Liver Graft Preservation Research Articles

A Global Overview on the Evolution, Debate, and Research Output on Liver Transplant Perfusion Machines.

Machine perfusion of liver grafts has gained popularity for its abilities to preserve liver grafts,reduce cold storage damage, and evaluate graft viability before transplant. However, debate persists regarding the optimal solutions, logistics, and biomarkers for assessing graft quality. To shed light on the lengthy debates surrounding the use of machine perfusion in liver graft preservation,this study utilized bibliometric analysis to evaluate the status and development trends of main research areas. On December 10th, 2022, we conducted a literature search using the Web of Science database to identify articles related to liver machine perfusion. The search included only original studies and reviews and excluded meeting abstracts, letters, notes, editorials, short surveys, book chapters, and errata. We identified the number of citations and encompassed various aspects, such as annual trends, countries, institutions, authors, journals, and key words. We used VOSviewer version 1.6.18 to generate tables and figures. After manually removing irrelevant papers, we included 264 articles (89 reviews; remaining were original studies). The articles were cited 5743 times, averaging 21.92 per article. We found that the United Kingdom (n = 76) was the country that produced the most articles,followed by theUnited States (66 articles). Most papers in our search were published in Liver Transplantation (n = 31) and Transplantation (n = 16). Bibliometric analysis provided insights into debates and advancements in liver graft preservation using machine perfusion. The analysis showed leading countries and key research areas in the field. This overview serves as a valuable resource for researchers, offering a foundation for further exploration and guiding future investigations in the field of machine perfusion for liver graft preservation.

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.

The Role of Normothermic Machine Perfusion in Extended Criteria Donor Grafts: A New Direction in Liver Graft Assessment and Preservation

Despite improvements in short-term and long-term outcomes of liver transplant patients, the discrepancy between the number of available livers and transplant candidates continues to increase. The use of expanded criteria donors is one strategy that can be used to address donor shortages. In recent years, preservation strategies such as normothermic machine perfusion (NMP) have been explored to improve the preservation of organs and test their viability before transplantation. We reviewed the recent literature and trials assessing the use of NMP in the setting of liver transplantation. Multiple feasibility trials have demonstrated the clinical prospect of NMP and proved its numerous advantages compared to conventional static cold storage. These advantages include preservation and viability assessment of high-risk donor allografts and grafts that would have otherwise been discarded. This review aims to address the topic of liver NMP in the setting of current and future applications in the setting of extended criteria donor grafts.

A propensity score matched analysis of liver transplantation outcomes in the setting of preservation solution shortage

The recent shortage of the University of Wisconsin (UW) solution prompted increased utilization of histidine-tryptophan-ketoglutarate (HTK) solution for liver graft preservation. This contemporary study analyzed deceased donor liver transplant outcomes following preservation with HTK vs UW. Patients receiving deceased donor liver transplantations between January 1, 2019, and June 30, 2022, were retrospectively identified utilizing the Organ Procurement and Transplant Network database, stratified by preservation with HTK vs UW, and a propensity score matching analysis was performed. Outcomes assessed included rates of primary nonfunction, graft survival, and patient survival. There were 4447 patients in each cohort. Primary nonfunction occurred in 60 (1.35%) patients in the HTK group vs 25 (0.54%) in the UW group (P < .001). HTK was associated with lower 90-day graft survival (94.39% vs 96.09%; P < .001) and 90-day patient survival (95.97% vs 97.38%; P = .001). Unmatched donation after cardiac death-specific analysis of HTK vs UW demonstrated respective rates of primary nonfunction of 1.63% vs 0.82% (P = .20), 90-day graft survival of 92.50% vs 95.29% (P = .069), and 90-day patient survival of 93.90% vs 96.35% (P = .077). These results suggest that HTK may not be an equivalent preservation solution for deceased donor liver transplantation.

The Distinct Innate Immune Response of Warm Ischemic Injured Livers during Continuous Normothermic Machine Perfusion.

Although normothermic machine perfusion (NMP) provides superior preservation of liver grafts compared to static cold storage and allows for viability testing of high-risk grafts, its effect on the liver immune compartment remains unclear. We investigated the innate immune response during 6 h of continuous NMP (cNMP) of livers that were directly procured (DP, n = 5) or procured after 60 min warm ischemia (WI, n = 5), followed by 12 h of whole blood (WB) reperfusion. WI livers showed elevated transaminase levels during cNMP but not after WB reperfusion. Perfusate concentrations of TNF-α were lower in WI livers during cNMP and WB reperfusion, whereas IL-8 concentrations did not differ significantly. TGF-β concentrations were higher in WI livers during NMP but not after WB reperfusion, whereas IL-10 concentrations were similar. Endoplasmic stress and apoptotic signaling were increased in WI livers during cNMP but not after WB reperfusion. Additionally, neutrophil mobilization increased to a significantly lesser extent in WI livers at the end of NMP. In conclusion, WI livers exhibit a distinct innate immune response during cNMP compared to DP livers. The cytokine profile shifted towards an anti-inflammatory phenotype during cNMP and WB reperfusion, and pro-apoptotic signaling was stronger during cNMP. During WB reperfusion, livers exhibited a blunted cytokine release, regardless of ischemic damage, supporting the potential reconditioning effect of cNMP.

Protective effects of diclofenac on liver graft preservation.

This study aims to evaluate the effect of diclofenac addition to the preservation solution Celsior on liver graft preservation. Liver from Wistar rats were cold flushed in situ, harvested, and then stored in Celsior solution (24h, 4 °C) supplemented or not with 50mg/L of diclofenac sodium salt. Reperfusion was performed (120min, 37 °C) using the isolated perfusion rat liver model. Perfusate samples were collected to evaluate transaminases' activities after cold storage and by the end of reperfusion. To evaluate liver function, bile flow, hepatic clearance of bromosulfophthalein, and vascular resistance were assessed. Diclofenac scavenging property (DPPH assay) as well as oxidative stress parameters (SOD and MPO activities and the concentration of glutathione, conjugated dienes, MDA, and carbonylated proteins) were measured. Transcription factors (PPAR-γ and NF-κB), inflammation (COX-2, IL-6, HMGB-1, and TLR-4), as well as apoptosis markers (Bcl-2 and Bax) were determined by quantitative RT-PCR. Enriching the preservation solution Celsior with diclofenac sodium salt attenuated liver injuries and improved graft function. Oxidative stress, inflammation, and apoptosis were significantly reduced in Celsior+Diclo solution. Also, diclofenac activated PPAR-γ and inhibited NF-κB transcription factors. To decrease graft damage and improve transplant recovery, diclofenac sodium salt may be a promising additive to preservation solution.

Prolonged Normothermic Machine Perfusion: Buying More Time for Liver Graft Assessment and Repair.

Prolonged Normothermic Machine Perfusion: Buying More Time for Liver Graft Assessment and Repair.

Predictive value of portal fibrosis and inflammation in transplanted liver grafts treated with hypothermic oxygenated perfusion.

Hypothermic oxygenated perfusion (HOPE) has become widespread for the preservation of liver grafts, making tangled the relationship among the use of extended criteria donors (ECD), graft histology and transplant outcome. To prospectively validate the impact of the graft histology on transplant outcome in recipient receiving liver grafts from ECD after HOPE. Ninety-three ECD grafts were prospectively enrolled; 49 (52.7 %) were perfused with HOPE according to our protocols. All clinical, histological and follow-up data were collected. Grafts with portal fibrosis stage ≥3 according to Ishak's (evaluated with Reticulin stain) had a significantly higher incidence of early allograft dysfunction (EAD) and 6-month-dysfunction (p=0.026 and p=0.049), with more days in Intensive Care Unit (p=0.050). Lobular fibrosis correlated with post-liver transplant kidney function (p=0.019). Moderate-to-severe chronic portal inflammation was correlated with graft survival on both multivariate and univariate analyses (p<0.001), but this risk factor is sensibly reduced by the execution of HOPE. The use of liver grafts with portal fibrosis stage ≥3 implies a higher risk of post-transplant complications. Portal inflammation represents an important prognostic factor as well, but the execution of HOPE represents a valid tool to improve graft survival.

Novel strategies in liver graft preservation-The French perspective.

Given the increasing graft shortage, the transplant community is forced to use so called marginal liver grafts with a higher susceptibility to ischemia-reperfusion injury. This exposes the recipient to a higher risk of graft failure and post-transplant complications. While static cold storage remains the gold standard in low-risk transplant scenarios, dynamic preservation strategies may allow to improve outcomes after transplantation of marginal liver grafts. Two dynamic preservation strategies, end-ischemic hypothermic oxygenated perfusion (HOPE) and continuous normothermic machine perfusion (cNMP), have been evaluated in randomized clinical trials. The results show improved preservation of liver grafts after cNMP and reduction of post-transplant biliary complications after HOPE. In comparison to cNMP, HOPE has the advantage of requiring less logistics and expertise with the possibility to return to default static cold storage. Both strategies allow to assess graft viability prior to transplantation and may thus contribute to optimizing graft selection and reducing discard rates. The use of dynamic preservation is rapidly increasing in France and results from a national randomized trial on the use of HOPE in marginal grafts will soon be available. Future applications should focus on controlled donation after circulatory death liver grafts, split grafts and graft treatment during perfusion. The final aim of dynamic liver graft preservation is to improve post-transplant outcomes, increase the number of transplanted grafts and allow expansion of transplant indications.

Normothermic Machine Perfusion as a Tool for Safe Transplantation of High-Risk Recipients

Normothermic machine perfusion (NMP) should no longer be considered a novel liver graft preservation strategy, but rather viewed as the standard of care for certain graft–recipient scenarios. The ability of NMP to improve the safe utilisation of liver grafts has been demonstrated in several publications, from numerous centres. This is partly mediated by its ability to limit the cold ischaemic time while also extending the total preservation period, facilitating the difficult logistics of a challenging transplant operation. Viability assessment of both the hepatocytes and cholangiocytes with NMP is much debated, with numerous different parameters and thresholds associated with a reduction in the incidence of primary non-function and biliary strictures. Maximising the utilisation of liver grafts is important as many patients require transplantation on an urgent basis, the waiting list is long, and significant morbidity and mortality is experienced by patients awaiting transplants. If applied in an appropriate manner, NMP has the ability to expand the pool of grafts available for even the sickest and most challenging of recipients. In addition, this is the group of patients that consume significant healthcare resources and, therefore, justify the additional expense of NMP. This review describes, with case examples, how NMP can be utilised to salvage suboptimal grafts, and our approach of transplanting them into high-risk recipients.

Biventricular Assist Devices for Acute Heart Failure After Orthotopic Liver Transplantation

Background: Medical comorbidities augment surgical risk of liver transplantation. This is a report of immediate post-operative biventricular failure following liver transplant requiring venoarterial extracorporeal membrane oxygenation (VA-ECMO) and subsequent conversion to minimally invasive biventricular assist devices (BIVAD) for cardiac recovery and liver graft preservation. Case Report: 66-year-old male decompensated alcoholic cirrhotic with a pre-operative stress echocardiogram (ECHO) showing no significant valvular or coronary disease and a left ventricular ejection fraction (LVEF) of 65% underwent liver transplantation. Transesophageal echocardiogram at the conclusion of the case demonstrated a LVEF of 10% with biventricular dysfunction and severe mitral regurgitation requiring four pressors. VA-ECMO was initiated for temporary stabilization with subsequent transition to biventricular support using an Impella® 5.5 left ventricular device (VAD) via axillary artery graft and a Protek-Duo percutaneous right VAD via the right internal jugular vein, both placed peripherally through a minimally invasive approach. Serial echocardiograms showed recovery of myocardial function. BIVAD were removed on day 8 and day 13. Excellent liver function was maintained. Conclusion: This is the first report of minimally invasive BIVAD used for acute cardiogenic shock after liver transplantation. A multidisciplinary team approach to prompt mechanical support ensured preservation of liver graft while allowing for cardiac recovery.

Editorial introductions.

Current Opinion in Organ Transplantation was launched in 1996. It is part of a successful series of review journals whose unique format is designed to provide a systematic and critical assessment of the literature as presented in the many primary journals. The field of organ transplantation is divided into 18 sections that are reviewed once a year. Each section is assigned a Section Editor, a leading authority in the area, who identifies the most important topics at that time. Here we are pleased to introduce the Section Editors for this issue. SECTION EDITORS Joseph F. MaglioccaJoseph F. MaglioccaJoseph F. Magliocca, MD, is Assistant Professor in the Division of Transplantation in the Department of Surgery at Emory University School of Medicine. Dr Magliocca, a board certified surgeon specializing in liver transplantation, also serves as Surgical Director of the Liver Transplant Program at Children's Healthcare of Atlanta. Prior to his work at Emory, Dr Magliocca was the surgical director of adult and pediatric liver transplantation as well as pancreas transplantation at the University of Florida College of Medicine. He also directed the medical student and resident education components of University of Florida's transplant and hepatobiliary surgery program. Dr Magliocca belongs to numerous professional organizations including American College of Surgeons, American Society of Transplant Surgeons, The Transplantation Society, American Society of Transplantation, International Pediatric Transplant Association, International Pancreas and Islet Transplant Association, and Association for Academic Surgery. He is a member of the Cancer Prevention and Control Research Program at Winship. Dr Magliocca currently serves as an associate editor of the American Journal of Transplantation, and is actively engaged in clinical and translational research investigating the preservation and resuscitation of liver grafts. Dr Magliocca's research interests include organ preservation, ischemia/reperfusion injury and management of immunosuppression in patients following transplantation. Laurens J. CeulemansLaurens J. CeulemansLaurens J. Ceulemans (1985) graduated as medical doctor in 2010 at KU Leuven, Belgium (MD). In 2017 he obtained his PhD with his contributions to the clinical and basic science field of intestinal transplantation and ischemia reperfusion injury. After his specialization in general surgery (2018), he completed a clinical and research fellowship in thoracic surgery and transplantation at the University Hospitals and ETH Zürich in Switzerland. This fellowship was supported by several grants including the prestigious Horlait-Dapsens and ESOT schorlarships. Since 2019 he has worked as a thoracic and transplant surgeon at the department of Thoracic Surgery and the Leuven Intestinal Failure and Transplant (LIFT) center at the University Hospitals Leuven. He is appointed as professor in Surgery at KU Leuven and his basic research focuses on both the intestine and the lung. He is the author of 100 peer-reviewed papers and actively enrolled in several transplant societies. He is a council member for IRTA since 2018 and chair of the Membership and Education committee since 2021.

Hypothermic machine perfusion for liver graft preservation.

Ex-vivo machine perfusion has emerged as a promising alternative to static cold storage (SCS) for preservation of liver grafts over the last decade. This review describes the mechanistic benefits associated with hypothermic machine perfusion (HMP) for preservation of liver grafts and highlights clinical outcomes of liver transplantation using HMP technology. Over the last decade, several single-centre studies have shown decreased biliary complications, decreased early allograft dysfunction (EAD) rates and improved patient survival in liver transplant recipients after application of HMP for liver graft preservation. This has led to initiation of prospective, multicentre, randomized controlled trials (RCTs) in both Europe and North America focused on clinical outcomes in liver transplant recipients using HMP-preserved liver grafts. In addition, recent single-centre studies have shown the utility of perfusate biomarker analysis during HMP in predicting EAD after liver transplantation. HMP technology has potential to increase the available donor liver organ pool for liver transplant recipients and improve clinical outcomes after liver transplantation. Broader clinical application of HMP in resuscitation and preservation of liver grafts is anticipated over the next decade once regulatory, logistical and financial challenges are overcome.

PEG35 and Glutathione Improve Mitochondrial Function and Reduce Oxidative Stress in Cold Fatty Liver Graft Preservation.

The need to meet the demand for transplants entails the use of steatotic livers, more vulnerable to ischemia-reperfusion (IR) injury. Therefore, finding the optimal composition of static cold storage (SCS) preservation solutions is crucial. Given that ROS regulation is a therapeutic strategy for liver IR injury, we have added increasing concentrations of PEG35 and glutathione (GSH) to the preservation solutions (IGL-1 and IGL-2) and evaluated the possible protection against energy depletion and oxidative stress. Fatty livers from obese Zücker rats were isolated and randomly distributed in the control (Sham) preserved (24 h at 4 °C) in IGL-0 (without PEG35 and 3 mmol/L GSH), IGL-1 (1 g/L PEG35, and 3 mmol/L GSH), and IGL-2 (5 g/L PEG35 and 9 mmol/L GSH). Energy metabolites (ATP and succinate) and the expression of mitochondrial oxidative phosphorylation complexes (OXPHOS) were determined. Mitochondrial carrier uncoupling protein 2 (UCP2), PTEN-induced kinase 1 (PINK1), nuclear factor-erythroid 2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the inflammasome (NLRP3) expressions were analyzed. As biomarkers of oxidative stress, protein oxidation (AOPP) and carbonylation (DNP derivatives), and lipid peroxidation (malondialdehyde (MDA)–thiobarbituric acid (TBA) adducts) were measured. In addition, the reduced and oxidized glutathione (GSH and GSSG) and enzymatic (Cu–Zn superoxide dismutase (SOD), CAT, GSH S-T, GSH-Px, and GSH-R) antioxidant capacities were determined. Our results showed that the cold preservation of fatty liver graft depleted ATP, accumulated succinate and increased oxidative stress. In contrast, the preservation with IGL-2 solution maintained ATP production, decreased succinate levels and increased OXPHOS complexes I and II, UCP2, and PINK-1 expression, therefore maintaining mitochondrial integrity. IGL-2 also protected against oxidative stress by increasing Nrf2 and HO-1 expression and GSH levels. Therefore, the presence of PEG35 in storage solutions may be a valuable option as an antioxidant agent for organ preservation in clinical transplantation.

IGL-2 as a Unique Solution for Cold Static Preservation and Machine Perfusion in Liver and Mitochondrial Protection

Hypothermic static cold storage and machine perfusion strategies remain the clinical standard of care for liver graft preservation. Recently, the protection of the mitochondrial function and the energetic levels derived from it has emerged as one of the key points for organ preservation. However, the complex interactions between liver mitochondrial protection and its relation with the use of solutions/perfusates has been poorly investigated. The use of an alternative IGL-2 solution to Belzer MPS one for hypothermic oxygenated perfusion (HOPE), as well as in static cold storage, introduce a new kind of perfusate to be used for liver grafts subjected to HOPE strategies, either alone or in combination with hypothermic static preservation strategies. IGL-2 not only protected mitochondrial integrity, but also avoided the mixture of different solutions/perfusates reducing. Thus, the operational logistics and times prior to transplantation, a critical factor when suboptimal organs such as donation after circulatory death or steatotic ones, are used for transplantation. The future challenges in graft preservation will go through (1) the improvement of the mitochondrial status and its energetic status during the ischemia and (2) the development of strategies to reduce ischemic times at low temperatures, which should translate in a better transplantation outcome.

Regulation of autophagy protects against liver injury in liver surgery-induced ischaemia/reperfusion.

Transient ischaemia and reperfusion in liver tissue induce hepatic ischaemia/reperfusion (I/R) tissue injury and a profound inflammatory response in vivo. Hepatic I/R can be classified into warm I/R and cold I/R and is characterized by three main types of cell death, apoptosis, necrosis and autophagy, in rodents or patients following I/R. Warm I/R is observed in patients or animal models undergoing liver resection, haemorrhagic shock, trauma, cardiac arrest or hepatic sinusoidal obstruction syndrome when vascular occlusion inhibits normal blood perfusion in liver tissue. Cold I/R is a condition that affects only patients who have undergone liver transplantation (LT) and is caused by donated liver graft preservation in a hypothermic environment prior to entering a warm reperfusion phase. Under stress conditions, autophagy plays a critical role in promoting cell survival and maintaining liver homeostasis by generating new adenosine triphosphate (ATP) and organelle components after the degradation of macromolecules and organelles in liver tissue. This role of autophagy may contribute to the protection of hepatic I/R‐induced liver injury; however, a considerable amount of evidence has shown that autophagy inhibition also protects against hepatic I/R injury by inhibiting autophagic cell death under specific circumstances. In this review, we comprehensively discuss current strategies and underlying mechanisms of autophagy regulation that alleviates I/R injury after liver resection and LT. Directed autophagy regulation can maintain liver homeostasis and improve liver function in individuals undergoing warm or cold I/R. In this way, autophagy regulation can contribute to improving the prognosis of patients undergoing liver resection or LT.

An oxygenated perfluorocarbon emulsion improves liver graft preservation evaluated in DCD livers of male sprague dawley rats.

The application of perfluorocarbons, which can carry large quantities of oxygen, in organ preservation was limited by their poor solubility in water. A stable form of perfluorocarbon dispersed in suitable buffers is urgently needed. Perfluorocarbon emulsion was designed and characterized with respect to size distribution, rheology, stability, and oxygen-carrying capacity. The state of DCD rat donor livers preserved by the oxygenated perfluorocarbon emulsion was studied after exvivo reperfusion by using biochemistry, pathology, and immunohistochemistry methods. Perfluorocarbon emulsion was successfully prepared by high-pressure homogenization. Optimized perfluorocarbon emulsion showed nanoscale size distribution, good stability, and higher oxygen loading capacity than that of HTK solution or water. The state of preserved livers after cardiac death rat liver was improved significantly after static cold storage for 48 hours in this oxygenated perfluorocarbon emulsion. The ATP content and down-regulation of HIF-1a expression after preservation of the liver graft by the oxygenated perfluorocarbon emulsion suggested the advantage of adequate oxygen supply for adequate time. This perfluorocarbon emulsion reported here might be considered a promising system for oxygenated donor liver storage by attenuation of hypoxia.

The future of liver transplantation: Ex-vivo machine perfusion

Long-term preservation of liver grafts outside of the body (ex vivo) may enable treatment, repair, assessment of poor-quality livers currently declined for transplantation and regeneration of partial livers, thereby mitigating global donated liver shortage. The challenge, however, is to keep injured or resected human livers viable for multiple days, a time window necessary for expanded therapeutic interventions. Here, we present a liver perfusion technology that maintains ex vivo human liver function for seven days. The perfusion apparatus was engineered recapitulating core endocrine, renal, pulmonary, cardiac, diaphragmatic, and other physiologic functions for the liver, which are prerequisite for successful long-term liver preservation. The machine was developed in a stepwise fashion using swine livers and eventually tested in injured human livers declined for transplantation and in partial livers from patients, who have undergone formal hepatectomy. Perfused human livers, discarded for poor quality and predicted failure after transplantation, as well as the partial livers unveiled preserved function during ex vivo machine perfusion, as indicated by bile production, synthesis of coagulation factors and maintained cellular energy, among many others. Histological examinations of serial biopsies confirmed an intact liver structure at day seven. This data demonstrates, first, that injured human livers may recover from lethal injury and maintain function for one week outside of the body and second, that the availability of this machine perfusion system may provide an important tool for assessment of liver quality, to induce liver regeneration in partial livers, and to perform therapeutic interventions prior to transplantation.

Adenosine Diphosphate and the P2Y13 Receptor Are Involved in the Autophagic Protection of Ex Vivo Perfused Livers From Fasted Rats: Potential Benefit for Liver Graft Preservation.

Studies on how to protect livers perfused ex vivo can help design strategies for hepatoprotection and liver graft preservation. The protection of livers isolated from 24-hour versus 18-hour starved rats has been previously attributed to autophagy, which contributes to the energy-mobilizing capacity ex vivo. Here, we explored the signaling pathways responsible for this protection. In our experimental models, 3 major signaling candidates were considered in view of their abilities to trigger autophagy: high mobility group box 1 (HMGB1), adenosine monophosphate-activated protein kinase (AMPK), and purinergic receptor P2Y13. To this end, ex vivo livers isolated from starved rats were perfused for 135minutes, after which perfusate samples were studied for protein release and biopsies were performed for evaluating signaling protein contents. For HMGB1, no significant difference was observed between livers isolated from rats starved for 18 and 24hours at perfusion times of both 0 and 135minutes. The phosphorylated and total forms of AMPK, but not their ratios, were significantly higher in 24-hour fasted than in 18-hour fasted livers. However, although the level of phosphorylated AMPK increased, perfusing ex vivo 18-hour fasted livers with 1mM 5-aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, did not protect the livers. In addition, the adenosine diphosphate (ADP; and not adenosine monophosphate [AMP]) to AMP + ADP + adenosine triphosphate ratio increased in the 24-hour starved livers compared with that in the 18-hour starved livers. Moreover, perfusing 24-hour starved livers with 0.1mM 2-[(2-chloro-5-nitrophenyl)azo]-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-4-pyridinecarboxaldehyde (MRS2211), a specific antagonist of the P2Y13 receptor, induced an increase in cytolysis marker levels in the perfusate samples and a decrease in the levels of autophagic marker microtubule-associated proteins 1 light chain 3 II (LC3II)/actin (and a loss of p62/actin decrease), indicating autophagy inhibition and a loss of protection. The P2Y13 receptor and ADP (a physiological activator of this receptor) are involved in the protection of ex vivo livers. Therapeutic opportunities for improving liver graft preservation through the stimulation of the ADP/P2Y13 receptor axis are further discussed.

Use of biventricular assist devices for acute heart failure after orthotopic liver transplantation: a case report

Presenter: Anushi Shah MD | Massachusetts General Hospital Background: Medical co-morbidities in liver transplantation augment surgical risk. We present this case report of a patient with immediate post-operative biventricular failure following liver transplant requiring veno-arterial extracorporeal membrane oxygenation (VA ECMO) and subsequent conversion to minimally invasive biventricular assist devices for cardiac recovery and new graft preservation. Methods: 66-year-old male decompensated alcoholic cirrhotic (MELD-Na 38) on the liver transplant waitlist had a pre-operative ECHO showing no evidence of overt valvular or coronary disease, ejection fraction (EF) 65%. He underwent an liver transplant on veno-venous bypass, our institutional standard procedure. Transesophageal echocardiography (TEE) pre-reperfusion showed normal biventricular function and at the end of the case showed an EF approximately 10-16% with biventricular dysfunction and severe mitral regurgitation requiring epinephrine, norepinephrine, vasopressin and ionotropic support. Due to continued poor perfusion and poor biventricular function in the ICU post-operatively, the patient was placed on VA ECMO for temporary stabilization and subsequent biventricular support using an Impella® 5.5 (Abiomed, Danvers MA) left ventricular assist device (LVAD) via axillary artery graft and a Protek-Duo (CardiacAssist Inc, Pittsburgh PA) percutaneous right ventricular assist device (RVAD) via the right internal jugular vein. Results: Over the course of post-operative days (POD) 3-11, the patient was weaned off pressors, extubated with close monitoring of liver function (Figure 1). Serial transthoracic echocardiography recovery of myocardial function. RVAD and LVAD were removed on POD 8 and POD 13, respectively. The liver graft function was maintained throughout. Serial TTE post mechanical support removal showed his EF had improved to 52%. Conclusion: This is the first report of minimally invasive biventricular support devices used for acute cardiogenic shock status post liver transplantation. We hypothesized that myocardial stress in the setting of the patient’s history of alcohol abuse was the contributing factors of acute global pump failure. A multidisciplinary team approach to prompt mechanical support ensured preservation of liver graft while allowing for cardiac recovery.