Consequences of cold-ischemia time on primary nonfunction and patient and graft survival in liver transplantation: a meta-analysis

Impact of late-night liver transplantation on recipient outcome

When liver graft procurements take place in the late afternoon or in the evening, transplantation is often performed at night when alertness and psychomotor abilities may be altered. Our objective was to determine whether liver transplantation performed at night increases severe 90-day postoperative complication rates. In this observational study, we analyzed all consecutive patients who were transplanted between January 1, 2012 and December 31, 2018. Outcomes were compared according to whether all or part of the liver transplantation was performed or not (control group) at late night, i.e., between midnight and 5 a.m. The main outcome was rate of Clavien-Dindo ≥ IIIb complications within 90 days post-transplantation. 790 liver transplantations were analyzed. In a multivariable analysis adjusted for cold ischemic time, late-night procedures required more blood transfusions (P = 0.010) and had higher odds of severe complication occurrence than controls (odds ratio 1.67; 95% CI, [1.10-2.54]). One-year graft and patient survival was similar. We conclude that the organization of liver transplant surgery should be reconsidered to avoid LN surgery as much as can be done. Except to create teams dedicated to night work (which represents a considerable cost), such organization may require safe extension of liver graft preservation times. The alternative could be to extend the use of oxygenated machine perfusion preservation with the unique purpose of safely extending the graft preservation time.

Kidney Transplantation Outcomes From Uncontrolled Donation After Circulatory Death: A Systematic Review and Meta-analysis

BACKGROUND

Uncontrolled donation after circulatory death (uDCD) is a potential additional source of donor kidneys. This study reviewed uDCD kidney transplant outcomes to determine if these are comparable to controlled donation after circulatory death (cDCD).

METHODS

MEDLINE, Cochrane, and Embase databases were searched. Data on demographic information and transplant outcomes were extracted from included studies. Meta-analyses were performed, and risk ratios (RR) were estimated to compare transplant outcomes from uDCD to cDCD.

RESULTS

Nine cohort studies were included, from 2178 uDCD kidney transplants. There was a moderate degree of bias, as 4 studies did not account for potential confounding factors. The median incidence of primary nonfunction in uDCD was 12.3% versus 5.7% for cDCD (RR, 1.85; 95% confidence intervals, 1.06-3.23; P  = 0.03, I 2  = 75). The median rate of delayed graft function was 65.1% for uDCD and 52.0% for cDCD. The median 1-y graft survival for uDCD was 82.7% compared with 87.5% for cDCD (RR, 1.43; 95% confidence intervals, 1.02-2.01; P  = 0.04; I 2  = 71%). The median 5-y graft survival for uDCD and cDCD was 70% each. Notably, the use of normothermic regional perfusion improved primary nonfunction rates in uDCD grafts.

CONCLUSIONS

Although uDCD outcomes may be inferior in the short-term, the long-term outcomes are comparable to cDCD.

Normothermic Machine Perfusion Reduces Transfusion Requirements Even After Static Cold Storage: A 1 y Retrospective Single-center Analysis

Background

Normothermic machine perfusion (NMP) of liver grafts has been shown to reduce intraoperative catecholamine consumption and the need for allogenic blood products after reperfusion compared with organs undergoing classical static cold storage (SCS). This study aimed to investigate the effects of an NMP phase after SCS (NMP after SCS) of liver grafts in terms of postreperfusion hemodynamics and transfusion requirements.

Methods

Eighteen recipients of NMP after SCS grafts were matched according to recipient age, donor age, and model for end-stage liver disease score in a 1:2 ratio with recipients of an SCS graft. Postreperfusion hemodynamics and the need for catecholamines, blood products, and clotting factors were compared.

Results

After reperfusion of the organ, patients in the NMP after SCS group showed significantly reduced transfusion requirements for packed red blood cells and platelet concentrates compared with patients of the SCS group (P < 0.001 and P = 0.018, respectively). In addition, patients in the NMP after SCS group received less fibrinogen concentrate (NMP after SCS group 0 [0-1.5] g versus SCS group 2 [0-4] g; P = 0.0163). No differences in postreperfusion hemodynamics could be detected between groups.

Conclusions

This retrospective analysis shows that NMP reduces postreperfusion requirements of red blood cells, platelet concentrates, and fibrinogen concentrate even if installed after a phase of organ SCS, because it may be practiced on most centers where NMP is available.

Perioperative Characteristics and Outcomes of Fontan Versus Non-Fontan Patients Undergoing Combined Heart-Liver Transplantation: A Retrospective Cohort Study

OBJECTIVES

Combined heart-liver transplantation (CHLT) is becoming increasingly frequent as a maturing population of patients with Fontan-palliated congenital heart disease develop advanced liver fibrosis or cirrhosis. The authors present their experience with CHLT for congenital and noncongenital indications, and identify characteristics associated with poor outcomes that may guide intervention in high-risk patients.

DESIGN

This was a single-center retrospective cohort study.

SETTING

This study was conducted at Vanderbilt University Medical Center in Nashville, Tennessee.

PARTICIPANTS

The study included 16 consecutive adult recipients of CHLT at the authors' institution between April 2017 and February 2022.

INTERVENTIONS

Eleven patients underwent transplantation for Fontan indications, and 5 were transplanted for non-Fontan indications.

MEASUREMENTS AND MAIN RESULTS

Compared with non-Fontan patients, Fontan recipients had longer cardiopulmonary bypass duration (199 v 119 minutes, p =m0.002), operative times (786 v 599 minutes, p = 0.01), and larger blood product transfusions (15.4 v 6.3 L, p = 0.18). Six of 16 patients required extracorporeal membrane oxygenation (ECMO), of whom 4 were Fontan patients who subsequently died. Patients who required ECMO had lower 5-hour lactate clearance (0.0 v 3.5 mmol/L, p = 0.001), higher number of vasoactive infusions, lower pulmonary artery pulsatility indices (0.58 v 1.77, p = 0.03), and higher peak inspiratory pressures (28.0 v 18.5 mmHg, p = 0.01) after liver reperfusion.

CONCLUSIONS

Combined heart-liver transplantation in patients with Fontan-associated end-organ disease is particularly challenging and associated with higher recipient morbidity compared with non-Fontan-related CHLT. Early hemodynamic intervention for signs of ventricular dysfunction may improve outcomes in this growing high-risk population.

Factors affecting survival after liver retransplantation: a systematic review and meta-analysis

Background

Liver retransplantation (reLT) has historically had inferior survival relative to primary liver transplant (LT). To improve outcomes after reLT, researchers have identified factors predicting overall (OS) and/or graft survival (GS) after reLT. This systematic review and random effects meta-analysis sought to summarize this literature to elucidate the strongest independent predictors of post-reLT.

Methods

A systematic review was conducted to identify manuscripts reporting factors affecting survival in multivariable Cox proportional hazards analyses. Papers with overlapping cohorts were excluded.

Results

All 25 included studies were retrospective, and 15 (60%) were single-center studies. Patients on pre-transplant ventilation (HR, 3.11; 95% CI, 1.56-6.20; p = 0.001) and with high serum creatinine (HR, 1.46; 95% CI, 1.15-1.87; p = 0.002) had the highest mortality risk after reLT. Recipient age, Model for End-Stage Liver Disease score, donor age, and cold ischemia time >12 h also conferred a significant risk of post-reLT death (all p < 0.05). Factors affecting GS included donor age and retransplant interval (the time between LT and reLT; both p < 0.05). OS is significantly higher when the retransplant interval is ≤7 days relative to 8-30 days (p = 0.04).

Conclusions

The meta-analysis was complicated by papers utilizing non-standardized cut-off values to group variables, which made between-study comparisons difficult. However, it did identify 7 variables that significantly impact survival after reLT, which could stimulate future research into improving post-reLT outcomes.

Is Liver Transplant Justified at Any MELD Score?

BACKGROUND

Assessing the survival benefit of transplantation in patients with end-stage liver disease is critical in guiding the decision-making process for liver allocation. Previous studies established increased mortality risk for those transplanted below Model for End-Stage Liver Disease (MELD) 18 compared with candidates who remained on the waitlist; however, improved outcomes of liver transplantation and a changing landscape in the donor supply warrant re-evaluation of this idea.

METHODS

Using the United Network for Organ Sharing database, we analyzed 160 290 candidates who were waitlisted for liver transplantation within MELD cohorts. We compared patients who were transplanted in a MELD cohort with those listed but not transplanted in that listed MELD cohort with an intent-to-treat analysis.

RESULTS

Those transplanted at a MELD between 6 and 11 showed a 31% reduction in adjusted mortality (HR = 0.69 [95% confidence interval [CI], 0.66-0.75]; P < 0.001) compared with the intent-to-treat cohort in a Cox multivariate regression. This mortality benefit increased to a 37% adjusted reduction for those transplanted at MELD between 12 and 14 (HR = 0.63 [95% CI, 0.60-0.66]; P < 0.001) and a 46% adjusted reduction for those transplanted at a MELD between 15 and 17 (HR = 0.54 [95% CI, 0.52-0.57]; P < 0.001), effects that remained in sensitivity analyses excluding patients with hepatocellular carcinoma, encephalopathy, ascites, and variceal bleeds. A multivariate analysis of patients transplanted at MELD < 18 found younger age and cold ischemia time were protective, whereas older age, lower functional status, and socioeconomic factors increased mortality risk.

CONCLUSIONS

These findings challenge the current practice of deferring liver transplants below a particular MELD score by demonstrating survival benefits for most transplant patients at the lowest MELD scores and providing insight into who benefits within these subgroups.

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

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

Consequences of Changes in the Liver Allocation System for Transplantation in the Silesian Voivodeship and in the Transplantation Center in Katowice

BACKGROUND

For a number of years, the system of procured livers for transplantation by transplant centers in a fixed order, regardless of the location of the procurement site, was in force in Poland. In mid-2018, priority was introduced in the collection of livers by a team from a given province. The aim of the study was to evaluate the impact of changing the liver transplantation allocation system at the Katowice Transplant Center (KTW) on the number of transplanted livers and on the selected parameters of donors from which the liver was procured.

METHODS

The rates and cold ischemia time (CIT) of procured livers were analyzed.

RESULTS

The rate of livers procured by the KTW transplant team increased from 36.6% to 53.3%, and at the same time the rate of livers procured by this team and sent for transplantation in other transplant centers increased. The rate of livers transplanted in the KTW, which were procured in the Silesian Voivodeship, increased from 37.4% to 61.0%, and the rate of livers procured outside the Silesian Voivodeship decreased from 54.8% to 36.4%. The CIT of livers transplanted in the KTW was reduced from 407.5 to 360.0 minutes. The comparative analysis of donor parameters of livers procured by the KTW transplant team and transplanted in Katowice revealed no differences regarding analyzed clinical and biochemical parameters.

CONCLUSION

The change in the allocation system increased the number of livers procured by the local team and shortened CIT of livers transplanted at the KTW.

Impact of length of donor ICU stay on outcome of patients after pediatric liver transplantation with whole and ex situ split liver grafts

BACKGROUND

Patients who have a prolonged stay in the intensive care unit (ICU) are often excluded for organ donation because of supposed deleterious effects of a lengthy ICU stay. We aimed to determine the effects of a prolonged donor stay in the ICU on the outcome of liver transplantation (LT) in children.

METHODS

Retrospective review of 89 pediatric LT patients, age 0-18 years, period 2003-2018, including patients having undergone whole organ or in situ split LT. The patients were divided into two groups according to the donor length of stay in the ICU. A prolonged stay was defined as >5 days. Recipient, graft, and donor characteristics were compared; outcome parameters included recipient and graft survival rates and postoperative complications.

RESULTS

Group short (donor ICU stay <5 days) included 75 patients, group long (donor ICU stay >5 days) 14 patients. Baseline characteristics between recipients did not differ. Donors in group long had significantly more infectious complications and a higher gamma glutamyl transferase (gGT) the day of organ recovery. Incidence of biliary complications post-LT was significantly higher in group long (p = .029). Patient and graft survival rates did not differ significantly between groups.

CONCLUSIONS

Donors with a prolonged stay in the ICU should still be considered for liver donation if they fulfill most other selection criteria. Recipients from donors having stayed in ICU >5 days may be at increased risk of biliary complications.

Cold Ischemia Time and Graft Fibrosis Are Associated with Autoantibodies after Pediatric Liver Transplantation: A Retrospective Cohort Study of the European Reference Network TransplantChild

The reported prevalence of autoantibodies (AAB) (ANA, SMA, LKM, SLA) after pediatric liver transplantation (pLTX) varies considerably from 26-75%, but their clinical impact on outcome is uncertain. We aimed to study the prevalence of AAB after pLTX, their association with donor-, transplant-, and recipient-characteristics, and their relation to outcome. In our multicenter retrospective study, we aimed to clarify conflicting results from earlier studies. Six ERN TransplantChild centers reported data on 242 patients, of whom 61% were AAB positive. Prevalence varied across these centers. Independent of the interval between pLTX and AAB analysis, a one-hour increase in CIT resulted in an odds ratio (OR) of 1.37 (95% CI 1.11-1.69) for SMA positivity and an OR of 1.42 (95%CI 1.18-1.72) for ANA positivity. Steroid-free immunosuppression (IS) versus steroid-including IS (OR 5.28; 95% CI 1.45-19.28) was a risk factor for SMA positivity. Liver enzymes were not associated with ANA or SMA positivity. We did not observe an association of rejection activity index with ANA or SMA. However, the liver fibrosis score in follow-up biopsies was associated with ANA titer and donor age. In conclusion, this first multicenter study on AAB after pLTX showed high AAB prevalence and varied widely between centers. Longer CIT and prednisolone-free-IS were associated with AAB positivity, whereas AAB were not indicative of rejection, but instead were associated with graft fibrosis. The detection of AAB may be a marker of liver fibrosis and may be taken into consideration when indications for liver biopsy and immunosuppressive regimes, or reduction of immunosuppression in long-term follow-up, are being discussed. Prospective immunological profiling of pLTX patients, including AAB, is important to further improve our understanding of transplant immunology and silent graft fibrosis.

The effect of blood cells retained in rat livers during static cold storage on viability outcomes during normothermic machine perfusion

In transplantation, livers are transported to recipients using static cold storage (SCS), whereby livers are exposed to cold ischemic injury that contribute to post-transplant risk factors. We hypothesized that flushing organs during procurement with cold preservation solutions could influence the number of donor blood cells retained in the allograft thereby exacerbating cold ischemic injury. We present the results of rat livers that underwent 24 h SCS after being flushed with a cold University of Wisconsin (UW) solution versus room temperature (RT) lactated ringers (LR) solution. These results were compared to livers that were not flushed prior to SCS and thoroughly flushed livers without SCS. We used viability and injury metrics collected during normothermic machine perfusion (NMP) and the number of retained peripheral cells (RPCs) measured by histology to compare outcomes. Compared to the cold UW flush group, livers flushed with RT LR had lower resistance, lactate, AST, and ALT at 6 h of NMP. The number of RPCs also had significant positive correlations with resistance, lactate, and potassium levels and a negative correlation with energy charge. In conclusion, livers exposed to cold UW flush prior to SCS appear to perform worse during NMP, compared to RT LR flush.

Statistical methods versus machine learning techniques for donor-recipient matching in liver transplantation

Donor-Recipient (D-R) matching is one of the main challenges to be fulfilled nowadays. Due to the increasing number of recipients and the small amount of donors in liver transplantation, the allocation method is crucial. In this paper, to establish a fair comparison, the United Network for Organ Sharing database was used with 4 different end-points (3 months, and 1, 2 and 5 years), with a total of 39, 189 D-R pairs and 28 donor and recipient variables. Modelling techniques were divided into two groups: 1) classical statistical methods, including Logistic Regression (LR) and Naïve Bayes (NB), and 2) standard machine learning techniques, including Multilayer Perceptron (MLP), Random Forest (RF), Gradient Boosting (GB) or Support Vector Machines (SVM), among others. The methods were compared with standard scores, MELD, SOFT and BAR. For the 5-years end-point, LR (AUC = 0.654) outperformed several machine learning techniques, such as MLP (AUC = 0.599), GB (AUC = 0.600), SVM (AUC = 0.624) or RF (AUC = 0.644), among others. Moreover, LR also outperformed standard scores. The same pattern was reproduced for the others 3 end-points. Complex machine learning methods were not able to improve the performance of liver allocation, probably due to the implicit limitations associated to the collection process of the database.

The Endothelial Glycocalyx and Organ Preservation-From Physiology to Possible Clinical Implications for Solid Organ Transplantation

The endothelial glycocalyx is a thin layer consisting of proteoglycans, glycoproteins and glycosaminoglycans that lines the luminal side of vascular endothelial cells. It acts as a barrier and contributes to the maintenance of vascular homeostasis and microperfusion. During solid organ transplantation, the endothelial glycocalyx of the graft is damaged as part of Ischemia Reperfusion Injury (IRI), which is associated with impaired organ function. Although several substances are known to mitigate glycocalyx damage, it has not been possible to use these substances during graft storage on ice. Normothermic machine perfusion (NMP) emerges as an alternative technology for organ preservation and allows for organ evaluation, but also offers the possibility to treat and thus improve organ quality during storage. This review highlights the current knowledge on glycocalyx injury during organ transplantation, presents ways to protect the endothelial glycocalyx and discusses potential glycocalyx protection strategies during normothermic machine perfusion.

Changing Trends in Liver Transplantation: Challenges and Solutions

Despite improvements in postliver transplant outcomes through refinements in perioperative management and surgical techniques, several changing trends in liver transplantation have presented challenges. Mortality on the waitlist remains high. In the United States, Europe, and the United Kingdom, there is an increasing need for liver transplantation, primarily as a result of increased incidence of nonalcoholic steatohepatitis-related cirrhosis and cancer indications. Meanwhile, donor suitability has decreased, as donors are often older and have more comorbidities. Despite a mismatch between organ need and availability, many organs are discarded. Notwithstanding this, many solutions have been developed to overcome these challenges. Innovative techniques in allograft preservation, viability assessment, and reconditioning have allowed the use of suboptimal organs with adequate results. Refinements in surgical procedures, including live donor liver transplantations, have increased the organ pool and are decreasing the time and mortality on the waitlist. Despite many challenges, a similar number of solutions and prospects are on the horizon. This review seeks to explore the changing trends and challenges in liver transplantation and highlight possible solutions and future directions.

Factors Associated with Prolonged Recipient Hepatectomy Time During Liver Transplantation: A Single-Centre Experience

BACKGROUND

Recipient hepatectomy during liver transplantation can be a challenging operation and can increase cold ischaemic time. The aim of this study is to assess factors associated with prolonged recipient hepatectomy.

METHODS

From 2005 to 2015, 930 patients were submitted to liver transplantation in our hospital. Prolonged hepatectomy time was defined as operative time >180 min (from knife on skin to total hepatectomy). Patients undergoing early liver retransplantation and living donation were excluded.

RESULTS

A total of 715 patients were included in our study. Median age at transplantation was 53 (18-70) years, and median BMI was 26.2 (16-40). Median hepatectomy time was 131 min. Prolonged hepatectomy time occurred in 89 (12.4%) patients. At univariate analysis, previous decompensated cirrhosis with variceal bleeding and/or ascites, higher BMI and previous abdominal surgery were associated with prolonged operating time. Higher surgeon experience and acute liver failure were associated with shorter hepatectomy time. At multivariate analysis, previous episodes of variceal bleeding (p = 0.027, OR 1.78), BMI > 27 (p = 0.01, OR 1.75), previous abdominal surgery (p = 0.04, OR 1.68) and surgeon experience (p = 0.007, OR 2.04) were independently associated with operating time. Prolonged hepatectomy time was significantly associated with cold and total ischaemic time and intraoperative bleeding (p < 0.001, p = 0.002 and p = 0.002, respectively).

CONCLUSIONS

Recipient BMI, previous episodes of variceal bleeding, previous abdominal surgery and surgeon experience are independently associated with hepatectomy duration. These factors can be helpful to identify those patients with potentially prolonged hepatectomy time, and therefore, strategies can be put in place to optimize outcomes in this group of patients.

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

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

Deep learning quantification of percent steatosis in donor liver biopsy frozen sections

Background

Pathologist evaluation of donor liver biopsies provides information for accepting or discarding potential donor livers. Due to the urgent nature of the decision process, this is regularly performed using frozen sectioning at the time of biopsy. The percent steatosis in a donor liver biopsy correlates with transplant outcome, however there is significant inter- and intra-observer variability in quantifying steatosis, compounded by frozen section artifact. We hypothesized that a deep learning model could identify and quantify steatosis in donor liver biopsies.

Methods

We developed a deep learning convolutional neural network that generates a steatosis probability map from an input whole slide image (WSI) of a hematoxylin and eosin-stained frozen section, and subsequently calculates the percent steatosis. Ninety-six WSI of frozen donor liver sections from our transplant pathology service were annotated for steatosis and used to train (n = 30 WSI) and test (n = 66 WSI) the deep learning model.

Findings

The model had good correlation and agreement with the annotation in both the training set (r of 0.88, intraclass correlation coefficient [ICC] of 0.88) and novel input test sets (r = 0.85 and ICC=0.85). These measurements were superior to the estimates of the on-service pathologist at the time of initial evaluation (r = 0.52 and ICC=0.52 for the training set, and r = 0.74 and ICC=0.72 for the test set).

Interpretation

Use of this deep learning algorithm could be incorporated into routine pathology workflows for fast, accurate, and reproducible donor liver evaluation.

Funding

Mid-America Transplant Society

Dealing With Liver Transplantation during Coronavirus Disease 2019 Pandemic: Normothermic Machine Perfusion Enables for Donor, Organ, and Recipient Assessment: A Case Report

The coronavirus disease 2019 (COVID-19) pandemic has changed life on a global scale. The numbers of transplantations have plummeted as a result of fear of disease transmission, recipient coronavirus disease 2019 infection, priority shift, and resource limitations. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) complicates transplantation because donor testing, (re)allocation of limited resources, and recipient testing may exceed permissible ischemia times.

Normothermic machine perfusion (NMP) helps safely prolong liver preservation up to 38 hours. Additional time is essential under the current circumstances. Here we present the case of a 29-year-old liver transplant recipient in whom prolonged liver preservation required for SARS-CoV-2 screening was accomplished through NMP. Donor and recipient test results for SARS-CoV-2 were negative, and intensive care unit capacity was eventually available. The surgical procedure and postoperative course were uneventful.

NMP can extend preservation times in liver transplantation while awaiting SARS-CoV-2 test results and available intensive care unit capacity.

Implications of liver donor age on ischemia reperfusion injury and clinical outcomes

The aging process causes detrimental changes in a variety of organ systems. These changes include: lesser ability to cope with stress, impaired repair mechanisms and decreased cellular functional reserve capacity. Not surprisingly, aging has been associated with increased susceptibility of donor heart and kidneys grafts to ischemia reperfusion injury (IRI). In the context of liver transplantation, however, the effect of donor age seems to be less influential in predisposing the graft to IRI. In fact, a widely comprehensive understanding of IRI in the aged liver has yet to be agreed upon in the literature. Nevertheless, there have been many reported implications of increased liver donor age with poor clinical outcomes besides IRI. These other poor outcomes include: earlier HCV recurrence, increased rates of acute rejection and greater resistance to tolerance induction. While these other correlations have been identified, it is important to re-emphasize the fact that a unified consensus in regard to liver donor age and IRI has not yet been reached among researchers in this field. Many researchers have even demonstrated that the extent of IRI in aged livers can be ameliorated by careful donor selection, strict allocation or novel therapeutic modalities to decrease IRI. Thus, the goals of this review paper are twofold: 1) To delineate and summarize the conflicting data in regard to liver donor age and IRI. 2) Suggest that careful donor selection, appropriate allocation and strategic effort to minimize IRI can reduce the frequency of a variety of poor outcomes with aged liver donations.

Results of Green Indocyanine in the Use of the R1T1 Robot as Aid in the Pre-operative Process of Hepatic Organ Transplant: Experiment in Wistar Rats

Since the beginning of the history of transplants, numerous difficulties have been faced in the effective implementation of this therapeutic practice, especially with regard to the transplantation of solid organs and their teaching and training, together with the time of removal and transplantation of the organ that directly influences the results of the transplant surgical procedure. The objective of this research was to demonstrate the results found on the process of using green indocyanine during the invention of the Automatic Portable Surgical Communication Equipment with the Robot R1T1 (APSCERR), as well as to demonstrate its capabilities in the medical area of organ transplantation. Biochemical exams, liver profile exams, and mitochondrial breathing exams were performed on the control group and on the indocyanine group. The Mann-Whitney U test was used for statistical evaluations with a significance level of P < .05. As a result of this research, the effectiveness of using the APSCERR equipment on detecting the green indocyanine marker was proven, along with its ability to analyze macroscopic parameters together with the standard color "Dianin Boin scale" used to analyze the level of metabolism/reperfusion of the liver when observed with the APSCERR equipment connected to the R1T1 robot in the presence of green indocyanine. A patent for the development of APSCERR has been registered. It was possible to demonstrate the effectiveness of the equipment in detecting green indocyanine when analyzing parameters in the liver and the absence of a significant impact on the organ with the use of green indocyanine.

Successful Implementation of Unmanned Aircraft Use for Delivery of a Human Organ for Transplantation

OBJECTIVE

To understand and overcome the challenges associated with moving life-urgent payloads using unmanned aircraft.

BACKGROUND DATA

Organ transportation has not been substantially innovated in the last 60 years. Unmanned aircraft systems (UAS; ie, drones) have the potential to reduce system inefficiencies and improve access to transplantation. We sought to determine if UASs could successfully be integrated into the current system of organ delivery.

METHODS

A multi-disciplinary team was convened to design and build an unmanned aircraft to autonomously carry a human organ. A kidney transplant recipient was enrolled to receive a drone-shipped kidney.

RESULTS

A uniquely designed organ drone was built. The aircraft was flown 44 times (total of 7.38 hours). Three experimental missions were then flown in Baltimore City over 2.8 miles. For mission #1, no payload was carried. In mission #2, a payload of ice, saline, and blood tubes (3.8 kg, 8.4 lbs) was flown. In mission #3, a human kidney for transplant (4.4 kg, 9.7 lbs) was successfully flown by a UAS. The organ was transplanted into a 44-year-old female with a history of hypertensive nephrosclerosis and anuria on dialysis for 8 years. Between postoperative days (POD) 1 and 4, urine increased from 1.0 L to 3.6 L. Creatinine decreased starting on POD 3, to an inpatient nadir of 6.9 mg/dL. The patient was discharged on POD 4.

CONCLUSIONS

Here, we completed the first successful delivery of a human organ using unmanned aircraft. This study brought together multidisciplinary resources to develop, build, and test the first organ drone system, through which we performed the first transplant of a drone transported kidney. These innovations could inform not just transplantation, but other areas of medicine requiring life-saving payload delivery as well.

Acetyl-3-Aminoethyl Salicylate Ameliorates Hepatic Ischemia/Reperfusion Injury and Liver Graft Survival Through a High-Mobility Group Box 1/Toll-Like Receptor 4-Dependent Mechanism

In liver transplant cases, severe hepatic ischemia/reperfusion injury (HIRI) is a strong predictor of adverse liver graft and overall outcomes. During HIRI, high-mobility group box 1 (HMGB1) promotes hepatocellular death and proinflammatory cytokine secretion by toll-like receptor 4 (TLR4). Because salicylates inhibit HMGB1/TLR4 interaction, we hypothesized that salicylates may ameliorate HIRI-induced liver damage by inhibiting HMGB1/TLR4 axis activation. Using a murine model of HIRI, we found that the salicylate acetyl-3-aminoethyl salicylic acid (ac3AESA) reduced serum alanine aminotransferase and aspartate aminotransferase as well as Suzuki scores and apoptotic cell counts after HIRI. Ac3AESA also down-regulated hepatocellular HMGB1 and TLR4 expression, phosphorylated inhibitor of κBα, extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, cleaved caspase 3, and cleaved caspase 1 levels after HIRI. Ac3AESA reduced liver Kupffer cell transcription of proinflammatory mediators tumor necrosis factor α (TNF-α), interleukin (IL) 6, IL1β, chemokine (C-X-C motif) ligand (CXCL) 1, CXCL2, and CXCL8 after HIRI. Ac3AESA also dose-dependently reduced in vitro release of Kupffer cell TNF-α. Employing a murine orthotopic liver transplantation model, we found daily ac3AESA administration up to day 10 after transplant improved liver graft survival, suppressed allograft damage, and down-regulated HMGB1/TLR4 signaling. These benefits to survival and allograft health were maintained for cold ischemia times of 12 and 18 hours. Notably, TLR4 knockout eliminated all foregoing ac3AESA-induced effects. In conclusion, ac3AESA partially rescues the negative effects of HIRI and prolongs liver graft survival in a TLR4-dependent manner.

Impact of nighttime procedures on outcomes after liver transplantation

Background

Sleep deprivation is a well-known risk factor for the performance of medical professionals. Solid organ transplantation (especially orthotopic liver transplantation (oLT)) appears to be vulnerable since it combines technically challenging operative procedures with an often unpredictable start time, frequently during the night. Aim of this study was to analyze whether night time oLT has an impact on one-year graft and patient survival.

Material and methods

Deceased donor oLTs between 2006 and 2017 were retrospectively analyzed and stratified for recipients with a start time at day (8 a.m. and 6 p.m.) or at night (6 p.m. to 8 a.m.). We examined donor as well as recipient demographics and primary outcome measure was one-year patient and graft survival.

Results

350 oLTs were conducted in the study period, 154 (44%) during daytime and 196 (56%) during nighttime. Donor and recipient variables were comparable. One-year patient survival (daytime 75.3% vs nighttime 76.5%, p = 0.85) as well as graft survival (daytime 69.5% vs nighttime 73.5%, p = 0.46) were similar between the two groups. Frequencies of reoperation (daytime 53.2% vs nighttime 55.1%, p = 0.74) were also not significantly different.

Conclusion

Our retrospective single center data derived from a German transplant center within the Eurotransplant region provides evidence that oLT is a safe procedure irrespective of the starting time. Our data demonstrate that compared to daytime surgery nighttime liver transplantation is not associated with a greater risk of surgical complications. In addition, one-year graft and patient survival do not display inferior results in patients undergoing nighttime transplantation.

High serum caspase-3 levels in hepatocellular carcinoma prior to liver transplantation and high mortality risk during the first year after liver transplantation

Background: Higher liver caspase-3 activity has been found in patients with different liver diseases. However, there is no published data about circulating caspase-3 levels in patients with hepatocellular carcinoma (HCC) who underwent liver transplantation (LT). Therefore, our objective in this study was to determine whether an association between circulating caspase-3 levels in HCC patients prior to LT and one-year mortality after LT exists. Methods: In this observational and retrospective study, we included HCC patients who underwent LT. We measured serum levels of caspase-3 (as the main executor of apoptosis) and caspase-cleaved cytokeratin (CCCK)-18 (to estimate apoptosis degree) before LT. Results: One-year surviving LT patients (n = 129) showed lower serum levels of caspase-3 (p = 0.004) and CCCK-18 (p = 0.001) than non-surviving LT patients (n = 16). Logistic regression analysis showed that serum caspase-3 levels prior to LT were associated with one-year after LT mortality (Odds Ratio = 2.612; 95% CI = 1.519-4.493; p = 0.001). We found a positive association between serum levels of caspase-3 and CCCK-18 (rho = 0.26; p = 0.002). Conclusions: Our study is the first one reporting data of circulating caspase-3 levels prior to LT for HCC, and an association between high serum caspase-3 levels previously to LT and survival at first year after LT.

Different effects of partial pressure in a high-pressure gaseous mixture of carbon monoxide and oxygen for rat heart preservation

We maintained the function of an extracted rat heart after 24–48 h preservation in a high-pressure gaseous mixture of carbon monoxide (CO) and oxygen (O₂). Here, we assessed the effects of different partial pressures of hyperbaric CO and O₂ for 24–48 h at 4 °C on rat heart preservation and compared conditions including immersion in University of Wisconsin solution. Preserved hearts were transplanted into recipient rats via heterotopic cervical heart transplantation for in vivo evaluation and perfused using the Langendorff system for ex vivo evaluation. The survival rate of transplanted hearts was 100% at postoperative day 7 in the CO + O₂ (PCO:PO₂ = 1.5:2.0 atm) group but only 33% in the CO + O₂ (PCO:PO₂ = 2.0:1.5 atm) group. Langendorff system and histopathological analysis revealed that the left ventricular pressure of preserved hearts in the CO + O₂ (PCO:PO₂ = 1.5:2.0 atm) group was better than the CO + O₂ (PCO:PO₂ = 2.0:1.5 atm). We demonstrate that exposure of rat hearts to hyperbaric CO and O₂ is superior to the immersion method and that partial pressure of hyperbaric CO and O₂ is crucial to preservation.

Proteomic Analysis of Liver Preservation Solutions Prior to Liver Transplantation

Material/Methods:

Samples were collected from the pre-transplant preservation mediums of 23 liver donors. For all donors, the cases involved Donation after Brain Death (DBD). 2D-PAGE and LCMSMS methodologies were used to detect the proteins and peptides from the preservation mediums.

Results:

A total of 198 proteins originating from the liver were detected.

Conclusion:

The data provide valuable insights into biomarkers that may be used to evaluate organ injury, functional status, and suitability for transplantation. Additionally, the findings could be valuable for the development of new strategies for effective preservation of solid organs prior to transplantation.

Liver Transplant Survival Index for Patients with Model for End-Stage Liver Disease Score ≥ 35: Modeling Risk and Adjusting Expectations in the Share 35 Era

BACKGROUND

The Share 35 policy for liver allocation prioritizes patients with Model for End-Stage Liver Disease (MELD) scores ≥ 35 for regional sharing of liver allografts. To better assess donor-recipient interactions and inform expectations, this study identified factors affecting graft survival independent of MELD score and derived a risk index for transplantation in the MELD ≥ 35 population.

STUDY DESIGN

The United Network for Organ Sharing (UNOS) STAR database was evaluated for deceased donor liver transplants with recipients' MELD ≥ 35, between January 2006 and June 2016. Data were randomly split into test and validate cohorts. Four individual models of graft survival spanning 90 days to 5 years were evaluated with univariate and multivariate Cox proportional hazards analyses against donor- and recipient-specific characteristics. Significant factors were compiled to generate the Liver Transplant Survival Index (LTSI-35), and survival analyses were performed.

RESULTS

Five risk groups (very low, low, moderate, high, and severe) were identified, with 1-year graft survival rates of 90.8% ± 0.2%, 89.3% ± 0.3%, 85.0% ± 0.3%, 79.8% ± 0.3%, and 70.3% ± 0.4% (p < 0.001 across groups), respectively. The greatest risk of graft loss was associated with donation after circulatory death (DCD) donors (1-year hazard ratio [HR] = 1.61 [95% CI 1.26 to 2.05], p = 0.001), recipients' requiring ventilator support (HR 1.32 [95% CI 1.17 to 1.51], p < 0.001), and recipient portal vein thrombosis (HR 1.21 [95% CI 1.03 to 1.42], p = 0.003). Subgroup analysis revealed increased risk of graft loss with graft macrosteatosis ≥ 30% on pre-donation biopsy at 90 days (HR 1.64 [1.33 to 1.99], p < 0.001).

CONCLUSIONS

The LTSI-35 identifies risk factors for graft loss in a high-MELD population which, when combined, may portend worse outcomes. The LTSI-35 may be used to influence donor selection, organ allocation, and to inform expectations for allograft survival.

Impact of Machine Perfusion on Biliary Complications after Liver Transplantation

We describe in this review the different types of injuries caused to the biliary tree after liver transplantation. Furthermore, we explain underlying mechanisms and why oxygenated perfusion concepts could not only protect livers, but also repair high-risk grafts to prevent severe biliary complications and graft loss. Accordingly, we summarize experimental studies and clinical applications of machine liver perfusion with a focus on biliary complications after liver transplantation. Key points: (1) Acute inflammation with subsequent chronic ongoing liver inflammation and injury are the main triggers for cholangiocyte injury and biliary tree transformation, including non-anastomotic strictures; (2) Hypothermic oxygenated perfusion (HOPE) protects livers from initial oxidative injury at normothermic reperfusion after liver transplantation. This is a unique feature of a cold oxygenation approach, which is effective also end-ischemically, e.g., after cold storage, due to mitochondrial repair mechanisms. In contrast, normothermic oxygenated perfusion concepts protect by reducing cold ischemia, and are therefore most beneficial when applied instead of cold storage; (3) Due to less downstream activation of cholangiocytes, hypothermic oxygenated perfusion also significantly reduces the development of biliary strictures after liver transplantation.

Complement Activation in Liver Transplantation: Role of Donor Macrosteatosis and Implications in Delayed Graft Function

The complement system anchors the innate inflammatory response by triggering both cell-mediated and antibody-mediated immune responses against pathogens. The complement system also plays a critical role in sterile tissue injury by responding to damage-associated molecular patterns. The degree and duration of complement activation may be a critical variable controlling the balance between regenerative and destructive inflammation following sterile injury. Recent studies in kidney transplantation suggest that aberrant complement activation may play a significant role in delayed graft function following transplantation, confirming results obtained from rodent models of renal ischemia/reperfusion (I/R) injury. Deactivating the complement cascade through targeting anaphylatoxins (C3a/C5a) might be an effective clinical strategy to dampen reperfusion injury and reduce delayed graft function in liver transplantation. Targeting the complement cascade may be critical in donor livers with mild to moderate steatosis, where elevated lipid burden amplifies stress responses and increases hepatocyte turnover. Steatosis-driven complement activation in the donor liver may also have implications in rejection and thrombolytic complications following transplantation. This review focuses on the roles of complement activation in liver I/R injury, strategies to target complement activation in liver I/R, and potential opportunities to translate these strategies to transplanting donor livers with mild to moderate steatosis.

Cold ischemia time is an important risk factor for post-liver transplant prolonged length of stay

Risk analysis of cold ischemia time (CIT) in liver transplantation has largely focused on patient and graft survival. Posttransplant length of stay is a sensitive marker of morbidity and cost. We hypothesize that CIT is a risk factor for posttransplant prolonged length of stay (PLOS) and aim to conduct an hour-by-hour analysis of CIT and PLOS. We retrospectively reviewed all adult, first-time liver transplants between March 2002 and September 2016 in the United Network for Organ Sharing database. The 67,426 recipients were categorized by hourly CIT increments. Multivariate logistic regression of PLOS (defined as >30 days), CIT groups, and an extensive list of confounding variables was performed. Linear regression between length of stay and CIT as continuous variables was also performed. CIT 1-6 hours was protective against PLOS, whereas CIT >7 hours was associated with increased odds for PLOS. The lowest odds for PLOS were observed with 1-2 hours (odds ratio [OR], 0.65; 95% confidence interval [CI], 0.45-0.92) and 2-3 hours (OR, 0.65; 95% CI, 0.55-0.78) of CIT. OR for PLOS steadily increased with increasing CIT, reaching the greatest odds for PLOS with 13-14 hours (OR, 2.05; 95% CI, 1.57-2.67) and 15-16 hours (OR, 2.06; 95% CI, 1.27-3.33) of CIT. Linear regression revealed a positive correlation between length of stay and CIT with a correlation coefficient of +0.35 (P < 0.001). In conclusion, post-liver transplant length of stay is sensitive to CIT, with a substantial increase in the odds of PLOS observed with nearly every additional hour of cold ischemia. We conclude that CIT should be minimized to protect against the morbidity and cost associated with posttransplant PLOS. Liver Transplantation 24 762-768 2018 AASLD.

Compared efficacy of preservation solutions on the outcome of liver transplantation: Meta-analysis

AIM

To compare the effects of the four most commonly used preservation solutions on the outcome of liver transplantations.

METHODS

A systematic literature search was performed using MEDLINE, Scopus, EMBASE and the Cochrane Library databases up to January 31st, 2017. The inclusion criteria were comparative, randomized controlled trials (RCTs) for deceased donor liver (DDL) allografts with adult and pediatric donors using the gold standard University of Wisconsin (UW) solution or histidine-tryptophan-ketoglutarate (HTK), Celsior (CS) and Institut Georges Lopez (IGL-1) solutions. Fifteen RCTs (1830 livers) were included; the primary outcomes were primary non-function (PNF) and one-year post-transplant graft survival (OGS-1).

RESULTS

All trials were homogenous with respect to donor and recipient characteristics. There was no statistical difference in the incidence of PNF with the use of UW, HTK, CS and IGL-1 (RR = 0.02, 95%CI: 0.01-0.03, P = 0.356). Comparing OGS-1 also failed to reveal any difference between UW, HTK, CS and IGL-1 (RR = 0.80, 95%CI: 0.80-0.80, P = 0.369). Two trials demonstrated higher PNF levels for UW in comparison with the HTK group, and individual studies described higher rates of biliary complications where HTK and CS were used compared to the UW and IGL-1 solutions. However, the meta-analysis of the data did not prove a statistically significant difference: the UW, CS, HTK and IGL-1 solutions were associated with nearly equivalent outcomes.

CONCLUSION

Alternative solutions for UW yield the same degree of safety and effectiveness for the preservation of DDLs, but further well-designed clinical trials are warranted.

Development of models to predict early post-transplant recurrence of hepatocellular carcinoma that also integrate the quality and characteristics of the liver graft: A national registry study in China

BACKGROUND

Donor characteristics and graft quality were recently reported to play an important role in the recurrence of hepatocellular carcinoma after liver transplantation. Our aim was to establish a prognostic model by using both donor and recipient variables.

METHODS

Data of 1,010 adult patients (training/validation: 2/1) undergoing primary liver transplantation for hepatocellular carcinoma were extracted from the China Liver Transplant Registry database and analyzed retrospectively. A multivariate competing risk regression model was developed and used to generate a nomogram predicting the likelihood of post-transplant hepatocellular carcinoma recurrence.

RESULTS

Of 673 patients in the training cohort, 70 (10.4%) had hepatocellular carcinoma recurrence with a median recurrence time of 6 months (interquartile range: 4-25 months). Cold ischemia time was the only independent donor prognostic factor for predicting hepatocellular carcinoma recurrence (hazard ratio = 2.234, P = .007). The optimal cutoff value was 12 hours when patients were grouped according to cold ischemia time at 2-hour intervals. Integrating cold ischemia time into the Milan criteria (liver transplantation candidate selection criteria) improved the accuracy for predicting hepatocellular carcinoma recurrence in both training and validation sets (P < .05). A nomogram composed of cold ischemia time, tumor burden, differentiation, and α-fetoprotein level proved to be accurate and reliable in predicting the likelihood of 1-year hepatocellular carcinoma recurrence after liver transplantation. Additionally, donor anti-hepatitis B core antibody positivity, prolonged cold ischemia time, and anhepatic time were linked to the intrahepatic recurrence, whereas older donor age, prolonged donor warm ischemia time, cold ischemia time, and ABO incompatibility were relevant to the extrahepatic recurrence.

CONCLUSION

The graft quality integrated models exhibited considerable predictive accuracy in early hepatocellular carcinoma recurrence risk assessment. The identification of donor risks can further help understand the mechanism of different patterns of recurrence.

Hemodynamic Changes Are Predictive of Coagulopathic Hemorrhage After Living Donor Liver Transplant

OBJECTIVES

Our goal was to evaluate the predictors of coagulopathic hemorrhage after living-donor liver transplant.

MATERIALS AND METHODS

We retrospectively evaluated 161 patients who had undergone living-donor liver transplant from July 2005 to April 2014 at a single medical institution. Of these patients, 32 developed hemorrhage after transplant. Patients were separated into those with coagulopathy-related hemorrhage (n=15) or noncoagulopathy-related hemorrhage (n=17) based on the results of computed tomography images. Predictors of hemorrhage after living-donor liver transplant evaluated in this study included preoperative, perioperative, and posttransplant factors and hemodynamic status.

RESULTS

Patients who developed coagulopathy-related hemorrhage had significantly lower pretransplant platelet counts (P = .040), a longer cold-ischemia time (P = .045), more blood loss (P = .040), and earlier onset of hemorrhage (P = .048) than patients who had noncoagulopathy-related hemorrhage after transplant. Results of the generalized estimating equation analysis showed that heart rate and central venous pressure differed significantly between the 2 groups of patients. Heart rates increased significantly during hemorrhage (P < .010). Central venous pressure was higher in the coagulopathic group (P = .005) than in the noncoagulopathic group.

CONCLUSIONS

Lower pretransplant platelet counts, longer cold ischemia time, more blood loss, earlier onset of hemorrhage, and higher central venous pressure level are indicators of coagulopathic hemorrhage after living-donor liver transplant.

Early cytokine signatures of ischemia/reperfusion injury in human orthotopic liver transplantation

BACKGROUND. Orthotopic liver transplant (OLT) is the primary therapy for end-stage liver disease and acute liver failure. However, ischemia/reperfusion injury (IRI) can severely compromise allograft survival. To understand the evolution of immune responses underlying OLT-IRI, we evaluated longitudinal cytokine expression profiles from adult OLT recipients before transplant through 1 month after transplant. METHODS. We measured the expression of 38 cytokines, chemokines, and growth factors in preoperative and postoperative recipient circulating systemic blood (before transplant and 1 day, 1 week, and 1 month after transplant) and intraoperative portal blood (before and after reperfusion) of 53 OLT patients and analyzed this expression in relation to biopsy-proven IRI (n = 26 IRI+; 27 IRI-), clinical liver function tests early (days 1-7) after transplant, and expression of genes encoding cytokine receptors in biopsies of donor allograft taken before and after reperfusion. RESULTS. Bilirubin and arginine transaminase levels early after transplant correlated with IRI. Fourteen cytokines were significantly increased in the systemic and/or portal blood of IRI+ recipients that shifted from innate to adaptive-immune responses over time. Additionally, expression of cognate receptors for 10 of these cytokines was detected in donor organ biopsies by RNAseq. CONCLUSION. These results provide a mechanistic roadmap of the early immunological events both before and after IRI and suggest several candidates for patient stratification, monitoring, and treatment. FUNDING. Ruth L. Kirschstein National Research Service Award T32CA009120, Keck Foundation award 986722, and a Quantitative & Computational Biosciences Collaboratory Postdoctoral Fellowship.

Functional evaluation of rat hearts transplanted after preservation in a high-pressure gaseous mixture of carbon monoxide and oxygen

We recently succeeded in resuscitating an extracted rat heart following 24–48 hours of preservation in a high-pressure gaseous mixture of carbon monoxide (CO) and oxygen (O₂). This study aimed to examine the function of rat hearts transplanted after being preserved in the high-pressure CO and O₂ gas mixture. The hearts of donor rats were preserved in a chamber filled with CO and O₂ under high pressure for 24 h (CO24h) or 48 h at 4 °C. For the positive control (PC) group, hearts immediately extracted from donor rats were used for transplantation. The preserved hearts were transplanted into recipient rats by heterotopic cervical heart transplantation. CO toxicity does not affect the grafts or the recipients. Light microscopy and [¹⁸F]-fluorodeoxyglucose positron emission tomography revealed that there were no significant differences in the size of the myocardial infarction or apoptosis of myocardial cells in post-transplant hearts between the PC and CO24h groups. Furthermore, at 100 days after the transplantation, the heart rate, weight and histological staining of the post-transplanted hearts did not differ significantly between the PC and CO24h groups. These results indicate that the function of rat hearts is well preserved after 24 hours of high-pressure preservation in a CO and O₂ gas mixture. Therefore, high-pressure preservation in a gas mixture can be a useful method for organ preservation.

Key Points in Establishing a Model of Mouse Liver Transplantation

The explosion of interest in research into the mouse genome and immune system has meant that the mouse orthotopic liver transplantation (MOLT) model has become a popular means of studying transplantation immunity, organ preservation, ischemia-reperfusion injury, and surgical techniques, among others. Although numerous modifications and refinements of surgical techniques have simplified the operation, the relatively short duration of postoperative survival after MOLT remains an obstacle to longer-term follow-up studies. Here, we summarize the scientific basis of MOLT and our experience improving and refining the model in six key areas: anesthesia, operative technique, perfusion and preservation of the liver, cuff technique, anhepatic time, and the value of rearterialization for the liver graft. We also compare the characteristics of different surgical techniques, and give recommendations for the best means of tailoring technique to the objectives of a study. In doing so, we aim to assist other investigators in establishing and perfecting the MOLT model in their routine research practice.

Hypoxia-inducible factors as molecular targets for liver diseases

Liver disease is a growing global health problem, as deaths from end-stage liver cirrhosis and cancer are rising across the world. At present, pharmacologic approaches to effectively treat or prevent liver disease are extremely limited. Hypoxia-inducible factor (HIF) is a transcription factor that regulates diverse signaling pathways enabling adaptive cellular responses to perturbations of the tissue microenvironment. HIF activation through hypoxia-dependent and hypoxia-independent signals have been reported in liver disease of diverse etiologies, from ischemia-reperfusion-induced acute liver injury to chronic liver diseases caused by viral infection, excessive alcohol consumption, or metabolic disorders. This review summarizes the evidence for HIF stabilization in liver disease, discusses the mechanistic involvement of HIFs in disease development, and explores the potential of pharmacological HIF modifiers in the treatment of liver disease.

Uterus transplantation: current progress and future prospects

Even if reproductive medicine has been remarkably successful during the past few decades, with the introduction of in vitro fertilization in the late 1970s and intracytoplasmic sperm injection in the early 1990s, it has been repeatedly mocked by infertility due to an absolute uterine factor. No treatment has been available for the women suffering from an absent or dysfunctional uterus, in terms of carrying a pregnancy. Approximately one in 500 women suffer from absolute uterine infertility, and the option so far to become a mother has been to either adopt or utilize gestational surrogacy. As of today, a total of eleven cases of human uterus transplantations have been reported worldwide, conducted in three different countries. The results of these initial experimental cases far exceed what might be expected of a novel surgical method. Many more uterus transplantations are to be expected in the near future, as other research teams' preparations are being ready to be put into clinical practice. In this review, we summarize the current worldwide experience of uterus transplantation as a treatment of absolute uterine factor infertility and the future prospects of human uterus transplantation.

Effects of Donor Age and Cold Ischemia on Liver Transplantation Outcomes According to the Severity of Recipient Status

BackgroundProlonged cold ischemic time (CIT) and increased donor age are well-known factors negatively influencing outcomes after liver transplantation (LT).

AIMS

The aim of this study was to evaluate whether the magnitude of their negative effects is related to recipient model for end-stage liver disease (MELD) score.

METHODS

This retrospective study was based on a cohort of 1402 LTs, divided into those performed in low-MELD (<10), moderate-MELD (10–20), and high-MELD (>20) recipients.

RESULTS

While neither donor age (p = 0.775) nor CIT (p = 0.561) was a significant risk factor for worse 5-year graft survival in low-MELD recipients, both were found to yield independent effects (p = 0.003 and p = 0.012, respectively) in moderate-MELD recipients, and only CIT (p = 0.004) in high-MELD recipients. However, increased donor age only triggered the negative effect of CIT in moderate-MELD recipients, which was limited to grafts recovered from donors aged ≥46 years (p = 0.019). Notably, utilization of grafts from donors aged ≥46 years with CIT ≥9 h in moderate-MELD recipients (p = 0.003) and those with CIT ≥9 h irrespective of donor age in high-MELD recipients (p = 0.031) was associated with particularly compromised outcomes.

CONCLUSIONS

In conclusion, the negative effects of prolonged CIT seem to be limited to patients with moderate MELD receiving organs procured from older donors and to high-MELD recipients, irrespective of donor age. Varying effects of donor age and CIT according to recipient MELD score should be considered during the allocation process in order to avoid high-risk matches.

Donor gluconate rescues livers from uncontrolled donation after cardiac death

BACKGROUND

Ischemia from organ preservation or donation causes cells and tissues to swell owing to loss of energy-dependent mechanisms of control of cell volume. These volume changes cause substantial preservation injury, because preventing these changes by adding cell impermeants to preservation solutions decreases preservation injury. The objective of this study was to assess if this effect could be realized early in uncontrolled donation after cardiac death (DCD) livers by systemically loading donors with gluconate immediately after death to prevent accelerated swelling injury during the warm ischemia period before liver retrieval.

METHODS

Uncontrolled DCD rat livers were cold-stored in University of Wisconsin solution for 24 hours and reperfused on an isolated perfused liver (IPL) device for 2 hours or transplanted into a rat as an allograft for 7 days. Donors were pretreated with a solution of the impermeant gluconate or a saline control immediately after cardiac death. Livers were retrieved after 30 minutes.

RESULTS

In vivo, gluconate infusion in donors immediately before or after cardiac death prevented DCD-induced increases in total tissue water, decreased vascular resistance, increased oxygen consumption and synthesis of adenosine triphosphate, increased bile production, decreased lactate dehydrogenase release, and decreased histology injury scores after reperfusion on the IPL relative to saline-treated DCD controls. In the transplant model, donor gluconate pretreatment significantly decreased both alanine aminotransferase the first day after transplantation and total bilirubin the seventh day after transplantation.

CONCLUSION

Cell and tissue swelling plays a key role in preservation injury of uncontrolled DCD livers, which can be mitigated by early administration of gluconate solutions to the donor immediately after death.