. Several risk factors underscore the reluctance to accept DCD organs, and we discuss the modern strategies to mitigate them. The advent of machine perfusion technology has revolutionized the field of DCD transplantation, leading to improved outcomes and better organ usage. With many strategies at our disposal, there is an urgent need for comparative trials to determine the optimal use of perfusion technologies for each donated organ type. Additional progress in defining therapeutic strategies to repair the damage sustained during the dying process should further improve DCD organ utilization and outcomes. However, there remains wide variability in access to DCD donation and transplantation, and organizational efforts should be doubled up with consensus on key ethical issues that still surround DCD donation in the era of machine perfusion.

Long-term outcomes after hypothermic oxygenated machine perfusion and transplantation of 1,202 donor livers in a real-world setting (HOPE-REAL study)

BACKGROUND & AIMS

Despite strong evidence for improved preservation of donor livers by machine perfusion, longer post-transplant follow-up data are urgently needed in an unselected patient population. We aimed to assess long-term outcomes after transplantation of hypothermic oxygenated machine perfusion (HOPE)-treated donor livers based on real-world data (i.e., IDEAL-D stage 4).

METHODS

In this international, multicentre, observational cohort study, we collected data from adult recipients of HOPE-treated livers transplanted between January 2012 and December 2021. Analyses were stratified by donation after brain death (DBD) and donation after circulatory death (DCD), sub-divided by their respective risk categories. The primary outcome was death-censored graft survival. Secondary outcomes included the incidence of primary non-function (PNF) and ischaemic cholangiopathy (IC).

RESULTS

We report on 1,202 liver transplantations (64% DBD) performed at 22 European centres. For DBD, a total number of 99 benchmark (8%), 176 standard (15%), and 493 extended-criteria (41%) cases were included. For DCD, 117 transplants were classified as low risk (10%), 186 as high risk (16%), and 131 as futile (11%), with significant risk profile variations among centres. Actuarial 1-, 3-, and 5-year death-censored graft survival rates for DBD and DCD livers were 95%, 92%, and 91%, vs. 92%, 87%, and 81%, respectively (log-rank p = 0.003). Within DBD and DCD strata, death-censored graft survival was similar among risk groups (log-rank p = 0.26, p = 0.99). Graft loss due to PNF or IC was 2.3% and 0.4% (DBD), and 5% and 4.1% (DCD).

CONCLUSIONS

This study shows excellent 5-year survival after transplantation of HOPE-treated DBD and DCD livers with low rates of graft loss due to PNF or IC, irrespective of their individual risk profile. HOPE treatment has now reached IDEAL-D stage 4, which further supports its implementation in routine clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05520320.

IMPACT AND IMPLICATIONS

This study demonstrates the excellent long-term performance of hypothermic oxygenated machine perfusion (HOPE) treatment of donation after circulatory and donation after brain death liver grafts irrespective of their individual risk profile in a real-world setting, outside the evaluation of randomised-controlled trials. While previous studies have established safety, feasibility, and efficacy against the current standard, according to the IDEAL-D evaluation framework, HOPE treatment has now reached the final IDEAL-D stage 4, which further supports its implementation in routine clinical practice.

A novel cytoprotective organ perfusion platform for reconstructing homeostasis of DCD liver while alleviating IRI injury

Pump is a vital component for expelling the perfusate in small animal isolated organ normothermic machine perfusion (NMP) systems whose flexible structure and rhythmic contraction play a crucial role in maintaining perfusion system homeostasis. However, the continuous extrusion forming with the rigid stationary shaft of the peristaltic pumps can damage cells, leading to metabolic disorders and eventual dysfunction of transplanted organs. Here, we developed a novel biomimetic blood-gas system (BBGs) for preventing cell damage. This system mimics the cardiac cycle and features an adjustable inspiratory-to-expiratory (IE) ratio to mitigate acidosis caused by continuous oxygen inhalation. In our study, adipose stem cells (ADSCs) were cultured within the circulatory system for 10 min, 2, and 4 h. Compared to the peristaltic pump, the BBGs significantly reduced cell apoptosis and morphological injury while enhancing cell proliferation and adhesion. Additionally, when the supernatant from ADSCs was introduced to LPS-induced macrophages for 24 h, the BBGs group demonstrated a more pronounced anti-inflammatory effect, characterized by reduced M1 macrophage expression. Besides, with isolated rat livers from donation after circulatory death (DCD) perfusion with ADSCs for 6 h by the BBGs, we detected fewer apoptotic cells and a reduced inflammatory response, evidenced by down-regulated TNF-α expression. The development of BBGs demonstrates the feasibility of recreating physiological liquid-gas circulation in vitro, offering an alternative platform for isolated organ perfusion, especially for applications involving cell therapy.

Ethical issues in organ procurement: donation after normothermic regional perfusion in liver transplantation

PURPOSE OF REVIEW

With ongoing organ shortages, new perfusion technologies are being embraced to help fill the unmet requirement. Improvement in utilization of donation after cardiac death (DCD) donors has the potential to greatly expand the pool of usable liver allografts. Normothermic regional perfusion (NRP) has been shown to increase usage of DCD donors and improve recipient outcomes. Yet, there remains heterogeneity in its usage worldwide.

RECENT FINDINGS

Results from the first US multicenter study show improved biliary outcomes with NRP, consistent with prior data from Europe. Internationally, there are wide variations in DCD and NRP usage, highlighting the opportunities for improvement and increased utilization. The ethics of this technique continue to be considered.

SUMMARY

NRP is a sound technique that can improve utilization for DCD donors, thereby increasing organ supply. Its usage is increasing worldwide. New data continue to show the benefit of this procurement strategy. NRP agrees with the principles of ethics.

Revolutionizing Liver Transplantation: Transitioning to an Elective Procedure Through Ex Situ Normothermic Machine Perfusion - A Benefit Analysis

OBJECTIVE

To assess the impact of normothermic machine perfusion (NMP) on patients, medical teams, and costs by gathering global insights and exploring current limitations.

BACKGROUND

NMP for ex situ liver graft perfusion is gaining increasing attention for its capability to extend graft preservation. It has the potential to transform liver transplantation (LT) from an urgent to a purely elective procedure, which could revolutionize LT logistics, reduce burden on patients and health care providers, and decrease costs.

METHODS

A 31-item survey was sent to international transplant directors to gather their NMP experiences and vision. In addition, we performed a systematic review on cost-analysis in LT and assessed studies on cost-benefit in converting urgent-to-elective procedures. We compared the costs of available NMPs and conducted a sensitivity analysis of NMP's cost benefits.

RESULTS

Of 120 transplant programs contacted, 64 (53%) responded, spanning North America (31%), Europe (42%), Asia (22%), and South America (5%). Of the total, 60% had adopted NMP, with larger centers (>100 transplants/year) in North America and Europe more likely to use it. The main NMP systems were OrganOx-metra (39%), XVIVO (36%), and TransMedics-OCS (15%). Despite NMP adoption, 41% of centers still perform >50% of LTs at nights/weekends. Centers recognized NMP's benefits, including improved work satisfaction and patient outcomes, but faced challenges like high costs and machine complexity. 16% would invest $100,000 to 500'000, 33% would invest $50,000 to 100'000, 38% would invest $10,000 to 50'000, and 14% would invest <$10,000 in NMP. These results were strengthened by a cost analysis for NMP in emergency-to-elective LT transition. Accordingly, while liver perfusions with disposables up to $10,000 resulted in overall positive net balances, this effect was lost when disposables' cost amounted to >$40,000/organ.

CONCLUSIONS

The adoption of NMP is hindered by high costs and operational complexity. Making LT elective through NMP could reduce costs and improve outcomes, but overcoming barriers requires national reimbursements and simplified, automated NMP systems for multiday preservation.

Liver transplantation for acute liver failure and acute-on-chronic liver failure

Acute liver failure (ALF) and acute-on-chronic liver (ACLF) are distinct phenotypes of liver failure and, thus, need to be compared and contrasted for appropriate management. There has been a significant improvement in the outcomes of these patients undergoing liver transplantation (LT). Survival post-LT for ALF and ACLF ranges between 90% and 95% and 80% and 90% at 1 year, futility criteria have been described in both ALF and ACLF where organ failures define survival. Plasma exchange and continuous renal replacement therapy may serve as bridging therapies. Identifying the futility of LT is as necessary as the utility of LT in patients with ALF and ACLF. The role of regenerative therapies such as granulocyte colony-stimulating factors in ACLF and hepatocyte and xenotransplantation in both conditions remains uncertain. Measures to increase the donor pool through increasing deceased donor transplants in Asian countries, living donations in Western countries, auxiliary liver transplants, and ABO-incompatible liver transplants are necessary to improve the survival of these patients. In this review, we discuss the similarities and differences in clinical characteristics and the timing and outcomes of LT for ALF and ACLF, briefly highlighting the role of bridging therapies and providing an overview of recent advances in the management of ALF and ACLF.

Multinational Analysis of Marginal Liver Grafts Based on the Eurotransplant Extended Donor Criteria

OBJECTIVE

To evaluate the outcome of marginal liver grafts based on the Eurotransplant extended criteria donor (ECD) criteria.

BACKGROUND

Eurotransplant uses a broad definition of ECD criteria (age >65 years, steatosis >40%, body mass index >30 kg/m 2 , intensive care unit stay >7 days, donation after circulatory death, and certain laboratory parameters) for allocating organs to recipients who have consented to marginal grafts. Historically, marginal liver grafts were associated with increased rates of dysfunction.

METHODS

Retrospective cohort analysis using the German Transplant Registry and the U.S. Scientific Registry of Transplant Recipients (SRTR) from 2006 to 2016. Results were validated with recent SRTR data (2017-2022). Donors were classified according to the Eurotransplant ECD criteria, donation after circulatory death was excluded. Data were analyzed with cutoff prediction, binomial logistic regression, and multivariate Cox regression.

RESULTS

The study analyzed 92,330 deceased brain-dead donors (87% SRTR) and 70,374 transplants (87% SRTR) in adult recipients. Predominant ECD factors were donor age in Germany (30%) and body mass index in the United States (28%). Except for donor age, grafts meeting ECD criteria were not associated with impaired 1 or 3-year survival. Cutoffs had little to no predictive value for 30-day graft survival (area under the receiver operating curve: 0.49-0.52) and were nominally higher for age (72 vs 65 years) in Germany as compared with those defined by current Eurotransplant criteria.

CONCLUSIONS

The outcome of transplanted grafts from higher risk donors was nearly equal to standard donors with Eurotransplant criteria failing to predict survival of marginal grafts. Modifying ECD criteria could improve graft allocation and potentially expand the donor pool.

Providing red blood cells to facilitate organ transplant via normothermic perfusion techniques: A single-center experience

BACKGROUND

Normothermic regional perfusion (NRP) and normothermic machine perfusion (NMP) are organ procurement and transport techniques that can improve organ quality, facilitate longer transport, and reduce postoperative complications, increasing organ availability and improving outcomes. NRP and NMP often require allogeneic red blood cells (RBCs). Our academic transfusion service began providing RBCs to support NRP and NMP for adult heart transplant (HT), orthotopic liver transplant (OLT), and multiorgan transplant (MOT) in August 2020.

METHODS

This single-center, retrospective study describes the implementation process and analyzes the characteristics of RBC support during the first 3 years of the perfusion programs. Timing and quantity of units issued and used, organ recipient demographics, and transplant outcomes were obtained from transfusion service and electronic medical records.

RESULTS

From 2020 to 2023, the transfusion service received 233 requests to support NRP and NMP perfusion cases. Of these, 105 cases resulted in RBC use, and units were returned or discarded in 112 cases. A total of 131 patients received perfusion-facilitated transplants (92 HT, 27 OLT, and 12 MOT). The majority of perfusion-facilitated HTs utilized NRP (81/92, 88%), whereas most perfusion-facilitated OLTs utilized NMP (21/27, 78%). Across all 233 requests, a total of 381 RBC units were used to facilitate 131 transplants, averaging 2.91 units/transplant.

DISCUSSION

Provision of RBCs for NRP and NMP techniques represents a novel method for transfusion services to support and facilitate life-saving organ transplants with only modest product use, about three RBC units per organ transplant in this single-center study.

Normothermic Regional Perfusion Experience of Organ Procurement Organizations in the US

Importance

Despite the unmet need for donor organs, organ use from donation after circulatory determination of death (DCD) donors has been limited by inferior transplant outcomes. Normothermic regional perfusion (NRP) improves recipient outcomes and organ utilization from DCD donors. There is variability in NRP policies and experience among US organ procurement organizations (OPOs).

Objectives

To determine OPO experience, identify operational inconsistencies, and explore needs related to NRP.

Design, Setting, and Participants

This survey study included 55 OPOs in the US that had recovered DCD organs and completed a survey on operational, administrative, and educational components related to NRP in November to December 2023. Data analysis was performed from February to April 2024.

Main Outcome and Measures

The primary outcome was the number of OPOs participating in and/or anticipating NRP participation. Secondary outcomes were NRP implementation barriers, OPO education practices, and future needs regarding consensus NRP recommendations and standards.

Results

Of 55 respondents, 11 (20%) were chief executive officers, 8 (15%) were chief operating officers, and 36 (65%) were medical directors or chief clinical officers. Forty-nine OPOs facilitated NRP cases: 26 OPOs (53%) facilitated both thoracoabdominal NRP (TA-NRP) and abdominal NRP (A-NRP) cases, 16 OPOs (33%) facilitated only TA-NRP, and 7 OPOs (14%) facilitated only A-NRP. OPOs reported 606 NRP cases (421 TA-NRP [69%], 185 A-NRP [31%]); median (range) case experience was 8 (1-52). Fifty-two of 55 OPOs (95%) thought standardized guidance documents would be helpful. All 49 OPOs facilitated NRP at a transplant center's request; 39 (80%) had NRP initiated by a nonlocal transplant center. Twenty-three of 49 OPOs (47%) participated in NRP without a policy and without a policy pending approval. Positive donor hospital feedback was received by 29 OPOs (59%), primarily focused on increased organs transplanted and prerecovery communication. Allocation challenges were experienced by 21 OPOs (43%); their median (range) case volume was higher than those with no reported allocation challenges (11 [3-52] vs 6.5 [1-29]; P = .03). Eleven OPOs (22%) had incorporated NRP into general donor hospital education.

Conclusions

In this survey study of US OPOs, wide variation existed with respect to NRP experience and practice. Allocation challenges occurred more frequently with increased NRP experience. NRP guidelines and standardization were desired by most OPOs to decrease allocation challenges and maximize the gift of organ donation.

Healthcare Worker Attitudes to Living Donation Prior to Planned Withdrawal of Care

Background and Aims

This study assesses the attitudes of healthcare practitioners toward Living Donation Prior to Planned Withdrawal of Care (LD-PPW): the recovery of a living donor organ before withdrawal of life-sustaining measures in a patient who does not meet criteria for brain death, but for whom medical care toward meaningful recovery is deemed futile.

Methods

An electronic survey was administered to 1735 members of the American Society of Transplant Surgeons mailing list with 187 responses (10.8%).

Results

Data from this study revealed that 70% of responding practitioners agreed with LD-PPW due to principles of beneficence and autonomy. Also, 65% of participants felt confident in their ability to declare the futility of care and 70% felt that LD-PPW should be added as an option when registering to become an organ donor.

Conclusion

Currently, nearly half of all donation after circulatory determination of death do not proceed to donation. LD-PPW has been proposed as an alternative procedure targeted at increasing the quality and quantity of transplantable organs while respecting the donor's right to donate, though its implementation has been hindered by concerns over public and provider perception. This study revealed support for LD-PPW among healthcare practitioners as an alternative procedure to increase the quality and quantity of transplantable organs while respecting the donor's right to donate.

Safety and use of late-turndown liver allografts to increase rate of transplantation

BACKGROUND

The demand for liver transplants (LT) in the United States far surpasses the availability of allografts. New allocation schemes have resulted in occasional difficulties with allograft placement and increased intraoperative turndowns. We aimed to evaluate the outcomes related to use of late-turndown liver allografts.

METHODS

A review of prospectively collected data of LTs at a single center from July 2019 to July 2023 was performed. Late-turndown placement was defined as an open offer 6 h prior to donation, intraoperative turndown by primary center, or post-cross-clamp turndown.

RESULTS

Of 565 LTs, 25.1% (n = 142) received a late-turndown liver allograft. There were no significant differences in recipient age, gender, BMI, or race (all p > 0.05), but MELD was lower for the late-turndown LT recipient group (median 15 vs 21, p < 0.001). No difference in 30-day, 6-month, or 1-year survival was noted on logistic regression, and no difference in patient or graft survival was noted on Cox proportional hazard regression. Late-turndown utilization increased during the study from 17.2% to 25.8%, and median waitlist time decreased from 77 days in 2019 to 18 days in 2023 (p < 0.001).

CONCLUSION

Use of late-turndown livers has increased and can increase transplant rates without compromising post-transplant outcomes with appropriate selection.

Impact of Back-to-Base Normothermic Machine Perfusion on Complications and Costs: A Multicenter, Real-World Risk-Matched Analysis

OBJECTIVE

Assess cost and complication outcomes after liver transplantation (LT) using normothermic machine perfusion (NMP).

BACKGROUND

End-ischemic NMP is often used to aid logistics, yet its impact on outcomes after LT remains unclear, as does its true impact on costs associated with transplantation.

METHODS

Deceased donor liver recipients at 2 centers (January 1, 2019, to June 30, 2023) were included. Retransplants, splits, and combined grafts were excluded. End-ischemic NMP (OrganOx-Metra) was implemented in October 2022 for extended-criteria donation after brain death (DBDs), all donations after circulatory deaths (DCDs), and logistics. NMP cases were matched 1:2 with static cold storage controls (SCS) using the Balance-of-Risk [donation after brain death (DBD)-grafts] and UK-DCD Score (DCD-grafts).

RESULTS

Overall, 803 transplantations were included, 174 (21.7%) receiving NMP. Matching was achieved between 118 NMP-DBDs with 236 SCS; and 37 NMP-DCD with 74 corresponding SCS. For both graft types, median inpatient comprehensive complications index values were comparable between groups. DCD-NMP grafts experienced reduced cumulative 90-day comprehensive complications index (27.6 vs 41.9, P =0.028). NMP also reduced the need for early relaparotomy and renal replacement therapy, with subsequently less frequent major complications (Clavien-Dindo ≥IVa). This effect was more pronounced in DCD transplants. NMP had no protective effect on early biliary complications. Organ acquisition/preservation costs were higher with NMP, yet NMP-treated grafts had lower 90-day pretransplant costs in the context of shorter waiting list times. Overall costs were comparable for both cohorts.

CONCLUSIONS

This is the first risk-adjusted outcome and cost analysis comparing NMP and SCS. In addition to logistical benefits, NMP was associated with a reduction in relaparotomy and bleeding in DBD grafts, and overall complications and post-LT renal replacement for DCDs. While organ acquisition/preservation was more costly with NMP, overall 90-day health care costs-per-transplantation were comparable.

[Organ donation and organ assessment after primary circulatory death and secondary brain death]

BACKGROUND

The global organ shortage is the biggest obstacle to expand urgently needed liver transplantation activities. In addition to donation after brain death (DBD), donation after primary circulatory death (DCD) has also been introduced in many European countries to increase the number of donated organs.

OBJECTIVE

This article summarizes the legal and ethical aspects of DCD, the practical donation process of DCD, the clinical results of DCD liver transplantation with a special focus on organ assessment before a planned DCD liver transplantation.

RESULTS

In Europe 11 countries have active DCD liver transplantation programs and a total of 1230 DCD liver transplantations were performed in Europe in 2023. The highest proportion of DCD liver transplantations were recorded in Belgium (52.8%), the Netherlands (42.8%) and Switzerland (32.1%). The adequate selection of donors and recipients is crucial in DCD transplantation and the use of DCD livers particularly depends on the preparedness of the healthcare system for routine machine perfusion. The leaders are Belgium, France and Italy which implant around 68-74% of DCD organs. With an adequate organ assessment, the long-term results of DBD and DCD liver transplantations are comparable. To assess mitochondrial damage and thus organ quality, hypothermic oxygenated machine perfusion (HOPE) was introduced and has the secondary benefit of mitochondrial protection through oxygenation. The establishment of aerobic metabolism in mitochondria under hypothermia leads to a reduction of toxic metabolites and the restoration of ATP storage, which subsequently leads to a reperfusion light during implantation.

CONCLUSION

Expanding the donor pool with DCD donors can counteract the global organ shortage. With adequate patient selection and routine organ assessment short-term and also long-term outcomes of DBD and DCD liver transplantation are comparable.

Machine perfusion in liver transplantation: recent advances and coming challenges

PURPOSE OF REVIEW

Machine perfusion has been adopted into clinical practice in Europe since the mid-2010s and, more recently, in the United States (US) following approval of normothermic machine perfusion (NMP). We aim to review recent advances, provide discussion of potential future directions, and summarize challenges currently facing the field.

RECENT FINDINGS

Both NMP and hypothermic-oxygenated perfusion (HOPE) improve overall outcomes after liver transplantation versus traditional static cold storage (SCS) and offer improved logistical flexibility. HOPE offers additional protection to the biliary system stemming from its' protection of mitochondria and lessening of ischemia-reperfusion injury. Normothermic regional perfusion (NRP) is touted to offer similar protective effects on the biliary system, though this has not been studied prospectively.The most critical question remaining is the optimal use cases for each of the three techniques (NMP, HOPE, and NRP), particularly as HOPE and NRP become more available in the US. There are additional questions regarding the most effective criteria for viability assessment and the true economic impact of these techniques. Finally, with each technique purported to allow well tolerated use of riskier grafts, there is an urgent need to define terminology for graft risk, as baseline population differences make comparison of current data challenging.

SUMMARY

Machine perfusion is now widely available in all western countries and has become an essential tool in liver transplantation. Identification of the ideal technique for each graft, optimization of viability assessment, cost-effectiveness analyses, and proper definition of graft risk are the next steps to maximizing the utility of these powerful tools.

Should advanced perfusion be the standard of care for donation after circulatory death liver transplant?

As an alternative to static cold storage (SCS), advanced perfusion techniques such as normothermic regional perfusion and ex-situ perfusion (normothermic or hypothermic) have emerged as a way to improve the ischemic injury suffered by donation after circulatory death (DCD) livers. Multiple studies have been published that have demonstrated superior post-DCD liver transplant outcomes when using advanced perfusion compared with SCS. In particular, these studies have shown lower rates of ischemic cholangiopathy with advanced perfusion. In addition to the improved post-liver transplant outcomes, studies have also demonstrated higher rates of liver utilization from DCD donors when advanced perfusion is used compared with SCS. Given the high rates of graft loss in patients who develop ischemic cholangiopathy, the significant reduction seen in DCD donor livers that have undergone advanced perfusion represents a key step in more broad utilization of these livers. With such compelling evidence from multiple trials, it seems reasonable to ask the question: should advanced perfusion be the standard of care for DCD liver transplant?

Return of the cold: How hypothermic oxygenated machine perfusion is changing liver transplantation

Hypothermic Oxygenated machine PErfusion (HOPE) has recently emerged as a preservation technique which can reduce ischemic injury and improve clinical outcomes following liver transplantation. First developed with the advent solid organ transplantation techniques, hypothermic machine perfusion largely fell out of favour following the development of preservation solutions which can satisfactorily preserve grafts using the cheap and simple method, static cold storage (SCS). However, with an increasing need to develop techniques to reduce graft injury and better utilise marginal and donation after circulatory death (DCD) grafts, HOPE has emerged as a relatively simple and safe technique to optimise clinical outcomes following liver transplantation. Perfusing the graft with cold, acellular, oxygenated perfusate either via the portal vein (PV) alone, or via both the PV and hepatic artery (HA), HOPE is generally commenced for a period of 1-2 h immediately prior to implantation. The technique has been validated by multiple randomised control trials, and pre-clinical evidence suggests HOPE primarily reduces graft injury by decreasing the accumulation of harmful mitochondrial intermediates, and subsequently, the severity of post-reperfusion injury. HOPE can also facilitate real time graft assessment, most notably via the measurement of flavin mononucleotide (FMN) in the perfusate, allowing transplant teams to make better informed clinical decisions prior to transplantation. HOPE may also provide a platform to administer novel therapeutic agents to ex situ organs without risk of systemic side effects. As such, HOPE is uniquely positioned to revolutionise how liver transplantation is approached and facilitate optimised clinical outcomes for liver transplant recipients.

Sequential Normothermic Regional Perfusion and End-ischemic Ex Situ Machine Perfusion Allow the Safe Use of Very Old DCD Donors in Liver Transplantation

BACKGROUND

In Italy, 20 min of continuous, flat-line electrocardiogram are required for death declaration. Despite prolonged warm ischemia time, Italian centers reported good outcomes in controlled donation after circulatory death (cDCD) liver transplantation by combining normothermic regional and end-ischemic machine perfusion (MP). The aim of this study was to evaluate the safety and feasibility of the use of septuagenarian and octogenarian cDCD donors with this approach.

METHODS

All cDCD older than 70 y were evaluated during normothermic regional perfusion and then randomly assigned to dual hypothermic or normothermic MP.

RESULTS

In the period from April 2021 to December 2022, 17 cDCD older than 70 y were considered. In 6 cases (35%), the graft was not considered suitable for liver transplantation, whereas 11 (65%) were evaluated and eventually transplanted. The median donor age was 82 y, being 8 (73%) older than 80. Median functional warm ischemia and no-flow time were 36 and 28 min, respectively. Grafts were randomly assigned to ex situ dual hypothermic oxygenated MP in 6 cases (55%) and normothermic MP in 5 (45%). None was discarded during MP. There were no cases of primary nonfunction, 1 case of postreperfusion syndrome (9%) and 2 cases (18%) of early allograft dysfunction. At a median follow-up of 8 mo, no vascular complications or ischemic cholangiopathy were reported. No major differences were found in terms of postoperative hospitalization or complications based on the type of MP.

CONCLUSIONS

The implementation of sequential normothermic regional and end-ischemic MP allows the safe use of very old donation after circulatory death donors.

Challenges With the Implementation of Machine Perfusion in Clinical Liver Transplantation

Dynamic organ preservation is a relatively old technique which has regained significant interest in the last decade. Machine perfusion (MP) techniques are applied in various fields of solid organ transplantation today. The first clinical series of ex situ MP in liver transplantation was presented in 2010. Since then, the number of research and clinical applications has substantially increased. Despite the notable beneficial effect on organ quality and recipient outcome, MP is still not routinely used in liver transplantation. Based on the enormous need to better preserve organs and the subsequent demand to continuously innovate and develop perfusion equipment further, this technology is also beneficial to test and deliver future therapeutic strategies to livers before implantation. This article summarizes the various challenges observed during the current shift from static to dynamic liver preservation in the clinical setting. The different organ perfusion strategies are discussed first, together with ongoing clinical trials and future study design. The current status of research and the impact of costs and regulations is highlighted next. Factors contributing to costs and other required resources for a worldwide successful implementation and reimbursement are presented third. The impact of research on cost-utility and effectivity to guide the tailored decision-making regarding the optimal perfusion strategy is discussed next. Finally, this article provides potential solutions to the challenging field of innovation in healthcare considering the various social and economic factors and the role of clinical, regulatory, and financial stakeholders worldwide.

US Liver Transplant Outcomes After Normothermic Regional Perfusion vs Standard Super Rapid Recovery

Importance

Normothermic regional perfusion (NRP) is an emerging recovery modality for transplantable allografts from controlled donation after circulatory death (cDCD) donors. In the US, only 11.4% of liver recipients who are transplanted from a deceased donor receive a cDCD liver. NRP has the potential to safely expand the US donor pool with improved transplant outcomes as compared with standard super rapid recovery (SRR).

Objective

To assess outcomes of US liver transplants using controlled donation after circulatory death livers recovered with normothermic regional perfusion vs standard super rapid recovery.

Design, Setting, and Participants

This was a retrospective, observational cohort study comparing liver transplant outcomes from cDCD donors recovered by NRP vs SRR. Outcomes of cDCD liver transplant from January 2017 to May 2023 were collated from 17 US transplant centers and included livers recovered by SRR and NRP (thoracoabdominal NRP [TA-NRP] and abdominal NRP [A-NRP]). Seven transplant centers used NRP, allowing for liver allografts to be transplanted at 17 centers; 10 centers imported livers recovered via NRP from other centers.

Exposures

cDCD livers were recovered by either NRP or SRR.

Main Outcomes and Measures

The primary outcome was ischemic cholangiopathy (IC). Secondary end points included primary nonfunction (PNF), early allograft dysfunction (EAD), biliary anastomotic strictures, posttransplant length of stay (LOS), and patient and graft survival.

Results

A total of 242 cDCD livers were included in this study: 136 recovered by SRR and 106 recovered by NRP (TA-NRP, 79 and A-NRP, 27). Median (IQR) NRP and SRR donor age was 30.5 (22-44) years and 36 (27-49) years, respectively. Median (IQR) posttransplant LOS was significantly shorter in the NRP cohort (7 [5-11] days vs 10 [7-16] days; P < .001). PNF occurred only in the SRR allografts group (n = 2). EAD was more common in the SRR cohort (123 of 136 [56.1%] vs 77 of 106 [36.4%]; P = .007). Biliary anastomotic strictures were increased 2.8-fold in SRR recipients (7 of 105 [6.7%] vs 30 of 134 [22.4%]; P = .001). Only SRR recipients had IC (0 vs 12 of 133 [9.0%]; P = .002); IC-free survival by Kaplan-Meier was significantly improved in NRP recipients. Patient and graft survival were comparable between cohorts.

Conclusion and Relevance

There was comparable patient and graft survival in liver transplant recipients of cDCD donors recovered by NRP vs SRR, with reduced rates of IC, biliary complications, and EAD in NRP recipients. The feasibility of A-NRP and TA-NRP implementation across multiple US transplant centers supports increasing adoption of NRP to improve organ use, access to transplant, and risk of wait-list mortality.

Current role and perspectives of living donor liver transplantation for hepatocellular carcinoma: systematic review of the past 20 years

Hepatocellular carcinoma (HCC) poses a significant global health challenge, and liver transplantation (LT) remains the best curative option. Living donor liver transplantation (LDLT) emerged as a potential solution to organ scarcity, reducing waitlist times. This comprehensive review explores LDLT practices, focusing on patient selection criteria and oncologic outcomes. A systematic review following PRISMA guidelines included 50 studies (2004-2023) with 8062 patients. Data encompassed baseline characteristics, HCC features, and oncologic outcomes. Further analysis categorized results by geography and publication year. Heterogeneity in patient demographics, tumor burden, and transplant characteristics was observed. Recent LDLT series demonstrated a shift towards refined selection criteria, increased neoadjuvant treatment, and improved oncologic outcomes. Geographic disparities revealed unique challenges in Eastern and Western practices. LDLT proves effective for HCC, addressing donor shortages. Evolving practices highlight the importance of refining inclusion criteria and optimizing tumor management. While geographic differences exist, LDLT, when judiciously applied, offers promising outcomes.

Clinical outcomes after transplantation of domino grafts or standard deceased donor livers: a systematic review and meta-analysis

BACKGROUND AND AIM

Domino liver transplantation (DLT) utilizes otherwise discarded livers as donor grafts for another recipients. It is unclear whether DLT has less favorable outcomes compared to deceased donor liver transplantation (DDLT). We aimed to assess the outcomes of DLT compared to DDLT.

METHODS

MEDLINE, Embase, and Web of Science database were searched to identify studies comparing outcomes after DLT with DDLT. Data were pooled using random-effects modeling, evaluating odds ratios (OR) or mean difference (MD) for outcomes including waiting list time, severe hemorrhage, intensive care unit (ICU), length hospital stay (LOS), rejection, renal, vascular, and biliary events, and recipient survival at 1, 3, 5, and 10 years.

RESULTS

Five studies were identified including 945 patients (DLT = 409, DDLT = 536). The DLT recipients were older compared to the DDLT group (P = 0.04), and both cohorts were comparable regarding lab MELD, hepatocellular carcinoma, and waitlist time. There were no differences in vascular (OR: 1.60, P = 0.39), renal (OR: 0.62, P = 0.24), biliary (OR: 1.51, P = 0.21), severe hemorrhage (OR: 1.09, P = 0.86), rejection (OR: 0.78, P = 0.51), ICU stay (MD: 0.50, P = 0.21), or LOS (MD: 1.68, P = 0.46) between DLT and DDLT. DLT and DDLT were associated with comparable 1-year (78.9% vs 80.4%; OR: 1.03, P = 0.89), 3-year (56.2% vs 54.1%; OR: 1.35, P = 0.07), and 10-year survival (6.5% vs 8.5%; OR: 0.8, P = 0.67) rates. DLT was associated with higher 5-year survival (41.6% vs 36.4%; OR: 1.70; P = 0.003) compared to DDLT, which was not confirmed at sensitivity analysis.

CONCLUSION

This meta-analysis of the best available evidence (Level 2a) demonstrated that DLT and DDLT have comparable outcomes. As indications for liver transplantation expand, future high-quality research is encouraged to increase the DLT numbers in clinical practice, serving the growing waiting list candidates, with the caveat of uncertain de novo disease transmission risks.

Approach to Liver Transplantation: Is There a Difference between East and West?

Liver transplantation (LT) remains the only curative treatment for end-stage liver disease as well as acute liver failure. With the exponential increase in organ demand due to the increasing incidence and prevalence of liver diseases, the need to overcome the supply and demand mismatch has arisen. In this review, we discuss the current universal status of LT, emphasizing various LT practices worldwide.

Obstacles to implement machine perfusion technology in routine clinical practice of transplantation: Why are we not there yet?

Machine perfusion of solid human organs is an old technique, and the basic principles were presented as early as 1855 by Claude Barnard. More than 50 years ago, the first perfusion system was used in clinical kidney transplantation. Despite the well-known benefits of dynamic organ preservation and significant medical and technical development in the last decades, perfusion devices are still not in routine use. This article describes the various challenges to implement this technology in practice, critically analyzing the role of all involved stakeholders, including clinicians, hospitals, regulatory, and industry, on the background of regional differences worldwide. The clinical need for this technology is discussed first, followed by the current status of research and the impact of costs and regulations. Considering the need for strong collaborations between clinical users, regulatory bodies, and industry, integrated road maps and pathways required to achieve a wider implementation are presented. The role of research development, clear regulatory pathways, and the need for more flexible reimbursement schemes is discussed together with potential solutions to address the most relevant hurdles. This article paints an overall picture of the current liver perfusion landscape and highlights the role of clinical, regulatory, and financial stakeholders worldwide.

Strategies to Improve the Utilization and Function of DCD Livers

Despite the increased usage of livers from donation after circulatory death (DCD) donors in the last decade, many patients remaining on the waitlist who need a liver transplant. Recent efforts have focused on maximizing the utilization and outcomes of these allografts using advances in machine perfusion technology and other perioperative strategies such as normothermic regional perfusion (NRP). In addition to the standard donor and recipient matching that is required with DCD donation, new data regarding the impact of graft steatosis, extensive European experience with NRP, and the increasing use of normothermic and hypothermic machine perfusion have shown immense potential in increasing DCD organ overall utilization and improved outcomes. These techniques, along with viability testing of extended criteria donors, have generated early promising data to consider the use of higher-risk donor organs and more widespread adoption of these techniques in the United States. This review explores the most recent international literature regarding strategies to optimize the utilization and outcomes of DCD liver allografts, including donor-recipient matching, perioperative strategies including NRP versus rapid controlled DCD recovery, viability assessment of discarded livers, and postoperative strategies including machine perfusion versus pharmacologic interventions.

Modern-Day Practice of DCD Liver Transplantation: Controversies, Innovations, and Future Directions

PURPOSE OF REVIEW

Over the past decade, donation after circulatory death (DCD) liver transplantation has expanded in the United States due to improved surgical experience and perioperative management. Despite these advances, there remains a reluctance towards broader utilization of DCD liver allografts due to lack of standardized donation process, concern for inferior graft survival, and risk of ischemic cholangiopathy associated with temporary lack of oxygenated perfusion during withdrawal of life-supporting treatment during procurement.

RECENT FINDINGS

New perfusion technologies offer potential therapeutic options to mitigate biliary complications and expand utilization of marginal DCD grafts. As these modalities enter routine clinical practice, DCD utilization will continue to increase, and liver allocation policies in turn will evolve to reflect this growing practice. This review describes recent progress in DCD LT, current challenges with utilization of DCD liver allografts, and how novel technologies and policies could impact the future of the field.

Mitochondrial injury during normothermic regional perfusion (NRP) and hypothermic oxygenated perfusion (HOPE) in a rodent model of DCD liver transplantation

BACKGROUND

Normothermic regional perfusion (NRP) and hypothermic-oxygenated-perfusion (HOPE), were both shown to improve outcomes after liver transplantation from donors after circulatory death (DCD). Comparative clinical and mechanistical studies are however lacking.

METHODS

A rodent model of NRP and HOPE, both in the donor, was developed. Following asystolic donor warm ischemia time (DWIT), the abdominal compartment was perfused either with a donor-blood-based-perfusate at 37 °C (NRP) or with oxygenated Belzer-MPS at 10 °C (donor-HOPE) for 2 h. Livers were then procured and underwent 5 h static cold storage (CS), followed by transplantation. Un-perfused and HOPE-treated DCD-livers (after CS) and healthy livers (DBD) with direct implantation after NRP served as controls. Endpoints included the entire spectrum of ischemia-reperfusion-injury.

FINDINGS

Healthy control livers (DBD) showed minimal signs of inflammation during 2 h NRP and achieved 100% posttransplant recipient survival. In contrast, DCD livers with 30 and 60 min DWIT suffered from greater mitochondrial injury and inflammation as measured by increased perfusate Lactate, FMN- and HMGB-1-levels with subsequent Toll-like-receptor activation during NRP. In contrast, donor-HOPE (instead of NRP) led to significantly less mitochondrial-complex-I-injury and inflammation. Results after donor-HOPE were comparable to ex-situ HOPE after CS. Most DCD-liver recipients survived when treated with one HOPE-technique (86%), compared to only 40% after NRP (p = 0.0053). Following a reduction of DWIT (15 min), DCD liver recipients achieved comparable survivals with NRP (80%).

INTERPRETATION

High-risk DCD livers benefit more from HOPE-treatment, either immediately in the donor or after cold storage. Comparative prospective clinical studies are required to translate the results.

FUNDING

Funding was provided by the Swiss National Science Foundation (grant no: 32003B-140776/1, 3200B-153012/1, 320030-189055/1, and 31IC30-166909) and supported by University Careggi (grant no 32003B-140776/1) and the OTT (grant No.: DRGT641/2019, cod.prog. 19CT03) and the Max Planck Society. Work in the A.G. laboratory was partially supported by the NIH R01NS112381 and R21NS125466 grants.

Screening for mitochondrial function before use-routine liver assessment during hypothermic oxygenated perfusion impacts liver utilization

BACKGROUND

To report on a concept of liver assessment during ex situ hypothermic oxygenated perfusion (HOPE) and its significant impact on liver utilization.

METHODS

An analysis of prospectively collected data on donation after circulatory death (DCD) livers, treated by HOPE at our institution, during a 11-year period between January 2012 and December 2022.

FINDINGS

Four hundred and fifteen DCD Maastricht III livers were offered during the study period in Switzerland, resulting in 249 liver transplants. Of those, we performed 158 DCD III liver transplants at our institution, with 1-year patient survival and death censored graft survival (death with functioning graft) of 87 and 89%, respectively, thus comparable to benchmark graft survivals of ideal DBD and DCD liver transplants (89% and 86%). Correspondingly, graft loss for primary non-function or cholangiopathy was overall low, i.e., 7/158 (4.4%) and 11/158 (6.9%), despite more than 82% of DCD liver grafts ranked high (6-10 points) or futile risk (>10 points) according to the UK-DCD score. Consistently, death censored graft survival was not different between low-, high-risk or futile DCD III livers. The key behind these achievements was the careful development and implementation of a routine perfusate assessment of mitochondrial biomarkers for injury and function, i.e., release of flavin mononucleotide from complex I, perfusate NADH, and mitochondrial CO2 production during HOPE, allowing a more objective interpretation of liver quality on a subcellular level, compared to donor derived data.

INTERPRETATION

HOPE after cold storage is a highly suitable and easy to perform perfusion approach, which allows reliable liver graft assessment, enabling surgeons to make a fact based decision on whether or not to implant the organ. HOPE-treatment should be combined with viability assessment particularly when used for high-risk organs, including DCD livers or organs with relevant steatosis.

FUNDING

This study was supported by the Swiss National Foundation (SNF) grant 320030_189055/1 to PD.

Transplant Candidate Outcomes After Declining a DCD Liver in the United States

BACKGROUND

In the context of the organ shortage, donation after circulatory death (DCD) provides an opportunity to expand the donor pool. Although deceased-donor liver transplantation from DCD donors has expanded, DCD livers continue to be discarded at elevated rates; the use of DCD livers from older donors, or donors with comorbidities, is controversial.

METHODS

Using US registry data from 2009 to 2020, we identified 1564 candidates on whose behalf a DCD liver offer was accepted ("acceptors") and 16 981 candidates on whose behalf the same DCD offers were declined ("decliners"). We characterized outcomes of decliners using a competing risk framework and estimated the survival benefit (adjusted hazard ratio [95% confidence interval]) of accepting DCD livers using Cox regression.

RESULTS

Within 10 y of DCD offer decline, 50.9% of candidates died or were removed from the waitlist before transplantation with any type of allograft. DCD acceptors had lower mortality compared with decliners at 10 y postoffer (35.4% versus 48.9%, P < 0.001). After adjustment for candidate covariates, DCD offer acceptance was associated with a 46% reduction in mortality (0.54 [0.49-0.61]). Acceptors of older (age ≥50), obese (body mass index ≥30), hypertensive, nonlocal, diabetic, and increased risk DCD livers had 44% (0.56 [0.42-0.73]), 40% (0.60 [0.49-0.74]), 48% (0.52 [0.41-0.66]), 46% (0.54 [0.45-0.65]), 32% (0.68 [0.43-1.05]), and 45% (0.55 [0.42-0.72]) lower mortality risk compared with DCD decliners, respectively.

CONCLUSIONS

DCD offer acceptance is associated with considerable long-term survival benefits for liver transplant candidates, even with older DCD donors or donors with comorbidities. Increased recovery and utilization of DCD livers should be encouraged.

Benefit and harm of waiting time in liver transplantation for HCC

Liver transplantation is the most successful treatment for limited-stage HCC. The waiting time for liver transplantation (LT) can be a critical factor affecting the oncological prognosis and outcome of patients with HCC. Efficient strategies to optimize waiting time are essential to maximize the benefits of LT and to reduce the harm of delay in transplantation. The ever-increasing demand for donor livers emphasizes the need to improve the organization of the waiting list for transplantation and to optimize organ availability for patients with and without HCC. Current progress in innovations to expand the donor pool includes the implementation of living donor LT and the use of grafts from extended donors. By expanding selection criteria, an increased number of patients are eligible for transplantation, which necessitates criteria to prevent futile transplantations. Thus, the selection criteria for LT have evolved to include not only tumor characteristics but biomarkers as well. Enhancing our understanding of HCC tumor biology through the analysis of subtypes and molecular genetics holds significant promise in advancing the personalized approach for patients. In this review, the effect of waiting time duration on outcome in patients with HCC enlisted for LT is discussed.