Changing pattern of donor selection criteria in deceased donor liver transplant: a review of literature

Center-Level Variability in Use of Normothermic Machine Perfusion and the Association With Recipient Insurance

BACKGROUND

The rapid implementation of normothermic machine perfusion (NMP), since the FDA-approved NMP devices, has resulted in a paradigm shift in the ability to use marginal livers and allow for daytime operations. A major rate-limiting factor is costs which could lead to disparities among recipients. We aim to evaluate center-level variability in utilization of NMP, and to determine whether recipient insurance type was associated with NMP.

METHODS

We evaluated deceased donor liver transplants in high-volume NMP centers between January 2022 and December 2023, using the national registry. The primary outcome was whether the DDLT was performed using NMP. To explore center-level and factors associated with NMP, we evaluated variables related to donor quality and insurance. We fit multivariable logistic regression models to evaluate these factors.

RESULTS

Out of 142 liver transplant centers, 72 had ≥1 DDLT using NMP, and 28 were high-volume NMP centers. There was marked center-level variability in the proportion of donation after brain death (DCD) versus donation after brain death (DBD) allografts that underwent NMP. In logistic regression, liver allografts procured using NMP were more likely to occur during the nighttime (OR 1.26, p < 0.001), more likely to be used for DCD allografts (OR 13.2, p < 0.001), and less likely to occur in recipients insured by Medicaid, Medicare, or the Veterans Health Administration.

CONCLUSIONS

Our study demonstrates center-level variability in the use of NMP, and factors associated with these differences. Although the change in practice may help to increase DCD utilization, and shift the timing of transplants, the disparity based on insurance is alarming.

Liver machine perfusion technology: Expanding the donor pool to improve access to liver transplantation

The imbalance between organ supply and demand continues to limit the broader benefits of organ transplantation. Machine perfusion (MP) may increase the supply of donor livers by expanding the use of extended-criteria donors. Using the United Network for Organ Sharing/Organ Procurement and Transplantation Network and the Standard Transplant Analysis and Research dataset, we reviewed the effect of MP implementation on the behavior of transplant centers. We identified 15 high-utilizing MP centers that were matched to suitable controls based on volume and geographical proximity. We conducted a differences-in-differences analysis using linear regression to estimate the impact of MP adoption on the transplant centers' donor utilization. We found a significant increase in cold ischemia time and organs with donor warm ischemia time over 30 minutes (P < .05). After removing one outlier center, the analysis showed that these centers through MP accepted overall more donation after circulatory death donors, donation after circulatory death donors over 50 years old, donors with macrovesicular steatosis greater than 30% on liver biopsy, and donor warm ischemia time over 30 minutes (P < .05). MP has allowed centers to expand their use of extended-criteria donors beyond traditional cutoffs and to increase patient access to liver transplantation.

Volumetric graft changes after liver transplantation: evidence of adaptation to recipient body size

It is believed that whole liver grafts adjust their size to fit the body size of the recipient after transplantation, despite a lack of evidence. The aim of this study was to test this hypothesis. This was a retrospective cohort study of 113 liver transplantations performed at Karolinska University Hospital. The cohort was divided based on graft volume-to-standard liver volume ratio (GV/SLV) into quartiles of small, mid, and large grafts. Serial volumetric assessment was performed on the day of transplantation and at posttransplant check-ups early (<2 mo) and late (9-13 mo) after transplantation using computed tomography (CT) volumetry. Change in GV/SLV ratio over time was analyzed with ANOVA repeated measures. A multiple regression model was used to investigate the influence of intraoperative blood flow, recipient body size, age, and relative sickness on graft volume changes. Between the three time points, mean GV/SLV ratio adapted to 0.55-0.94-1.00 in small grafts (n = 29, P < 0.001); 0.87-1.18-1.13 in midgrafts (n = 56, P < 0.001); 1.11-1.51-1.18 in large grafts (n = 28, P < 0.001). Regression analysis showed a positive correlation between posttransplant graft growth and portal flow (β = 1.18, P = 0.005), arterial flow (β = 0.17, P = 0.001), and recipient body surface area (β = 59.85, P < 0.001). A negative correlation was observed for graft weight-to-recipient weight ratio (GRWR; β = -33.12, P < 0.001). Grafts with initial GV/SLV-ratio < 0.6 adapt toward the ideal volume for recipient body size 1 year after transplantation. The disparity between graft size relative to recipient body size, and the portal and arterial perfusion, influence volumetric graft changes.NEW & NOTEWORTHY This is the first and largest human study to verify the hypothesis that whole liver grafts adjust their size to match recipient body size 1 year after transplantation-a phenomenon that has previously only been observed in experimental animal studies and human case reports. The direction of volumetric changes is driven by the disparity between graft size relative to recipient body surface area and weight, as well as the intraoperative portal- and arterial graft perfusion.

Outcomes in organ transplants from donors with melanoma: a systematic review

Melanoma transmitted through organ transplantation is an increasingly reported event. Immunosuppression increases the risk of melanoma; however, transmission of malignancy from transplanted organs is a distinct etiology of melanoma occurrence. The risk of transmission of melanoma from an organ donor with melanoma has yet to be determined. The authors aimed to investigate this phenomenon by reviewing the outcomes of patients that received organs from donors with melanoma. A systematic literature review was conducted with emphasis on identifying organ donors with known histories of melanoma and reported information regarding recipients of their organs. The databases PubMed, MEDLINE, Embase, and JBI EBP were searched in January 2023. Search terms included "melanoma," terms for solid organs, "donor," "transplant," "transmission," and their variations as well as terms related to temporal relations. Inclusion criteria were articles that stated outcomes in organ recipients from donors that had a diagnosis of melanoma either pretransplant or postmortem. Reference lists of selected articles were hand searched for further studies. A total of 232 articles were identified from the search parameters. After applying inclusion and exclusion criteria, 13 articles were selected. Hand searching the references of these articles yielded four additional articles. Of the 75 organ recipients that received organs from donors with known melanoma, 43 developed melanoma. While a definitive quantitative risk cannot be ascertained based on our review, the numerous reported cases of melanoma in organ recipients from donors that have melanoma should still be considered by clinicians.

Are MELD and MELDNa Still Reliable Tools to Predict Mortality on the Liver Transplant Waiting List?

Liver transplantation is the only curative treatment for end-stage liver disease. Unfortunately, the scarcity of donor organs and the increasing pool of potential recipients limit access to this life-saving procedure. Allocation should account for medical and ethical factors, ensuring equal access to transplantation regardless of recipient's gender, race, religion, or income. Based on their short-term prognosis prediction, model for end-stage liver disease (MELD) and MELD sodium (MELDNa) have been widely used to prioritize patients on the waiting list for liver transplantation resulting in a significant decrease in waiting list mortality/removal. Recent concern has been raised regarding the prognostic accuracy of MELD and MELDNa due, in part, to changes in recipients' profile such as body mass index, comorbidities, and general condition, including nutritional status and cause of liver disease, among others. This review aims to provide a comprehensive view of the current state of MELD and MELDNa advantages and limitations and promising alternatives. Finally, it will explore future options to increase the donor pool and improve donor-recipient matching.

Extended criteria grafts and emerging therapeutics strategy in liver transplantation. The unstable balance between damage and repair

Due to increasing demand for donor organs, "extended criteria" donors are increasingly considered for liver transplantation, including elderly donors and donors after cardiac death. The grafts of this subgroup of donors share a major risk to develop significant features of ischemia reperfusion injury, that may eventually lead to graft failure. Ex-situ machine perfusion technology has gained much interest in liver transplantation, because represents both a useful tool for improving graft quality before transplantation and a platform for the delivery of therapeutics directly to the organ. In this review, we survey ongoing clinical evidences supporting the use of elderly and DCD donors in liver transplantation, and the underlying mechanistic aspects of liver aging and ischemia reperfusion injury that influence graft quality and transplant outcome. Finally, we highlight evidences in the field of new therapeutics to test in MP in the context of recent findings of basic and translational research.

The Utility of Extended Criteria Donor Livers in High Acuity Liver Transplant Recipients

BACKGROUND

Although the use of extended criteria donor (ECD) liver allografts has gained momentum as a potential method by which to expand the donor pool, their use largely remains relegated to low acuity liver transplant (LT) recipients. Thus, we sought to examine whether such grafts also have utility in high acuity (Model for End-Stage Liver Disease [MELD] ≥ 35) recipients.

STUDY DESIGN

Extended criteria donors were defined as donor age > 60 years, hepatitis C virus positive donor, split livers, livers with cold ischemia time > 12 h, donor after cardiac death livers, or having macrosteatosis > 30%. Outcomes were compared between standard liver (SL) and ECD grafts in recipients with MELD ≥ 35.

RESULTS

Of 225 patients, 46 (20.4%) received an ECD liver and 179 (79.6%) received a SL. Extended criteria donor graft recipients had significantly higher levels of post-LT maximal transaminases and rate of early allograft dysfunction. Nonetheless, high acuity ECD graft recipients had similar short- and long-term patient survival compared to SL recipients, with 1-,3-, and 5-year survivals of 86.9%, 82.3%, 79.3% and 86.9%, 80.5%, and 75.4%, respectively (P = .674). There were also no significant differences in graft survival or rejection-free survival between the 2 groups.

CONCLUSION

The lack of inferior patient/graft survival among high acuity ECD graft recipients suggests that ECD livers present a viable method by which to expand the donor pool for this group of patients.

Changes in Clinical Features and Demographics in Donors After Brain Death Over the Past 20 Years: A Single-Center Experience in the Republic of Korea

OBJECTIVES

We investigated clinical characteristics and demographics of brain death in patients from a single center in Korea to identify possible changes in organ procurement by comparing early and late periods.

MATERIALS AND METHODS

Potential donors diagnosed as brain dead and who had provided organ donation consent from May 2000 to May 2020 were considered. Donors were divided into 2 categories: early period (2000-2010) and late period (2011-2020).Demographic data, clinicalrisk factors, cause of death, use ofinotropic and vasoconstrictor agents, laboratory findings, intensive care unit stay data, loss of donors, and number of donated organs were analyzed.

RESULTS

Mean age of donors significantly increased in the late period (36.0 ± 12.0 vs 46.0 ± 15.1 years), but there were no significant differences in the proportion of females and the number of pediatric donors (<18 years). The number of donors who smoked decreased (61% vs 41%), but hypertension rate increased significantly in the late period (17.4% vs 31.0%). In the late period, fewer brain dead donors were lost (19.0% vs 7.59%) and use of vasoconstrictor agents was more frequent (25.3% vs 64.5%) than use of inotropic agents (73.1% vs 49.3%). In the late period, heart(19.0% vs 37.3%) and lung (0% vs 18.3%) procurement rates increased and the number of transplanted organs per donorincreased (2.58 ± 1.6 vs 3.14 ± 1.50; P = .016). Causes of death were primarily from head traumas (34.4%), cerebral aneurysms (21.7%), spontaneous intracerebral hemorrhage (21.3%), and asphyxia/hanging (16.3%). Head trauma decreased in the late period (46% vs 29.7%; P = .021) but still constituted the most common cause of death.

CONCLUSIONS

We found no definite demographic changes in brain dead donors. Donors with cerebrovascular disease increased annually, but trauma was still the most common cause of brain death, with suicides being highly frequent.

Ex vivo machine perfusion: current applications and future directions in liver transplantation

BACKGROUND

Liver transplantation is the only curative treatment option for end-stage liver disease; however, its use remains limited due to a shortage of suitable organs. In recent years, ex vivo liver machine perfusion has been introduced to liver transplantation, as a means to expand the donor organ pool.

PURPOSE

To present a systematic review of prospective clinical studies on ex vivo liver machine perfusion, in order to assess current applications and highlight future directions.

METHODS

A systematic literature search of both PubMed and ISI web of science databases as well as the ClinicalTrials.gov registry was performed.

RESULTS

Twenty-one articles on prospective clinical trials on ex vivo liver machine perfusion were identified. Out of these, eight reported on hypothermic, eleven on normothermic, and two on sequential perfusion. These trials have demonstrated the safety and feasibility of ex vivo liver machine perfusion in both standard and expanded criteria donors. Currently, there are twelve studies enrolled in the clinicaltrials.gov  registry, and these focus on use of ex vivo perfusion in extended criteria donors and declined organs.

CONCLUSION

Ex vivo liver machine perfusion seems to be a suitable strategy to expand the donor pool for liver transplantation and holds promise as a platform for reconditioning diseased organs.

Epidemiological characteristics of de novo hepatitis B infection in liver transplant recipients-An experience from a tertiary care centre in Qatar

BACKGROUND

The emergence of hepatitis B surface antigen in a patient with previously negative hepatitis B virus (HBV) serology post-orthotropic liver transplant (OTLX) is known as de novo hepatitis B (DNHB). As there are no data on patients with DNHB available from Qatar, we aim to do a pioneer study indexing their clinical profile and epidemiology of patients with DNHB in Qatar.

MATERIALS AND METHODS

This descriptive epidemiological study was done by retrospectively reviewing records of 159 post-OTLX patients. HBV serology of these patients post-OTLX was reviewed, and 17 were identified as DNHB cases. Baseline epidemiological characteristics were defined and compared between DNHB cases and the rest. DNHB cases were analyzed statistically using the chi-square test and Kaplan-Meier curve.

RESULTS

The majority of the subjects were men (65%) and Qataris (40%). Mean age was 57.4 ± 12.5 years. Bulk of them underwent OTLX in China (44%). The overall incidence of DNHB was 10.7%, with transplants in China having significantly higher incidence than transplants from all other countries. The mortality rate was 23.5% in DNHB cases compared to 2.8% in non-DNHB. 67% of patients survived at least 64 months after the diagnosis of DNHB. Five-year survival did not vary significantly between those with DNHB and those without.

CONCLUSION

Orthotropic liver transplant in centers selecting donors liberally without screening for HBV poses the risk of DNHB. We recommend having protective levels of HBs antibodies before OTLX. Prophylactic antiviral treatment should be considered until peri-operative HBV transmission has been excluded by screening hepatic tissue for HBV DNA.

Deceased Donor Predictors for Pediatric Liver Allograft Utilization

BACKGROUND

The number of pediatric deceased organ donors has recently declined, and the nonutilization of pediatric liver allografts has limited the development of liver transplantation. We determined the utilization rate of pediatric livers and identified risk factors for graft discard.

METHODS

We used data from the Scientific Registry of Transplant Recipients database from January 1, 2000, to December 31, 2012. The trends of pediatric liver donors and utilization rates were analyzed. Donor risk factors that impacted the graft use of pediatric livers were measured. Logistic regression modelling was performed to evaluate graft utilization and risk factors.

RESULTS

A total of 11,934 eligible pediatric liver donors were identified during this period. A total of 1191 authorized liver grafts did not recover or recovered without transplantation. Factors including pediatric donors >1 year of age (odds ratio [OR] = 2.956, 95% confidence interval [CI] 2.494-3.503, P < .001), nonhead trauma (OR = 2.243, 95% CI 1.903-2.642, P < .001), lack of heartbeat (OR = 7.534, 95% CI 5.899-9.623, P < .001), hepatitis B surface antigen positivity (OR = 4.588, 95% CI 1.021-20.625, P = .047), anti-hepatitis C virus positivity (OR = 4.691, 95% CI 1.352-16.280, P = .015), total bilirubin >1 mg/dL (OR = 1.743, 95% CI 1.469-2.068, P < .001), and blood urea nitrogen >21 mg/dL (OR = 1.941, 95% CI 1.546-2.436, P < .001) were significantly related to graft nonutilization. Steroids or diuretics administered prerecovery were significantly related to graft utilization (OR = 0.684, 95% CI 0.581-0.806, P < .001; OR = 0.744, 95% CI 0.634-0.874, P < .001; respectively).

CONCLUSIONS

The pediatric liver allograft utilization rate and risk factors for nonutilization of grafts were determined.

Deceased Brain Dead Donor Liver Transplantation and Utilization in the United States: Nighttime and Weekend Effects

BACKGROUND

Understanding factors that contribute to liver discards and nonusage is urgently needed to improve organ utilization.

METHODS

Using Scientific Registry of Transplant Recipient data, we studied a national cohort of all US adult, deceased brain dead donor, isolated livers available for transplantation from 2003 to 2016, including organ-specific and system-wide factors that may affect organ procurement and discard rates.

RESULTS

Of 73 686 available livers, 65 316 (88.64%) were recovered for transplant, of which 6454 (9.88%) were ultimately discarded. Livers that were not procured or, on recovery, discarded were more frequently from older, heavier, hepatitis B virus (HCV)+, and more comorbid donors (P < 0.001). However, even after adjustment for organ quality, the odds of liver nonusage were 11% higher on the weekend (defined as donor procurements with cross-clamping occurring from 5:00 PM Friday until 11:59 AM Sunday) compared with weekdays (P < 0.001). Nonuse rates were also higher at night (P < 0.001), defined as donor procurements with cross-clamping occurring from 5:00 PM to 5:00 AM; however, weekend nights had significantly higher nonuse rates compared with weekday nights (P = 0.005). After Share 35, weekend nonusage rates decreased from 21.77% to 19.51% but were still higher than weekday nonusage rates (P = 0.065). Weekend liver nonusage was higher in all 11 United Network of Organ Sharing regions, with an absolute average of 2.00% fewer available livers being used on the weekend compared with weekdays.

CONCLUSIONS

Although unused livers frequently have unfavorable donor characteristics, there are also systemic and operational factors, including time of day and day of the week a liver becomes available, that impact the chance of liver nonprocurement and discard.

Hepatic flow is an intraoperative predictor of early allograft dysfunction in whole-graft deceased donor liver transplantation: An observational cohort study

BACKGROUND

Early allograft dysfunction (EAD) after liver transplantation (LT) is an important cause of morbidity and mortality. To ensure adequate graft function, a critical hepatocellular mass is required in addition to an appropriate blood supply. We hypothesized that intraoperative measurement of portal venous and hepatic arterial flow may serve as a predictor in the diagnosis of EAD.

AIM

To study whether hepatic flow is an independent predictor of EAD following LT.

METHODS

This is an observational cohort study in a single institution. Hepatic arterial blood flow and portal venous blood flow were measured intraoperatively by transit flow. EAD was defined using the Olthoff criteria. Univariate and multivariate analyses were used to determine the intraoperative predictors of EAD. Survival analysis and prognostic factor analysis were performed using the Kaplan-Meier and Cox regression models.

RESULTS

A total of 195 liver transplant procedures were performed between January 2008 and December 2014 in 188 patients. A total of 54 (27.7%) patients developed EAD. The median follow-up was 39 mo. Portal venous flow, hepatic arterial flow (HAF) and total hepatic arterial flow were associated with EAD in both the univariate and multivariate analyses. HAF is an independent prognostic factor for 30-d patient mortality.

CONCLUSION

Intraoperative measurement of blood flow after reperfusion appears to be a predictor of EAD; Moreover, HAF should be considered a predictor of 30-d patient mortality.

Current understanding of adipose-derived mesenchymal stem cell-based therapies in liver diseases

The liver, the largest organ with multiple synthetic and secretory functions in mammals, consists of hepatocytes, cholangiocytes, hepatic stellate cells (HSCs), sinusoidal endothelial cells, Kupffer cells (KCs), and immune cells, among others. Various causative factors, including viral infection, toxins, autoimmune defects, and genetic disorders, can impair liver function and result in chronic liver disease or acute liver failure. Mesenchymal stem cells (MSCs) from various tissues have emerged as a potential candidate for cell transplantation to promote liver regeneration. Adipose-derived MSCs (ADMSCs) with high multi-lineage potential and self-renewal capacity have attracted great attention as a promising means of liver regeneration. The abundance source and minimally invasive procedure required to obtain ADMSCs makes them superior to bone marrow-derived MSCs (BMMSCs). In this review, we comprehensively analyze landmark studies that address the isolation, proliferation, and hepatogenic differentiation of ADMSCs and summarize the therapeutic effects of ADMSCs in animal models of liver diseases. We also discuss key points related to improving the hepatic differentiation of ADMSCs via exposure of the cells to cytokines and growth factors (GFs), extracellular matrix (ECM), and various physical parameters in in vitro culture. The optimization of culturing methods and of the transplantation route will contribute to the further application of ADMSCs in liver regeneration and help improve the survival rate of patients with liver diseases. To this end, ADMSCs provide a potential strategy in the field of liver regeneration for treating acute or chronic liver injury, thus ensuring the availability of ADMSCs for research, trial, and clinical applications in various liver diseases in the future.

Machine perfusion of the liver: Which is the best technique to mitigate ischaemia-reperfusion injury?

Longstanding research describes the mechanisms whereby the restoration of blood flow and reoxygenation (reperfusion) aggravates the ischaemic injury caused by a period of anoxia to a donor liver. This phenomenon, called ischaemia-reperfusion injury (IRI), leads to parenchymal cell death, microcirculatory failure, and inflammatory immune response. Clinically, IRI is the main factor responsible for the occurrence of posttransplant graft dysfunction and ischaemic-type biliary lesions. While extended criteria donor livers are more vulnerable to IRI, their utilisation is required to address the shortfall in donor organs. Thus, the mitigation of IRI should drive the setting of a new benchmark for marginal organ preservation. Herein, strategies incorporating different modalities of machine perfusion of the liver to alleviate IRI are discussed in conjunction with advantages and disadvantages of individual protocols. Techniques leading to reperfusion of the liver during machine perfusion (in situ normothermic regional perfusion and ex situ normothermic machine perfusion) may mitigate IRI by shortening the ischaemic period of the organs. This benefit potentially escalates from the minimum level, obtained following just partial alleviation of the ischaemic period, to the maximum level, which can be potentially achieved with ischaemia-free organ transplantation. Techniques that do not lead to reperfusion of the liver during machine perfusion (hypothermic, subnormothermic, and controlled-oxygenated rewarming) optimise mitochondrial oxidative function and replenish cellular energy stores, thereby lowering reactive oxygen species production as well as the activation of downstream inflammatory pathways during reperfusion. Further mechanistic insights into IRI may guide the development of donor-specific protocols of machine perfusion on the basis of the limitations of individual categories of extended criteria donor organs.

Orthotopic Liver Transplantation: Preliminary Analysis of Complications With Grafts From Elderly Donors

OBJECTIVE

This study aims to determine if donor grafts of patients older than 65 years develop more post-transplantation complications than those of younger patients.

DESIGN

This is a retrospective, observational study of liver transplant recipients during 12 months in Virgen del Rocio University Hospital. We compare incidence rates of reperfusion syndrome, acute kidney injury, and need for intra- and postoperative red blood cell transfusions in two donor age groups in which group A is <65 years old and group B is ≥65 years old.

RESULTS

Sixty cases were included. Reperfusion syndrome, acute kidney injury, and both intra- and postoperative red blood cell transfusion were more frequent in group A than group B (11.4% vs. 4%, P = .390; 44% vs. 32%, P = .423; 68.8% vs. 48%, P = .120; and 70.6% vs. 64%, P = .779, respectively). Six recipients (17.1%) died at 12 months from group A whereas there were no deaths register in group B during that time (P = .036).

CONCLUSION

Our results showed that including elderly donors does not aggravate incidence of complications, emphasizing that advanced age should not be an exclusion criteria for liver transplantation.

Organ Donation Attitudes Among Individuals With Stage 5 Chronic Kidney Disease

Background

The need for transplantable organs drastically outweighs the supply. Misconceptions are a barrier to increasing the rate of donor registration. Individuals with stage 5 chronic kidney disease (CKD) may incorrectly believe they are unable to be donors; however, their attitudes have not been studied. This study aims to explore beliefs of individuals with stage 5 CKD about their ability to donate and test the validity of an organ donation scale.

Methods

We examined the psychometric properties of a new 25-item organ donation scale among 554 patients with stage 5 CKD at 12 dialysis units in southeast Michigan. Patients completed surveys during dialysis treatment with assistance from a program coordinator or social worker.

Results

Two subscales with good psychometric properties were identified: general benefits (α = 0.86) and general barriers (α = 0.80). For both subscales, more positive attitudes were associated with higher intent to sign up on the donor registry, suggesting validity of the scale.

Conclusions

Patients who were older than 60 years, white, or of higher education status reported more positive attitudes. Misconceptions about the ability of patients with stage 5 CKD to donate are common and highlight a need for education about donor eligibility. Individuals with stage 5 CKD may be able to donate organs and tissues.

Hypothermic Machine Preservation of the Liver: State of the Art

PURPOSE OF REVIEW

In this review, we highlight which livers may benefit from additional treatment before implantation and describe the concept of hypothermic machine liver perfusion. Furthermore, we explain why cold oxygenated perfusion concepts could potentially lead to a breakthrough in this challenging field of transplantation. Accordingly, we summarize recent clinical applications of different hypothermic perfusion approaches.

RECENT FINDINGS

The impact of end-ischemic, hypothermic liver perfusion in liver transplantation is currently assessed by two multicenter, randomized controlled trials. Recently, new applications of hypothermic perfusion showed promising results and recipients were protected from severe intrahepatic biliary complications, despite the use of very extended criteria grafts including donation after circulatory death livers.

SUMMARY

Hypothermic machine liver perfusion is beneficial for high-risk livers and protects recipients from most feared complications. Importantly, such easy approach is currently implemented in several European centers and new markers obtained from perfusate may improve the prediction of liver function in the future.

In situ liver splitting under extracorporeal membrane oxygenation in brain-dead donor

Hemodynamic instability is generally considered as a contraindication to liver splitting, in particular when using an in situ technique. We describe the cases of two young donors with brain death in whom refractory cardiac arrest and hemodynamic instability were supported by veno-arterial extracorporeal membrane oxygenation (VA-ECMO), allowing uneventful in situ splitting. Two adult and two pediatric liver recipients were successfully transplanted with immediate graft function. Favorable outcomes were also observed for the other transplanted organs, including one heart, two lungs, and four kidneys. Refractory cardiac arrest and hemodynamic instability corrected by VA-ECMO should not be considered as a contraindication to in situ liver splitting.

Impact of a National Controlled Donation After Circulatory Death (DCD) Program on Organ Donation in the United Kingdom: A 10-Year Study

Organ transplantation is the most successful treatment for some forms of organ failure, yet a lack of organs means many die on the waiting list. In the United Kingdom, the Organ Donation Taskforce was set up to identify barriers to organ donation and in 2008 released its first report (Organ Donation Taskforce Report; ODTR). This study assesses the success since the ODTR and examines the impact of the United Kingdom's controlled donation after circulatory death (DCD) program and the controversies surrounding it. There were 12 864 intended donation after brain death (DBD) or DCD donors from April 2004 to March 2014. When the 5 years preceding the ODTR was compared to the 5 years following, intended DCD donors increased 292% (1187 to 4652), and intended DBD donors increased 11% (3327 to 3698). Organs retrieved per intended DBD donor remained static (3.30 to 3.26), whereas there was a decrease in DCD (1.54 to 0.99) due to a large rise in donors who did not proceed to donation (325 to 2464). The majority of DCD donors who proceeded did so within 30 min from time of withdrawal. Our study suggests further work on converting eligible referrals to organ donation and exploring methods of converting DCD to DBD donors.

PGC-1α Downregulation in Steatotic Liver Enhances Ischemia-Reperfusion Injury and Impairs Ischemic Preconditioning

AIMS

Liver steatosis is associated with mitochondrial dysfunction and elevated reactive oxygen species (ROS) levels together with enhanced sensitivity to ischemia-reperfusion (IR) injury and limited response to preconditioning protocols. Here, we sought to determine whether the downregulation in the steatotic liver of peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), a master regulator of mitochondrial metabolism and ROS that is known to play a role in liver metabolic control, could be responsible for the sensitivity of the steatotic liver to ischemic damage.

RESULTS

PGC-1α was induced in normal liver after exposure to an IR protocol, which was concomitant with an increase in the levels of antioxidant proteins. By contrast, its induction was severely blunted in the steatotic liver, resulting in a modest induction of antioxidant proteins. Livers of PGC-1α-/- mice on a chow diet were normal, but they exhibited an enhanced sensitivity to IR injury and also a lack of response to ischemic preconditioning (IPC), a phenotype that recapitulated the features of the steatotic liver in terms of liver damage, although the inflammatory response differed between both models. Utilizing an in vitro model of IPC, we found that PGC-1α expression was downregulated in hepatic cells cultured at 1% O2; whereas it was induced after reoxygenation (3% O2), and it was responsible for the recovery of antioxidant gene expression after the ischemic period. Innovation & Conclusion: PGC-1α plays an important role in the protection against IR injury in the liver, which is likely associated with its capacity to induce antioxidant gene expression. Antioxid. Redox Signal. 27, 1332-1346.

Role of temperature in reconditioning and evaluation of cold preserved kidney and liver grafts

Purpose of review

Organ shortage in transplantation medicine forces surgical research toward the development of more efficient approaches in organ preservation to enable the application of ‘less than optimal’ grafts. This review summarizes current techniques aiming to recondition cold-stored organ grafts prior to transplantation to reduce reperfusion-induced tissue injury and improve postimplantation graft function.

Recent findings

End-ischemic reconditioning has classically been attempted by cold oxygenated perfusion. By contrast, evaluation of graft performance prior to transplantation might be facilitated by perfusion at higher temperatures, ideally at normothermia. A drastic temperature shift from cold preservation to warm perfusion, however, has been incriminated to trigger a so-called rewarming injury associated with mitochondrial alterations. A controlled gradual warming up during machine perfusion could enhance the restitution of cellular homeostasis and improve functional outcome upon warm reperfusion.

Summary

Machine perfusion after conventional cold storage is beneficial for ulterior function after transplantation. Cold grafts should be initially perfused at low temperatures allowing for restitution of cellular homeostasis under protective hypothermic limitation of metabolic turnover. Delayed slow rewarming of the organ might further mitigate rewarming injury upon reperfusion and also increases the predictive power of evaluative measures, taken during pretransplant perfusion.

Guidelines for the assessment and acceptance of potential brain-dead organ donors

Organ transplantation is the only alternative for many patients with terminal diseases. The increasing disproportion between the high demand for organ transplants and the low rate of transplants actually performed is worrisome. Some of the causes of this disproportion are errors in the identification of potential organ donors and in the determination of contraindications by the attending staff. Therefore, the aim of the present document is to provide guidelines for intensive care multi-professional staffs for the recognition, assessment and acceptance of potential organ donors.

Cold preservation with hyperbranched polyglycerol-based solution improves kidney functional recovery with less injury at reperfusion in rats

Minimizing donor organ injury during cold preservation (including cold perfusion and storage) is the first step to prevent transplant failure. We recently reported the advantages of hyperbranched polyglycerol (HPG) as a novel substitute for hydroxyethyl starch in UW solution for both cold heart preservation and cold kidney perfusion. This study evaluated the functional recovery of the kidney at reperfusion after cold preservation with HPG solution. The impact of HPG solution compared to conventional UW and HTK solutions on tissue weight and cell survival at 4°C was examined using rat kidney tissues and cultured human umbilical vein endothelial cells (HUVECs), respectively. The kidney protection by HPG solution was tested in a rat model of cold kidney ischemia-reperfusion injury, and was evaluated by histology and kidney function. Here, we showed that preservation with HPG solution prevented cell death in cultured HUVECs and edema formation in kidney tissues at 4°C similar to UW solution, whereas HTK solution was less effective. In rat model of cold ischemia-reperfusion injury, the kidneys perfused and subsequently stored 1-hour with cold HPG solution showed less leukocyte infiltration, less tubular damage and better kidney function (lower levels of serum creatinine and blood urea nitrogen) at 48 h of reperfusion than those treated with UW or HTK solution. In conclusion, our data show the superiority of HPG solution to UW or HTK solution in the cold perfusion and storage of rat kidneys, suggesting that the HPG solution may be a promising candidate for improved donor kidney preservation prior to transplantation.

Preconditioning methods in the management of hepatic ischemia reperfusion- induced injury: Update on molecular and future perspectives

Hepatic IR (ischemia reperfusion) injury is a commonly encountered obstacle in the post-operative management of hepatic surgery. Hepatic IR occurs during 'Pringle maneuver' for reduction of blood loss or during a brief period of cold storage followed by reperfusion of liver grafts. The stress induced during hepatic IR, triggers a spectrum of cellular responses leading to the varying degrees of hepatic complications which in turn affect the post operative care. Different preconditioning methods either activate or subdue different sets of molecular signals, resulting in varied levels of protection against hepatic IR injury. Yet, there is a serious lacuna in the knowledge regarding the choice of preconditioning methods and the resulting molecular changes in order to assess the efficiency and choice of these methods correctly. This review provides an update on the various preconditioning approaches such as surgical/ischemic, antioxidant, pharmaceutical and genetic preconditioning strategies published during last six years (2009-2015). Further, we discuss the attenuation or inhibition of specific inflammatory, apoptotic and necrotic markers in the various experimental models of liver IR subjected to different preconditioning strategies. While enlisting the controversies in the ischemic preconditioning strategy, we bring out the uncertainties in the existing molecular targets and their reliability in the attenuation of hepatic IR injury. Future research studies would include the novel preconditioning strategies employ i) the targeted gene silencing of key molecular targets inducing IR, ii) hyper expression of beneficial molecular signals against IR via gene transfer techniques. The above studies would see the combination of these latest techniques with the established preconditioning strategies for better post-operative hepatic management.

Liver Transplantation in India: At the Crossroads

As the liver transplant journey in India reaches substantial numbers and suggests quality technical expertise, it is time to dispassionately look at the big picture, identify problems, and consider corrective measures for the future. Several features characterize the current scenario. Although the proportion of deceased donor liver transplants is increasing, besides major regional imbalances, the activity is heavily loaded in favor of the private sector and live donor transplants. The high costs of the procedure, the poor participation of public hospitals, the lack of a national registry, and outcomes reporting are issues of concern. Organ sharing protocols currently based on chronology or institutional rotation need to move to a more justiciable severity-based system. Several measures can expand the deceased donor pool. The safety of the living donor continues to need close scrutiny and focus. Multiple medical challenges unique to the Indian situation are also being thrown up. Although many of the deficits demand state intervention and policy changes the transplant community needs to take notice and highlight them. The future of liver transplantation in India should move toward a more accountable, equitable, and accessible form. We owe this to our citizens who have shown tremendous faith in us by volunteering to be living donors as well as consenting for deceased donation.

Strategies to optimize the use of marginal donors in liver transplantation

Liver transplantation is the treatment of choice for end stage liver disease, but availability of liver grafts is still the main limitation to its wider use. Extended criteria donors (ECD) are considered not ideal for several reasons but their use has dramatically grown in the last decades in order to augment the donor liver pool. Due to improvement in surgical and medical strategies, results using grafts from these donors have become acceptable in terms of survival and complications; nevertheless a big debate still exists regarding their selection, discharge criteria and allocation policies. Many studies analyzed the use of these grafts from many points of view producing different or contradictory results so that accepted guidelines do not exist and the use of these grafts is still related to non-standardized policies changing from center to center. The aim of this review is to analyze every step of the donation-transplantation process emphasizing all those strategies, both clinical and experimental, that can optimize results using ECD.

Infectious Complications After Liver Transplantation

Orthotopic liver transplantation (OLT) is the standard of care for patients with decompensated cirrhosis and for patients with hepatocellular carcinoma. More than 6000 liver transplants are performed annually in the United States. High patient and graft survival rates have been achieved in great part due to the availability of potent immunosuppressive agents. Systemic immunosuppression has rendered the liver recipient susceptible to de novo infections as well as reactivation of preexisting latent infections. Infections occurring during the first month post-OLT are usually nosocomial, donor-derived, or the result of a perioperative complication. The development of opportunistic infections (OIs) such as Aspergillus and the reactivation of latent infections such as Mycobacterium tuberculosis are more frequent 1 to 6 months posttransplant, when the net state of immunosuppression is the highest. Immunosuppressive therapy is tapered 6 to 12 months post-OLT; therefore, infections occurring during that time period and afterward generally resemble those of the general population. Screening strategies applied to determine the risk of an infection after transplantation and the use of prophylactic antimicrobial therapy have reduced the incidence of OIs after OLT. This article will review the various causes of infection post-OLT and the therapies used to manage complications.

Adipose-derived stem cells: A candidate for liver regeneration

The scarcity of donor livers and the impracticality of hepatocyte transplantation represent the biggest obstacles for the treatment of liver failure. Adipose-derived stem cells, with their ability to differentiate into the hepatic lineage, provide a reliable alternative cell source with clear ethical and practical advantages. Moreover, adipose-derived stem cells can effectively repair liver damage by the dominant indirect pattern and increase the number of hepatocytes by the secondary direct pattern. In recent years, the development of the indirect pattern, which mainly includes immunomodulatory and trophic effects, has become a hot topic in the field of cell engineering. Therefore, adipose-derived stem cells are considered to be ideal therapeutic stem cells for human liver regeneration. In this article, we reviewed the advantages of adipose-derived stem cells in liver regeneration, and explore their underlying mechanisms.