Differential Impact of Extended Criteria Donors After Brain Death or Circulatory Death in Adult Liver Transplantation

Impact of distance from liver transplant centre on outcomes following liver transplantation: an Australian single-centre study

BACKGROUND

Access to liver transplantation (LT) is affected by geographic disparities. Higher waitlist mortality is observed in patients residing farther from LT centres, but the impact of distance on post-LT outcomes is unclear.

AIMS

To evaluate whether the distance LT recipients reside from their LT centre affects graft and patient outcomes.

METHODS

We retrospectively studied consecutive adult patients who received deceased donor LT at a statewide LT referral centre, Royal Prince Alfred Hospital (RPAH), 2006-2021. The primary outcome was overall patient survival.

RESULTS

A total of 973 patients who underwent LT during the study period were analysed. The median distance from patient residence to RPAH was 44.9 km (interquartile range 21.9-168.0). Of these, 64.2% lived ≤100 km from RPAH. Compared to patients living ≤100 km from RPAH, those living >100 km away were less likely to be male, have chronic hepatitis B as their cause of liver disease or have hepatocellular carcinoma as their primary indication for LT. Living >100 km from RPAH was associated with fewer face-to-face clinic visits in the first year after LT (10 vs 11 visits, P < 0.001) and fewer readmissions to RPAH (32.4% vs 67.6%, P < 0.001). Distance from RPAH, regional code and socioeconomic code did not affect long-term graft or patient survival based on Kaplan-Meier survival analysis (log-rank P > 0.1).

CONCLUSION

In our single-centre Australian study, patients living farther from their LT centre had different demographics. Distance from the LT centre was not associated with long-term inferior graft or patient survival after LT.

Mechanisms and aetiology-dependent treatment of acute liver failure

This review compiles the mechanisms of acute liver failure (ALF) as well as the current and potential therapeutic approaches, including aetiology-specific treatment, and the issues encountered with such approaches. On a cellular level, ALF is characterized by massive hepatocyte death due to different types of cellular demise. Compensatory hyperplasia and functional recovery are possible when the regenerative capacity is sufficient to sustain hepatic function. ALF has a high mortality of about 30% and can lead to death in a very short time despite maximum therapeutic intervention. Besides aetiology-specific therapy and intensive care, the therapeutic option of emergency liver transplantation has significantly improved the prognosis of patients with ALF. However, due to limiting factors such as organ shortage, many patients die on the waiting list. In addition to graft assessment, machine perfusion may have the potential to recondition marginal organs and thus expand the organ donor pool.

Normothermic Machine Perfusion in Orphan Liver Graft Viability Assessment

Background: Liver transplantation constitutes a well-established treatment for patients with end-stage liver disease and selected hepatic malignancies. The introduction of normothermic machine perfusion (NMP) offers a platform for both extracorporeal organ maintenance and viability assessment, especially for organs with suspicious malfunction. These organs, discarded by the majority of transplant centers (so-called 'orphan livers'), may help to safely expand the donor pool thanks to pre-transplant appraisal; Methods: We identified all grafts undergoing normothermic ma-chine perfusions performed in the Department of General, Transplant, and Liver Surgery between December 2022 and August 2023. Their perfusion characteristics and immediate postoperative periods, as well as complications that occurred in the 90-day postoperative periods, were analyzed; Results: There were eight orphan liver grafts that underwent NMP in our Department. Postoperative complications occurring in patients receiving grafts after NMP did not seem associated with the procedure. One patient required laparotomy within the 90-day postoperative period due to biliary fistula and underwent bile duct stenting due to both fistula and nonanastomotic stricture. In one patient we observed the occurrence of anastomotic biliary stricture more than 90 days after LTx; Conclusions: NMP allows for the viability assessment of grafts with suspicious prepreservation malfunction. Some of these organs may help to expand the donor pool.

Are there any benefits of prolonged hypothermic oxygenated perfusion?: Results from a national retrospective study

Dual hypothermic oxygenated perfusion (DHOPE) is increasingly being used to extend liver preservation to improve transplant logistics. However, little is known about its benefits in high-risk liver grafts. This study aimed to investigate whether prolonged DHOPE provides benefits other than improved logistics in all liver types. We performed a national retrospective cohort study of 177 liver transplants from 12 Italian centers preserved with DHOPE for ≥4 hours between 2015 and 2022. A control group of 177 DHOPEs of <4 hours during the same period was created using 1:1 propensity score matching. The impact of risk profiles and preservation times on the outcomes was assessed using univariable and multivariable regression models. No significant differences in posttransplant outcomes were found between prolonged and short DHOPEs. However, the prolonged group had a significantly lower incidence of posttransplant acute kidney injury (AKI) compared to the short group (30.5% vs. 44.6%, p = 0.008). Among prolonged DHOPEs, no differences in transplant outcomes were observed according to donor risk index, Eurotransplant definition for marginal grafts, and balance of risk score. DHOPE duration was associated with a lower risk of AKI in multivariable models adjusted for donor risk index, Eutrotransplant marginal grafts, and balance of risk score. Prolonged hypothermic oxygenated perfusion confirmed its protective effect against AKI in a multivariable model adjusted for donor and recipient risk factors [OR: 0.412, 95% CI: 0.200-0.850, p = 0.016]. Prolonged DHOPE is widely used to improve transplant logistics, provides good results with high-risk grafts, and appears to be associated with a lower risk of posttransplant AKI. These results provide further insight into the important role of DHOPE in preventing posttransplant complications.

Long-term machine perfusion of human split livers: a new model for regenerative and translational research

Recent advances in machine perfusion have revolutionised the field of transplantation by prolonging preservation, permitting evaluation of viability prior to implant and rescue of discarded organs. Long-term perfusion for days-to-weeks provides time to modify these organs prior to transplantation. By using long-term normothermic machine perfusion to facilitate liver splitting and subsequent perfusion of both partial organs, possibilities even outside the clinical arena become possible. This model remains in its infancy but in the future, could allow for detailed study of liver injury and regeneration, and ex-situ treatment strategies such as defatting, genetic modulation and stem-cell therapies. Here we provide insight into this new model for research and highlight its great potential and current limitations.

Normothermic regional perfusion in controlled DCD liver procurement: Outcomes of the Swedish national implementation protocol

Liver transplantation (LTX) using donors after controlled circulatory death (cDCD) is associated with poorer graft survival and increased incidence of nonanastomotic biliary strictures (NASs) compared to livers procured from brain-dead donors (DBD). The use of normothermic regional perfusion (NRP) during cDCD procurement may improve posttransplant outcomes and reduce the incidence of NAS. In Sweden, cDCD LTX was introduced through a national pilot protocol with mandatory NRP. This study aims to evaluate the outcome of cDCD LTX during the pilot period. Donor and recipient data were collected on all cDCD liver transplants during the pilot period between January 2020 to December 2022. Outcome on NAS, patient and graft survival, early allograft dysfunction, acute kidney injury, and comprehensive complication index was compared to a matched cohort of 28 patients transplanted with a DBD liver between 2018 and 2022. Eighteen patients were transplanted with a liver from a cDCD donor after using NRP. The mean functional warm ischemia time was 29 ± 6 minutes. The mean lactate reduction during NRP was 8.7 ± 2.4 mmol/L, and the end NRP perfusate alanine aminotransferase was 1.4 ± 1 µkat/L. When comparing recipients of cDCD liver transplant to DBD, no significant differences were observed in the incidence of NAS, patient and graft survival, comprehensive complication index, early allograft dysfunction, or acute kidney injury. Study protocol magnetic resonance cholangiopancreatography in cDCD patients showed no signs of subclinical biliary strictures. Evaluation of the Swedish national pilot of cDCD LTX with mandatory NRP shows comparable outcomes to a matched DBD cohort with 94.4% 1-year patient and graft survival and no incidence of NAS within the first year.

Incidence, epidemiology, and outcomes of acute allograft rejection following liver transplantation in Australia

Acute allograft rejection is a well-known complication of liver transplantation (LT). The incidence, epidemiology, and outcomes of acute rejection have not been well described in Australia. We retrospectively studied consecutive adults who underwent deceased donor LT at a single center between 2010 and 2020. Donor and recipient data at the time of LT and recipient outcomes were collected from a prospective LT database. Liver biopsy reports were reviewed, and only a graft's first instance of biopsy-proven acute rejection was analyzed. During the study period, 796 liver transplants were performed in 770 patients. Biopsy-proven rejection occurred in 34.9% of transplants. There were no significant changes in the incidence of rejection over time (linear trend p =0.11). The median time to the first episode of rejection was 71 days after LT: 2.2% hyperacute, 50.4% early (≤90 d), and 47.5% late rejection (>90 d). Independent risk factors for rejection were younger recipient age at transplant (aHR 0.98 per year increase, 95% CI: 0.97-1.00, p =0.01), and ABO-incompatible grafts (aHR 2.55 vs. ABO-compatible, 95% CI: 1.27-5.09, p <0.01) while simultaneous multiorgan transplants were protective (aHR 0.21 vs. LT only, 95% CI: 0.08-0.58, p <0.01). Development of acute rejection (both early and late) was independently associated with significantly reduced graft (aHR 3.13, 95% CI: 2.21-4.42, p <0.001) and patient survival (aHR 3.42, 95% CI: 2.35-4.98, p <0.001). In this 11-year Australian study, acute LT rejection occurred in 35%, with independent risk factors of younger recipient age and ABO-incompatible transplant, while having a simultaneous multiorgan transplant was protective. Acute rejection was independently associated with reduced graft and patient survival after adjustment for other factors.

Combined Organ Transplantation in Patients with Advanced Liver Disease

Transplantation of the liver in combination with other organs is an increasingly performed procedure. Over the years, continuous improvement in survival could be realized through careful patient selection and refined organ preservation techniques, in spite of the challenges posed by aging recipients and donors, as well as the increased use of steatotic liver grafts. Herein, we revisit the epidemiology, allocation policies in different transplant zones, indications, and outcomes with regard to simultaneous organ transplants involving the liver, that is combined heart-liver, liver-lung, liver-kidney, and multivisceral transplantation. We address challenges surrounding combined organ transplantation such as equity, utility, and logistics of dual organ implantation, but also advantages that come along with combined transplantation, thereby focusing on molecular mechanisms underlying immunoprotection provided by the liver to the other allografts. In addition, the current standing and knowledge of machine perfusion in combined organ transplantation, mostly based on center experience, will be reviewed. Notwithstanding all the technical advances, shortage of organs, and the lack of universal eligibility criteria for certain multi-organ combinations are hurdles that need to be tackled in the future.

Advancements in Predictive Tools for Primary Graft Dysfunction in Liver Transplantation: A Comprehensive Review

Orthotopic liver transplantation stands as the sole curative solution for end-stage liver disease. Nevertheless, the discrepancy between the demand and supply of grafts in transplant medicine greatly limits the success of this treatment. The increasing global shortage of organs necessitates the utilization of extended criteria donors (ECD) for liver transplantation, thereby increasing the risk of primary graft dysfunction (PGD). Primary graft dysfunction (PGD) encompasses early allograft dysfunction (EAD) and the more severe primary nonfunction (PNF), both of which stem from ischemia-reperfusion injury (IRI) and mitochondrial damage. Currently, the only effective treatment for PNF is secondary transplantation within the initial post-transplant week, and the occurrence of EAD suggests an elevated, albeit still uncertain, likelihood of retransplantation urgency. Nonetheless, the ongoing exploration of novel IRI mitigation strategies offers hope for future improvements in PGD outcomes. Establishing an intuitive and reliable tool to predict upcoming graft dysfunction is vital for early identification of high-risk patients and for making informed retransplantation decisions. Accurate diagnostics for PNF and EAD constitute essential initial steps in implementing future mitigation strategies. Recently, novel methods for PNF prediction have been developed, and several models for EAD assessments have been introduced. Here, we provide an overview of the currently scrutinized predictive tools for PNF and EAD evaluation strategies, accompanied by recommendations for future studies.

Dynamic immune cell profiling identified natural killer cell shift as the key event in early allograft dysfunction after liver transplantation

Early allograft dysfunction (EAD) is a life-threatening and fast-developing complication after liver transplantation. The underlying mechanism needs to be better understood, and there has yet to be an efficient therapeutic target. This study retrospectively reviewed 109 patients undergoing liver transplantation, with dynamic profiling of CD3/4/8/16/19/45/56 on the peripheral immune cells (before transplant and 2-4 days after). Altogether, 35 out of the 109 patients developed EAD after liver transplantation. We observed a significant decrease in the natural killer cell proportion (NK cell shift, p = 0.008). The NK cell shift was linearly correlated with cold ischemic time (p = 0.016) and was potentially related to the recipients' outcomes. In mouse models, ischemic/reperfusion (I/R) treatments induced the recruitment of NK cells from peripheral blood into liver tissues. NK cell depletion blocked a series of immune cascades (including CD8+ CD127+ T cells) and inhibited hepatocyte injury effectively in I/R and liver transplantation models. We further found that I/R treatment increased hepatic expression of the ligands for natural killer group 2 member D (NKG2D), a primary activating cell surface receptor in NK cells. Blockade of NKG2D showed a similar protective effect against I/R injury, indicating its role in NK cell activation and the subsequent immunological injury. Our findings built a bridge for the translation from innate immune response to EAD at the bedside. Peripheral NK cell shift is associated with the incidence of EAD after liver transplantation. NKG2D-mediated NK cell activation is a potential therapeutic target.

Mitochondrial DNA levels in perfusate and bile during ex vivo normothermic machine correspond with donor liver quality

Ex vivo normothermic machine perfusion (NMP) preserves donor organs and permits real-time assessment of allograft health, but the most effective indicators of graft viability are uncertain. Mitochondrial DNA (mtDNA), released consequent to traumatic cell injury and death, including the ischemia-reperfusion injury inherent in transplantation, may meet the need for a biomarker in this context. We describe a real time PCR-based approach to assess cell-free mtDNA during NMP as a universal biomarker of allograft quality. Measured in the perfusate fluid of 29 livers, the quantity of mtDNA correlated with metrics of donor liver health including International Normalized Ratio (INR), lactate, and warm ischemia time, and inversely correlated with inferior vena cava (IVC) flow during perfusion. Our findings endorse mtDNA as a simple and rapidly measured feature that can inform donor liver health, opening the possibility to better assess livers acquired from extended criteria donors to improve organ supply.

L-GrAFT7 has High Accuracy in Predicting Early Allograft Failure after Liver Transplantation: A Multicenter Cohort Study in China

Background and Aims

Increasing utilization of extended criteria donor leads to an increasing rate of early allograft failure after liver transplantation. However, consensus of definition of early allograft failure is lacking.

Methods

A retrospective, multicenter study was performed to validate the Liver Graft Assessment Following Transplantation (L-GrAFT) risk model in a Chinese cohort of 942 adult patients undergoing primary liver transplantation at three Chinese centers. L-GrAFT (L-GrAFT7 and L-GrAFT10) was compared with existing models: the Early Allograft Failure Simplified Estimation (EASE) score, the model of early allograft function (MEAF), and the Early Allograft Dysfunction (EAD) model. Univariate and multivariate logistic regression were used to find risk factors of L-GrAFT high-risk group.

Results

L-GrAFT7 had an area under the curve of 0.85 in predicting 90-day graft survival, significantly superior to MEAF [area under the curve (AUC=0.78, p=0.044)] and EAD (AUC=0.78, p=0.006), while there was no statistical significance between the predicting abilities of L-GrAFT7 and EASE (AUC=0.84, p>0.05). Furthermore, L-GrAFT7 maintains good predicting ability in the subgroup of high-donor risk index (DRI) cases (AUC=0.83 vs. MEAF, p=0.007 vs. EAD, p=0.014) and recipients of donors after cardiac death (AUC=0.92 vs. EAD, p<0.001). Through multivariate analysis, pretransplant bilirubin level, units of packed red blood cells, and the DRI score were selected as independent risk factors of a L-GrAFT7 high-risk group.

Conclusions

The accuracy of L-GrAFT7 in predicting early allograft failure was validated in a Chinese multicenter cohort, indicating that it has the potential to become an accurate endpoint of clinical practice and transitional study of machine perfusion.

Immunosuppression for older liver transplant recipients

Older liver transplant recipients have a lower risk of acute rejection than younger patients (9% for patients aged ≥65 years versus 23% for those aged 18-34 years) and are more vulnerable to immunosuppression-related complications. The number of liver transplant recipients ≥65 years has risen to 22% in Europe and the US, but limited information is available on the optimal immunosuppressive regimen for these patients. In this review, we discuss the appropriate management of immunosuppressive agents in older adults to minimize adverse events while avoiding acute rejection. The way the body processes drugs greatly depends on age. In the case of calcineurin inhibitor drugs, aging reduces hepatic metabolism, leading to changes in their pharmacokinetics. Corticosteroids also show decreased clearance as the patient ages. In severe cases of hypoalbuminemia, dose adjustment of mycophenolate acid derivatives may be necessary. However, the pharmacokinetic profiles of the mammalian target of rapamycin inhibitors, basiliximab, and rabbit anti-thymocyte globulin remain unaffected by age. Furthermore, age-related frailty may impact drug metabolism and require tailored interventions and closer follow-up. Although there is limited research, elderly liver transplant recipients require less immunosuppression with double or triple-agent regimens, lower exposure to calcineurin inhibitors, and a shorter course of corticosteroids. The usage of mammalian target of rapamycin inhibitors in older transplant populations has not been specifically investigated, and thus their usage should align with indications for younger patient groups.

Age and liver graft: a systematic review with meta-regression

Increasing organ shortage results in extended criteria donors (ECD) being used to face the growing demand for liver grafts. The demographic change leads to greater use of elderly donors for liver transplantation, historically considered marginal donors. Age is still considered amongst ECD in liver transplantation as it could affect transplant outcomes. However, what is the cutoff for donor age is still unclear and debated. A search of PubMed, Scopus and Cochrane Library was performed. The primary outcome was 1-year graft survival (GS). The secondary outcome was overall biliary complications and 3-5 years of graft and overall survival. A meta-regression model was used to analyse the temporal trend relation in the survival outcome. The meta-analysis included 11 studies. Hazard ratios for 1-year (age cutoff of 70 and 80,) and 5-year GS (I2:0%) were similar irrespectively of the age group. The meta-regression analysis showed a significant correlation between the 1-year graft survival and the year of publication. (coef. 0.00027, 95% CI - 0.0001 to - 0.0003 p = 0.0009). Advanced-age donors showed an increased risk of overall biliary complications with an odd ratio (OR) of 1.89 (95% CI 1-3.65). Liver grafts potentially discharged because of high-risk failure show encouraging results, and GS in ECD has progressively improved with a temporal trend. Currently, the criteria of marginality vary amongst centres. Age alone cannot be considered amongst the extended criteria. First of all, because of the positive results in terms of septuagenarian graft survival. Moreover, the potential elderly donor-related adjunctive risk can be balanced by reducing other risk factors. A prospective multicentre study should investigate a multi-factorial model based on donor criteria, recipient features and new functional biomarkers to predict graft outcome, as proper donor-recipient matching seems to be the critical point for good outcomes.

Application of extended criteria donor grafts in liver transplantation for acute-on-chronic liver failure: A retrospective cohort study

BACKGROUND

There is no consensus on the usage of extended criteria donor (ECD) grafts in liver transplantation (LT) for acute-on-chronic liver failure (ACLF) patients.

AIM

To summarize the experience of using ECD livers in ACLF-LT.

METHODS

A retrospective cohort study was conducted, enrolling patients who underwent LT at the First Affiliated Hospital of Sun Yat-Sen University from January 2015 to November 2021. The patients were divided into ECD and non-ECD groups for analysis.

RESULTS

A total of 145 recipients were enrolled in this study, of which ECD and non-ECD recipients accounted for 53.8% and 46.2%, respectively. Donation after cardiac death (DCD) recipients accounted for the minority compared with donation after brain death (DBD) recipients (16.6% vs 83.4%). Neither overall survival nor graft survival significantly differed between ECD and non-ECD and DCD and DBD recipients. ECD grafts were associated with a significantly higher incidence of early allograft dysfunction (EAD) than non-ECD grafts (67.9% vs 41.8%, P = 0.002). Postoperative outcomes between DCD and DBD recipients were comparable (P > 0.05). ECD graft (P = 0.009), anhepatic phase (P = 0.034) and recipient gamma glutamyltransferase (P = 0.016) were independent risk factors for EAD. Recipient preoperative number of extrahepatic organ failures > 2 (P = 0.015) and intraoperative blood loss (P = 0.000) were independent predictors of poor post-LT survival.

CONCLUSION

Although related to a higher risk of EAD, ECD grafts can be safely used in ACLF-LT. The main factors affecting post-LT survival in ACLF patients are their own severe preoperative disease and intraoperative blood loss.

Alcohol-Associated Liver Disease: Evolving Concepts and Treatments

Alcohol is a prominent cause of liver disease worldwide with higher prevalence in developed nations. The spectrum of alcohol-associated liver disease (ALD) encompasses a diverse range of clinical entities, from asymptomatic isolated steatosis to decompensated cirrhosis, and in some cases, acute or chronic liver failure. Consequently, it is important for healthcare practitioners to maintain awareness and systematically screen for ALD. The optimal evaluation and management of ALD necessitates a collaborative approach, incorporating a multidisciplinary team and accounting for concurrent medical conditions. A repertoire of therapeutic interventions exists to support patients in achieving alcohol cessation and sustaining remission, with complete abstinence being the ultimate objective. This review explores the existing therapeutic options for ALD acknowledging geographical discrepancies in accessibility. Recent innovations, including the inclusion of alcohol consumption biomarkers into clinical protocols and the expansion of liver transplantation eligibility to encompass severe alcohol-associated hepatitis, are explored.

Perioperative clinical practice in liver transplantation: a cross-sectional survey

PURPOSE

The objective of this study was to describe some components of the perioperative practice in liver transplantation as reported by clinicians.

METHODS

We conducted a cross-sectional clinical practice survey using an online instrument containing questions on selected themes related to the perioperative care of liver transplant recipients. We sent email invitations to Canadian anesthesiologists, Canadian surgeons, and French anesthesiologists specialized in liver transplantation. We used five-point Likert-type scales (from "never" to "always") and numerical or categorical answers. Results are presented as medians or proportions.

RESULTS

We obtained answers from 130 participants (estimated response rate of 71% in Canada and 26% in France). Respondents reported rarely using transesophageal echocardiography routinely but often using it for hemodynamic instability, often using an intraoperative goal-directed hemodynamic management strategy, and never using a phlebotomy (medians from ordinal scales). Fifty-nine percent of respondents reported using a restrictive fluid management strategy to manage hemodynamic instability during the dissection phase. Forty-two percent and 15% of respondents reported using viscoelastic tests to guide intraoperative and postoperative transfusions, respectively. Fifty-four percent of respondents reported not pre-emptively treating preoperative coagulations disturbances, and 91% reported treating them intraoperatively only when bleeding was significant. Most respondents (48-64%) did not have an opinion on the maximal graft ischemic times. Forty-seven percent of respondents reported that a piggyback technique was the preferred vena cava anastomosis approach.

CONCLUSION

Different interventions were reported to be used regarding most components of perioperative care in liver transplantation. Our results suggest that significant equipoise exists on the optimal perioperative management of this population.

Extended criteria brain-dead organ donors: Prevalence and impact on the utilisation of livers for transplantation in Brazil

BACKGROUND

Despite its association with higher postoperative morbidity and mortality, the use of extended criteria donor (ECD) livers for transplantation has increased globally due to the high demand for the procedure.

AIM

To investigate the prevalence of ECD in donation after brain death (DBD) and its impact on organ acceptance for transplantation.

METHODS

Retrospective analysis of DBD organ offers for liver transplantation between 2017 and 2020 in a high-volume transplant centre. The incidence of the Eurotransplant risk factors to define an ECD (ET-ECD) among DBD donors and the likelihood of organ acceptance over the years were analysed. The relationship between organ refusal for transplantation, the occurrence, and the number of ET-ECD was assessed by simple and multiple logistic regression adjustment.

RESULTS

A total of 1619 organ donors were evaluated. Of these, 78.31% (n = 1268) had at least one ET-ECD criterion. There was an increase in the acceptance of ECD DBD organs for transplantation (1 criterion: from 23.40% to 31.60%; 2 criteria: from 13.10% to 27.70%; 3 criteria: From 6.30% to 13.60%). For each addition of one ET-ECD variable, the estimated chance of organ refusal was 64.4% higher (OR 1.644, 95%CI 1.469-1.839, P < 0.001). Except for the donor serum sodium > 165 mmol/L (P = 0.310), all ET-ECD criteria increased the estimated chance of organ refusal for transplantation.

CONCLUSION

A high prevalence of ECD DBD was observed. Despite the increase in their utilisation, the presence and the number of extended donor criteria were associated with an increased likelihood of their refusal for transplantation.

Changing liver utilization and discard rates in clinical transplantation in the ex-vivo machine preservation era

Liver transplantation is a well-established treatment for many with end-stage liver disease. Unfortunately, the increasing organ demand has surpassed the donor supply, and approximately 30% of patients die while waiting for a suitable liver. Clinicians are often forced to consider livers of inferior quality to increase organ donation rates, but ultimately, many of those organs end up being discarded. Extensive testing in experimental animals and humans has shown that ex-vivo machine preservation allows for a more objective characterization of the graft outside the body, with particular benefit for suboptimal organs. This review focuses on the history of the implementation of ex-vivo liver machine preservation and how its enactment may modify our current concept of organ acceptability. We provide a brief overview of the major drivers of organ discard (age, ischemia time, steatosis, etc.) and how this technology may ultimately revert such a trend. We also discuss future directions for this technology, including the identification of new markers of injury and repair and the opportunity for other ex-vivo regenerative therapies. Finally, we discuss the value of this technology, considering current and future donor characteristics in the North American population that may result in a significant organ discard.

Machine perfusion in liver transplantation

Although liver transplantation is a true success story, many patients still die awaiting an organ. The increasing need for liver grafts therefore remains an unsolved challenge to the transplant community. To address this, transplant donor criteria have been expanded and, for example, more liver grafts with significant steatosis or from donors with circulatory death are being used. These marginal grafts, however, carry an increased risk of graft-associated complications, such as primary nonfunction, delayed graft function, or late biliary injuries. Therefore, reliable assessment of graft viability before use is essential for further success. To achieve this, machine liver perfusion, a procedure developed more than 50 years ago but almost forgotten at the end of the last century, is again of great interest. We describe in this review the clinical most applied machine perfusion techniques, their mechanistic background, and a novel concept of combining immediate organ assessment during hypothermic oxygenated perfusion, followed by an extended phase of normothermic machine perfusion, with simultaneous ex situ treatment of the perfused liver. Such a new approach may allow the pool of usable livers to dramatically increase and improve outcomes for recipients.

MELD-GRAIL and MELD-GRAIL-Na Are Not Superior to MELD or MELD-Na in Predicting Liver Transplant Waiting List Mortality at a Single-center Level

Controversy exists regarding the best predictive model of liver transplant waiting list (WL) mortality. Models for end-stage liver disease–glomerular filtration rate assessment in liver disease (MELD-GRAIL) and MELD-GRAIL-Na were recently described to provide better prognostication, particularly in females. We evaluated the performance of these scores compared to MELD and MELD-Na.

Single Center Experience with Incidence, Impact and Predictors of Biliary Complications in Donation After Circulatory Death Liver Transplantation

Introduction: Utilizing allografts from donors after cardiac death (DCD) has improved organ availability, and DCD livers comprise a growing proportion of transplantations. However, it has been suggested that DCD transplantations have worse outcomes. Research Questions: We aimed to characterize outcomes in a large cohort of DCD transplantations, identify trends in outcomes over time, and identify factors associated with the development of biliary complications. Design: We conducted an observational retrospective cohort study of patients receiving DCD liver allografts within a large academic teaching hospital with a high transplantation volume. Consecutive patients who underwent Type III DCD liver transplantation from 2006-2016 were included in our cohort. Re-transplantations and multi-organ transplant recipients were excluded. Results: Ninety-six type III DCD transplantations occurred between 2006-2016. We report a 1one-year patient survival of 90.6% (87) and a 5five-year patient survival of 69.8% (67). Twenty-nine (30.2%) patients experienced any biliary complication in the first year following discharge, with 17 (17.7%) experiencing ischemic cholangiopathy. Five-year patient (P = 0.04) and graft (P = 0.005) survival improved over time. Post-operative biliary complications experienced during index admission and prior to discharge were found to be associated with the development of biliary complications (P = 0.005) and ischemic cholangiopathy (P = 0.01) following discharge. Conclusion: Our data suggested that outcomes using DCD allografts have improved, however biliary complications remain a significant issue in DCD transplantation. Patients who experienced post-operative biliary complications during index admission may require more frequent screening to allow the initiation of earlier treatment for biliary complications.

Prediction of Graft Survival Post-liver Transplantation by L-GrAFT Risk Score Model, EASE Score, MEAF Scoring, and EAD

Background: Early allograft dysfunction (EAD) is correlated with poor patient or graft survival in liver transplantation. However, the power of distinct definitions of EAD in prediction of graft survival is unclear. Methods: This retrospective, single-center study reviewed data of 677 recipients undergoing orthotopic liver transplant between July 2015 and June 2020. The following EAD definitions were compared: liver graft assessment following transplantation (L-GrAFT) risk score model, early allograft failure simplified estimation score (EASE), model for early allograft function (MEAF) scoring, and Olthoff criteria. Risk factors for L-GrAFT₇ high risk group were evaluated with univariate and multivariable logistic regression analysis. Results: L-GrAFT₇ had a satisfied C-statistic of 0.87 in predicting a 3-month graft survival which significantly outperformed MEAF (C-statistic = 0.78, P = 0.01) and EAD (C-statistic = 0.75, P < 0.001), respectively. L-GrAFT₁₀, EASE was similar to L-GrAFT₇, and they had no statistical significance in predicting survival. Laboratory model for end-stage liver disease score and cold ischemia time are risk factors of L-GrAFT₇ high-risk group. Conclusion: L-GrAFT₇ risk score is capable for better predicting the 3-month graft survival than the MEAF and EAD in a Chinese cohort, which might standardize assessment of early graft function and serve as a surrogate endpoint in clinical trial.

Are split liver grafts a suitable option in high-risk liver transplant recipients?

PURPOSE OF REVIEW

To assess the outcomes of split liver transplantation (SLT) in adults and children and evaluate its role in high-risk recipients with a high model for end-stage liver disease (MELD) score, an urgent indication or requiring retransplantation.

RECENT FINDINGS

Split liver grafts in general have equivalent long-term survival outcomes to whole grafts despite an increase in biliary complications. Recent success and technical advances have encouraged use of these grafts in high-risk recipients. Split liver grafts can be used successfully in recipients with a high MELD score if there is adequate weight-matching. There are mixed results in urgent indication recipients and for retransplantation such that use in this group of patients remains controversial.

SUMMARY

SLT addresses donor shortages by facilitating the transplant of two recipients from the same donor liver. By using careful donor and recipient selection criteria, SLT can achieve equivalent long-term outcomes to whole grafts. These grafts have been used successfully in recipients with a high MELD score, but should be used selectively in urgent indication recipients and for retransplantation.

A review of split liver transplantation with full right/left hemi-liver grafts for 2 adult recipients

Liver transplantation has become a routine operation in many transplantation centers worldwide. However, liver graft availability fails to meet patient demands. Split liver transplantation (SPLT), which divides a deceased donor liver into 2 partial liver grafts, is a promising strategy for increasing graft availability for transplantation and ameliorating organ shortage to a certain degree. However, the transplantation community has not yet reached a consensus on SPLT because of the variable results. Specifically, SPLT for 2 adult recipients using full right/left hemi-liver grafts is clinically more challenging in terms of surgical technique and potential postoperative complications. Therefore, this review summarizes the current status of SPLT, focusing on the transplantation of adult recipients. Furthermore, the initiation of the SPLT program, donor allocation, surgical aspects, recipient outcomes, and obstacles to developing this procedure will be thoroughly discussed. This information might help provide an optimal strategy for implementing SPLT for 2 adult recipients among current transplantation societies. Meanwhile, potential obstacles to SPLT might be overcome in the near future with growing knowledge, experience, and refinement of surgical techniques. Ultimately, the widespread diffusion of SPLT may increase graft availability and mitigate organ donation shortages.

The use of normothermic machine perfusion to rescue liver allografts from expanded criteria donors

The use of expanded criteria donors is one of the strategies used to overcome the gap between the demand for organs and the number of donors. Physicians debate the extent to which marginal grafts can be used. In recent years, normothermic machine perfusion (NMP) has been used to test liver viability before transplantation. Grafts underwent NMP whenever histological steatosis was > 40% or there were at least three Eurotransplant criteria for expanded criteria donor (ECD). We used NMP to test 19 grafts, 3 from donation after type 3 controlled cardiac death (DCD), and 16 from donation after brain death (DBD). Only two grafts from DBD were not transplanted, because perfusion proved they were not suitable (total of 17 transplanted grafts of 19 tested grafts). Kaplan-Meier survival estimates at 30, 90, 180, and 1 year after transplant were all 94% (95% CI 84-100%); estimated 3-years survival was 82% (95% CI 62-100%). Overall survival rates did not differ from those of patients transplanted with non-perfused grafts from an ECD. In our experience, the use of very marginal grafts preventively tested by NMP does not negatively influence the patient's outcome, and increases the number of transplants in low donation areas.

Role of FGF15 in Hepatic Surgery in the Presence of Tumorigenesis: Dr. Jekyll or Mr. Hyde?

The pro-tumorigenic activity of fibroblast growth factor (FGF) 19 (FGF15 in its rodent orthologue) in hepatocellular carcinoma (HCC), as well as the unsolved problem that ischemia-reperfusion (IR) injury supposes in liver surgeries, are well known. However, it has been shown that FGF15 administration protects against liver damage and regenerative failure in liver transplantation (LT) from brain-dead donors without tumor signals, providing a benefit in avoiding IR injury. The protection provided by FGF15/19 is due to its anti-apoptotic and pro-regenerative properties, which make this molecule a potentially beneficial or harmful factor, depending on the disease. In the present review, we describe the preclinical models currently available to understand the signaling pathways responsible for the apparent controversial effects of FGF15/19 in the liver (to repair a damaged liver or to promote tumorigenesis). As well, we study the potential pharmacological use that has the activation or inhibition of FGF15/19 pathways depending on the disease to be treated. We also discuss whether FGF15/19 non-pro-tumorigenic variants, which have been developed for the treatment of liver diseases, might be promising approaches in the surgery of hepatic resections and LT using healthy livers and livers from extended-criteria donors.

Addressing the challenges of split liver transplantation through technical advances. A systematic review

BACKGROUND

Split liver transplantation addresses donor shortages by facilitating the transplant of two recipients using one donor liver. Some still consider these grafts inferior due to prolonged cold ischaemia time and at times difficult vascular reconstruction. Techniques such as in-situ splitting, machine perfusion and interposition grafts may address these challenges and thereby address these concerns. The aim of this review is to assess these technical advances in split liver transplantation, their utility and outcomes.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Keywords included 'split liver transplantation', 'arterial reconstruction', and 'machine perfusion'. Data found was synthesised into sections including: methods of splitting, full-left full-right splitting, donor cholangiography, machine perfusion and arterial reconstruction.

RESULTS

A total of 78 articles met inclusion criteria after screening of 151 eligible articles. These were subdivided into the following categories: in-situ (25), ex-vivo (25), full-left full-right splitting (15), donor cholangiography (2), machine perfusion (6), and arterial reconstruction (5). The in-situ splitting technique reduces the cold ischaemia time compared to the ex-vivo technique which may improve graft quality and liver splitting during normothermic machine perfusion is a novel technique with the potential to incorporate the best aspects of both techniques. Interposition grafts are often required during split liver transplantation but have an increased risk of hepatic artery thrombosis.

CONCLUSION

Advancements in technique have allowed many of the unique challenges of split liver transplantation to be overcome. Overall, this supports the use of split liver transplantation in broader and riskier settings and we advocate for liver transplant surgeons to not hesitate in using these grafts liberally and expanding their recipient selection criteria.