Can we prevent ischemic-type biliary lesions in donation after circulatory determination of death liver transplantation?

Does Time to Asystole in Donors After Circulatory Death Impact Recipient Outcome in Liver Transplantation?

BACKGROUND

The agonal phase can vary following treatment withdrawal in donor after circulatory death (DCD). There is little evidence to support when procurement teams should stand down in relation to donor time to death (TTD). We assessed what impact TTD had on outcomes following DCD liver transplantation.

METHODS

Data were extracted from the UK Transplant Registry on DCD liver transplant recipients from 2006 to 2021. TTD was the time from withdrawal of life-sustaining treatment to asystole, and functional warm ischemia time was the time from donor systolic blood pressure and/or oxygen saturation falling below 50 mm Hg and 70%, respectively, to aortic perfusion. The primary endpoint was 1-y graft survival. Potential predictors were fitted into Cox proportional hazards models. Adjusted restricted cubic spline models were generated to further delineate the relationship between TTD and outcome.

RESULTS

One thousand five hundred fifty-eight recipients of a DCD liver graft were included. Median TTD in the entire cohort was 13 min (interquartile range, 9-17 min). Restricted cubic splines revealed that the risk of graft loss was significantly greater when TTD ≤14 min. After 14 min, there was no impact on graft loss. Prolonged hepatectomy time was significantly associated with graft loss (hazard ratio, 1.87; 95% confidence interval, 1.23-2.83; P  = 0.003); however, functional warm ischemia time had no impact (hazard ratio, 1.00; 95% confidence interval, 0.44-2.27; P  > 0.9).

CONCLUSIONS

A very short TTD was associated with increased risk of graft loss, possibly because of such donors being more unstable and/or experiencing brain stem death as well as circulatory death. Expanding the stand down times may increase the utilization of donor livers without significantly impairing graft outcome.

First consensus document of waiting list prioritization for liver transplantation by the Spanish Society of Liver Transplantation (SETH)

Spain is worldwide leader in deceased donation rates per million habitants and count on a strong network of twenty-five liver transplant institutions. Although the access to liver transplantation is higher than in other countries, approximately 10% of patients qualifying for liver transplantation in Spain will die in the waiting list or would be excluded due to clinical deterioration. A robust waiting list prioritization system is paramount to grant the sickest patients with the first positions in the waiting list for an earlier access to transplant. In addition, the allocation policy may not create or perpetuate inequities, particularly in a public and universal healthcare system. Hitherto, Spain lacks a unique national allocation system for elective liver transplantation. Most institutions establish their own rules for liver allocation and only two autonomous regions, namely Andalucía and Cataluña, share part of their waiting list within their territory to provide regional priority to patients requiring more urgent transplantation. This heterogeneity is further aggravated by the recently described sex-based disparities for accessing liver transplantation in Spain, and by the expansion of liver transplant indications, mainly for oncological indications, in absence of clear guidance on the optimal prioritization policy. The present document contains the recommendations from the first consensus of waiting list prioritization for liver transplantation issued by the Spanish Society of Liver Transplantation (SETH). The document was supported by all liver transplant institutions in Spain and by the Organización Nacional de Trasplantes (ONT). Its implementation will allow to homogenize practices and to improve equity and outcomes among patients with end-stage liver disease.

Normothermic Regional Perfusion in Controlled Donation After Circulatory Death Liver Transplantation: A Systematic Review and Meta-Analysis

Liver grafts from controlled donation after circulatory death (cDCD) donors have lower utilization rates due to inferior graft and patient survival rates, largely attributable to the increased incidence of ischemic cholangiopathy, when compared with grafts from brain dead donors (DBD). Normothermic regional perfusion (NRP) may improve the quality of cDCD livers to allow for expansion of the donor pool, helping to alleviate the shortage of transplantable grafts. A systematic review and metanalysis was conducted comparing NRP cDCD livers with both non-NRP cDCD livers and DBD livers. In comparison to non-NRP cDCD outcomes, NRP cDCD grafts had lower rates of ischemic cholangiopathy [RR = 0.23, 95% CI (0.11, 0.49), p = 0.0002], primary non-function [RR = 0.51, 95% CI (0.27, 0.97), p = 0.04], and recipient death [HR = 0.5, 95% CI (0.36, 0.69), p < 0.0001]. There was no difference in outcomes between NRP cDCD donation compared to DBD liver donation. In conclusion, NRP improved the quality of cDCD livers compared to their non-NRP counterparts. NRP cDCD livers had similar outcomes to DBD grafts. This provides further evidence supporting the continued use of NRP in cDCD liver transplantation and offers weight to proposals for its more widespread adoption.

Defatting of Human Livers During Long-Term e x situ Normothermic Perfusion: Novel Strategy to Rescue Discarded Organs for Transplantation

OBJECTIVE

To develop a protocol for the defatting of steatotic liver grafts during long-term ex situ normothermic machine perfusion.

BACKGROUND

Despite the alarming increase in donor organ shortage, the highly prevalent fatty liver grafts are often discarded due to the risk of primary nonfunction. Effective strategies preventing such outcomes are currently lacking. An exciting new avenue is the introduction of ex situ normothermic machine perfusion (NMP), enabling a liver to remain fully functional for up to 2 weeks and providing a unique window of opportunity for defatting before transplantation.

METHODS

Over a 5-year period, 23 discarded liver grafts and 28 partial livers from our resection program were tested during ex situ normothermic machine perfusion. The steatosis degree was determined on serial biopsies by expert pathologists, and triglyceride contents were measured simultaneously.

RESULTS

Of 51 liver grafts, 20 were steatotic, with up to 85% macrovesicular steatosis, and were perfused for up to 12 days. Ten livers displayed marked (5 of which almost complete) loss of fat, while the other 10 did not respond to long-term perfusion. Successful defatting was related to prolonged perfusion, automated glucose control, circadian nutrition, and L-carnitine/fenofibrate supplementation. Pseudopeliotic steatosis and the associated activation of Kupffer/stellate cells were unexpected processes that might contribute to defatting. Synthetic and metabolic functions remained preserved for most grafts until perfusion ended.

CONCLUSION

Ex situ long-term perfusion effectively reduces steatosis while preserving organ viability and may in the future allow transplantation of primarily unusable high-risk grafts, significantly increasing the number of organs available for transplantation.

Outcomes of liver transplantation with thoracoabdominal normothermic regional perfusion: a matched-controlled initial experience in Spain

Thoracoabdominal (TA) normothermic regional perfusion (NRP) should allow the safe recovery of heart and liver grafts simultaneously in the context of controlled donation after circulatory death (cDCD). We present the initial results of cDCD liver transplantation with simultaneous liver and heart procurement in Spain until October 2021. Outcomes were compared with a matched cohort of cDCD with abdominal NRP (A-NRP) from participating institutions. Primary endpoints comprised early allograft dysfunction (EAD) or primary non-function (PNF), and the development of ischemic-type biliary lesions (ITBL). Six transplants were performed using cDCD with TA-NRP during the study period. Donors were significantly younger in the TA-NRP group than in the A-NRP group (median 45.6 years and 62.9 years respectively, p = 0.011), with a median functional warm ischemia time of 12.5 min in the study group and 13 min in the control group. Patient characteristics, procurement times, and surgical baseline characteristics did not differ significantly between groups. No patient in the study group developed EAD or PNF, and over a median follow-up of 9.8 months, none developed ITBL or graft loss. Extending A-NRP to TA-NRP for cardiac procurement may be technically challenging, but it is both feasible and safe, showing comparable postoperative outcomes to 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.

New therapeutic concepts against ischemia-reperfusion injury in organ transplantation

INTRODUCTION

Ischemia-reperfusion injury (IRI) involves a positive amplification feedback loop that stimulates innate immune-driven tissue damage associated with organ procurement from deceased donors and during transplantation surgery. As our appreciation of its basic immune mechanisms has improved in recent years, translating putative biomarkers into therapeutic interventions in clinical transplantation remains challenging.

AREAS COVERED

This review presents advances in translational/clinical studies targeting immune responses to reactive oxygen species in IRI-stressed solid organ transplants, especially livers. Here we focus on novel concepts to rejuvenate suboptimal donor organs and improve transplant function using pharmacologic and machine perfusion (MP) strategies. Cellular damage induced by cold ischemia/warm reperfusion and the latest mechanistic insights into the microenvironment's role that leads to reperfusion-induced sterile inflammation is critically discussed.

EXPERT OPINION

Efforts to improve clinical outcomes and increase the donor organ pool will depend on improving donor management and our better appreciation of the complex mechanisms encompassing organ IRI that govern the innate-adaptive immune interface triggered in the peritransplant period and subsequent allo-Ag challenge. Computational techniques and deep machine learning incorporating the vast cellular and molecular mechanisms will predict which peri-transplant signals and immune interactions are essential for improving access to the long-term function of life-saving transplants.

Bioenergetic and Cytokine Profiling May Help to Rescue More DCD Livers for Transplantation

The majority of organs used for liver transplantation come from brain-dead donors (DBD). In order to overcome the organ shortage, increasingly donation after circulatory death (DCD) organs are also considered. Since normothermic machine perfusion (NMP) restores metabolic activity and allows for in-depth assessment of organ quality and function prior to transplantation, such organs may benefit from NMP. We herein compare the bioenergetic performance through a comprehensive evaluation of mitochondria by high-resolution respirometry in tissue biopsies and the inflammatory response in DBD and DCD livers during NMP. While livers were indistinguishable by perfusate biomarker assessment and histology, our findings revealed a greater impairment of mitochondrial function in DCD livers after static cold storage compared to DBD livers. During subsequent NMPs, DCD organs recovered and eventually showed a similar performance as DBD livers. Cytokine expression analysis showed no differences in the early phase of NMP, while towards the end of NMP, significantly elevated levels of IL-1β, IL-5 and IL-6 were found in the perfusate of DCD livers. Based on our results, we find it worthwhile to reconsider more DCD organs for transplantation to further extend the donor pool. Therefore, donor organ quality criteria must be developed, which may include an assessment of bioenergetic function and cytokine quantification.

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.

Ultrasound-Targeted Microbubble Cavitation During Machine Perfusion Reduces Microvascular Thrombi and Graft Injury in a Rat Liver Model of Donation After Circulatory Death

BACKGROUND

Ischemic cholangiopathy is a process of bile duct injury that might result from peribiliary vascular plexus (PBP) thrombosis and remains a dreaded complication in liver transplantation from donors after circulatory death (DCD). The aim of this study was to propose a mechanical method of clot destruction to clear microvascular thrombi in DCD livers before transplantation.

METHODS

Sonothrombolysis (STL) is a process by which inertial cavitation of circulating microbubbles entering an ultrasound field create a high-energy shockwave at a microbubble-thrombus interface, causing mechanical clot destruction. The effectiveness of STL in DCD liver treatment remains unclear. We carried out STL treatment during normothermic, oxygenated, ex vivo machine perfusion (NMP), introducing microbubbles into the perfusate with the liver enveloped in an ultrasound field.

RESULTS

The STL livers showed reduction in hepatic arterial and PBP thrombus and decreases in hepatic arterial and portal venous flow resistance, reduced parenchymal injury as measured by aspartate transaminase release and oxygen consumption, and improved cholangiocyte function. Light and electron microscopy showed reduction of hepatic arterial and PBP thrombus in STL livers compared with controls and preserved hepatocyte structure, sinusoid endothelial morphology, and biliary epithelial microvilli.

CONCLUSION

In this model, STL improved flow and functional measures in DCD livers undergoing NMP. These data suggest a novel therapeutic approach to treat PBP injury in DCD livers, which may ultimately increase the pool of grafts available to patients awaiting liver transplantation.

Assessing Donor Liver Quality and Restoring Graft Function in the Era of Extended Criteria Donors

Liver transplantation (LT) is the final treatment option for patients with end-stage liver disease. The increasing donor shortage results in the wide usage of grafts from extended criteria donors across the world. Using such grafts is associated with the elevated incidences of post-transplant complications including initial nonfunction and ischemic biliary tract diseases, which significantly reduce recipient survival. Although several clinical factors have been demonstrated to impact donor liver quality, accurate, comprehensive, and effective assessment systems to guide decision-making for organ usage, restoration or discard are lacking. In addition, the development of biochemical technologies and bioinformatic analysis in recent years helps us better understand graft injury during the perioperative period and find potential ways to restore graft function. Moreover, such advances reveal the molecular profiles of grafts or perfusate that are susceptible to poor graft function and provide insight into finding novel biomarkers for graft quality assessment. Focusing on donors and grafts, we updated potential biomarkers in donor blood, liver tissue, or perfusates that predict graft quality following LT, and summarized strategies for restoring graft function in the era of extended criteria donors. In this review, we also discuss the advantages and drawbacks of these potential biomarkers and offer suggestions for future research.

The biliary microbiome in ischaemic-type biliary lesions can be shaped by stenting but is resilient to antibiotic treatment

This study aims to characterize the biliary microbiome as neglected factor in patients with ischaemic-type biliary lesions (ITBL) after liver transplantation. Therefore, the V1-V2 region of the 16S rRNA gene was sequenced in 175 bile samples. Samples from patients with anastomotic strictures (AS) served as controls. Multivariate analysis and in silico metagenomics were applied cross-sectionally and longitudinally. The microbial community differed significantly between ITBL and AS in terms of alpha and beta diversity. Both, antibiotic treatment and stenting were associated independently with differences in the microbial community structure. In contrast to AS, in ITBL stenting was associated with pronounced differences in the biliary microbiome, whereas no differences associated with antibiotic treatment could be observed in ITBL contrasting the pronounced differences found in AS. Bacterial pathways involved in the production of antibacterial metabolites were increased in ITBL with antibiotic treatment. After liver transplantation, the biliary tract harbours a complex microbial community with significant differences between ITBL and AS. Fundamental changes in the microbial community in ITBL can be achieved with biliary stenting. However, the effect of antibiotic treatment in ITBL was minimal. Therefore, antibiotics should be administered wisely in order to reduce emerging resistance of the biliary microbiome towards external antibiotics.

Abdominal normothermic regional perfusion in controlled donation after circulatory determination of death liver transplantation: Outcomes and risk factors for graft loss

Postmortem normothermic regional perfusion (NRP) is a rising preservation strategy in controlled donation after circulatory determination of death (cDCD). Herein, we present results for cDCD liver transplants performed in Spain 2012-2019, with outcomes evaluated through December 31, 2020. Results were analyzed retrospectively and according to recovery technique (abdominal NRP [A-NRP] or standard rapid recovery [SRR]). During the study period, 545 cDCD liver transplants were performed with A-NRP and 258 with SRR. Median donor age was 59 years (interquartile range 49-67 years). Adjusted risk estimates were improved with A-NRP for overall biliary complications (OR 0.300, 95% CI 0.197-0.459, p < .001), ischemic type biliary lesions (OR 0.112, 95% CI 0.042-0.299, p < .001), graft loss (HR 0.371, 95% CI 0.267-0.516, p < .001), and patient death (HR 0.540, 95% CI 0.373-0.781, p = .001). Cold ischemia time (HR 1.004, 95% CI 1.001-1.007, p = .021) and re-transplantation indication (HR 9.552, 95% CI 3.519-25.930, p < .001) were significant independent predictors for graft loss among cDCD livers with A-NRP. While use of A-NRP helps overcome traditional limitations in cDCD liver transplantation, opportunity for improvement remains for cases with prolonged cold ischemia and/or technically complex recipients, indicating a potential role for complimentary ex situ perfusion preservation techniques.

Temporal Trends in Utilization and Outcomes of DCD Livers in the United States

BACKGROUND

Historically, donation after circulatory death (DCD) livers were frequently discarded because of higher mortality and graft loss after liver transplantation (LT). However, the demand for LT continues to outstrip the supply of "acceptable" organs. Additionally, changes in the donor pool, organ allocation, and clinical management of donors and recipients, and improved clinical protocols might have altered post-DCD-LT outcomes.

METHODS

We studied 5975 recovered DCD livers using US Scientific Registry of Transplant Recipients data from 2005 to 2017, with a comparison group of 78 235 adult donation after brain death (DBD) livers recovered during the same time period. We quantified temporal trends in discard using adjusted multilevel logistic regression and temporal trends in post-LT mortality and graft loss for DCD LT recipients using adjusted Cox regression.

RESULTS

DCD livers were more likely to be discarded than DBD livers across the entire study period, and the relative likelihood of discard increased over time (adjusted odds ratio [aOR] of discard DCD versus DBD 3.854.455.14 2005-2007, 5.225.876.59 2015-2017) despite improving outcomes after DCD LT. Mortality risk for DCD LTs decreased in each time period (compared with 2005-2007, aHR 2008-2011 0.720.840.97, aHR 2012-2014 0.480.580.70, aHR 2015-2017 0.340.430.55), as did risk of graft loss (compared with 2005-2007, aHR 2008-2011 0.690.810.94, aHR 2012-2014 0.450.550.67, aHR 2015-2017 0.360.450.56).

CONCLUSIONS

Despite dramatic improvements in outcomes of DCD LT recipients, DCD livers remain substantially more likely to be discarded than DBD livers, and this discrepancy has actually increased over time. DCD livers are underutilized and have the potential to expand the donor pool.

Mitochondrial respiratory chain and Krebs cycle enzyme function in human donor livers subjected to end-ischaemic hypothermic machine perfusion

INTRODUCTION

Marginal human donor livers are highly susceptible to ischaemia reperfusion injury and mitochondrial dysfunction. Oxygenation during hypothermic machine perfusion (HMP) was proposed to protect the mitochondria but the mechanism is unclear. Additionally, the distribution and uptake of perfusate oxygen during HMP are unknown. This study aimed to examine the feasibility of mitochondrial function analysis during end-ischaemic HMP, assess potential mitochondrial viability biomarkers, and record oxygenation kinetics.

METHODS

This was a randomised pilot study using human livers retrieved for transplant but not utilised. Livers (n = 38) were randomised at stage 1 into static cold storage (n = 6), hepatic artery HMP (n = 7), and non-oxygen supplemented portal vein HMP (n = 7) and at stage 2 into oxygen supplemented and non-oxygen supplemented portal vein HMP (n = 11 and 7, respectively). Mitochondrial parameters were compared between the groups and between low- and high-risk marginal livers based on donor history, organ steatosis and preservation period. The oxygen delivery efficiency was assessed in additional 6 livers using real-time measurements of perfusate and parenchymal oxygen.

RESULTS

The change in mitochondrial respiratory chain (complex I, II, III, IV) and Krebs cycle enzyme activity (aconitase, citrate synthase) before and after 4-hour preservation was not different between groups in both study stages (p > 0.05). Low-risk livers that could have been used clinically (n = 8) had lower complex II-III activities after 4-hour perfusion, compared with high-risk livers (73 nmol/mg/min vs. 113 nmol/mg/min, p = 0.01). Parenchymal pO2 was consistently lower than perfusate pO2 (p ≤ 0.001), stabilised in 28 minutes compared to 3 minutes in perfusate (p = 0.003), and decreased faster upon oxygen cessation (75 vs. 36 minutes, p = 0.003).

CONCLUSIONS

Actively oxygenated and air-equilibrated end-ischaemic HMP did not induce oxidative damage of aconitase, and respiratory chain complexes remained intact. Mitochondria likely respond to variable perfusate oxygen levels by adapting their respiratory function during end-ischaemic HMP. Complex II-III activities should be further investigated as viability biomarkers.

Thromboelastography profiles for controlled circulatory death donors: Validating the role of heparin

Controlled donation after circulatory death (cDCD) liver transplants are associated with increased ischemic-type biliary complications. Microvascular thrombosis secondary to decreased donor fibrinolysis may contribute to bile duct injury. We hypothesized that cDCD donors are hypercoagulable with impaired fibrinolysis and aim to use thromboelastography to characterize cDCD coagulation profiles.

Hemoderivative Transfusion in Liver Transplantation: Comparison Between Recipients of Grafts From Brain Death Donors and Recipients of Uncontrolled Donors After Circulatory Death

INTRODUCTION

Intraoperative bleeding during liver transplantation has been correlated with a higher risk of morbidity and mortality and decrease in patient and graft survival.

MATERIALS AND METHODS

Between January 2006 and December 2016 we performed 783 orthotopic liver transplants. After applying exclusion criteria, we found liver grafts from donors after circulatory death (DCD, group A) were used in 69 patients and liver grafts from donors after brain death (group B) were used in 265 patients.

RESULTS

No difference was found in terms of sex, body mass index, Model for End-Stage Liver Disease score, indication for transplantation, intensive care unit stay, and Child-Pugh score. The mean transfusion of hemoderivates was as follows: red blood cell 9 (0-28) units in group A vs 6 (0-20) units in group B (P = .004) and fresh frozen plasma 10 (0-29) units in group A vs 9.5 (0-23) in group B (P = .000). The only 2 factors related to massive blood transfusion (>6 units of red blood cell) were uncontrolled DCD condition (odds ratio = 2.38; 95% confidence interval, 1.32-4.31; P = .004), and higher Model for End-Stage Liver Disease score (odds ratio = 2.63; 95% confidence interval, 1.53-4.55; P = .001). Survival at 1, 3, and 5 years was 81.3%, 70.2%, and 68.9% in group A vs 89%, 83.7%, and 78% in group B (P = .070).

CONCLUSION

The use of liver grafts from DCDs is associated with increased necessity of transfusion of hemoderivates in comparison with the use of liver grafts from donors after brain death.

CEUS detection of biliary ischaemia during the first 4 weeks after liver transplantation predicts non-anastomotic biliary stricture

BACKGROUND

Biliary ischaemia is an important factor in the pathogenesis of non-anastomotic biliary stricture (NAS) after liver transplantation (LT). Contrast-enhanced ultrasound (CEUS) can be used to detect biliary ischaemia, but no study has examined the utility of CEUS in predicting NAS.

OBJECTIVE

To evaluate whether repeated CEUS as a non-invasive method of biliary ischaemia can identify NAS.

METHODS

Consecutive LT patients who underwent CEUS examinations at 1-4 weeks after LT from September 2012 to December 2015 at our institution were included. The CEUS images and clinical data were analysed.

RESULTS

Among 116 eligible LT patients, 39 (33.6%) were diagnosed with NAS within 1 year after LT. The patients with NAS had a significantly higher CEUS score at weeks 2-4 (all P <  0.05) and a higher slope of CEUS score progression (0.480 vs -0.044, P <  0.001). The accuracy of CEUS in identifying NAS improved over time after LT, reaching its maximum at week 4, with a sensitivity of 66.7%, a specificity of 87.9%, a positive predictive value (PPV) of 75.9%, a negative predictive value (NPV) of 82.3%, and an accuracy of 80.2%in the full cohort when a CEUS score≥3 was used as the cut-off. Multivariate analysis identified gamma-glutamyl transpeptidase (GGT), alanine transaminase (ALT) and the CEUS score at week 4 as independent predictors of NAS. In the task of identifying NAS, an NAS score combining the above 3 variables at week 4 showed areas under the receiver operating characteristic curve of 0.88 (95%CI, 0.78-0.99) in the estimation group (n = 60) and 0.82 (95%CI, 0.69-0.96) in the validation group (n = 56). An NAS score cut-off of 0.396 identified 87.2%of NAS cases in the estimation group, with a PPV of 93.3%; and 75.0%of NAS cases in the validation group, with a PPV of 58.8%.

CONCLUSIONS

CEUS examination during the first 4 weeks is useful in assessing the risk of NAS within 1 year after LT. In particular, an NAS score combining the CEUS score, GGT level, and ALT level at week 4 can be used to accurately predict the risk of NAS in LT patients.

Normothermic Ex Situ Liver Perfusion Enhances Mitochondrial Function of DCD Grafts as Evidenced by High-throughput Metabolomics

BACKGROUND

Normothermic ex situ liver perfusion (NEsLP) reduces reperfusion injury of donation after circulatory death (DCD) grafts and optimizes graft function. The goal of our study was to elucidate how NEsLP impacts global metabolism in DCD grafts using high-throughput metabolomics.

METHODS

Pig livers were preserved by 2 different techniques: static cold storage and NEsLP. Grafts obtained from heart-beating donors were compared with donation after circulatory death (DCD) grafts with either 30 minutes (DCD30) or 60 minutes (DCD60) ischemia time. Liver tissues were collected at the end of preservation period (T0) with either cold storage or NEsLP (n = 5 per group). Grafts were transplanted into recipient pigs and a second liver biopsy was collected 2 hours following liver transplantation (T1). Snap-frozen tissue was processed and analyzed by Sciex 6600 Q-TOF high-resolution mass spectrometer. Data analysis was performed using MetaboAnalyst 4.0 software.

RESULTS

Prolonged ischemia resulted in 38 out of 81 metabolites being differentially abundant over time. Mitochondrial metabolism was significantly affected, with disruption in oxidative phosphorylation capacity i.e the Warburg effect (P = 3.62E-03) and urea cycle (P = 7.95E-0.4). NEsLP resulted in improved mitochondrial metabolism and glycolysis (4.20E-02) oxidation of branched chain fatty acids (P = 4.07E-02).

CONCLUSIONS

This unbiased, high-throughput metabolomics study reveals that mitochondrial function is globally rescued with NEsLP, associated with improvement in DCD graft function. NEsLP is able to rescue DCD grafts, improving their metabolic function to that of livers not exposed to DCD procurement.

Comparable graft survival is achievable with the usage of donation after circulatory death liver grafts from donors at or above 70 years of age: A long-term UK national analysis

The aim of the study was to assess the UK donation after circulatory death (DCD) liver transplant experience from donors ≥70 years. Nationwide UK DCD retrospective analysis was conducted between 2001 and 2015 (n = 1163). Recipients were divided into group 1 vs. group 2 (donors 70≥ vs. <70 years, respectively). group 1 (n = 69, 5.9%) recipients were older (median 59 vs. 55 years, p = .001) and had longer waitlist time (128 vs. 84 days; p = .039). 94.2% of group 1 clustered in London and Birmingham, where the two busiest centers are located. group 1 allografts had higher UKDRI and UK DCD Risk Scores but similar WIT and CIT and were more likely to have been imported. Both groups had similar 1-, 3-, and 5-year graft survival (group 1, 90%, 81.4%, and 74% vs. group 2, 88.6%, 81.4%, and 78.6%, respectively; p = .54). Both groups had similar ICU stay length (p = .22), 3-month hepatic artery thrombosis rates (4.4% vs 4.0%; p = .9), and 12-month readmission rates for all biliary complications (20.3% vs 25.7%; p = .32). This study demonstrates that acceptable outcomes are achievable using older grafts in a highly selected cohort at experienced centers. Advanced age should not be an absolute contraindication to utilizing a DCD graft from donors aged ≥70 years.

Association between indocyanine green clearance test and ischemic type biliary lesions within one year after orthotopic liver transplantation

BACKGROUND

Ischemic type biliary lesions (ITBLs), a particular subset of non-anastomotic biliary strictures (NAS), are characterized by intra and extrahepatic strictures that occur in the absence of either hepatic artery thrombosis or stenosis. When they occur within the first year after liver transplantation their development is mostly related to ischemia-reperfusion injury (IRI). The indocyanine green plasma disappearance rate (ICG-PDR) might be able to predict the probability of IRI-induced graft damage after liver transplantation.

OBJECTIVE

Our aim was to evaluate the association between ICG-PDR and the occurrence of ITBLs. Secondly, we searched for evidence of IRI in patients presenting ITBLs.

METHODS

This retrospective single-center observational study assessed a cohort of 60 liver transplant patients. Each patient underwent ICG-PDR on the 1st postoperative day. ITBLs were identified by means of either cholangiography or magnetic resonance imaging evidence of a deformity and narrowing of the biliary tree in the absence of hepatic artery thrombosis/stenosis.

RESULTS

ITBLs were discovered in 10 patients out of 60 liver recipients (16.67%) within one year after transplantation. A low ICG-PDR value was found to be a significant predictive factor for ITBL development, with an OR of 0.87 and a 95% CI of 0.77-0.97. Liver biopsies were performed in 56 patients presenting unexplained abnormal liver function test results. A statistically significant association was found between the development of ITBLs and anatomopathological evidence of IRI.

LIMITATIONS

Retrospective, single-center study.

CONCLUSIONS

The findings from this study show a relationship between low ICG-PDR values on first post-operative-day and the occurrence of ITBLs within 1 year after transplantation.

Predicting the Safe Use of Deceased After Circulatory Death Liver Allografts in Primary Sclerosing Cholangitis

OBJECTIVES

The use of deceased after circulatory death liver allografts in patients with primary sclerosing cholangitis is controversial, given the increased risk of graft complications in patients with primary sclerosing cholangitis. We hypothesized that transplant of deceased after circulatory death livers into recipients with primary sclerosing cholangitis when appropriately selected using the UK deceased after circulatory death scoring system is not associated with increased graft failure and mortality.

MATERIALS AND METHODS

We analyzed 99 229 transplants (between January 2001 and December 2018) from the Organ Procurement and Transplantation Network database. Deceased after circulatory death transplants were stratified by the UK scoring system as low risk or high risk. We identified 3958 patients with primary sclerosing cholangitis who received deceased after brain death transplant and 95 patients with primary sclerosing cholangitis who received deceased after circulatory death transplant.

RESULTS

As expected, 5-year graft survival was lower in the circulatory death recipient group (69.0% vs 78.4%; P = .02). However, 5-year graft survival was significantly lower in the high-risk versus low-risk UK scoring system group (60.0% vs 75.4%; P = .02), with rate in the low-risk group similar to the brain death recipient group (78.4% vs 75.4%; P = .52). On multivariate analysis, the high-risk group had significantly increased risk of graft loss (hazard ratio of 1.92; P = .01). However, the low-risk group had equivalent graft survival to the brain death recipient group (hazard ratio of 1.23; P = .31).

CONCLUSIONS

Graft failure was higher in patients with primary sclerosing cholangitis who received livers from deceased after circulatory death donors; however, the risk of graft loss was abrogated using appropriately matched donor and recipient combinations.

Expanding controlled donation after the circulatory determination of death: statement from an international collaborative

A decision to withdraw life-sustaining treatment (WLST) is derived by a conclusion that further treatment will not enable a patient to survive or will not produce a functional outcome with acceptable quality of life that the patient and the treating team regard as beneficial. Although many hospitalized patients die under such circumstances, controlled donation after the circulatory determination of death (cDCDD) programs have been developed only in a reduced number of countries. This International Collaborative Statement aims at expanding cDCDD in the world to help countries progress towards self-sufficiency in transplantation and offer more patients the opportunity of organ donation. The Statement addresses three fundamental aspects of the cDCDD pathway. First, it describes the process of determining a prognosis that justifies the WLST, a decision that should be prior to and independent of any consideration of organ donation and in which transplant professionals must not participate. Second, the Statement establishes the permanent cessation of circulation to the brain as the standard to determine death by circulatory criteria. Death may be declared after an elapsed observation period of 5 min without circulation to the brain, which confirms that the absence of circulation to the brain is permanent. Finally, the Statement highlights the value of perfusion repair for increasing the success of cDCDD organ transplantation. cDCDD protocols may utilize either in situ or ex situ perfusion consistent with the practice of each country. Methods to accomplish the in situ normothermic reperfusion of organs must preclude the restoration of brain perfusion to not invalidate the determination of death.

Beyond Ice and the Cooler: Machine Perfusion Strategies in Liver Transplantation

Machine perfusion (MP) has emerged as a promising preservation technique to reduce the risks associated with transplant of high risk (steatotic, elderly, and donation after circulatory death) hepatic allografts. Multiple strategies for MP are under investigation. MP facilitates assessment of organ viability and enables liver-directed therapy before transplant. Clinical trials suggest MP may improve the use of hepatic allografts, mitigate ischemia-reperfusion injury, and reduce the incidences of early allograft dysfunction, biliary complications, and ischemic cholangiopathy. As MP sees more widespread use outside of trial settings, more investigation will be needed to establish optimal application of this technology.

The effect of organ preservation solutions on short-term outcomes after liver transplantation: a single-center retrospective study

The effect of preservation solutions on outcomes has been subject of many debates but the relative benefits of the various solutions remain unclear. We retrospectively compared short-term outcomes of 885 liver transplantations performed between 1/2000 and 12/2017 and preserved with either Histidine-Tryptophan-Ketoglutarate (HTK, n = 190), University of Wisconsin (UW, n = 557), or Institute George Lopez 1 preservation solution (IGL-1, n = 139). Inverse probability of treatment weighting (IPTW) was performed to account for baseline differences between groups and analyses were adjusted for confounders. In the IPTW analyses, peak AST within 7 days was 44% higher (95% CI 15-81%, P < 0.001) in HTK than in UW. Mean model of early allograft function (MEAF) score was 0.61 points (95% CI 0.12-1.10, P = 0.01) higher in HTK than in UW. Early allograft dysfunction (EAD) was more likely to occur with HTK compared to IGL-1 (IPTW OR = 2.87, 95% CI = 1.00-8.19, P = 0.049) and UW (IPTW OR = 1.75, 95% CI = 1.06-2.88, P = 0.023). The type of preservation solution had no impact on hospital stay, ICU stay, incidence of biliary strictures, or graft and recipient survival. HTK was the least effective on reducing graft injury and increased the probability of graft dysfunction after transplantation. UW and IGL-1 were equally effective in reducing graft injury and dysfunction.

Scaffolds obtained from decellularized human extrahepatic bile ducts support organoids to establish functional biliary tissue in a dish

Biliary disorders can lead to life‐threatening disease and are also a challenging complication of liver transplantation. As there are limited treatment options, tissue engineered bile ducts could be employed to replace or repair damaged bile ducts. We explored how these constructs can be created by seeding hepatobiliary LGR5⁺ organoids onto tissue‐specific scaffold. For this, we decellularized discarded human extrahepatic bile ducts (EBD) that we recellularized with organoids of different origin, that is, liver biopsies, extrahepatic bile duct biopsies, and bile samples. Here, we demonstrate efficient decellularization of EBD tissue. Recellularization of the EBD extracellular matrix (ECM) with the organoids of extrahepatic origin (EBD tissue and bile derived organoids) showed more profound repopulation of the ductal ECM when compared with liver tissue (intrahepatic bile duct) derived organoids. The bile duct constructs that were repopulated with extrahepatic organoids expressed mature cholangiocyte‐markers and had increased electrical resistance, indicating restoration of the barrier function. Therefore, the organoids of extrahepatic sources are identified to be the optimal candidate for the development of personalized tissue engineered EBD constructs.

The ultrastructural characteristics of bile canaliculus in porcine liver donated after cardiac death and machine perfusion preservation

The effects of each type of machine perfusion preservation (MP) of liver grafts donated after cardiac death on the bile canaliculi of hepatocytes remain unclear. We analyzed the intracellular three-dimensional ultrastructure of the bile canaliculi and hepatocyte endomembrane systems in porcine liver grafts after warm ischemia followed by successive MP with modified University of Wisconsin gluconate solution. Transmission and osmium-maceration scanning electron microscopy revealed that lumen volume of the bile canaliculi decreased after warm ischemia. In liver grafts preserved by hypothermic MP condition, bile canaliculi tended to recover in terms of lumen volume, while their microvilli regressed. In contrast, midthermic MP condition preserved the functional form of the microvilli of the bile canaliculi. Machine perfusion preservation potentially restored the bile canaliculus lumen and alleviated the cessation of cellular endocrine processes due to warm ischemia. In addition, midthermic MP condition prevented the retraction of the microvilli of bile canaliculi, suggesting further mitigation of the damage of the bile canaliculi.

Does Normothermic Regional Perfusion Improve the Results of Donation After Circulatory Death Liver Transplantation?

BACKGROUND

The so-called grafts or donors with extended criteria are a risk factor for the development of liver transplant activity. One source comes from controlled donation after circulatory death (cDCD). The hypothesis was to verify the improvement in results by comparing DCD liver transplants performed with postmortem normothermic regional perfusion (NRP) vs super-rapid recovery (SRR), the current standard for cDCD. A prospective study comparing both techniques was carried out.

METHODS

A total of 42 transplants were performed with cDCD, 22 of which were with SRR and 23 with NRP from April 2014 to September 2019.

RESULTS

Differences were found in early allograft dysfunction (68.1% in the SRR group vs 25% in the NRP group; P < .01) and biliary complications (22.7% vs 5%, respectively; P = .04). Differences were also found, although not statistically significant, in ischemic cholangiopathy (13.6% in the SRR group vs 5% in the NRP group; P = .09), and retransplant rate (9.1% vs 0%, respectively; P = .3).

CONCLUSIONS

With the use of NRP machines, results are similar to the standard donation with donors in brain death in terms of rate of early allograft dysfunction and survival of the patient and graft attempted, reducing the rate of ischemic cholangiopathy compared with SRR.

Donor Brain Death Leads to a Worse Ischemia-Reperfusion Injury and Biliary Injury After Liver Transplantation in Rats

BACKGROUND

Brain-dead (BD) donor is the main source for liver transplantation (LT). We aim to investigate the effect of brain death on donor liver inflammatory activity and its association with ischemia-reperfusion (I/R) injury and biliary tract injury after LT.

MATERIAL AND METHOD

A brain death model using male Lewis rats was established, in both BD and non-BD groups; livers were harvested for transplantation using a 2-cuff technique. The rats were sacrificed 12 hours (n = 10) or 4 weeks (n = 10) after transplantation. I/R injury and long-term biliary tract injury were observed after transplantation.

RESULTS

All rats survived for 4 weeks after transplantation. At 12 hours after BD-donor LT (BDDLT), liver injury worsened; serum transaminases, bilirubin, oxidative stress, inflammatory responses and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining level substantially increased (P < .05). At 4 weeks after BDDLT, serum bilirubin and bile lactate dehydrogenase and γ-glutamyl transpeptidase levels were elevated (P < .05). Biliary fibrosis and epithelial-mesenchymal transition (EMT) were detectable and NDRG1 gene expression was decreased.

CONCLUSIONS

These results suggested that brain death-induced inflammatory response in donor organs and resulted in a worse I/R injury and biliary tract injury after LT in rats. The brain death-related biliary tract injury may be associated with the regulation of EMT through NDRG1.

Controlled donation after circulatory death up to 80 years for liver transplantation: Pushing the limit again

Our main objective was to compare liver transplant (LT) results between donation after circulatory death (DCD) and donation after brainstem death (DBD) in our hospital and to analyze, within the DCD group, the influence of age on the results obtained with DCD donors aged >70 years and up to 80 years. All DCD-LTs performed were analyzed prospectively. The results of the DCD group were compared with those of a control group who received a DBD-LT immediately after each DCD-LT. Later, the results obtained within the DCD group were analyzed according to the age of the donors, considering 2 subgroups with a cut-off point at 70 years. Survival results for LT with DCD and super rapid recovery were not inferior to those obtained in a similar group of patients transplanted with DBD livers. However, the cost of DCD was a higher rate of biliary complications, including ischemic cholangiopathy. Donor age was not a negative factor.

Heterogeneity of Bile Duct Management in the Development of Ischemic Cholangiopathy After Liver Transplantation: Results of a European Liver and Intestine Transplant Association Survey

BACKGROUND

Surgical factors and direct cytotoxicity of bile salts on cholangiocytes may play a role in the development of ischemic cholangiopathy (IC) after liver transplantation (LTx). There is no validated consensus on how to protect the bile ducts during procurement, static preservation, and LTx. Meanwhile, IC remains the most troublesome complication after LTx.

AIM

To characterize bile duct management techniques during the LTx process among European transplant centers in cases of donation after brain death (DBD) and circulatory death (DCD).

METHOD

An European Liver and Intestine Transplant Association-European Liver Transplant Registry web survey designed to conceal respondents' personal information was sent to surgeons procuring and/or transplanting livers in Europe.

RESULTS

Sixty-five percent of responses came from large transplant centers (>50 procurements/y). In 8% of DBDs and 14% of DCDs the bile duct is not rinsed. In 46% of DBDs and 52% of DCDs surgeons prefer to remove the gallbladder after graft reperfusion. Protocols concerning preservation solutions (nature, pressure, volume) are extremely heterogeneous. In 54% of DBDs and 61% of DCDs an arterial back table pressure perfusion is performed. Steroids (20%-10%), heparin (72%-60%), prostacyclin (3%-7%), and fibrinolytics (4%-11%) are used as donor-protective interventions in DBD and DCD cases, respectively. In 2% of DBD and 6% of DCD cases a hepatic artery reperfusion is performed first. In 4% of DBD and 6% of DCD cases, fibrinolytics are administered through the hepatic artery during the bench and/or implantation.

CONCLUSION

This European web survey shows for the first time the heterogeneity in the management of bile ducts during procurement, preservation, and transplantation in Europe. In the context of sharing more marginal liver grafts, an expert meeting must be organized to formulate guidelines to be applied to protect liver grafts against IC.

Hypothermic Oxygenated Machine Perfusion of Liver Grafts from Brain-Dead Donors

Hypothermic oxygenated machine perfusion (HOPE) was introduced in liver transplantation (LT) to mitigate ischemia-reperfusion injury. Available clinical data mainly concern LT with donors after circulatory-determined death, whereas data on brain-dead donors (DBD) are scarce. To assess the impact of end-ischemic HOPE in DBD LT, data on primary adult LTs performed between March 2016 and June 2018 were analyzed. HOPE was used in selected cases of donor age >80 years, apparent severe graft steatosis, or ischemia time ≥10 hours. Outcomes of HOPE-treated cases were compared with those after static cold storage. Propensity score matching (1:2) and Bayesian model averaging were used to overcome selection bias. During the study period, 25 (8.5%) out of 294 grafts were treated with HOPE. After matching, HOPE was associated with a lower severe post-reperfusion syndrome (PRS) rate (4% versus 20%, p = 0.13) and stage 2–3 acute kidney injury (AKI) (16% versus 42%, p = 0.046). Furthermore, Bayesian model averaging showed lower transaminases peak and a lower early allograft dysfunction (EAD) rate after HOPE. A steeper decline in arterial graft resistance throughout perfusion was associated with lower EAD rate. HOPE determines a significant reduction of ischemia reperfusion injury in DBD LT.

In situ normothermic perfusion of livers in controlled circulatory death donation may prevent ischemic cholangiopathy and improve graft survival

Livers from controlled donation after circulatory death (DCD) donors suffer a higher incidence of nonfunction, poor function, and ischemic cholangiopathy. In situ normothermic regional perfusion (NRP) restores a blood supply to the abdominal organs after death using an extracorporeal circulation for a limited period before organ recovery. We undertook a retrospective analysis to evaluate whether NRP was associated with improved outcomes of livers from DCD donors. NRP was performed on 70 DCD donors from whom 43 livers were transplanted. These were compared with 187 non-NRP DCD donor livers transplanted at the same two UK centers in the same period. The use of NRP was associated with a reduction in early allograft dysfunction (12% for NRP vs. 32% for non-NRP livers, P = .0076), 30-day graft loss (2% NRP livers vs. 12% non-NRP livers, P = .0559), freedom from ischemic cholangiopathy (0% vs. 27% for non-NRP livers, P < .0001), and fewer anastomotic strictures (7% vs. 27% non-NRP, P = .0041). After adjusting for other factors in a multivariable analysis, NRP remained significantly associated with freedom from ischemic cholangiopathy (P < .0001). These data suggest that NRP during organ recovery from DCD donors leads to superior liver outcomes compared to conventional organ recovery.

Normothermic regional perfusion vs. super-rapid recovery in controlled donation after circulatory death liver transplantation

BACKGROUND & AIMS

Although there is increasing interest in its use, definitive evidence demonstrating a benefit for postmortem normothermic regional perfusion (NRP) in controlled donation after circulatory death (cDCD) liver transplantation is lacking. The aim of this study was to compare results of cDCD liver transplants performed with postmortem NRP vs. super-rapid recovery (SRR), the current standard for cDCD.

METHODS

This was an observational cohort study including all cDCD liver transplants performed in Spain between June 2012 and December 2016, with follow-up ending in December 2017. Each donor hospital determined whether organ recovery was performed using NRP or SRR. The propensity scores technique based on the inverse probability of treatment weighting (IPTW) was used to balance covariates across study groups; logistic and Cox regression models were used for binary and time-to-event outcomes.

RESULTS

During the study period, there were 95 cDCD liver transplants performed with postmortem NRP and 117 with SRR. The median donor age was 56 years (interquartile range 45-65 years). After IPTW analysis, baseline covariates were balanced, with all absolute standardised differences <0.15. IPTW-adjusted risks were significantly improved among NRP livers for overall biliary complications (odds ratio 0.14; 95% CI 0.06-0.35, p <0.001), ischaemic type biliary lesions (odds ratio 0.11; 95% CI 0.02-0.57; p = 0.008), and graft loss (hazard ratio 0.39; 95% CI 0.20-0.78; p = 0.008).

CONCLUSIONS

The use of postmortem NRP in cDCD liver transplantation appears to reduce postoperative biliary complications, ischaemic type biliary lesions and graft loss, and allows for the transplantation of livers even from cDCD donors of advanced age.

LAY SUMMARY

This is a propensity-matched nationwide observational cohort study performed using livers recovered from donors undergoing cardiac arrest provoked by the intentional withdrawal of life support (controlled donation after circulatory death, cDCD). Approximately half of the livers were recovered after a period of postmortem in situ normothermic regional perfusion, which restored warm oxygenated blood to the abdominal organs, whereas the remainder were recovered after rapid preservation with a cold solution. The study results suggest that the use of postmortem normothermic regional perfusion helps reduce rates of post-transplant biliary complications and graft loss and allows for the successful transplantation of livers from older cDCD donors.

Vascular and Biliary Complications Following Deceased Donor Liver Transplantation: A Meta-analysis

OBJECTIVE

To assess biliary and vascular complications after liver transplantations (LTs) sourced from deceased donors.

METHODS

This study reviewed potentially relevant English-language articles gathered from PubMed and Medline published from 2012 to 2017. One additional study was carried out using our institution's database for articles published from 2013 to 2017. Biliary and vascular complications from adult patients receiving their first deceased-donor LT were included. This meta-analysis was performed using Review Manager version 5.2 (Cochrane Collaboration, Copenhagen, Denmark) and the study quality was evaluated using the Newcastle-Ottawa Scale.

RESULTS

Ten studies met our inclusion criteria. Heterogeneity in donation after cardiac death (DCD) and donation after brain death (DBD) recipients was observed and minimized after pooling a subgroup analysis. This latter analysis focused on biliary stricture, biliary leaks and stones, and vascular thrombosis and stenosis. Meta-analyses showed that patients receiving DCD organs have a greatly increased risk of biliary complications compared to those receiving DBD organs, particularly the following: biliary leaks and stones (odds ratio [OR] = 1.69, 95% confidence interval [CI] 1.22-2.34); and biliary stricture (OR = 1.58, 95% CI 1.21-2.06). DCD grafts tended to be but were not significantly associated with DBD regarding vascular thrombosis (OR = 1.62, 95% CI 1.05-2.50), and the risk of vascular stenosis in DCD grafts was not statistically significant (OR = 1.25, 95% CI, .70-2.25).

CONCLUSION

DCD was associated with an increased risk of biliary complications after LT, tended to indicate an increased risk of vascular thrombosis versus, and was not associated with an increased risk of vascular stenosis compared to DBD. There was no significant difference between the grafts.

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

BACKGROUND & AIMS

Donation after circulatory death (DCD) liver transplantation is known for potentially worse outcomes because of higher rates of graft non-function or irreversible cholangiopathy. The impact of machine liver perfusion techniques on these complications remains elusive. We aimed to provide data on 5-year outcomes in patients receiving DCD liver transplants, after donor organs had been treated by hypothermic oxygenated perfusion (HOPE).

METHODS

Fifty HOPE-treated DCD liver transplants performed in Zurich between 2012 and 3/2017 were matched with 50 primary donation after brain death (DBD) liver transplants, and with 50 untreated DCD liver transplants in Birmingham. Match factors focussed on short cold ischaemia, comparable recipient age and low recipient laboratory model for end-stage liver disease scores. Primary endpoints were post-transplant complications, and non-tumour-related patient death or graft loss.

RESULTS

Despite extended donor warm ischaemia, HOPE-treated DCD liver transplants achieved similar overall graft survival, compared to standard DBD liver transplants. Particularly, graft loss due to any non-tumour-related causes occurred in 8% (4/50) of cases. In contrast, untreated DCD livers resulted in non-tumour-related graft failure in one-third (16/50) of cases (p = 0.005), despite significantly (p <0.001) shorter functional donor warm ischaemia. Five-year graft survival, censored for tumour death, was 94% for HOPE-treated DCD liver transplants vs. 78% in untreated DCD liver transplants (p = 0.024).

CONCLUSIONS

The 5-year outcomes of HOPE-treated DCD liver transplants were similar to those of DBD primary transplants and superior to those of untreated DCD liver transplants, despite much higher risk. These results suggest that a simple end-ischaemic perfusion approach is very effective and may open the field for safe utilisation of extended DCD liver grafts.

LAY SUMMARY

Machine perfusion techniques are currently being introduced into the clinic, with the aim of optimising injured grafts prior to implantation. While short-term effects of machine liver perfusion have been frequently reported in terms of hepatocellular enzyme release and early graft function, the long-term benefit on irreversible graft loss has been unclear. Herein, we report on 5-year graft survival in donation after cardiac death livers, treated either by conventional cold storage, or by 1-2 h of hypothermic oxygenated perfusion (HOPE) after cold storage. Graft loss was significantly less in HOPE-treated livers, despite longer donor warm ischaemia times. Therefore, HOPE after cold storage appears to be a simple and effective method to treat high-risk livers before implantation.

[Frontiers in liver transplantation in indication and techniques]

BACKGROUND

The frontiers in liver transplantation are intrinsically expansions of indications, e.g. hepatocellular carcinoma and (perihilar) cholangiocarcinoma, recipients with more severe concomitant diagnoses or "soft" contraindications and technically demanding reconstruction procedures of vascular structures (for portal vein thrombosis or aorto-hepatic conduits). In addition, an extension of the donor pool with suboptimal donor organs (old donors and steatotic livers) is of interest.

METHODS

This article presents the current situation based on personal experiences in daily practice and an appropriate literature review.

RESULTS

A significant reduction of 1‑year patient survival has been reported in Germany. The percentage of so-called marginal donor organs is inversely proportional to the very low donation rate and parallel to the waiting list mortality. Simultaneously, the proportion of inpatients with multiple organ failure is rising.

CONCLUSION

Results-oriented and controlled liver transplantation currently prohibits making inroads into the previously intrinsic frontiers. As long as the current circumstances do not change, a shift in the intrinsic frontiers of that which is surgically feasible will not be possible. The current situation forces the transplant surgeon to apply a more restrictive indications and organ acceptance policy. With this approach we can try to regain the previously excellent short- and long-term results of a 1‑year survival of 90% and a 20-year survival of 50%.

Impact of machine perfusion of the liver on post-transplant biliary complications: A systematic review

AIM

To review the clinical impact of machine perfusion (MP) of the liver on biliary complications post-transplantation, particularly ischaemic-type biliary lesions (ITBL).

METHODS

This systematic review was performed in accordance with the Preferred Reporting Systematic Reviews and Meta-Analysis (PRISMA) protocol. The following databases were searched: PubMed, MEDLINE and Scopus. The keyword “liver transplantation” was used in combination with the free term “machine perfusion”. Clinical studies reporting results of transplantation of donor human livers following ex situ or in situ MP were analysed. Details relating to donor characteristics, recipients, technique of MP performed and post-operative biliary complications (ITBL, bile leak and anastomotic strictures) were critically analysed.

RESULTS

Fifteen articles were considered to fit the criteria for this review. Ex situ normothermic MP was used in 6 studies, ex situ hypothermic MP in 5 studies and the other 4 studies investigated in situ normothermic regional perfusion (NRP) and controlled oxygenated rewarming. MP techniques which have per se the potential to alleviate ischaemia-reperfusion injury: Such as hypothermic MP and NRP, have also reported lower rates of ITBL. Other biliary complications, such as biliary leak and anastomotic biliary strictures, are reported with similar incidences with all MP techniques. There is currently less clinical evidence available to support normothermic MP as a mitigator of biliary complications following liver transplantation. On the other hand, restoration of organ to full metabolism during normothermic MP allows assessment of hepatobiliary function before transplantation, although universally accepted criteria have yet to be validated.

CONCLUSION

MP of the liver has the potential to have a positive impact on post-transplant biliary complications, specifically ITBL, and expand extended criteria donor livers utilisation.

"Super-rapid" Technique in Donation After Circulatory Death Liver Donors: Advantages and Disadvantages

In recent years, donation after circulatory death (DCD) has increased as an option to overcome the organ donor shortage crisis and to decrease the large number of patients on liver transplant waiting lists. The "super-rapid" technique is now the "gold standard" procurement method because of its availability, reproducibility, low cost, and extensive experience. Recently, extracorporeal support has been implemented, with encouraging results. Strict donor acceptance criteria have proven to be essential to optimize the DCD liver graft outcomes and minimize biliary complication rates. In this study we assessed the state of the art of DCD liver transplantation with regard to its development and the actual strategies to prevent graft complications, with aim of expanding the pool of marginal liver donors.

The Impact of Implantation Time During Liver Transplantation on Outcome: A Eurotransplant Cohort Study

Supplemental digital content is available in the text.

Background

The liver graft quickly rewarms during transplantation when the vascular anastomoses are being performed, potentially impacting on outcomes.

Methods

We investigated the relationship between implantation time and outcome in 5223 recipients of deceased-donor livers transplanted in Eurotransplant (2004-2013). Cox regression analyses were corrected for donor, preservation, and recipient variables. Transplant loss represents all-cause graft failure.

Results

Median implantation time was 41 minutes (interquartile range, 34-51). Implantation time independently associated with transplant loss (adjusted hazard ratio, 1.04 for every 10-minute increase; 95% confidence interval, 1.01-1.07; P = 0.007). The magnitude of the implantation time effect was comparable to the effect of each additional hour of cold ischemia (adjusted hazard ratio, 1.03; 95% confidence interval, 1.02-1.05; P < 0.001). The effect was most pronounced early posttransplant with no evidence of a significant effect beyond 3 months. A similar detrimental effect of implantation time was seen for graft and patient survivals. The increased risk for transplant loss in livers donated after circulatory determination of death could be attributed to donor warm ischemia time.

Conclusions

Implantation time associates with inferior liver transplant outcome in a continuous way. These findings need confirmation and further study of confounding factors is needed so steps toward improving outcomes can be made.

Heparin but not tissue plasminogen activator improves outcomes in donation after circulatory death liver transplantation in a porcine model

Ischemic-type biliary lesions (ITBLs) arise most frequently after donation after circulatory death (DCD) liver transplantation and result in high morbidity and graft loss. Many DCD grafts are discarded out of fear for this complication. In theory, microvascular thrombi deposited during donor warm ischemia might be implicated in ITBL pathogenesis. Herein, we aim to evaluate the effects of the administration of either heparin or the fibrinolytic drug tissue plasminogen activator (TPA) as means to improve DCD liver graft quality and potentially avoid ITBL. Donor pigs were subjected to 1 hour of cardiac arrest (CA) and divided among 3 groups: no pre-arrest heparinization nor TPA during postmortem regional perfusion; no pre-arrest heparinization but TPA given during regional perfusion; and pre-arrest heparinization but no TPA during regional perfusion. In liver tissue sampled 1 hour after CA, fibrin deposition was not detected, even when heparin was not given prior to arrest. Although it was not useful to prevent microvascular clot formation, pre-arrest heparin did offer cytoprotective effects during CA and beyond, reflected in improved flows during regional perfusion and better biochemical, functional, and histological parameters during posttransplantation follow-up. In conclusion, this study demonstrates the lack of impact of TPA use in porcine DCD liver transplantation and adds to the controversy over whether the use of TPA in human DCD liver transplantation really offers any protective effect. On the other hand, when it is administered prior to CA, heparin does offer anti-inflammatory and other cytoprotective effects that help improve DCD liver graft quality. Liver Transplantation 24 665-676 2018 AASLD.

Impact of donor age in donation after circulatory death liver transplantation: Is the cutoff "60" still of relevance?

Advanced donor age has been identified as a risk factor when combined with donor warm ischemia time (WIT), eg, in donation after circulatory death (DCD). In several countries, DCD livers older than 60 years are not considered suitable due to concerns related to poor graft function and development of ischemic cholangiopathy. In this study, we evaluate outcomes after DCD liver transplantation using grafts from donors older than 60 years. We analyzed outcomes after DCD liver transplantation (n = 315), comparing donors > 60 years (n = 93) and donors ≤ 60 years (n = 222) from our center between 2005 and 2015. End points included graft function and complications and patient and graft survival. Multivariate risk analysis was performed to define further key factors that predicted inferior outcome. Donor age at the cutoff 60 years failed to stratify patient and graft survival. The rate of vascular, biliary, and overall complications was comparably low in both cohorts, and the median comprehensive complication index was 42.7 points, independent from the donor age. Second, donor body mass index (BMI) above a threshold of 25 kg/m² significantly impacted on graft and patient survival at any donor age, whereas donor WIT and cold ischemia times were not predictive for graft loss. In conclusion, older DCD donors can be successfully used for liver transplantation with good longterm outcomes when further risk factors are limited. Additional risk is transmitted by an increased donor BMI regardless of donor age. Liver Transplantation 24 352-362 2018 AASLD.