Microthrombi are often observed in the glomerular tufts of peri-transplant renal biopsies, and occult fibrin has been described in livers undergoing normothermic perfusion, with its presence associated with cholangiopathy and poorer transplant survival. To further examine the phenomenon, we measured D-dimers in the perfusates of kidneys and livers that were part of organ perfusion studies conducted by the Consortium for Organ Preservation in Europe. Both kidneys and livers were found to contain variable amounts of D-dimers. The need for dialysis in kidneys donated after circulatory death (DCD) was associated with higher levels of D-dimers in the hypothermic kidney perfusate. Higher amounts of D-dimers in the liver perfusate were associated with poorer liver transplant survival. There was no significant difference in D-dimer release from livers and kidneys between donors who died from head trauma, stroke, or hypoxia. Organs from donors who died by euthanasia had significantly fewer D-dimers. This study shows that occult fibrin is common in both livers and kidneys from deceased donors and has adverse consequences. The different D-dimer loads by donor cause of death suggest a donor origin for at least some of the occult fibrin.

Donor livers may contain occult fibrin, which is associated with adverse transplant outcomes in livers donated after brain death (DBD) and circulatory death (DCD). Ex situ normothermic machine perfusion (NMP) may allow fibrinolytic therapy before transplantation. Before undertaking a large efficacy study for the prophylaxis of cholangiopathy, we wished to assess the safety of a protocol comprising alteplase and fresh frozen plasma (FFP), the latter as a source of plasminogen, and also to ascertain which of the 4 possible treatment strategies was associated with the greatest fibrin breakdown, as judged by D-dimer release. Eighty livers, 40 DBD and 40 DCD, were randomized to 1 of 5 groups of 16 each, receiving 10 mg or 20 mg alteplase, 1 or 2 units (250 mL) of FFP, with alteplase and FFP being delivered into either the hepatic artery cannula or portal reservoir at the start of NMP. The primary endpoint was bleeding post-transplant. Forty-four of 64 treated livers were transplanted, as were 12 of the 16 control livers receiving FFP alone. There was no increase in post-implant bleeding or blood transfusion requirement of any alteplase-treated liver compared with the FFP alone control group. All 4 alteplase groups were associated with more D-dimer release than the FFP alone control group; 10 mg alteplase was as effective as 20 mg, and delivery into the portal reservoir was as effective as delivery into the hepatic artery cannula. The protocol achieving release of most D-dimers involved 10 mg alteplase being delivered directly into the portal reservoir containing 2 units of FFP. Portal delivery was found to be more straightforward than infusion into the hepatic artery cannula. The combination of alteplase with FFP appeared safe, with no bleeding complications.

The fast-track pancreas scheme (FTS) was brought in to improve pancreas utilisation. It created a scheme for the allocation of pancreas grafts not yet allocated at the time retrieval commenced. There are no previous reports of pancreas allocation using such a scheme. This study compares the outcomes of pancreas grafts allocated via the FTS versus those allocated before retrieval. Data were collected on 1,297 pancreas donors offered through the FTS between 1/12/2010-31/03/2023from the UK Transplant Registry. Donor and recipient characteristics were compared, and graft and patient survival analyses conducted using Kaplan Meier plots. Pancreases offered through the FTS were more likely to be from older, heavier, taller, male, and donation after circulatory death (DCD) donors, with all differences statistically significant (p<0.0001). Recipients of FTS grafts tended to be older (p=0.0074). 166 simultaneous pancreas and kidney transplants were performed from the organs offered. No significant differences were found in graft survival at 1 year (FTS 92.4%, no-FTS 87.6%, p=0.104), 3 years (FTS 83.6%, no-FTS 82.9%, p=0.460), and 5 years (FTS 80.9%, no-FTS 79.4%, p=0.417). Patient survival was comparable between groups at 1 year (FTS 98.3%, no-FTS 95.6%, p=0.185), 3 years (FTS 94.3%, no-FTS 91.5%, p=0.287), and 5 years (FTS 87.7%, no FTS 86.6%, p=0.519). Graft and patient survival rates are similar between those receiving fast-tracked pancreases and those receiving pre-allocated pancreases. This study confirms that despite the perception FTS grafts may be more high risk, pancreas transplant outcomes are comparable with no impact on overall outcomes.

Deceased Cardiac Donors (DCD) organs are increasingly being used for simultaneous pancreas and kidney (SPK) transplant. The number recovered following in-situ normothermic regional perfusion (NRP) is also increasing. This study reviewed a 10-year UK experience of SPK transplantation following NRP in DCD. Data were collected on all first DCD SPK transplants (n=426) performed during 2013-2023 from the UK Transplant Registry. NRP and non-NRP donors were compared using adjusted regression models. Multiple imputation was used to deal with missing data. Most grafts were from non-NRP donors n=379 (89%) with n=47 (11%) from NRP donors. Median warm ischaemic time (withdrawal to start of aortic cold or normothermic perfusion) was longer with NRP (17 vs 12 minutes; p=0.005). For all other parameters donors and recipients were well matched. Univariable analysis showed no statistically significant difference in one-year pancreas graft (NRP 93.6%, non-NRP 89.2%, p=0.206). A multivariable model adjusted for donor and recipient factors showed lower pancreas graft loss with NRP, but this did not reach statistical significance (aHR 0.56, 95%CI 0.17-1.80, p=0.327). Sensitivity analyses adjusting for PDRI showed similar results. NRP was not associated with 3-month insulin independence (p=0.51) or pancreas graft rejection (p=0.48). Concerns exist that NRP may be detrimental to the pancreas. This 10-year UK analysis is the largest reported. We found lower pancreas graft loss in the NRP group, though not statistically significant. This data, along with previous benefits demonstrated in liver and kidney, support continued expansion of the NRP programmes.

Ex situ normothermic machine perfusion (NMP) is rapidly emerging as a novel platform for testing therapeutics in human donor livers. Recently, perfusion of explanted patient livers was achieved, raising the possibility of using these diseased organs to increase the fidelity and resolution of drug testing and development. Here, we provide proof-of-principle for the feasibility of this approach in the context of gene therapy. We report the first successful administration of adeno-associated virus serotype 8 (AAV8) vector treatment in the explanted liver of a 34-year-old patient with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), using machine perfusion. MNGIE is caused by mutations in the thymidine phosphorylase (TYMP) gene, leading to nucleoside accumulation. The patient's liver was split into anatomical left and right lobes and perfused using separate machine perfusion devices. Prior to treatment, nucleoside accumulation was observed in the perfusate of both lobes, recapitulating the cardinal feature of MNGIE. An AAV8 vector carrying the human TYMP gene was administered in the left lobe with the right serving as a control. AAV8 gene therapy resulted in successful vector uptake, with complete nucleoside clearance within 6 days of administration. Our results constitute the first demonstration of the efficacy of gene therapy for MNGIE in a human organ and provide proof-of-principle for using machine perfusion as a new strategy for disease modelling and testing novel therapeutics, e.g. gene therapy, in explanted livers.

In controlled donation after circulatory death (DCD) liver transplantation, ischemiareperfusion injury is linked to postreperfusion syndrome (PRS), acute kidney injury (AKI), and early allograft dysfunction. Normothermic regional perfusion (NRP) and normothermic machine perfusion (NMP) are techniques that mitigate ischemic injury and associated complications. In this single-center retrospective study, we compared early transplant outcomes of DCD livers undergoing direct procurement (DP) and static cold storage (SCS) (DCD-DP-SCS), NRP procurement with SCS (DCD-NRP-SCS), or DP with NMP (DCD-DP-NMP). Two hundred thirty-eight DCD liver recipients were evaluated, comprising 59 DCD-DP-SCS, 101 DCD-NRP-SCS, and 78 DCD-DP-NMP. Overall, the PRS incidence was 19%. DCD-DP-SCS had a higher incidence of PRS (37%; P < .001), AKI stage >2 (47%; P = .033), and an increased model for early allograft function score (P < .001). In adjusted multivariate analysis, recipient age (odds ratio [OR] 1.10, 95% CI 1.05-1.17; P < 0.001), and normothermic perfusion (DCD-NRP-SCS: OR 0.16, 95% CI 0.06-0.39; P <.001; DCD-DP-NMP: OR 0.38, 95% CI 0.15-0.91; P-.032) were significant predictors of PRS, which itself was associated with worse 5-year transplant survival (graft survival non-censored-todeath; Hazard ratio (HR) 2.9, 95% CI 1.3-6.7; P-.012). Compared to SCS alone, the use either NRP or NMP significantly reduced the incidence of PRS and AKI with better early graft function.

Farnesoid X receptor (FXR) was identified as an orphan nuclear receptor resembling the steroid receptor in the late '90s. Activation of FXR is a crucial step in many physiological functions of the liver. A vital role of FXR is impacting the amount of bile acids in the hepatocytes, which it performs by reducing bile acid synthesis, stimulating the bile salt export pump, and inhibiting its enterohepatic circulation, thus protecting the hepatocytes against the toxic accumulation of bile acids. Furthermore, FXR mediates bile acid biotransformation in the intestine, liver regeneration, glucose hemostasis, and lipid metabolism. In this review, we first discuss the mechanisms of the disparate pleiotropic actions of FXR agonists. We then delve into the pharmacokinetics of Obeticholic acid (OCA), the first-in-class selective, potent FXR agonist. We additionally discuss the clinical journey of OCA in humans, its current evidence in various human diseases, and its plausible roles in the future.

On June 3, 2023, the American Society of Transplant Surgeons convened a meeting in San Diego, California to (1) develop a consensus statement with supporting data on the ethical tenets of thoracoabdominal normothermic regional perfusion (NRP) and abdominal NRP; (2) provide guidelines for the standards of practice that should govern thoracoabdominal NRP and abdominal NRP; and (3) develop and implement a central database for the collection of NRP donor and recipient data in the United States. National and international leaders in the fields of neuroscience, transplantation, critical care, NRP, Organ Procurement Organizations, transplant centers, and donor families participated. The conference was designed to focus on the controversial issues of neurological flow and function in donation after circulatory death donors during NRP and propose technical standards necessary to ensure that this procedure is performed safely and effectively. This article discusses major topics and conclusions addressed at the meeting.

Introduction Successful organ transplantation in patients with end-stage organ failure improves long-term survival, improves quality of life and reduces costs to the NHS. Despite an increase in the number of deceased organ donors over the last decade, there remains a considerable shortfall of suitable organs available for transplantation. Over half of UK donors are certified dead by neurological criteria following brain stem compression, which leads to severe physiological stress in the donor, combined with a hyperinflammatory state. Brain stem death-related dysfunction is an important reason for poor organ function and hence utilisation. For example, more than 30% of donation after brain stem death cardiac transplant recipients need short-term mechanical cardiac support, reflecting donor heart dysfunction.A small, randomised study previously showed improved outcomes for cardiac transplant recipients if the donor was given simvastatin. SIGNET takes inspiration from that study and hypothesises a potential reduction in damage to the heart and other organs during the period after diagnosis of death and prior to organ retrieval in donors that receive simvastatin.Methods and analysis SIGNET is a multicentre, single-blind, prospective, group sequential, randomised controlled trial to evaluate the benefits of a single high dose of simvastatin given to potential organ donors diagnosed dead by neurological criteria on outcomes in all organ recipients. The trial will run across a minimum of 89 UK sites with a recruitment target of 2600 donors over 4 years.Ethics and dissemination SIGNET received a favourable opinion from the London, Queen Square Research Ethics Committee (Ref: 21/LO/0412) and following approval of substantial amendment 1 in January 2023, the current protocol is version 2 (7 December 2022). Substantial amendment 1 clarified consent procedures and added additional sites and prescribers. Findings from the study will be publicly available and disseminated locally and internationally through manuscript publications in peer-reviewed journals and conference presentations at national and international platforms.Trial registration number ISRCTN11440354

Clinical TransplantationVolume 38, Issue 4 e15291 OPINION In memoriam: Sir Roy Yorke Calne Christopher Watson, Christopher WatsonSearch for more papers by this authorPeter Friend, Peter FriendSearch for more papers by this author Christopher Watson, Christopher WatsonSearch for more papers by this authorPeter Friend, Peter FriendSearch for more papers by this author First published: 28 March 2024 https://doi.org/10.1111/ctr.15291Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume38, Issue4April 2024e15291 RelatedInformation

BACKGROUND:Liver disease is the third leading cause of premature death in the UK. Transplantation is the only successful treatment for end-stage liver disease but is limited by a shortage of suitable donor organs. As a result, up to 20% of patients on liver transplant waiting lists die before receiving a transplant. A third of donated livers are not suitable for transplant, often due to steatosis. Hepatic steatosis, which affects 33% of the UK population, is strongly associated with obesity, an increasing problem in the potential donor pool. We have recently tested defatting interventions during normothermic machine perfusion (NMP) in discarded steatotic human livers that were not transplanted. A combination of therapies including forskolin (NKH477) and L-carnitine to defat liver cells and lipoprotein apheresis filtration were investigated. These interventions resulted in functional improvement during perfusion and reduced the intrahepatocellular triglyceride (IHTG) content. We hypothesise that defatting during NMP will allow more steatotic livers to be transplanted with improved outcomes. METHODS:In the proposed multi-centre clinical trial, we will randomly assign 60 livers from donors with a high-risk of hepatic steatosis to either NMP alone or NMP with defatting interventions. We aim to test the safety and feasibility of the defatting intervention and will explore efficacy by comparing ex-situ and post-reperfusion liver function between the groups. The primary endpoint will be the proportion of livers that achieve predefined functional criteria during perfusion which indicate potential suitability for transplantation. These criteria reflect hepatic metabolism and injury and include lactate clearance, perfusate pH, glucose metabolism, bile composition, vascular flows and transaminase levels. Clinical secondary endpoints will include proportion of livers transplanted in the two arms, graft function; cell-free DNA (cfDNA) at follow-up visits; patient and graft survival; hospital and ITU stay; evidence of ischemia-reperfusion injury (IRI); non-anastomotic biliary strictures and recurrence of steatosis (determined on MRI at 6 months). DISCUSSION:This study explores ex-situ pharmacological optimisation of steatotic donor livers during NMP. If the intervention proves effective, it will allow the safe transplantation of livers that are currently very likely to be discarded, thereby reducing waiting list deaths. TRIAL REGISTRATION:ISRCTN ISRCTN14957538. Registered in October 2022.

Background. Normothermic ex situ liver perfusion (NESLiP) has the potential to increase organ utilization. Radiological evidence of localized liver injury due to compression at the time of NESLiP, termed cradle compression, is a recognized phenomenon but is poorly characterized. Methods. A retrospective analysis of a prospectively collected database was performed of transplanted livers that underwent NESLiP and subsequently had a computed tomography performed within the first 14 d posttransplant. The primary study outcome was 1-y graft survival. Results. Seventy livers (63%) were included in the analysis. Radiological evidence of cradle compression was observed in 21 of 70 (30%). There was no difference in rate of cradle compression between donor after circulatory death and donated after brain death donors ( P = 0.37) or with duration of NESLiP. Univariate analysis demonstrated younger (area under the receiver operating characteristic, 0.68; P = 0.008; 95% confidence interval [CI], 0.55-0.82) and heavier (area under the receiver operating characteristic, 0.80; P < 0.001; 95% CI, 0.69-0.91) livers to be at risk of cradle compression. Only liver weight was associated with cradle compression on multivariate analysis (odds ratio, 1.003; P = 0.005; 95% CI, 1.001-1.005). There was no difference in 1-y graft survival (16/17 [94.1%] versus 44/48 [91.6%]; odds ratio, 0.69; P = 0.75; 95% CI, 0.07-6.62). Conclusions. This is the first study assessing the impact of cradle compression on outcome. We have identified increased donor liver weight and younger age as risk factors for the development of this phenomenon. Increasing utilization of NESLiP will result in the increased incidence of cradle compression but the apparent absence of long-term sequelae is reassuring. Routine postoperative axial imaging may be warranted.

BACKGROUND:Bile chemistry during normothermic ex situ liver perfusion (NESLiP) has been suggested to be an indicator of cholangiopathy. The normal range of biochemical variables in bile of livers undergoing NESLiP has not been defined, nor have published biliary viability criteria been assessed against instances of posttransplant nonanastomotic bile strictures (NASs). METHODS:The bile and perfusate chemistry of 200 livers undergoing NESLiP between February 1, 2018, and October 30, 2023, was compared. In addition, 11 livers that underwent NESLiP and later developed NAS were selected and their bile chemistry was also examined. RESULTS:In livers that did not develop cholangiopathy, concentrations of sodium, potassium, and chloride were slightly higher in bile than in perfusate, whereas the concentration of calcium was slightly lower. Bile was alkali and had a lower glucose concentration than perfusate. Cholangiocyte glucose reabsorption was shown to saturate at high perfusate concentrations and was more impaired in livers donated after circulatory death than in livers donated after brain death. Published criteria failed to identify all livers that went on to develop NASs. CONCLUSIONS:A significant false-negative rate exists with current biliary viability criteria, probably reflecting the patchy and incomplete nature of the development of NASs in the biliary tree. The data presented here provide a benchmark for future assessment of bile duct chemistry during NESLiP.

Background. Ex situ normothermic liver perfusion (NMP) in a blood-based perfusate is associated with a risk of microbe growth, resulting in life-threatening posttransplant sepsis. Antibiotics are widely used, but the pharmacokinetics of these agents are unknown as is their efficacy. We wished to assess the perfusate concentrations of the meropenem and fluconazole that we use and to audit the incidence of infection with this antimicrobial therapy. Methods. Fluconazole and meropenem (100 mg each) were added to the perfusate before NMP began, and serial samples were taken and assayed for drug concentrations. Perfusate cultures were available from 210 of the 242 perfusions performed between February 1, 2018, and April 6, 2023; these were reviewed. Results. Following administration of 100 mg fluconazole, levels fell slightly from a median of 24.9 mg/L at 1 h to 22.6 mg/L at 10 h. In contrast, meropenem concentrations fell over time, from a median of 21.8 mg/L at 1 h to 9.4 mg/L at 10 h. There were 4 significant microorganisms grown in the perfusions, including 3 Candida species and an Enterococcus faecium . All the Candida -infected livers were transplanted with no adverse consequences, the recipients being treated with anidulafungin upon identification of the infecting organism; the Enterococcus -infected liver was not transplanted. Conclusions. Serious infection is a risk with NMP but appears to be mitigated with a protocol combining fluconazole and meropenem. This combination may not be appropriate in areas where resistance is prevalent. Routine culture of NMP perfusate is essential to identify breakthrough organisms early and enable recipient treatment.

AIMS:There is a shortage of livers for transplantation in the United Kingdom; despite this, more than a fifth of those retrieved are not transplanted. Normothermic machine perfusion (NMP) allows a functional assessment of marginal organs using biochemical parameters. This study describes the histological changes in livers undergoing NMP. METHODS AND RESULTS:A total of 170 biopsies taken pre-NMP, after 4 h of NMP, end-NMP and at implantation from 50 livers undergoing NMP as part of standard local transplant practice were retrospectively reviewed. Thirty-eight per cent had large droplet macrovesicular steatosis pre-NMP, which was associated with reduced organ utilisation, P = 0.096, subsequent extracellular fat and a neutrophilic reaction; 32% had small droplet macrovesicular steatosis pre-NMP suggestive of acute cellular stress, the severity of which was unchanged in 64% during the perfusion period. Those showing at least moderate hepatocellular necrosis at end-NMP were less likely to be transplanted (55 versus 24%, P = 0.0505). Variation in the extent of hepatocyte necrosis was seen between biopsies, with 43% of transplanted cases showing less hepatocyte necrosis at implantation compared to end-NMP and 21% more severe necrosis. Patchy portal inflammation was present in 96% of pre-NMP biopsies, although identifiable duct injury was rare and portal thrombi were not identified. Sinusoidal dilation pre-NMP was more frequent in donation after circulatory death donors, typically persisted during NMP although had improved by implantation in most and had resolved in cases with an early post-transplant biopsy. CONCLUSIONS:Histological changes in NMP livers predominantly comprise donor-derived steatosis, stress-associated small droplet steatosis, retrieval- and procedure-associated sinusoidal dilation and ischaemic injury.

Background: Biomarkers with strong predictive capacity towards transplantation outcome for livers undergoing normothermic machine perfusion (NMP) are needed. We investigated lactate clearing capacity as a basic function of liver viability during the first 6 h of NMP. Methods: A trial conducted in 6 high-volume transplant centres in Europe. All centres applied a back-to-base NMP approach with the OrganOx metra system. Perfusate lactate levels at start, 1, 2, 4 and 6 h of NMP were assessed individually and as area under the curve (AUC) and correlated with EAD (early allograft dysfunction), MEAF (model for early allograft function) and modified L-GrAFT (liver graft assessment following transplantation) scores. Results: A total of 509 livers underwent >= 6 h of NMP before transplantation in 6 centres in the UK, Germany and Austria. The donor age was 53 (40-63) years (median, i.q.r.). The total NMP time was 10.8 (7.9-15.7) h. EAD occurred in 26%, MEAF was 4.72 (3.54-6.05) and L-GrAFT(10) -0.96 (-1.52--0.32). Lactate at 1, 2 and 6 h correlated with increasing robustness with MEAF. Rather than a binary assessment with a cut-off value at 2 h, the actual 2 h lactate level correlated with the MEAF (P = 0.0306 versus P = 0.0002, Pearson r = 0.01087 versus r = 0.1734). The absolute lactate concentration at 6 h, the AUC of 0-6 h and 1-6 h (P < 0.0001, r = 0.3176) were the strongest predictors of MEAF. Conclusion: Lactate measured 1-6 h and lactate levels at 6 h correlate strongly with risk of liver allograft dysfunction upon transplantation. The robustness of predicting MEAF by lactate increases with perfusion duration. Monitoring lactate levels should be extended to at least 6 h of NMP routinely to improve clinical outcome.