Hypothermic Oxygenated Perfusion Research Articles

Machine Perfusion Liver Preservation: Highlights From the International Liver Transplant Society 2024.

The 2024 International Liver Transplantation Society (ILTS) Congress, held in Houston, Texas, brought together a dynamic, multidisciplinary community of global experts to explore and discuss cutting-edge innovations and unmet needs in liver transplantation. Key themes included liver machine perfusion and donation after circulatory death (DCD), reflecting the ongoing effort to expand the donor pool and improve transplantation outcomes. Machine perfusion technologies, including normothermic machine perfusion (NMP), hypothermic oxygenated perfusion (HOPE), and normothermic regional perfusion (NRP) have demonstrated great promise in optimizing graft quality, mitigating ischemia-reperfusion injury, and enhancing the use of marginal and DCD liver grafts. At this year's congress a total of 63 abstracts on liver machine perfusion were presented. For this report we selected all orally presented abstracts highlighting advances in organ preservation, artificial intelligence, treatments during ex-situ perfusion including cellular therapy as well as new the use of new biomarkers. Preclinical highlights included the potential of long-term NMP to sustain and regenerate grafts during extended ex-situ preservation, spontaneous defatting of steatotic grafts during LT-NMP, the delivery of regulatory T cells to enable organ-level immunomodulation and the removal of damage-associated molecular patterns from porcine DCD livers during NMP. On the clinical side, key points included the progression of HOPE to IDEAL-D Stage 4 evidence, increased transplant volumes through the application of NMP, the cost-effectiveness of NMP as well as the utilization of very old DCD donors through NRP. Collectively, these advancements mark a transition toward dynamic, data-driven, and personalized transplantation strategies. Machine perfusion remains central to optimizing grafts, expanding the pool of organs suitable for transplantation enhancing access to liver transplantation and improving outcomes for liver transplant recipients worldwide.

Preservation of Liver Graft Using the Hypothermic Oxygenated Perfusion (HOPE) System: A single-center experience

Preservation of Liver Graft Using the Hypothermic Oxygenated Perfusion (HOPE) System: A single-center experience

A Novel Machine Perfusion System for Enhancing Hepatic Microcirculation Perfusion

ABSTRACTBackgroundMachine perfusion is a promising strategy for safeguarding liver transplants donated after cardiac death (DCD). In this study, we developed and validated a novel machine perfusion approach for mitigating risk factors and salvaging severe DCD livers.MethodsA novel hypothermic oxygenated perfusion (HOPE) system was developed, incorporating two pumps and an elastic water sac to emulate the functionality of the cardiac cycle. Compared to conventional systems (HOPE S1 and S2), the novel HOPE system (HOPE S3) was evaluated in rats, utilizing healthy livers perfused with methylene blue diluted using Histidine‐tryptophan‐ketoglutarate (HTK) solution or DCD livers subjected to 60 min of warm ischemia without heparin administration. Liver perfusion outcomes were assessed through macroscopic and microscopic evaluations, molecular analyses, and orthotopic liver transplantation (OLT).ResultsDCD livers subjected to HOPE systems' perfusion exhibited decreased injury and enhanced survival rates compared to static cold storage following 60 min of warm ischemia (DCD + SCS). The 4‐week post‐transplantation survival rates were 0%, 20%, and 33% in the DCD + SCS, HOPE S1, and HOPE S2 groups, respectively. HOPE S3 conferred protection against hepatocyte and non‐parenchymal cell injury, resulting in a 67% animal survival rate following 60 min of warm donor ischemia (HOPE S3). Assessments of hepatic sinusoidal microcirculation, morphological changes, and molecular alterations in preserved livers further confirmed these findings.ConclusionsThe newly devised machine perfusion system can enhance and uniform liver perfusion and may become a promising tool for revitalizing DCD liver grafts afflicted with severe warm ischemic injuries.

Hypothermic oxygenated perfusion inhibits CLIP1-mediated TIRAP ubiquitination via TFPI2 to reduce ischemia‒reperfusion injury of the fatty liver

The use of fatty livers in liver transplantation has emerged as a crucial strategy to expand the pool of donor livers; however, fatty livers are more sensitive to ischemia‒reperfusion injury (IRI). Excessive congenital inflammatory responses are crucial in IRI. Hypothermic oxygenated perfusion (HOPE) is a novel organ preservation technique that may improve marginal donor liver quality by reducing the inflammatory response. Tissue factor pathway inhibitor-2 (TFPI2) and CAP-Gly domain-containing linker protein 1 (CLIP1) exhibit modulatory effects on the inflammatory response. However, the underlying mechanisms of HOPE in fatty liver and the effects of TFPI2 and CLIP1 in fatty liver IRI remain unclear. Here, we aimed to explore the impact of HOPE on the inflammatory response in a rat model of fatty liver IRI and the mechanisms of action of TFPI2 and CLIP1. HOPE significantly reduces liver injury, especially the inflammatory response, and alleviates damage to hepatocytes and endothelial cells. Mechanistically, HOPE exerts its effects by inhibiting TFPI2, and CLIP1 can rescue the damaging effects of TFPI2. Moreover, HOPE promoted the ubiquitination and subsequent degradation of Toll/interleukin-1 receptor domain-containing adapter protein (TIRAP) by regulating the binding of R24 of the KD1 domain of TFPI2 with CLIP1, thereby negatively regulating the TLR4/NF-κB-mediated inflammatory response and reducing IRI. Furthermore, TFPI2 expression increased and CLIP1 expression decreased following cold ischemia in human fatty livers. Overall, our results suggest that targeting the inflammatory response by modulating the TFPI2/CLIP1/TIRAP signaling pathway via HOPE represents a potential therapeutic approach to ameliorate IRI during fatty liver transplantation.

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

While it is currently assumed that liver assessment is only possible during normothermic machine perfusion, there is uncertainty regarding a reliable and quick prediction of graft injury during ex situ hypothermic oxygenated perfusion (HOPE). We therefore intended to test, in an international liver transplant cohort, recently described mitochondrial injury biomarkers measured during HOPE before liver transplantation. Perfusate samples of human livers from ten centers in seven countries with HOPE experience were analyzed for released mitochondrial compounds, i.e. flavin mononucleotide (FMN), NADH, purine derivatives and inflammatory markers. Livers deemed unsuitable for transplantation served as negative controls. We collected 473 perfusate samples of human donation after cardiac death (n= 315) and donation after brain death (n= 158) livers. Fluorometric assessment of FMN in perfusate was validated by mass spectrometry (R= 0.7011, p <0.0001). Graft loss due to primary non-function or cholangiopathy was predicted by perfusate FMN values (c-statistic mass spectrometry 0.8418, 95% CI 0.7466-0.9370, p <0.0001; c-statistic fluorometry 0.7733, 95% CI 0.7006-0.8461, p <0.0001). Perfusate FMN values were also significantly correlated with symptomatic non-anastomotic strictures and kidney failure, and superior for the prediction of graft loss than conventional scores derived from donor and recipient parameters, such as the donor risk index and the balance of risk score. Mitochondrial FMN values in liver tissues of non-utilized livers were low, and inversely correlated to high perfusate FMN values and purine metabolite release. This first international study validates the predictive value of the mitochondrial cofactor FMN, released from complex I during HOPE, and may therefore contribute to a better risk stratification of injured livers before implantation. Analysis of 473 perfusates, collected from ten international centers during HOPE (hypothermic oxygenated perfusion), revealed that mitochondria-derived flavin mononucleotide values in perfusate are predictive of graft loss, cholangiopathy, and kidney failure after liver transplantation. This result is of high clinical relevance, as recognition of graft quality is urgently needed to improve the safe utilization of marginal livers. Ex situ machine perfusion approaches, such as HOPE, are therefore likely to increase the number of useable liver grafts.

HOPE Mitigates Ischemia-Reperfusion Injury in Ex-Situ Split Grafts: A Comparative Study With Living Donation in Pediatric Liver Transplantation.

Optimizing graft preservation is key for ex-situ split grafts in pediatric liver transplantation (PSLT). Hypothermic Oxygenated Perfusion (HOPE) improves ischemia-reperfusion injury (IRI) and post-operative outcomes in adult LT. This study compares the use of HOPE in ex-situ partial grafts to static cold storage ex-situ partial grafts (SCS-Split) and to the gold standard living donor liver transplantation (LDLT). All consecutive HOPE-Split, SCS-Split and LDLT performed between 2018-2023 for pediatric recipients were included. Post-reperfusion syndrome (PRS, drop ≥30% in systolic arterial pressure) and reperfusion biopsies served as early indicators of IRI. We included 47 pediatric recipients (15 HOPE-Split, 17 SCS-Split, and 15 LDLT). In comparison to SCS-Split, HOPE-Split had a significantly shorter cold ischemia time (CIT) (470min vs. 538min; p =0.02), lower PRS rates (13.3% vs. 47.1%; p = 0.04) and a lower IRI score (3 vs. 4; p = 0.03). The overall IRI score (3 vs. 3; p = 0.28) and PRS (13.3% vs. 13.3%; p = 1) after HOPE-Split were comparable to LDLT, despite a longer CIT (470min vs. 117min; p < 0.001). Surgical complications, one-year graft, and recipient survival did not differ among the groups. In conclusion, HOPE-Split mitigates early IRI in pediatric recipients in comparison to SCS-Split, approaching the gold standard of LDLT.

Machine perfusion in liver transplantation: recent advances and coming challenges.

Machine perfusion has been adopted into clinical practice in Europe since the mid-2010s and, more recently, in the United States (US) following approval of normothermic machine perfusion (NMP). We aim to review recent advances, provide discussion of potential future directions, and summarize challenges currently facing the field. Both NMP and hypothermic-oxygenated perfusion (HOPE) improve overall outcomes after liver transplantation versus traditional static cold storage (SCS) and offer improved logistical flexibility. HOPE offers additional protection to the biliary system stemming from its' protection of mitochondria and lessening of ischemia-reperfusion injury. Normothermic regional perfusion (NRP) is touted to offer similar protective effects on the biliary system, though this has not been studied prospectively.The most critical question remaining is the optimal use cases for each of the three techniques (NMP, HOPE, and NRP), particularly as HOPE and NRP become more available in the US. There are additional questions regarding the most effective criteria for viability assessment and the true economic impact of these techniques. Finally, with each technique purported to allow well tolerated use of riskier grafts, there is an urgent need to define terminology for graft risk, as baseline population differences make comparison of current data challenging. Machine perfusion is now widely available in all western countries and has become an essential tool in liver transplantation. Identification of the ideal technique for each graft, optimization of viability assessment, cost-effectiveness analyses, and proper definition of graft risk are the next steps to maximizing the utility of these powerful tools.

Efficiency of machine perfusion in pediatric liver transplantation.

Liver transplantation is the only life-saving procedure for children with end-stage liver disease. The field is however heterogenic with various graft types, recipient age, weight, and underlying diseases. Despite recently improved overall outcomes and the expanded use of living donors, waiting list mortality remains unacceptable, particularly in small children and infants. Based on the known negative effects of elevated donor age, higher body mass index, and prolonged cold ischemia time, the number of available donors for pediatric recipients is limited. Machine perfusion has regained significant interest in the adult liver transplant population during the last decade. Ten randomized controlled trials are published with an overall advantage of machine perfusion techniques over cold storage regarding postoperative outcomes, including graft survival. The concept of hypothermic oxygenated perfusion (HOPE) was the first and only perfusion technique used for pediatric liver transplantation today. In 2018 the first pediatric candidate received a full-size graft donated after circulatory death with cold storage and HOPE, followed by a few split liver transplants after HOPE with an overall limited case number until today. One series of split procedures during HOPE was recently presented by colleagues from France with excellent results, reduced complications, and better graft survival. Such early experience paves the way for more systematic use of machine perfusion techniques for different graft types for pediatric recipients. Clinical reports of pediatric liver transplants with other perfusion techniques are awaited. Strong collaborative efforts are needed to explore the effect of perfusion techniques in this vulnerable population impacting not only the immediate posttransplant outcome but the development and success of an entire life.

Hypothermic Oxygenated Perfusion Improves Vascular and Contractile Function by Preserving Endothelial Nitric Oxide Production in Cardiac Grafts Obtained With Donation After Circulatory Death.

Cardiac donation after circulatory death is a promising option to increase graft availability. Graft preservation with 30 minutes of hypothermic oxygenated perfusion (HOPE) before normothermic machine perfusion may improve cardiac recovery as compared with cold static storage, the current clinical standard. We investigated the role of preserved nitric oxide synthase activity during HOPE on its beneficial effects. Using a rat model of donation after circulatory death, hearts underwent insitu ischemia (21 minutes), were explanted for a cold storage period (30 minutes), and then reperfused under normothermic conditions (60 minutes) with left ventricular loading. Three cold storage conditions were compared: cold static storage, HOPE, and HOPE with Nω-nitro-L-arginine methyl ester (nitric oxide synthase inhibitor). To evaluate potential confounding effects of high coronary flow during early reperfusion in HOPE hearts, bradykinin was administered to normalize coronary flow to HOPE levels in 2 additional groups (cold static storage and HOPE with Nω-nitro-L-arginine methyl ester). Cardiac recovery was significantly improved in HOPE versus cold static storage hearts, as determined by cardiac output, left ventricular work, contraction and relaxation rates, and coronary flow (P<0.05). Furthermore, HOPE attenuated postreperfusion calcium overload. Strikingly, the addition of Nω-nitro-L-arginine methyl ester during HOPE largely abolished its beneficial effects, even when early reperfusion coronary flow was normalized to HOPE levels. HOPE provides superior preservation of ventricular and vascular function compared with the current clinical standard. Importantly, HOPE's beneficial effects require preservation of nitric oxide synthase activity during the cold storage. Therefore, the application of HOPE before normothermic machine perfusion is a promising approach to optimize graft recovery in donation after circulatory death cardiac grafts.

O92: Machine perfusion in liver transplantation; Cochrane review and meta-analysis

Abstract Introduction Several novel machine perfusion technologies have been developed which attempt to improve outcomes compared with ice-box static cold storage (SCS). We aimed to evaluate the effects of different methods of machine perfusion liver transplantation. Methods We used standard, extensive Cochrane search methods to identify randomised machine perfusion trials. Data extraction was performed independently by two authors. Pairwise random-effects meta-analysis was performed. We assessed bias using Risk of Bias 2 and used GRADE to assess certainty of evidence. Results We included seven randomised trials (1024 transplant recipients from 1301 randomised/included livers); four compared end-ischaemic hypothermic oxygenated perfusion (HOPE) with SCS, and three compared normothermic machine perfusion (NMP) with SCS. When compared with SCS, HOPE was associated with improvement in the following clinically relevant outcomes: graft survival (HR=0.45, 95% CI=0.23-0.87; P=0.02; high-certainty evidence), serious adverse events (OR=0.45, 0.22-0.91; P=0.03; moderate-certainty evidence) and clinically significant ischaemic cholangiopathy (OR=0.31, 0.11-0.92; P=0.03; high-certainty evidence). NMP was not associated with improvement in any of these clinically relevant outcomes, although evidence for these outcomes was low certainty. NMP was associated with improved utilisation compared with SCS (one trial found a 50% lower rate of organ discard; P = 0.008). Conclusions Where the decision has been made to transplant a DCD or marginal DBD liver, HOPE will provide superior clinically relevant outcomes compared with SCS alone (graft survival, adverse events, cholangiopathy). NMP appears to improve utilisation of grafts that would otherwise be discarded, but well-powered trials specifically designed to assess utilisation are required.

HTK vs. HTK-N for Coronary Endothelial Protection during Hypothermic, Oxygenated Perfusion of Hearts Donated after Circulatory Death.

Protection of the coronary arteries during donor heart maintenance is pivotal to improve results and prevent the development of coronary allograft vasculopathy. The effect of hypothermic, oxygenated perfusion (HOP) with the traditional HTK and the novel HTK-N solution on the coronary microvasculature of donation-after-circulatory-death (DCD) hearts is known. However, the effect on the coronary macrovasculature is unknown. Thus, we maintained porcine DCD hearts by HOP with HTK or HTK-N for 4 h, followed by transplantation-equivalent reperfusion with blood for 2 h. Then, we removed the left anterior descending coronary artery (LAD) and compared the endothelial-dependent and -independent vasomotor function of both groups using bradykinin and sodium-nitroprusside (SNP). We also determined the transcriptome of LAD samples using microarrays. The endothelial-dependent relaxation was significantly better after HOP with HTK-N. The endothelial-independent relaxation was comparable between both groups. In total, 257 genes were expressed higher, and 668 genes were expressed lower in the HTK-N group. Upregulated genes/pathways were involved in endothelial and vascular smooth muscle cell preservation and heart development. Downregulated genes were related to ischemia/reperfusion injury, oxidative stress, mitochondrion organization, and immune reaction. The novel HTK-N solution preserves the endothelial function of DCD heart coronary arteries more effectively than traditional HTK.

Comprehensive bile acid pool analysis during ex-vivo liver perfusion in a porcine model of ischemia-reperfusion injury

Bile acids (BA) are key for liver regeneration and injury. This study aims at analyzing the changes in the BA pool induced by ischemia-reperfusion (IRI) and investigates the impact of hypothermic oxygenated perfusion (HOPE) on the BA pool compared to static cold storage (SCS). In a porcine model of IRI, liver grafts underwent 30 min of asystolic warm ischemia followed by 6 h of SCS (n = 6) ± 2 h of HOPE (n = 6) and 2 h of ex-situ warm reperfusion. The BA pool in bile samples was analyzed with liquid chromatography coupled with tandem mass spectrometry. We identified 16 BA and observed significant changes in response to ischemia-reperfusion, which were associated with both protective and injury mechanisms. Second, HOPE-treated liver grafts exhibited a more protective BA phenotype, characterized by a more hydrophilic BA pool compared to SCS. Key BA, such as GlycoCholic Acid, were identified and were associated with a decreased transaminase release and improved lactate clearance during reperfusion. Partial Least Square-Discriminant Analysis revealed a distinct injury profile for the HOPE group. In conclusion, the BA pool changes with liver graft IRI, and preservation with HOPE results in a protective BA phenotype compared to SCS.

The role of cold ischemia time and hypothermic perfusion in predicting early hepatocellular carcinoma recurrences after liver transplantation.

The aim of the study was to identify predictors of early tumor recurrence in patients with hepatocellular carcinoma (HCC) after liver transplantation (LT). Retrospective cohort study in 237 consecutive liver recipients with HCC between 2016 and 2021. Multivariate logistic analysis was performed to identify predictors of early HCC recurrences. The impact of hypothermic-oxygenated perfusion (HOPE) on outcome was analyzed after propensity score weighting. Early recurrences were observed in 15 cases. Microvascular invasion (OR 3.737, 95% CI 1.246-11.206, p = 0.019) and cold ischemia time (OR 1.155, 95% CI 1.001-1.333, p = 0.049) were independently associated with a lower risk of HCC recurrences. After balancing for relevant variables, patients in the HOPE group had lower rates of tumor recurrence (weighted OR 0.126, 95% CI 0.016-0.989, p = 0.049) and higher recurrence free survival (weighted HR 0.132, 95% CI 0.017-0.999, p = 0.050). Reducing cold ischemia time and graft perfusion with HOPE can lead to lower rates of early HCC recurrences and higher recurrence-free survival.

Flavin mononucleotide as a biomarker of viability in liver perfusion HOPE (Hypothermic Oxygenated Perfusion)

Flavin mononucleotide as a biomarker of viability in liver perfusion HOPE (Hypothermic Oxygenated Perfusion)

A Single Preservation Solution for Static Cold Storage and Hypothermic Oxygenated Perfusion of Marginal Liver Grafts: A Preclinical Study.

Hypothermic oxygenated perfusion (HOPE) improves outcomes of marginal liver grafts. However, to date, no preservation solution exists for both static cold storage (SCS) and HOPE. After 30 min of asystolic warm ischemia, porcine livers underwent 6 h of SCS followed by 2 h of HOPE. Liver grafts were either preserved with a single preservation solution (IGL2) designed for SCS and HOPE (IGL2-Machine Perfusion Solution [MPS] group, n = 6) or with the gold-standard University of Wisconsin designed for for SCS and Belzer MPS designed for HOPE (MPS group, n = 5). All liver grafts underwent warm reperfusion with whole autologous blood for 2 h, and surrogate markers of hepatic ischemia-reperfusion injury (IRI) were assessed in the hepatocyte, cholangiocyte, vascular, and immunological compartments. After 2 h of warm reperfusion, livers in the IGL2-MPS group showed no significant differences in transaminase release (aspartate aminotransferase: 65.58 versus 104.9 UI/L/100 g liver; P = 0.178), lactate clearance, and histological IRI compared with livers in the MPS group. There were no significant differences in biliary acid composition, bile production, and histological biliary IRI. Mitochondrial and endothelial damage was also not significantly different and resulted in similar hepatic inflammasome activation. This preclinical study shows that a novel IGL2 allows for the safe preservation of marginal liver grafts with SCS and HOPE. Hepatic IRI was comparable with the current gold standard of combining 2 different preservation solutions (University of Wisconsin + Belzer MPS). These data pave the way for a phase I first-in-human study and it is a first step toward tailored preservation solutions for machine perfusion of liver grafts.

Establishing a HOPE Program in a Real-life Setting: A Brazilian Case Series.

Although hypothermic oxygenated perfusion (HOPE) improves posttransplant outcomes, setting up machine perfusion programs may be subjected to specific obstacles under different conditions. This study aims to describe the establishment of HOPE in a real-life setting in Brazil. Extended criteria donors in donation after brain death organs preserved by HOPE were accepted for higher-risk candidates needing expedited transplantation, perceived as those who would benefit most from the technique because of its limited availability. Extended criteria donors was defined by the Eurotransplant criteria. High-risk transplant candidates were characterized by suboptimal surgical conditions related to the recipient or the procedure. Six HOPE-preserved grafts were transplanted from February 2022 to August 2022. The mean donor risk index was 1.7 (SD 0.5). One organ was severely steatotic, and 3 had an anticipated cold ischemia time above 12 h. Recipients' mean model for end-stage liver disease was 28.67 (SD 6.79), with 1 case of retransplant, 1 of refractory ascites, and 1 of acute-on-chronic liver failure. The mean cold ischemia time was 5 h 42 min (SD 82 min), HOPE 6 h 3 min (SD 150 min), and total preservation time 11 h 46 min (SD 184 min). No case had early allograft dysfunction. The mean length of hospital stay was 10 d with 100% graft and patient survival and no ischemic cholangiopathies at a median follow-up of 15 mo (min 12, max 18). Costs and country-specific legal regulations for device utilization were the major hurdles to implementing the program. We presented a pathway to introduce and rationalize the use of HOPE in a scenario of challenging donor-recipient matching with good results. These findings may aid in implementing machine perfusion programs, especially in settings with limited resources or complex transplant logistics.

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

Normothermic regional perfusion (NRP) and hypothermic-oxygenated-perfusion (HOPE), were both shown to improve outcomes after liver transplantation from donors after circulatory death (DCD). Comparative clinical and mechanistical studies are however lacking. A rodent model of NRP and HOPE, both in the donor, was developed. Following asystolic donor warm ischemia time (DWIT), the abdominal compartment was perfused either with a donor-blood-based-perfusate at 37°C (NRP) or with oxygenated Belzer-MPS at 10°C (donor-HOPE) for 2h. Livers were then procured and underwent 5h static cold storage (CS), followed by transplantation. Un-perfused and HOPE-treated DCD-livers (after CS) and healthy livers (DBD) with direct implantation after NRP served as controls. Endpoints included the entire spectrum of ischemia-reperfusion-injury. Healthy control livers (DBD) showed minimal signs of inflammation during 2h NRP and achieved 100% posttransplant recipient survival. In contrast, DCD livers with 30 and 60 min DWIT suffered from greater mitochondrial injury and inflammation as measured by increased perfusate Lactate, FMN- and HMGB-1-levels with subsequent Toll-like-receptor activation during NRP. In contrast, donor-HOPE (instead of NRP) led to significantly less mitochondrial-complex-I-injury and inflammation. Results after donor-HOPE were comparable to ex-situ HOPE after CS. Most DCD-liver recipients survived when treated with one HOPE-technique (86%), compared to only 40% after NRP (p=0.0053). Following a reduction of DWIT (15 min), DCD liver recipients achieved comparable survivals with NRP (80%). High-risk DCD livers benefit more from HOPE-treatment, either immediately in the donor or after cold storage. Comparative prospective clinical studies are required to translate the results. Funding was provided by the Swiss National Science Foundation (grant no: 32003B-140776/1, 3200B-153012/1, 320030-189055/1, and 31IC30-166909) and supported by University Careggi (grant no 32003B-140776/1) and the OTT (grant No.: DRGT641/2019, cod.prog. 19CT03) and the Max Planck Society. Work in the A.G. laboratory was partially supported by the NIH R01NS112381 and R21NS125466 grants.

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

To report on a concept of liver assessment during ex situ hypothermic oxygenated perfusion (HOPE) and its significant impact on liver utilization. An analysis of prospectively collected data on donation after circulatory death (DCD) livers, treated by HOPE at our institution, during a 11-year period between January 2012 and December2022. Four hundred and fifteen DCD Maastricht III livers were offered during the study period in Switzerland, resulting in 249 liver transplants. Of those, we performed 158 DCD III liver transplants at our institution, with 1-year patient survival and death censored graft survival (death with functioning graft) of 87 and 89%, respectively, thus comparable to benchmark graft survivals of ideal DBD and DCD liver transplants (89% and 86%). Correspondingly, graft loss for primary non-function or cholangiopathy was overall low, i.e., 7/158 (4.4%) and 11/158 (6.9%), despite more than 82% of DCD liver grafts ranked high (6-10 points) or futile risk (>10 points) according to the UK-DCD score. Consistently, death censored graft survival was not different between low-, high-risk or futile DCD III livers. The key behind these achievements was the careful development and implementation of a routine perfusate assessment of mitochondrial biomarkers for injury and function, i.e., release of flavin mononucleotide from complex I, perfusate NADH, and mitochondrial CO2 production during HOPE, allowing a more objective interpretation of liver quality on a subcellular level, compared to donor derived data. HOPE after cold storage is a highly suitable and easy to perform perfusion approach, which allows reliable liver graft assessment, enabling surgeons to make a fact based decision on whether or not to implant the organ. HOPE-treatment should be combined with viability assessment particularly when used for high-risk organs, including DCD livers or organs with relevant steatosis. This study was supported by the Swiss National Foundation (SNF) grant 320030_189055/1 to PD.

Hypothermic oxygenated perfusion (HOPE) safely and effectively extends acceptable donor heart preservation times: Results of the Australian and New Zealand trial

Cold static storage preservation of donor hearts for periods longer than 4hours increases the risk of primary graft dysfunction (PGD). The aim of the study was to determine if hypothermic oxygenated perfusion (HOPE) could safely prolong the preservation time of donor hearts. We conducted a nonrandomized, single arm, multicenter investigation of the effect of HOPE using the XVIVO Heart Preservation System on donor hearts with a projected preservation time of 6 to 8hours on 30-day recipient survival and allograft function post-transplant. Each center completed 1 or 2 short preservation time followed by long preservation time cases. PGD was classified as occurring in the first 24hours after transplantation or secondary graft dysfunction (SGD) occurring at any time with a clearly defined cause. Trial survival was compared with a comparator group based on data from the International Society of Heart and Lung Transplantation (ISHLT) Registry. We performed heart transplants using 7 short and 29 long preservation time donor hearts placed on the HOPE system. The mean preservation time for the long preservation time cases was 414minutes, the longest being 8hours and 47minutes. There was 100% survival at 30days. One long preservation time recipient developed PGD, and 1 developed SGD. One short preservation time patient developed SGD. Thirty day survival was superior to the ISHLT comparator group despite substantially longer preservation times in the trial patients. HOPE provides effective preservation out to preservation times of nearly 9hours allowing retrieval from remote geographic locations.

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

BackgroundHepatic ischemia–reperfusion injury (IRI) in donation after cardiac death (DCD) donors is a major determinant of transplantation success. Endoplasmic reticulum (ER) stress plays a key role in hepatic IRI, with potential involvement of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway and the antiapoptotic protein hematopoietic-lineage substrate-1-associated protein X-1 (HAX1). In this study, we aimed to investigate the effects of hypothermic oxygenated perfusion (HOPE), an organ preservation modality, on ER stress and apoptosis during hepatic IRI in a DCD rat model.MethodsTo investigate whether HOPE could improve IRI in DCD livers, levels of different related proteins were examined by western blotting and quantitative real-time polymerase chain reaction. Further expression analyses, immunohistochemical analyses, immunofluorescence staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, and transmission electron microscopy were conducted to analyze the effects of HOPE on ER stress and apoptosis. To clarify the role of the JAK2/STAT3 pathway and HAX1 in this process, AG490 inhibitor, JAX1 plasmid transfection, co-immunoprecipitation (CO-IP), and flow cytometry analyses were conducted.ResultsHOPE reduced liver injury and inflammation while alleviating ER stress and apoptosis in the DCD rat model. Mechanistically, HOPE inhibited unfolded protein responses by activating the JAK2/STAT3 pathway, thus reducing ER stress and apoptosis. Moreover, the activated JAK2/STAT3 pathway upregulated HAX1, promoting the interaction between HAX1 and SERCA2b to maintain ER calcium homeostasis. Upregulated HAX1 also modulated ER stress and apoptosis by inhibiting the inositol-requiring enzyme 1 (IRE1) pathway.ConclusionsJAK2/STAT3-mediated upregulation of HAX1 during HOPE alleviates hepatic ER stress and apoptosis, indicating the JAK2/STAT3/HAX1 pathway as a potential target for IRI management during DCD liver transplantation.Graphical