Outcomes of DCD liver transplantation using organs treated by hypothermic oxygenated perfusion before implantation

Portable hypothermic oxygenated machine perfusion for organ preservation in liver transplantation: A randomized, open-label, clinical trial

BACKGROUND AND AIMS

In liver transplantation, cold preservation induces ischemia, resulting in significant reperfusion injury. Hypothermic oxygenated machine perfusion (HMP-O 2 ) has shown benefits compared to static cold storage (SCS) by limiting ischemia-reperfusion injury. This study reports outcomes using a novel portable HMP-O 2 device in the first US randomized control trial.

APPROACH AND RESULTS

The PILOT trial (NCT03484455) was a multicenter, randomized, open-label, noninferiority trial, with participants randomized to HMP-O 2 or SCS. HMP-O 2 livers were preserved using the Lifeport Liver Transporter and Vasosol perfusion solution. The primary outcome was early allograft dysfunction. Noninferiority margin was 7.5%. From April 3, 2019, to July 12, 2022, 179 patients were randomized to HMP-O 2 (n=90) or SCS (n=89). The per-protocol cohort included 63 HMP-O 2 and 73 SCS. Early allograft dysfunction occurred in 11.1% HMP-O 2 (N=7) and 16.4% SCS (N=12). The risk difference between HMP-O 2 and SCS was -5.33% (one-sided 95% upper confidence limit of 5.81%), establishing noninferiority. The risk of graft failure as predicted by Liver Graft Assessment Following Transplant score at seven days (L-GrAFT 7 ) was lower with HMP-O 2 [median (IQR) 3.4% (2.4-6.5) vs. 4.5% (2.9-9.4), p =0.024]. Primary nonfunction occurred in 2.2% of all SCS (n=3, p =0.10). Biliary strictures occurred in 16.4% SCS (n=12) and 6.3% (n=4) HMP-O 2 ( p =0.18). Nonanastomotic biliary strictures occurred only in SCS (n=4).

CONCLUSIONS

HMP-O 2 demonstrates safety and noninferior efficacy for liver graft preservation in comparison to SCS. Early allograft failure by L-GrAFT 7 was lower in HMP-O 2 , suggesting improved early clinical function. Recipients of HMP-O 2 livers also demonstrated a lower incidence of primary nonfunction and biliary strictures, although this difference did not reach significance.

Benefits of Hypothermic Oxygenated Perfusion Versus Static Cold Storage in Liver Transplant: A Comprehensive Systematic Review and Meta-analysis

Background

The magnitude of potential benefits that hypothermic oxygenated perfusion (HOPE) may provide for liver transplantation (LT) patients compared to static cold storage (SCS) remains uncertain. In this systematic review and meta-analysis, we aimed to investigate the therapeutic effect that HOPE can offer LT recipients relative to SCS by synthesizing available evidence.

Methods

A literature search was conducted in Embase, Medline, Web of Science, and the Cochrane database up to 1 June, 2023. The included studies were pooled for meta-analysis to synthesize their findings. Subgroup analysis was performed to investigate potential differences between HOPE and SCS for specific subgroups.

Results

A total of 11 studies comprising 1765 patients were included. Compared with SCS, HOPE was associated with a significant reduction in the incidence of early allograft dysfunction (EAD) (OR: 0.36, 95% CI: 0.26-0.50), as well as a noteworthy decrease in graft loss rate within one year (OR: 0.57, 95% CI: 0.33-0.97) and a lower occurrence of Clavien-Dindo grade IIIa or higher complications (OR: 0.62, 95% CI: 0.43-0.89). Subgroup analysis revealed that HOPE significantly reduced the one-year mortality rate, any biliary complications incidence, and acute rejection of transplanted liver rate in patients who received organs from donation after cardiac death (DCD).

Conclusions

HOPE has demonstrated efficacy in reducing the incidence of EAD after LT and shows some potential in diminishing postoperative complications such as biliary complications and acute rejection. This ultimately leads to improved patient prognosis, particularly among those receiving DCD grafts.

Donor heart dysfunction and graft survival in liver and kidney transplants-A register-based study from Sweden

BACKGROUND AND AIM

Stress cardiomyopathy in donors can potentially affect graft function and longevity. This study aims to investigate the association between echocardiographic left ventricular ejection fraction (LVEF) < 50%, and/or the presence of left ventricular regional wall motion abnormalities (RWMA) in organ donors, and short- and long-term liver and kidney graft survival. Our secondary aim was to link graft survival with donor and recipient characteristics.

METHODS

All donors considered for liver and kidney donation with echocardiographic records at Sahlgrenska University Hospital between 2006 and 2016 were matched with their recipients through the Scandiatransplant register. The studied outcomes were graft survival, re-transplantation, and recipient death. Kaplan-Meier curves were used to plot time to event. Multivariate Cox-regression was used to test independence.

RESULTS

There were 370 liver donors and 312 kidney donors (matched with 458 recipients) with echocardiographic records at Sahlgrenska University Hospital between June 2006 and November 2016. Of patients with LV dysfunction by echocardiography, there were 102 liver- and 72 kidney donors. Univariate survival analyses showed no statistical difference in the short- and long-term graft survival from donors with LV dysfunction compared to donors without. Donor age > 65 years, recipient re-transplantation and recipient liver tumor were predictors of worse outcome in liver transplants (p < .05). Donor age > 65, donor hypertension, recipient re-transplantation, and a recipient diagnosis of diabetes or nephritis/glomerulonephritis had a negative association with graft survival in kidney transplants (p < .05).

CONCLUSION

We found no significant association between donor LV dysfunction and short- and long-term graft survival in liver and kidney transplants, suggesting that livers and kidneys from such donors can be safely transplanted.

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?

Liver machine perfusion technology: Expanding the donor pool to improve access to liver transplantation

The imbalance between organ supply and demand continues to limit the broader benefits of organ transplantation. Machine perfusion (MP) may increase the supply of donor livers by expanding the use of extended-criteria donors. Using the United Network for Organ Sharing/Organ Procurement and Transplantation Network and the Standard Transplant Analysis and Research dataset, we reviewed the effect of MP implementation on the behavior of transplant centers. We identified 15 high-utilizing MP centers that were matched to suitable controls based on volume and geographical proximity. We conducted a differences-in-differences analysis using linear regression to estimate the impact of MP adoption on the transplant centers' donor utilization. We found a significant increase in cold ischemia time and organs with donor warm ischemia time over 30 minutes (P < .05). After removing one outlier center, the analysis showed that these centers through MP accepted overall more donation after circulatory death donors, donation after circulatory death donors over 50 years old, donors with macrovesicular steatosis greater than 30% on liver biopsy, and donor warm ischemia time over 30 minutes (P < .05). MP has allowed centers to expand their use of extended-criteria donors beyond traditional cutoffs and to increase patient access to liver transplantation.

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.

Improved outcomes after hypothermic oxygenated machine perfusion in liver transplantation-Long-term follow-up of a multicenter randomized controlled trial

BACKGROUND

While 4 randomized controlled clinical trials confirmed the early benefits of hypothermic oxygenated machine perfusion (HOPE), high-level evidence regarding long-term clinical outcomes is lacking. The aim of this follow-up study from the HOPE-ECD-DBD trial was to compare long-term outcomes in patients who underwent liver transplantation using extended criteria donor allografts from donation after brain death (ECD-DBD), randomized to either HOPE or static cold storage (SCS).

METHODS

Between September 2017 and September 2020, recipients of liver transplantation from 4 European centers receiving extended criteria donor-donation after brain death allografts were randomly assigned to HOPE or SCS (1:1). Follow-up data were available for all patients. Analyzed endpoints included the incidence of late-onset complications (occurring later than 6 months and graded according to the Clavien-Dindo Classification and the Comprehensive Complication Index) and long-term graft survival and patient survival.

RESULTS

A total of 46 patients were randomized, 23 in both arms. The median follow-up was 48 months (95% CI: 41-55). After excluding early perioperative morbidity, a significant reduction in late-onset morbidity was observed in the HOPE group (median reduction of 23 Comprehensive Complication Index-points [p=0.003] and lower incidence of major complications [Clavien-Dindo ≥3, 43% vs. 85%, p=0.009]). Primary graft loss occurred in 13 patients (HOPE n=3 vs. SCS n=10), resulting in a significantly lower overall graft survival (p=0.029) and adverse 1-, 3-, and 5-year survival probabilities in the SCS group, which did not reach the level of significance (HOPE 0.913, 0.869, 0.869 vs. SCS 0.783, 0.606, 0.519, respectively).

CONCLUSIONS

Our exploratory findings indicate that HOPE reduces late-onset morbidity and improves long-term graft survival providing clinical evidence to further support the broad implementation of HOPE in human liver transplantation.

Role of Machine Perfusion in Liver Transplantation

Given the current severe shortage of available livers for transplantation, there is an urgent need to maximize the utilization of donor organs. One of the strategies to increase the number of available livers for transplantation is to improve organ utilization through the use of elderly, overweight, or organs donated after circulatory death. However, the utilization of these "marginal" organs was associated with an increased risk of early allograft dysfunction, primary nonfunction, ischemic biliary complications, or even re-transplantation. Ischemia-reperfusion injury is a key mechanism in the pathogenesis of these complications.

Donation After Circulatory Death Liver Transplantation: Early Challenges, Clinical Improvement, and Future Directions

Donation after circulatory death (DCD) liver allografts remain a widely underutilized source of donor organs for transplantation. Although initially linked with inferior outcomes, DCD liver transplant can achieve excellent patient and graft survival with suitable matching of donor and recipient characteristics, rapid donor recovery and precise donor assessment, and appropriate perioperative management. The advent of clinical liver perfusion modalities promises to redefine the viability parameters for DCD liver allografts and hopefully will encourage more widespread usage of this growing source of donor livers.

Liver transplantation with uncontrolled versus controlled DCD donors using normothermic regional perfusion and ex-situ machine perfusion

In Italy, 20 minutes of continuous, flat-line electrocardiogram are required for death declaration, which significantly increases the risks of donation after circulatory death (DCD) LT. Despite prolonged warm ischemia time, Italian centers reported good outcomes in controlled donation after circulatory death LT by combining normothermic regional and end-ischemic machine perfusion. However, data on uncontrolled DCD (uDCD) LT performed by this approach are lacking. This was a multicenter, retrospective study performed at 3 large-volume centers comparing clinical outcomes of uncontrolled versus controlled DCD LT. The aim of the study was to assess outcomes of sequential normothermic regional perfusion and end-ischemic machine perfusion in uncontrolled DCD liver transplantation (LT). Of 153 DCD donors evaluated during the study period, 40 uDCD and 59 donation after circulatory death grafts were transplanted (utilization rate 52% vs. 78%, p = 0.004). Recipients of uDCD grafts had higher MEAF (4.9 vs. 3.5, p < 0.001) and CCI scores at discharge (24.4 vs. 8.7, p = 0.026), longer ICU stay (5 vs. 4 d, p = 0.047), and a trend toward more severe AKI. At multivariate analysis, 90-day graft loss was associated with recipient BMI and lactate downtrend during normothermic regional perfusion. One-year graft survival was lower in uDCD (75% vs. 90%, p = 0.007) but became comparable when non-liver-related graft losses were treated as censors (77% vs. 90%, p = 0.100). The incidence of ischemic cholangiopathy was 10% in uDCD versus 3% in donation after circulatory death, p = 0.356. uDCD LT with prolonged warm ischemia is feasible by the sequential use of normothermic regional perfusion and end-ischemic machine perfusion. Proper donor and recipient selection are key to achieving good outcomes in this setting.

Hypothermic oxygenated perfusion in liver transplantation: a meta-analysis of randomized controlled trials and matched studies

BACKGROUND

Hypothermic oxygenated machine perfusion (HOPE) is a novel organ-preservation technology designed to optimize organ quality. However, the effects of HOPE on morbidity and mortality after liver transplantation remain unclear. This meta-analysis evaluated the potential benefits of HOPE in liver transplantation.

MATERIALS AND METHODS

The Embase, Web of Science, PubMed, Cochrane Library, and Scopus databases were searched for articles published up to 15 June 2023 (updated on 12 August 2023). Mean differences (MDs), risk ratios (RRs), and 95% confidence intervals were calculated.

RESULTS

Eleven studies encompassing five randomized controlled trials and six matched studies were included, with a total of 1000 patients. HOPE did not reduce the incidence of major postoperative complications (RR 0.80), primary non-function (PNF) (RR 0.54), reperfusion syndrome (RR 0.92), hepatic artery thrombosis (RR 0.92), renal replacement therapy (RR 0.98), length of hospital stay (MD, -1.38 days), 1-year recipient death (RR 0.67), or intensive care unit stay (MD, 0.19 days) after liver transplantation. HOPE reduced the incidence of biliary complications (RR 0.74), non-anastomotic biliary strictures (NAS) (RR 0.34), early allograft dysfunction (EAD) (RR 0.54), and acute rejection (RR 0.54). In addition, HOPE improved the retransplantation (RR 0.42) and 1-year graft loss rates (RR 0.38).

CONCLUSIONS

Compared with static cold storage (SCS), HOPE can reduce the incidence of biliary complications, NAS, EAD, and acute rejection and retransplantation rate after liver transplantation and improve the 1-year graft loss rate. These findings suggest that HOPE, when compared to SCS, can contribute to minimizing complications and enhancing graft survival in liver transplantation. Further research is needed to investigate long-term outcomes and confirm the promising advantages of HOPE in liver transplantation settings.

Progress in preservation of intestinal grafts by oxygenated hypothermic machine perfusion

Intestine transplantation (IT) is a critical treatment strategy for irreversible intestinal failure. Among all abdominal solid organ transplants, the intestine was the most vulnerable to ischemia and reperfusion injury (IRI). The static cold storage (SCS) technique is currently the most commonly used graft preservation method, but its hypoxia condition causes metabolic disorders, resulting in the occurrence of IRI, limiting its application in marginal organs. It is especially important to improve preservation techniques in order to minimize damage to marginal donor organs, which draws more attention to machine perfusion (MP). There has been much debate about whether it is necessary to increase oxygen in these conditions to support low levels of metabolism since the use of machine perfusion to preserve organs. There is evidence that oxygenation helps to restore intracellular ATP levels in the intestine after thermal or cold ischemia damage. The goal of this review is to provide an overview of the role of oxygen in maintaining environmental stability in the gut under hypoxic conditions, as well as to investigate the possibilities and mechanisms of oxygen delivery during preservation in intestine transplantation studies and clinical models.

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.

End-ischemic hypothermic oxygenated machine perfusion does not improve renal outcome following liver transplantation from aged donors: A single-center retrospective report

BACKGROUND

Organ transplantation using grafts from elderly donors entails a higher risk for severe ischemia-reperfusion injury (IRI). Advanced IRI after liver transplantation (LT) seems to be associated with the development of acute kidney injury (AKI). We studied if end-ischemic hypothermic oxygenated machine perfusion (HOPE) of liver grafts, aimed at mitigating liver IRI, impacts on the frequency and severity of AKI after LT.

METHODS

LTs performed at our center between January 2017 and December 2022 using organs from deceased brain-dead donors aged 70 or older were reviewed. From November 2020 on, HOPE was performed routinely in this donor category. The frequency and severity of AKI (KDIGO criteria) within 48 hours of graft reperfusion and the model of early allograft function (MEAF) were compared between HOPE-LTs (n = 30) and control LTs (n = 71).

RESULTS

AKI developed in 23/30 (77%) HOPE-LTs and in 40/71 (56%) control LTs (p = n.s.), with no difference in severity and timing between groups. Renal replacement therapy was required in 3/30 (10%) HOPE-LTs and 6/71 (8%) control LTs. In addition, transaminase leak during the first week (marker of IRI) and MEAF were similar between groups. These findings persisted after propensity matching. Histology showed more hepatocyte vacuolization and higher Suzuki score in HOPE-LTs. Although this analysis could have been underpowered, no trends supporting the benefit of HOPE on liver and renal injury after LT were ever identified.

CONCLUSIONS

In conclusion, HOPE in this group of older donors does not seem to improve either graft IRI, or the incidence of early AKI after LT.

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.

Factors associated with mechanical ventilation longer than 24 h after liver transplantation in patients at risk for bleeding

BACKGROUND

This risk analysis aimed to explore all modifiable factors associated with prolonged mechanical ventilation (lasting > 24 h) after liver transplantation, based on prospectively collected data from a clinical trial.

METHODS

We evaluated 306 candidates. Ninety-three patients were excluded for low risk for transfusion (preoperative haemoglobin > 130 g.l-1), and 31 patients were excluded for anticoagulation therapy, bleeding disorders, familial polyneuropathy, or emergency status. Risk factors were initially identified with a log-binomial regression model. Relative risk was then calculated and adjusted for age, sex, and disease severity (Model for End-Stage Liver Disease [MELD] score).

RESULTS

Early tracheal extubation was performed in 149 patients (84.7%), and 27 patients (15.3%) required prolonged mechanical ventilation. Reoperations were required for 6.04% of the early extubated patients and 44% of patients who underwent prolonged ventilation (p = 0.001). A MELD score > 23 was the main risk factor for prolonged ventilation. Once modifiable risk factors were adjusted for MELD score, sex, and age, three factors were significantly associated with prolonged ventilation: tranexamic acid (p = 0.007) and red blood cell (p = 0.001) infusion and the occurrence of postreperfusion syndrome (p = 0.004). The median (IQR) ICU stay was 3 (2-4) days in the early extubation group vs. 5 (3-10) days in the prolonged ventilation group (p = 0.001). The median hospital stay was also significantly shorter after early extubation, at 14 (10-24) days, vs. 25 (14-55) days in the prolonged ventilation group (p = 0.001). Eight patients in the early-extubation group (5.52%) were readmitted to the ICU, nearly all for reoperations, with no between-group differences in ICU readmissions (prolonged ventilation group, 3.7%).

CONCLUSION

We conclude that bleeding and postreperfusion syndrome are the main modifiable factors associated with prolonged mechanical ventilation and length of ICU stay, suggesting that trials should explore vasopressor support strategies and other interventions prior to graft reperfusion that might prevent potential fibrinolysis.

TRIAL REGISTRATION

European Clinical Trials Database (EudraCT 2018-002510-13,) and on ClinicalTrials.gov (NCT01539057).

The yesterday, today and tomorrow of liver transplant

With a very long history of setbacks and successes, organ transplantation is one of the greatest medical achievements of the twentieth century. Liver transplantation is currently the most effective method for treating end-stage liver disease. From humble beginnings, improvements in surgical technique, perioperative management, and immunosuppressive therapy have yielded excellent graft and patient outcomes. Most established 'liver transplant' (LT) centres have a 1-year survival rate exceeding 90%, and a 3-year survival rate of over 80%. With immense success, the need for hepatic grafts substantially exceeds their availability. This problem has been partially addressed by using split grafts, living donor liver transplantation (LDLT), and extended criteria grafts (ECG). This article reviews the immense progress made in various aspects of LT including evaluation, increasing donor pool, surgical advances, immunosuppression and anaesthesia related aspects and the way forward. With ongoing cutting edge research in technologies like artificial liver devices, tissue bioengineering and hepatocyte 'farms', the future of LT is more exciting than ever before.

Pushing the boundaries of innovation: the potential of ex vivo organ perfusion from an interdisciplinary point of view

Ex vivo machine perfusion (EVMP) is an emerging technique for preserving explanted solid organs with primary application in allogeneic organ transplantation. EVMP has been established as an alternative to the standard of care static-cold preservation, allowing for prolonged preservation and real-time monitoring of organ quality while reducing/preventing ischemia-reperfusion injury. Moreover, it has paved the way to involve expanded criteria donors, e.g., after circulatory death, thus expanding the donor organ pool. Ongoing improvements in EVMP protocols, especially expanding the duration of preservation, paved the way for its broader application, in particular for reconditioning and modification of diseased organs and tumor and infection therapies and regenerative approaches. Moreover, implementing EVMP for in vivo-like preclinical studies improving disease modeling raises significant interest, while providing an ideal interface for bioengineering and genetic manipulation. These approaches can be applied not only in an allogeneic and xenogeneic transplant setting but also in an autologous setting, where patients can be on temporary organ support while the diseased organs are treated ex vivo, followed by reimplantation of the cured organ. This review provides a comprehensive overview of the differences and similarities in abdominal (kidney and liver) and thoracic (lung and heart) EVMP, focusing on the organ-specific components and preservation techniques, specifically on the composition of perfusion solutions and their supplements and perfusion temperatures and flow conditions. Novel treatment opportunities beyond organ transplantation and limitations of abdominal and thoracic EVMP are delineated to identify complementary interdisciplinary approaches for the application and development of this technique.

Viability assessment of livers donated after circulatory determination of death during normothermic regional perfusion

BACKGROUND

Abdominal normothermic regional perfusion (A-NRP) allows in-situ reperfusion and recovery of abdominal organs metabolism in donors after circulatory death (DCD). Besides improving liver transplantation outcomes, liver injury and function can be assessed during A-NRP.

METHODS

To refine liver viability assessment during A-NRP, prospectively collected data of controlled DCD donors managed at our Institution between October 2019 and May 2022 were retrospectively analyzed. Baseline characteristics, procedural variables and A-NRP parameters of donors whose liver was successfully transplanted were compared to those of donors whose liver was discarded.

RESULTS

Twenty-seven donors were included and in 20 (74%) the liver was accepted (positive outcome). No differences between study groups were observed concerning baseline characteristics and warm ischemia times (WIT). Initial lactate levels were positively correlated with functional WIT (r2  = 0.4, p = 0.04), whereas transaminase levels were not. Blood flow during A-NRP was comparable, whereas oxygen consumption (VO2 ) was significantly higher in the positive outcome group after 1 h. Time courses of lactate, AST and ALT were significantly different between study groups (p < 0.001). Donors whose liver was accepted showed faster lactate clearance, a difference which was amplified by normalizing lactate clearance to oxygen delivery (DO2 ) and VO2 . Lactate clearance was correlated to transaminase levels and DO2 -normalized lactate clearance was the parameter best discriminating between study groups.

CONCLUSIONS

DO2 -normalized lactate clearance may represent an element of liver viability assessment during A-NRP.

Complications in Post-Liver Transplant Patients

Liver transplantation (LT) is the treatment of choice for liver failure and selected cases of malignancies. Transplantation activity has increased over the years, and indications for LT have been widened, leading to organ shortage. To face this condition, a high selection of recipients with prioritizing systems and an enlargement of the donor pool were necessary. Several authors published their case series reporting the results obtained with the use of marginal donors, which seem to have progressively improved over the years. The introduction of in situ and ex situ machine perfusion, although still strongly debated, and better knowledge and treatment of the complications may have a role in achieving better results. With longer survival rates, a significant number of patients will suffer from long-term complications. An extensive review of the literature concerning short- and long-term outcomes is reported trying to highlight the most recent findings. The heterogeneity of the behaviors within the different centers is evident, leading to a difficult comparison of the results and making explicit the need to obtain more consent from experts.

Beneficial Effects of Combined Use of Extracorporeal Membrane Oxygenation and Hypothermic Machine Perfusion in Porcine Donors after Cardiac Death for Liver Transplantation

Grafts from donors after cardiac death (DCD) have greatly contributed to expanding the donor organ pool. This study aimed to determine the benefits of subnormothermic extracorporeal membrane oxygenation (ECMO) and hypothermic machine perfusion (HMP) in a porcine model of DCD liver. Female domestic crossbred Large Yorkshire and Landrace pigs weighing approximately 20 kg were used. The abdominal aorta and inferior vena cava were cannulated and connected to an ECMO circuit for in situ perfusion of the abdominal organs at 22 °C for 60 min, 45 min after cardiac death. The pigs were divided into the cold storage (CS) group (n = 3), where liver grafts were preserved at 4 °C, and the HMP group (n = 3), where liver grafts were preserved by HMP at 8-10 °C. After 4 h of preservation, liver function was evaluated using an isolated liver reperfusion model for 2 h. Although the difference was insignificant, the liver effluent enzyme levels in the HMP group were lower than those in the CS group. Furthermore, morphological findings showed fewer injured hepatocytes in the HMP group than in the CS group. The combined use of in situ subnormothermic ECMO and HMP was beneficial for the functional improvement of DCD liver grafts.

Beyond the Concepts of Elder and Marginal in DCD Liver Transplantation: A Prospective Observational Matched-Cohort Study in the Italian Clinical Setting

Donation after circulatory determination of death (DCD) is a valuable strategy to increase the availability of grafts for liver transplantation (LT). As the average age of populations rises, the donor pool is likely to be affected by a potential increase in DCD donor age in the near future. We conducted a prospective cohort study to evaluate post-transplantation outcomes in recipients of grafts from elderly DCD donors compared with younger DCD donors, and elderly donors after brainstem determination of death (DBD). From August 2020 to May 2022, consecutive recipients of deceased donor liver-only transplants were enrolled in the study. DCD recipients were propensity score matched 1:3 to DBD recipients. One-hundred fifty-seven patients were included, 26 of whom (16.6%) were transplanted with a DCD liver graft. After propensity score matching and stratification, three groups were obtained: 15 recipients of DCD donors ≥75 years, 11 recipients of DCD donors <75 years, and 28 recipients of DBD donors ≥75 years. Short-term outcomes, as well as 12 months graft survival rates (93.3%, 100%, and 89.3% respectively), were comparable among the groups. LT involving grafts retrieved from very elderly DCD donors was feasible and safe in an experienced high-volume center, with outcomes comparable to LTs from younger DCD donors and age-matched DBD donors.

Liver Transplantation for Colorectal Liver Metastases: Is It Appropriate?

Colorectal cancer with liver metastases is a condition with significant morbidity and mortality that affects many people around the world. Many treatments exist to target liver metastases, including surgical resection, chemotherapy, nonsurgical liver-directed therapies, and liver transplantation. The field of transplant oncology is emerging as a promising alternative to palliative chemotherapy alone in appropriately selected patients. Though few clinical trials have been completed to evaluate safety of liver transplant for colorectal cancer metastases, there are several ongoing trials to hopefully make transplant a viable option for more patients with limited options.

Acute rejection after liver transplantation with machine perfusion versus static cold storage: A systematic review and meta-analysis

BACKGROUND AND AIMS

Acute cellular rejection (ACR) is a frequent complication after liver transplantation. By reducing ischemia and graft damage, dynamic preservation techniques may diminish ACR. We performed a systematic review to assess the effect of currently tested organ perfusion (OP) approaches versus static cold storage (SCS) on post-transplant ACR-rates.

APPROACH AND RESULTS

A systematic search of Medline, Embase, Cochrane Library, and Web of Science was conducted. Studies reporting ACR-rates between OP and SCS and comprising at least 10 liver transplants performed with either hypothermic oxygenated perfusion (HOPE), normothermic machine perfusion, or normothermic regional perfusion were included. Studies with mixed perfusion approaches were excluded. Eight studies were identified (226 patients in OP and 330 in SCS). Six studies were on HOPE, one on normothermic machine perfusion, and one on normothermic regional perfusion. At meta-analysis, OP was associated with a reduction in ACR compared with SCS [OR: 0.55 (95% CI, 0.33-0.91), p =0.02]. This effect remained significant when considering HOPE alone [OR: 0.54 (95% CI, 0.29-1), p =0.05], in a subgroup analysis of studies including only grafts from donation after cardiac death [OR: 0.43 (0.20-0.91) p =0.03], and in HOPE studies with only donation after cardiac death grafts [OR: 0.37 (0.14-1), p =0.05].

CONCLUSIONS

Dynamic OP techniques are associated with a reduction in ACR after liver transplantation compared with SCS. PROSPERO registration: CRD42022348356.

Maximizing the Donor Potential for Patients with Acute-on-Chronic Liver Failure Listed for Liver Transplant

Owing to inherent limitations of static cold storage, marginal liver grafts from donors after circulatory death and extended criteria donors after brain death are prone to be discarded secondary to the increased risk of severe early allograft dysfunction and ischemic cholangiopathy. Marginal liver grafts resuscitated with hypothermic machine perfusion and normothermic machine perfusion demonstrate lower degree of ischemia-reperfusion injury and have decreased risk of severe early allograft dysfunction and ischemic cholangiopathy. Marginal grafts preserved by ex vivo machine perfusion technology can be used to rescue patients with acute-on-chronic liver failure who are underserved by the current deceased donor liver allocation system.

Comparative Analysis of Donor Liver Allograft Outcomes in Hepatocellular Carcinoma Patients Who Underwent Liver Transplant

OBJECTIVES

Liver transplant for patients with hepatocellular carcinoma involves 3 main types of donor allografts: donation after brain death, donation after cardiac death, and donation after brain and cardiac death. Data on this topic are limited, and controversies exist regarding liver transplant outcomes in hepatocellular carcinoma patients who have received these allografts.

MATERIALS AND METHODS

Data from 490 hepatocellular carcinoma patients who received liver transplant from 2015 to 2021 at the Shulan (Hangzhou) Hospital were retrospectively analyzed. Participants were divided into 3 cohorts according to allograft type: donation after brain death, donation after cardiac death, and donation after brain and cardiac death. Kaplan-Meier and Cox regression methods were used to evaluate patient survival, graft survival, and recurrence-free survival rates after liver transplant.

RESULTS

Kaplan-Meier analysis revealed that 3-year patient survival rates were 69.2% for donations after brain death, 69.2% for donations after cardiac death, and 46.6% for donations after brain and cardiac death (P = .42); the 3-year graft survival rates were 53.3% for donations after brain death, 56.4% for donations after cardiac death, and 46.6% for donations after brain and cardiac death (P = .44); and 3-year recurrence-free survival rates were 55% for donations after brain death, 56.6% for donations after cardiac death, and 39.5% for donations after brain and cardiac death (P = .46). Complications were also similar across the 3 cohorts (P = .36). Multivariable analysis showed that intraoperative red blood cell transfusion (hazard ratio: 1.820; P = .042) and early allograft dysfunction (hazard ratio: 3.240; P = .041) were independent risk factors for graft survival.

CONCLUSIONS

Similar outcomes can be achieved for hepatocellular carcinoma patients who undergo liver transplant with donations after brain death, donations after cardiac death, or donations after brain and cardiac death allografts, especially when strict donor selection criteria are applied.

Hypothermic oxygenated perfusion attenuates DCD liver ischemia-reperfusion injury by activating the JAK2/STAT3/HAX1 pathway to regulate endoplasmic reticulum stress

BACKGROUND

Hepatic ischemia-reperfusion injury (IRI) in donation after cardiac death (DCD) donors is a major determinant of transplantation success. Endoplasmic reticulum (ER) stress plays a key role in hepatic IRI, with potential involvement of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway and the antiapoptotic protein hematopoietic-lineage substrate-1-associated protein X-1 (HAX1). In this study, we aimed to investigate the effects of hypothermic oxygenated perfusion (HOPE), an organ preservation modality, on ER stress and apoptosis during hepatic IRI in a DCD rat model.

METHODS

To investigate whether HOPE could improve IRI in DCD livers, levels of different related proteins were examined by western blotting and quantitative real-time polymerase chain reaction. Further expression analyses, immunohistochemical analyses, immunofluorescence staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, and transmission electron microscopy were conducted to analyze the effects of HOPE on ER stress and apoptosis. To clarify the role of the JAK2/STAT3 pathway and HAX1 in this process, AG490 inhibitor, JAX1 plasmid transfection, co-immunoprecipitation (CO-IP), and flow cytometry analyses were conducted.

RESULTS

HOPE reduced liver injury and inflammation while alleviating ER stress and apoptosis in the DCD rat model. Mechanistically, HOPE inhibited unfolded protein responses by activating the JAK2/STAT3 pathway, thus reducing ER stress and apoptosis. Moreover, the activated JAK2/STAT3 pathway upregulated HAX1, promoting the interaction between HAX1 and SERCA2b to maintain ER calcium homeostasis. Upregulated HAX1 also modulated ER stress and apoptosis by inhibiting the inositol-requiring enzyme 1 (IRE1) pathway.

CONCLUSIONS

JAK2/STAT3-mediated upregulation of HAX1 during HOPE alleviates hepatic ER stress and apoptosis, indicating the JAK2/STAT3/HAX1 pathway as a potential target for IRI management during DCD liver transplantation.

How to Preserve Steatotic Liver Grafts for Transplantation

Liver allograft steatosis is a significant risk factor for postoperative graft dysfunction and has been associated with inferior patient and graft survival, particularly in the case of moderate or severe macrovesicular steatosis. In recent years, the increasing incidence of obesity and fatty liver disease in the population has led to a higher proportion of steatotic liver grafts being used for transplantation, making the optimization of their preservation an urgent necessity. This review discusses the mechanisms behind the increased susceptibility of fatty livers to ischemia-reperfusion injury and provides an overview of the available strategies to improve their utilization for transplantation, with a focus on preclinical and clinical evidence supporting donor interventions, novel preservation solutions, and machine perfusion techniques.

Exploration of Optimal pH in Hypothermic Machine Perfusion for Rat Liver Grafts Retrieved after Circulatory Death

Ex vivo hypothermic machine perfusion (HMP) is a strategy for controlling ischemia-reperfusion injury in donation after circulatory death (DCD) liver transplantation. The pH of blood increases with a decrease in temperature and water dissociation, leading to a decrease in [H⁺]. This study aimed to verify the optimal pH of HMP for DCD livers. Rat livers were retrieved 30 min post-cardiac arrest and subjected to 3-h cold storage (CS) in UW solution (CS group) or HMP with UW-gluconate solution (machine perfusion [MP] group) of pH 7.4 (original), 7.6, 7.8, and 8.0 (MP-pH 7.6, 7.8, 8.0 groups, respectively) at 7-10 °C. The livers were subjected to normothermic perfusion to simulate reperfusion after HMP. All HMP groups showed greater graft protection compared to the CS group due to the lower levels of liver enzymes in the former. The MP-pH 7.8 group showed significant protection, evidenced by bile production, diminished tissue injury, and reduced flavin mononucleotide leakage, and further analysis by scanning electron microscopy revealed a well-preserved structure of the mitochondrial cristae. Therefore, the optimum pH of 7.8 enhanced the protective effect of HMP by preserving the structure and function of the mitochondria, leading to reduced reperfusion injury in the DCD liver.

Center expansion of liver transplants using donation after circulatory death organs is associated with reduced overall waitlist mortality

INTRODUCTION

Waitlist outcomes in liver transplantation (LT) for individual recipients are improved by use of allografts procured through donation after circulatory death (DCD). However, the impact of increased DCD acceptance on overall center outcomes is unknown.

METHODS

Using the United Network for Organ Sharing database, 88 centers performing an average of ≥10 LTs/year between 1/2004 and 12/2019 were compared by percent DCD use quartile and categorized into four phenotypes according to temporal usage trends. Overall center median Model for End-stage Liver Disease at LT (MMaT), waitlist mortality, and waiting time were evaluated.

RESULTS

The overall DCD rate was 6.1% (N = 4906/80,709), ranging from 0% to 25.5%. Centers in the top DCD use quartile had lower MMaT (24 vs. 26; p < .001) and shorter overall waiting times (median 66 days vs. 90 days; p < .001) compared to bottom quartile centers. MMaT increased less over time at centers with increasing DCD use and was lower than at centers with declining DCD use (27 vs. 32; p = .017). Overall waitlist mortality between 2016 and 2019 was lower at increasing DCD use centers (17.8% vs. 22.5%, p = .034), yet did not affect 1-year mortality (p = .747).

CONCLUSIONS

The improved waitlist outcomes at centers with expanded DCD use extend beyond DCD recipients alone without negative consequences to overall post-LT center metrics.

Donation after circulatory death: Novel strategies to improve the liver transplant outcome

In many countries, donation after circulatory death (DCD) liver grafts are used to overcome organ shortages; however, DCD grafts have been associated with an increased risk of complications and even graft loss after liver transplantation. The increased risk of complications is thought to correlate with prolonged functional donor warm ischaemia time. Stringent donor selection criteria and utilisation of in situ and ex situ organ perfusion technologies have led to improved outcomes. Additionally, the increased use of novel organ perfusion strategies has led to the possibility of reconditioning marginal DCD liver grafts. Moreover, these technologies enable the assessment of liver function before implantation, thus providing valuable data that can guide more precise graft-recipient selection. In this review, we first describe the different definitions of functional warm donor ischaemia time and its role as a determinant of outcomes after DCD liver transplantation, with a focus on the thresholds proposed for graft acceptance. Next, organ perfusion strategies, namely normothermic regional perfusion, hypothermic oxygenated perfusion, and normothermic machine perfusion are discussed. For each technique, clinical studies reporting on the transplant outcome are described, together with a discussion on the possible protective mechanisms involved and the functional criteria adopted for graft selection. Finally, we review multimodal preservation protocols involving a combination of more than one perfusion technique and potential future directions in the field.

Machine perfusion and the prevention of ischemic type biliary lesions following liver transplant: What is the evidence?

The widespread uptake of different machine perfusion (MP) strategies for liver transplant has been driven by an effort to minimize graft injury. Damage to the cholangiocytes during the liver donation, preservation, or early posttransplant period may result in stricturing of the biliary tree and inadequate biliary drainage. This problem continues to trouble clinicians, and may have catastrophic consequences for the graft and patient. Ischemic injury, as a result of compromised hepatic artery flow, is a well-known cause of biliary strictures, sepsis, and graft failure. However, very similar lesions can appear with a patent hepatic artery and these are known as ischemic type biliary lesions (ITBL) that are attributed to microcirculatory dysfunction rather than main hepatic arterial compromise. Both the warm and cold ischemic period duration appear to influence the onset of ITBL. All of the commonly used MP techniques deliver oxygen to the graft cells, and therefore may minimize the cholangiocyte injury and subsequently reduce the incidence of ITBL. As clinical experience and published evidence grows for these modalities, the impact they have on ITBL rates is important to consider. In this review, the evidence for the three commonly used MP strategies (abdominal normothermic regional perfusion [A-NRP], hypothermic oxygenated perfusion [HOPE], and normothermic machine perfusion [NMP] for ITBL prevention has been critically reviewed. Inconsistencies with ITBL definitions used in trials, coupled with variations in techniques of MP, make interpretation challenging. Overall, the evidence suggests that both HOPE and A-NRP prevent ITBL in donated after circulatory death grafts compared to cold storage. The evidence for ITBL prevention in donor after brain death grafts with any MP technique is weak.

Comparison of Different Ex-Vivo Preservation Strategies on Cardiac Metabolism in an Animal Model of Donation after Circulatory Death

Transplantation of heart following donation after circulatory death (DCD) was recently introduced into clinical practice. Ex vivo reperfusion following DCD and retrieval is deemed necessary in order to evaluate the recovery of cardiac viability after the period of warm ischemia. We tested the effect of four different temperatures (4 °C-18 °C-25 °C-35 °C) on cardiac metabolism during 3-h ex vivo reperfusion in a porcine model of DCD heart. We observed a steep fall in high-energy phosphate (ATP) concentrations in the myocardial tissue at the end of the warm ischemic time and only limited regeneration during reperfusion. Lactate concentration in the perfusate increased rapidly during the first hour of reperfusion and slowly decreased afterward. However, the temperature of the solution does not seem to have an effect on either ATP or lactate concentration. Furthermore, all cardiac allografts showed a significant weight increase due to cardiac edema, regardless of the temperature.

The Current Role and Future Applications of Machine Perfusion in Liver Transplantation

The relative paucity of donor livers suitable for transplantation has sparked innovations to preserve and recondition organs to expand the pool of transplantable organs. Currently, machine perfusion techniques have led to the improvement of the quality of marginal livers and to prolonged cold ischemia time and have allowed for the prediction of graft function through the analysis of the organ during perfusion, improving the rate of organ use. In the future, the implementation of organ modulation might expand the scope of machine perfusion beyond its current usage. The aim of this review was to provide an overview of the current clinical use of machine perfusion devices in liver transplantation and to provide a perspective for future clinical use, including therapeutic interventions in perfused donor liver grafts.

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

BACKGROUND & AIMS

Liver graft utilization rates are a hot topic due to the worldwide organ shortage and the increasing number of transplant candidates on waiting lists. Liver perfusion techniques have been introduced in several countries, and may help to increase the organ supply, as they potentially enable the assessment of livers before use.

METHODS

Liver offers were counted from donation after circulatory death (DCD) donors (Maastricht type III) arising during the past decade in eight countries, including Belgium, France, Italy, the Netherlands, Spain, Switzerland, the UK, and the US. Initial type-III DCD liver offers were correlated with accepted, recovered and implanted livers.

RESULTS

A total number of 34,269 DCD livers were offered, resulting in 9,780 liver transplants (28.5%). The discard rates were highest in the UK and US, ranging between 70 and 80%. In contrast, much lower DCD liver discard rates, e.g. between 30-40%, were found in Belgium, France, Italy, Spain and Switzerland. In addition, we observed large differences in the use of various machine perfusion techniques, as well as in graft and donor risk factors. For example, the median donor age and functional donor warm ischemia time were highest in Italy, e.g. >40 min, followed by Switzerland, France, and the Netherlands. Importantly, such varying risk profiles of accepted DCD livers between countries did not translate into large differences in 5-year graft survival rates, which ranged between 60-82% in this analysis.

CONCLUSIONS

Overall, DCD liver discard rates across the eight countries were high, although this primarily reflects the situation in the Netherlands, the UK and the US. Countries where in situ and ex situ machine perfusion strategies were used routinely had better DCD utilization rates without compromised outcomes.

IMPACT AND IMPLICATIONS

A significant number of Maastricht type III DCD livers are discarded across Europe and North America today. The overall utilization rate among eight Western countries is 28.5% but varies significantly between 18.9% and 74.2%. For example, the median DCD-III liver utilization in five countries, e.g. Belgium, France, Italy, Switzerland, and Spain is 65%, in contrast to 24% in the Netherlands, UK and US. Despite this, and despite different rules and strategies for organ acceptance and preservation, 1- and 5-year graft survival rates remain fairly similar among all participating countries. A highly varying experience with modern machine perfusion technology was observed. In situ and ex situ liver perfusion concepts, and application of assessment tools for type-III DCD livers before transplantation, may be a key explanation for the observed differences in DCD-III utilization.

Impact of Hypothermic Oxygenated Machine Perfusion on Hepatocellular Carcinoma Recurrence after Liver Transplantation

BACKGROUND

Machine perfusion may be able to mitigate ischemia-reperfusion injury (IRI), which increases hepatocellular carcinoma (HCC) recurrence after liver transplantation (LT). This study aimed to investigate the impact of dual-hypothermic oxygenated machine perfusion (D-HOPE) on HCC recurrence in LT.

METHODS

A single-center retrospective study was conducted from 2016 to 2020. Pre- and postoperative data of HCC patients undergoing LT were analyzed. Recipients of a D-HOPE-treated graft were compared to those of livers preserved using static cold storage (SCS). The primary endpoint was recurrence-free survival (RFS).

RESULTS

Of 326 patients, 246 received an SCS-preserved liver and 80 received a D-HOPE-treated graft (donation after brain death (DBD), n = 66; donation after circulatory death (DCD), n = 14). Donors of D-HOPE-treated grafts were older and had higher BMI. All DCD donors were treated by normothermic regional perfusion and D-HOPE. The groups were comparable in terms of HCC features and estimated 5-year RFS according to the Metroticket 2.0 model. D-HOPE did not reduce HCC recurrence (D-HOPE 10%; SCS 8.9%; p = 0.95), which was confirmed using Bayesian model averaging and inverse probability of treatment weighting-adjusted RFS analysis. Postoperative outcomes were comparable between groups, except for lower AST and ALT peak in the D-HOPE group.

CONCLUSIONS

In this single-center study, D-HOPE did not reduce HCC recurrence but allowed utilizing livers from extended criteria donors with comparable outcomes, improving access to LT for patients suffering from HCC.

Hepatocyte-derived extracellular vesicles miR-122-5p promotes hepatic ischemia reperfusion injury by regulating Kupffer cell polarization

Ischemia reperfusion injury remains a major barrier to liver transplantation, especially using grafts from donation after circulatory death, and it is also a pressing issue to be solved in clinical practice. Kupffer cell polarization toward a proinflammatory M1 phenotype is an early trigger of liver ischemia-reperfusion injury. However, the molecular mechanism regulating Kupffer cell polarization has not yet been fully elucidated. We induced liver ischemia reperfusion injury in mice and obtained samples from patients undergoing liver transplantation, serum and hepatocytes-derived extracellular vesicles were isolated by differential ultracentrifugation. Kupffer cell polarization was examined by flow cytometry and immunofluorescence histochemistry. RNA-seq was conducted to detect the differentially expressed miRNAs in extracellular vesicles. The role and mechanism of exosomal miR-122-5p in liver ischemia-reperfusion injury were determined both in vitro and in vivo. We identified ischemia reperfusion induced extracellular vesicles as a major cause of hepatic inflammation and tissue damage using adoptive transfer and release inhibition. The study also demonstrated that hepatocyte-derived exosomal miR-122-5p mediates liver ischemia reperfusion injury by polarizing Kupffer cell via PPARδ down-regulation and NF-κB pathway activation using profiling and functional analysis. Moreover, inhibiting miR-122-5p with antagomir suppressed Kupffer cell M1 polarization and attenuated liver ischemia reperfusion injury. Overall, our study demonstrated that hepatocyte-derived exosomal miR-122-5p played a critical role in promoting hepatic ischemia reperfusion injury through modulating PPARδ signaling and NF-κB pathway to introduce M1 polarization of Kupffer cell. Inhibition of miR-122-5p exhibited a protective effect against liver ischemia reperfusion injury, suggesting a potential therapeutic target for liver transplantation.

How Can Machine Perfusion Change the Paradigm of Liver Transplantation for Patients with Perihilar Cholangiocarcinoma?

Perihilar cholangiocarcinomas (pCCA) are rare yet aggressive tumors originating from the bile ducts. While surgery remains the mainstay of treatment, only a minority of patients are amenable to curative resection, and the prognosis of unresectable patients is dismal. The introduction of liver transplantation (LT) after neoadjuvant chemoradiation for unresectable pCCA in 1993 represented a major breakthrough, and it has been associated with 5-year survival rates consistently >50%. Despite these encouraging results, pCCA has remained a niche indication for LT, which is most likely due to the need for stringent candidate selection and the challenges in preoperative and surgical management. Machine perfusion (MP) has recently been reintroduced as an alternative to static cold storage to improve liver preservation from extended criteria donors. Aside from being associated with superior graft preservation, MP technology allows for the safe extension of preservation time and the testing of liver viability prior to implantation, which are characteristics that may be especially useful in the setting of LT for pCCA. This review summarizes current surgical strategies for pCCA treatment, with a focus on unmet needs that have contributed to the limited spread of LT for pCCA and how MP could be used in this setting, with a particular emphasis on the possibility of expanding the donor pool and improving transplant logistics.

Sequential hypothermic and normothermic perfusion preservation and transplantation of expanded criteria donor livers

BACKGROUND

The purpose of this study was to assess the safety and feasibility of sequential hypothermic oxygenated perfusion and normothermic machine perfusion and the potential benefits of graft viability preservation and assessment before liver transplantation.

METHODS

With the Food and Drug Administration and institutional review board approval, 17 expanded criteria donor livers underwent sequential hypothermic oxygenated perfusion and normothermic machine perfusion using our institutionally developed perfusion device.

RESULTS

Expanded criteria donor livers were from older donors, donors after cardiac death, with steatosis, hypertransaminasemia, or calcified arteries. Perfusion duration ranged between 1 and 2 hours for the hypothermic oxygenated perfusion phase and between 4 and 9 hours for the normothermic machine perfusion phase. Three livers were judged to be untransplantable during normothermic machine perfusion based on perfusate lactate, bile production, and macro-appearance. One liver was not transplanted because of recipient issue after anesthesia induction and failed reallocation. Thirteen livers were transplanted, including 9 donors after cardiac death livers (donor warm ischemia time 16-25 minutes) and 4 from donors after brain death. All livers had the standardized lactate clearance >60% (perfusate lactate cleared to <4.0 mmol/L) within 3 hours of normothermic machine perfusion. Bile production rate was 0.2 to 10.7 mL/h for donors after brain death livers and 0.3 to 6.1 mL/h for donors after cardiac death livers. After transplantation, 5 cases had early allograft dysfunction (3 donors after cardiac death and 2 donors after brain death livers). No graft failure or patient death has occurred during follow-up time of 6 to 13 months. Two livers developed ischemic cholangiopathy. Compared with our previous normothermic machine perfusion study, the bile duct had fewer inflammatory cells in histology, but the post-transplant outcomes had no difference.

CONCLUSION

Sequential hypothermic oxygenated perfusion and normothermic machine perfusion preservation is safe and feasible and has the potential benefits of preserving and evaluating expanded criteria donor livers.

A Review of Machine Perfusion Strategies in Liver Transplantation

The acceptance of liver transplantation as the standard of care for end-stage liver diseases has led to a critical shortage of donor allografts. To expand the donor organ pool, many countries have liberalized the donor criteria including extended criteria donors and donation after circulatory death. These marginal livers are at a higher risk of injury when they are preserved using the standard static cold storage (SCS) preservation techniques. In recent years, research has focused on optimizing organ preservation techniques to protect these marginal livers. Machine perfusion (MP) of the expanded donor liver has witnessed considerable advancements in the last decade. Research has showed MP strategies to confer significant advantages over the SCS techniques, such as longer preservation times, viability assessment and the potential to recondition high risk allografts prior to implantation. In this review article, we address the topic of MP in liver allograft preservation, with emphasis on current trends in clinical application. We discuss the relevant clinical trials related to the techniques of hypothermic MP, normothermic MP, hypothermic oxygenated MP, and controlled oxygenated rewarming. We also discuss the potential applications of ex vivo therapeutics which may be relevant in the future to further optimize the allograft prior to transplantation.

Dynamic liver preservation: Are we still missing pieces of the puzzle?

To alleviate the persistent shortage of donor livers, high-risk liver grafts are increasingly being considered for liver transplantation. Conventional preservation with static cold storage falls short in protecting these high-risk livers from ischemia-reperfusion injury, as evident from higher rates of post-transplant complications such as early allograft dysfunction and ischemic cholangiopathy. Moreover, static cold storage does not allow for a functional assessment of the liver prior to transplantation. To overcome these limitations, dynamic strategies of liver preservation have been proposed, designed to provide a protective effect while allowing pre-transplant functional assessment. In this review, we discuss how different dynamic preservation strategies exert their effects, where we stand in assessing liver function and what challenges are lying ahead.

Introducing Machine Perfusion into Routine Clinical Practice for Liver Transplantation in the United States: The Moment Has Finally Come

While adoption of machine perfusion technologies into clinical practice in the United States has been much slower than in Europe, recent changes in the transplant landscape as well as device availability following FDA approval have paved the way for rapid growth. Machine perfusion may provide one mechanism to maximize the utilization of potential donor liver grafts. Indeed, multiple studies have shown increased organ utilization with the implementation of technologies such as ex-situ normothermic machine perfusion (NMP), ex-situ hypothermic machine perfusion (HMP) and in-situ normothermic regional perfusion (NRP). The current review describes the history and development of machine perfusion utilization in the Unites States along with future directions. It also describes the differences in landscape between Europe and the United States and how this has shaped clinical application of these technologies.

Hypothermic machine perfusion alleviates ischemia-reperfusion injury of intestinal transplantation in pigs

Background

Intestinal transplantation (IT) has become an important procedure for the treatment of irreversible intestinal failure. However, IT is extremely vulnerable to ischemia-reperfusion injury (IRI). Due to the limitations of static cold storage (SCS), hypothermic machine perfusion (HMP) is rapidly gaining popularity. In this study, the intestinal HMP system is established and HMP is compared with SCS.

Methods

An intestinal HMP system was built. Ten miniature pigs were randomly divided into the HMP and SCS groups, and their intestines were perfused using the HMP device and SCS, respectively, followed by orthotopic auto-transplantation. Analysis was done on the grafts between the two groups.

Results

Operation success rates of the surgery were 100% in both groups. The 7-day survival rate was 100% in the HMP group, which was significantly higher than that of the SCS group (20%, P< 0.05). The pathological results showed that fewer injuries of grafts were in the HMP group. Endotoxin (ET), IL-1, IL-6, IFN-γ and TNF-α levels in the HMP group were significantly lower than in the SCS group (P<0.05), whereas IL-10 levels were significantly higher (P<0.05).The intestinal expression levels of ZO-1 and Occludin were higher in the HMP group compared to the SCS group, whereas Toll-like receptor 4 (TLR4), nuclear factor kappa B (NFκB), and caspase-3 were lower.

Conclusions

In this study, we established a stable intestinal HMP system and demonstrated that HMP could significantly alleviate intestinal IRI and improve the outcome after IT.

Outcomes of Liver Transplantation Using Machine Perfusion in Donation after Cardiac Death vs Brain Death in the US

BACKGROUND

Liver transplant (LT) outcomes using machine perfusion (MP) in donation after brain death (DBD) is promising, but the LT outcomes of MP in donation after cardiac death (DCD) is limited in the US. The aim of this study was to compare LT outcomes of MP between DCD and DBD.

STUDY DESIGN

We analyzed data from the United Network for Organ Sharing between 2016 and 2021 among adult LT recipients. Propensity score matching was performed to assess the outcomes between DCD and DBD.

RESULTS

A total of 380 LTs (295 from DBD and 85 from DCD) were performed using MP. When compared with DBD, DCD group had older median recipient age (61 vs 58 years, p = 0.03), higher prevalence of diabetes (41% vs 28%, p = 0.02), lower model for end-stage liver disease score (17 vs 22, p < 0.01), longer wait time (276 vs 143 days, p < 0.01) and younger median donor age (40 vs 51 years, p < 0.01). The most common primary diagnosis was alcohol-related liver disease, and hepatocellular carcinoma was more common in the DCD group (22% vs 13%). On survival analysis, 1-year overall/graft survivals (DCD 95.4% vs DBD 92.1%, p = 0.54; DCD 91.7% vs DBD 89.8%, p = 0.86) were the same. After propensity score matching, overall/graft survivals were the same. In Cox regression analysis, DCD was not an independent risk factor of mortality (hazard ratio 0.80; 95% CI 0.25 to 2.52; p = 0.70) and graft failure (hazard ratio 0.58; 95% CI 0.17 to 1.97; p = 0.38).

CONCLUSIONS

In transplant recipients who underwent LT using MP, posttransplant outcomes of overall and graft survival were similar among DCD and DBD cohorts.

The first successful report of liver transplantation from category III donation after circulatory death in South Korea: a case report

Deceased donor liver transplantation (DDLT) using donations after brain death (DBDs) has been widely performed in Korea. However, to date, there is no report regarding donation after circulatory death (DCD) category III. A 56-year-old male patient diagnosed with hepatitis B virus-associated liver cirrhosis underwent DDLT using DCD category III. The recipient's recovery was uneventful, and he was discharged on postoperative day 37. Currently, the patient is alive, with no complications 20 months after transplantation. This case suggests that DCD with LT is both feasible and safe. Further studies are required to validate this finding.

A Meta-Analysis and Systematic Review of Normothermic and Hypothermic Machine Perfusion in Liver Transplantation

BACKGROUND

The gap between the demand and supply of donor livers is still a considerable challenge. Since static cold storage is not sufficient in marginal livers, machine perfusion is being explored as an alternative. The objective of this study was to assess (dual) hypothermic oxygenated machine perfusion (HOPE/D-HOPE) and normothermic machine perfusion (NMP) in contrast to static cold storage (SCS).

METHODS

Three databases were searched to identify studies about machine perfusion. Graft and patient survival and postoperative complications were evaluated using the random effects model.

RESULTS

the incidence of biliary complications was lower in HOPE vs. SCS (OR: 0.59, 95% CI: 0.36-0.98, p = 0.04, I²: 0%). There was no significant difference in biliary complications between NMP and SCS (OR: 0.76, 95% CI: 0.41-1.40, p = 0.38, I²: 55%). Graft and patient survival were significantly better in HOPE than in SCS (HR: 0.40, 95% CI: 0.23-0.71, p = 0.002, I²: 0%) and (pooled HR: 0.43, 95% CI: 0.20-0.93, p = 0.03, I²: 0%). Graft and patient survival were not significantly different between NMP and SCS.

CONCLUSION

HOPE/D-HOPE and NMP are promising alternatives to SCS for donor liver preservation. They may help address the widening gap between the demand for and availability of donor livers by enabling the rescue and transplantation of marginal livers.