Bile Chemistry During Ex Situ Normothermic Liver Perfusion Does Not Always Predict Cholangiopathy.

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

Localized Liver Injury During Normothermic Ex Situ Liver Perfusion Has No Impact on Short-term Liver Transplant Outcomes.

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

Infection and Prophylaxis During Normothermic Liver Perfusion: Audit of Incidence and Pharmacokinetics of Antimicrobial Therapy.

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

Current Techniques and Indications for Machine Perfusion and Regional Perfusion in Deceased Donor Liver Transplantation.

Since the advent of University of Wisconsin preservation solution in the 1980s, clinicians have learned to work within its confines. While affording improved outcomes, considerable limitations still exist and contribute to the large number of livers that go unused each year, often for fear they may never work. The last 10 years have seen the widespread availability of new perfusion modalities which provide an opportunity for assessing organ viability and prolonged organ storage. This review will discuss the role of in situ normothermic regional perfusion for livers donated after circulatory death. It will also describe the different modalities of ex situ perfusion, both normothermic and hypothermic, and discuss how they are thought to work and the opportunities afforded by them.

The taphonomic impact of scavenger guilds in peri-urban and rural regions of central and southern Alberta. Part I - Identification of forensically relevant vertebrate scavengers.

As a body decomposes in an outdoor environment, numerous taphonomic agents can act on the process of human decomposition. It is important to understand the impact of these agents as they can vary the rate of soft and hard tissue loss which may alter postmortem interval estimations. One taphonomic factor which has not been extensively investigated in many regions of the world, including Canada, are vertebrate scavengers. The current study aimed to identify scavenger guilds in the peri-urban and rural regions of two major cities in Alberta (Calgary and Edmonton) where human remains are frequently located. Vertebrate scavenger activity was recorded continuously using cellular and noncellular trail cameras. Images were analyzed to determine how the scavenging profiles (i.e., scavenger species, arrival time, and feeding behavior) impacted the loss of soft and hard tissue. We identified a range of mammalian and avian scavengers and found that coyote and black-billed magpie were the predominant scavengers recorded at the Edmonton peri-urban and rural sites, and the Calgary peri-urban sites. In contrast, when a site was within bear territory such as the Calgary rural sites, black and grizzly bears were the predominant scavengers. At all sites, the large mammalian scavengers were responsible for most soft tissue loss and subsequent hard tissue dispersal. None of the scavengers demonstrated a clear preference for open versus closed sites. This taphonomic information is important to consider when searching for human remains at these locations or in other North American regions with comparable scavenger guilds.

A national pilot of donation after circulatory death (DCD) heart transplantation within the United Kingdom.

BACKGROUND: The United Kingdom (UK) was one of the first countries to pioneer heart transplantation from donation after circulatory death (DCD) donors. To facilitate equity of access to DCD hearts by all UK heart transplant centers and expand the retrieval zone nationwide, a Joint Innovation Fund (JIF) pilot was provided by NHS Blood and Transplant (NHSBT) and NHS England (NHSE). The activity and outcomes of this national DCD heart pilot program are reported. METHODS: This is a national multi-center, retrospective cohort study examining early outcomes of DCD heart transplants performed across 7 heart transplant centers, adult and pediatric, throughout the UK. Hearts were retrieved using the direct procurement and perfusion (DPP) technique by 3 specialist retrieval teams trained in ex-situ normothermic machine perfusion. Outcomes were compared against DCD heart transplants before the national pilot era and against contemporaneous donation after brain death (DBD) heart transplants, and analyzed using Kaplan-Meier analysis, chi-square test, and Wilcoxon's rank-sum. RESULTS: From September 7, 2020 to February 28, 2022, 215 potential DCD hearts were offered of which 98 (46%) were accepted and attended. There were 77 potential donors (36%) which proceeded to death within 2 hours, with 57 (27%) donor hearts successfully retrieved and perfused ex situ and 50 (23%) DCD hearts going on to be transplanted. During this same period, 179 DBD hearts were transplanted. Overall, there was no difference in the 30-day survival rate between DCD and DBD (94% vs 93%) or 90 day survival (90% vs 90%) respectively. There was a higher rate of ECMO use post-DCD heart transplants compared to DBD (40% vs 16%, p = 0.0006), and DCD hearts in the pre pilot era, (17%, p = 0.002). There was no difference in length of ICU stay (9 DCD vs 8 days DBD, p = 0.13) nor hospital stay (28 DCD vs 27 DBD days, p = 0.46). CONCLUSION: During this pilot study, 3 specialist retrieval teams were able to retrieve DCD hearts nationally for all 7 UK heart transplant centers. DCD donors increased overall heart transplantation in the UK by 28% with equivalent early posttransplant survival compared with DBD donors.

The dominance-diversity dilemma in animal conservation biology.

The alteration of environmental conditions has two major outcomes on the demographics of living organisms: population decline of the common species and extinction of the rarest ones. Halting the decline of abundant species as well as the erosion of biodiversity require solutions that may be mismatched, despite being rooted in similar causes. In this study, we demonstrate how rank abundance distribution (RAD) models are mathematical representations of a dominance-diversity dilemma. Across 4,375 animal communities from a range of taxonomic groups, we found that a reversed RAD model correctly predicts species richness, based solely on the relative dominance of the most abundant species in a community and the total number of individuals. Overall, predictions from this RAD model explained 69% of the variance in species richness, compared to 20% explained by simply regressing species richness on the relative dominance of the most abundant species. Using the reversed RAD model, we illustrate how species richness is co-limited by the total abundance of a community and the relative dominance of the most common species. Our results highlight an intrinsic trade-off between species richness and dominance that is present in the structure of RAD models and real-world animal community data. This dominance-diversity dilemma suggests that withdrawing individuals from abundant populations might contribute to the conservation of species richness. However, we posit that the positive effect of harvesting on biodiversity is often offset by exploitation practices with negative collateral consequences, such as habitat destruction or species bycatches.

Organ Transplants From Deceased Donors With Primary Brain Tumors and Risk of Cancer Transmission.

Importance: Cancer transmission is a known risk for recipients of organ transplants. Many people wait a long time for a suitable transplant; some never receive one. Although patients with brain tumors may donate their organs, opinions vary on the risks involved. Objective: To determine the risk of cancer transmission associated with organ transplants from deceased donors with primary brain tumors. Key secondary objectives were to investigate the association that donor brain tumors have with organ usage and posttransplant survival. Design, Setting, and Participants: This was a cohort study in England and Scotland, conducted from January 1, 2000, to December 31, 2016, with follow-up to December 31, 2020. This study used linked data on deceased donors and solid organ transplant recipients with valid national patient identifier numbers from the UK Transplant Registry, the National Cancer Registration and Analysis Service (England), and the Scottish Cancer Registry. For secondary analyses, comparators were matched on factors that may influence the likelihood of organ usage or transplant failure. Statistical analysis of study data took place from October 1, 2021, to May 31, 2022. Exposures: A history of primary brain tumor in the organ donor, identified from all 3 data sources using disease codes. Main Outcomes and Measures: Transmission of brain tumor from the organ donor into the transplant recipient. Secondary outcomes were organ utilization (ie, transplant of an offered organ) and survival of kidney, liver, heart, and lung transplants and their recipients. Key covariates in donors with brain tumors were tumor grade and treatment history. Results: This study included a total of 282 donors (median [IQR] age, 42 [33-54] years; 154 females [55%]) with primary brain tumors and 887 transplants from them, 778 (88%) of which were analyzed for the primary outcome. There were 262 transplants from donors with high-grade tumors and 494 from donors with prior neurosurgical intervention or radiotherapy. Median (IQR) recipient age was 48 (35-58) years, and 476 (61%) were male. Among 83 posttransplant malignancies (excluding NMSC) that occurred over a median (IQR) of 6 (3-9) years in 79 recipients of transplants from donors with brain tumors, none were of a histological type matching the donor brain tumor. Transplant survival was equivalent to that of matched controls. Kidney, liver, and lung utilization were lower in donors with high-grade brain tumors compared with matched controls. Conclusions and Relevance: Results of this cohort study suggest that the risk of cancer transmission in transplants from deceased donors with primary brain tumors was lower than previously thought, even in the context of donors that are considered as higher risk. Long-term transplant outcomes are favorable. These results suggest that it may be possible to safely expand organ usage from this donor group.

D-dimer Release From Livers During Ex Situ Normothermic Perfusion and After In Situ Normothermic Regional Perfusion: Evidence for Occult Fibrin Burden Associated With Adverse Transplant Outcomes and Cholangiopathy.

BACKGROUND: Deceased donor livers are prone to biliary complications, which may necessitate retransplantation, and we, and others, have suggested that these complications are because of peribiliary vascular fibrin microthrombi. We sought to determine the prevalence and consequence of occult fibrin within deceased donor livers undergoing normothermic ex situ perfusion (NESLiP) and evaluate a role for fibrinolysis. METHODS: D-dimer concentrations, products of fibrin degradation, were assayed in the perfusate of 163 livers taken after 2 h of NESLiP, including 91 that were transplanted. These were related to posttransplant outcomes. Five different fibrinolytic protocols during NESLiP using alteplase were evaluated, and the transplant outcomes of these alteplase-treated livers were reviewed. RESULTS: Perfusate D-dimer concentrations were lowest in livers recovered using in situ normothermic regional perfusion and highest in alteplase-treated livers. D-dimer release from donation after brain death livers was significantly correlated with the duration of cold ischemia. In non-alteplase-treated livers, Cox proportional hazards regression analysis showed that D-dimer levels were associated with transplant survival ( P = 0.005). Treatment with alteplase and fresh frozen plasma during NESLiP was associated with significantly more D-dimer release into the perfusate and was not associated with excess bleeding postimplantation; 8 of the 9 treated livers were free of cholangiopathy, whereas the ninth had a proximal duct stricture. CONCLUSIONS: Fibrin is present in many livers during cold storage and is associated with poor posttransplant outcomes. The amount of D-dimer released after fibrinolytic treatment indicates a significant occult fibrin burden and suggests that fibrinolytic therapy during NESLiP may be a promising therapeutic intervention.

Honoring the gift: The transformative potential of transplant-declined human organs.

For decades, transplantation has been a life-saving treatment for those fortunate enough to gain access. Nevertheless, many patients die waiting for an organ and countless more never make it onto the waitlist because of a shortage of donor organs. Concurrently, thousands of donated organs are declined for transplant each year because of concerns about poor outcomes post-transplant. The decline of any donated organ-even if medically justified-is tragic for both the donor family and potential recipients. In this Personal Viewpoint, we discuss the need for a new mindset in how we honor the gift of organ donation. We believe that the use of transplant-declined human organs in translational research has the potential to hasten breakthrough discoveries in a multitude of scientific and medical areas. More importantly, such breakthroughs will allow us to properly value every donated organ. We further discuss the many practical challenges that such research presents and offer some possible solutions based on experiences in our own research laboratories. Finally, we share our perspective on what we believe are the necessary next steps to ensure a future where every donated organ realizes its full potential to impact the lives of current and future patients.

Improved Organ Utilization and Better Transplant Outcomes With In Situ Normothermic Regional Perfusion in Controlled Donation After Circulatory Death.

BACKGROUND: . We evaluated whether the use of normothermic regional perfusion (NRP) was associated with increased organ recovery and improved transplant outcomes from controlled donation after circulatory death (cDCD). METHODS: . This is a retrospective analysis of UK adult cDCD donors' where at least 1 abdominal organ was accepted for transplantation between January 1, 2011, and December 31, 2019. RESULTS: . A mean of 3.3 organs was transplanted when NRP was used compared with 2.6 organs per donor when NRP was not used. When adjusting for organ-specific donor risk profiles, the use of NRP increased the odds of all abdominal organs being transplanted by 3-fold for liver ( P < 0.0001; 95% confidence interval [CI], 2.20-4.29), 1.5-fold for kidney ( P = 0.12; 95% CI, 0.87-2.58), and 1.6-fold for pancreas ( P = 0.0611; 95% CI, 0.98-2.64). Twelve-mo liver transplant survival was superior for recipients of a cDCD NRP graft with a 51% lower risk-adjusted hazard of transplant failure (HR = 0.494). In risk-adjusted analyses, NRP kidneys had a 35% lower chance of developing delayed graft function than non-NRP kidneys (odds ratio, 0.65; 95% CI, 0.465-0.901)' and the expected 12-mo estimated glomerular filtration rate was 6.3 mL/min/1.73 m 2 better if abdominal NRP was used ( P < 0.0001). CONCLUSIONS: . The use of NRP during DCD organ recovery leads to increased organ utilization and improved transplant outcomes compared with conventional organ recovery.

Utilization and clinical outcomes of kidney transplants from deceased donors with albuminuria in the UK: a national cohort study.

BACKGROUND: Urinalysis is a standard component of potential deceased kidney donor assessment in the UK. The value of albuminuria as a biomarker for organ quality is uncertain. We examined the relationship between deceased donor albuminuria and kidney utilization, survival and function. METHODS: We performed a national cohort study on adult deceased donors and kidney transplant recipients between 2016 and 2020, using data from the UK Transplant Registry. We examined the influence of donor albuminuria, defined as ≥2+ on dipstick testing, on kidney utilization, early graft function, graft failure and estimated glomerular filtration rate (eGFR). RESULTS: Eighteen percent (1681/9309) of consented donors had albuminuria. After adjustment for confounders, kidneys from donors with albuminuria were less likely to be accepted for transplantation (74% versus 82%; odds ratio 0.70, 95% confidence interval 0.61 to 0.81). Of 9834 kidney transplants included in our study, 1550 (16%) came from donors with albuminuria. After a median follow-up of 2 years, 8% (118/1550) and 9% (706/8284) of transplants from donors with and without albuminuria failed, respectively. There was no association between donor albuminuria and graft failure (hazard ratio 0.91, 95% confidence interval 0.74 to 1.11). There was also no association with delayed graft function, patient survival or eGFR at 1 or 3 years. CONCLUSIONS: Our study suggests reluctance in the UK to utilize kidneys from deceased donors with dipstick albuminuria but no evidence of an association with graft survival or function. This may represent a potential to expand organ utilization without negatively impacting transplant outcomes.

Predicting Early Allograft Function After Normothermic Machine Perfusion.

BACKGROUND: Normothermic ex situ liver perfusion is increasingly used to assess donor livers, but there remains a paucity of evidence regarding criteria upon which to base a viability assessment or criteria predicting early allograft function. METHODS: Perfusate variables from livers undergoing normothermic ex situ liver perfusion were analyzed to see which best predicted the Model for Early Allograft Function score. RESULTS: One hundred fifty-four of 203 perfused livers were transplanted following our previously defined criteria. These comprised 84/123 donation after circulatory death livers and 70/80 donation after brain death livers. Multivariable analysis suggested that 2-h alanine transaminase, 2-h lactate, 11 to 29 mmol supplementary bicarbonate in the first 4 h, and peak bile pH were associated with early allograft function as defined by the Model for Early Allograft Function score. Nonanastomotic biliary strictures occurred in 11% of transplants, predominantly affected first- and second-order ducts, despite selection based on bile glucose and pH. CONCLUSIONS: This work confirms the importance of perfusate alanine transaminase and lactate at 2-h, as well as the amount of supplementary bicarbonate required to keep the perfusate pH > 7.2, in the assessment of livers undergoing perfusion. It cautions against the use of lactate as a sole indicator of viability and also suggests a role for cholangiocyte function markers in predicting early allograft function.

Seasonal impact of scavenger guilds as taphonomic agents in central and northern Ontario, Canada.

The process of human decomposition is driven by biological decomposers, mainly bacteria, vertebrates, and invertebrate scavengers. When vertebrate scavengers have access to a body, they can considerably accelerate decomposition through consumption of soft tissue and dispersal of skeletal elements. Presently, there are limited data available on vertebrate scavenging activity in Canada, particularly in densely populated provinces such as Ontario. This study aimed to determine which vertebrate species belong to the scavenger guilds in central and northern Ontario, and the impact of season and habitat on these taphonomic agents. Seasonal trials were conducted in summer, fall, and spring of 2020/2021 with pig carcasses placed in open (grassland) and closed (forest) sites. Vertebrate scavenger activity was recorded continuously using cellular and non-cellular trail cameras. Photographs were analyzed to identify species, quantify feeding intensity, and document scavenging behavior. We identified four mammalian scavengers, namely coyote, red fox, fisher, and pine marten, and three avian scavengers, namely bald eagle, turkey vulture, and American crows/northern ravens (grouped as corvids) across the trials. Season impacted scavenger presence with feeding and loss of soft tissue occurring more quickly in the summer, followed by spring and fall. None of the scavengers demonstrated a clear preference for the open versus closed sites. Our findings have identified the most prevalent vertebrate scavengers in central and northern Ontario and their taphonomic impact on soft and hard tissues. It is important to consider these agents and their ability to degrade and disperse remains during the search and recovery of human remains.

Liver Transplantation Outcomes From Controlled Circulatory Death Donors: SCS vs in situ NRP vs ex situ NMP.

OBJECTIVE: To compare the outcomes of livers donated after circulatory death (DCD) and undergoing either in situ normothermic regional perfusion (NRP) or ex situ normothermic machine perfusion (NMP) with livers undergoing static cold storage (SCS). SUMMARY OF BACKGROUND DATA: DCD livers are associated with increased risk of primary nonfunction, poor function, and nonanastomotic strictures (NAS), leading to underutilization. METHODS: A single center, retrospective analysis of prospectively collected data on 233 DCD liver transplants performed using SCS, NRP, or NMP between January 2013 and October 2020. RESULTS: Ninety-seven SCS, 69 NRP, and 67 NMP DCD liver transplants were performed, with 6-month and 3-year transplant survival (graft survival non-censored for death) rates of 87%, 94%, 90%, and 76%, 90%, and 76%, respectively. NRP livers had a lower 6-month risk-adjusted Cox proportional hazard for transplant failure compared to SCS (hazard ratio 0.30, 95% Confidence Interval 0.08-1.05, P = 0.06). NRP and NMP livers had a risk-adjusted estimated reduction in the mean model for early allograft function score of 1.52 (P < 0.0001) and 1.19 (P < 0.001) respectively compared to SCS. Acute kidney injury was more common with SCS (55% vs 39% NRP vs 40% NMP; P = 0.08), with a lower risk-adjusted peak-to-baseline creatinine ratio in the NRP (P = 0.02). No NRP liver had clinically significant NAS in contrast to SCS (14%) and NMP (11%, P = 0.009), with lower risk-adjusted odds of overall NAS development compared to SCS (odds ratio = 0.2, 95%CI 0.06-0.72, P = 0.01). CONCLUSION: NRP and NMP were associated with better early liver function compared to SCS, whereas NRP was associated with superior preservation of the biliary system.

The taphonomic impact of scavenger guilds in southern Quebec during summer and fall in two distinct habitats.

Decomposition of human remains is a complex process impacted by many intrinsic and extrinsic factors. A less-studied extrinsic factor in forensic taphonomy are the scavengers that consume soft and hard tissue. Scavengers physically degrade and remove soft tissue, disperse, and destroy skeletal elements, which can make locating remains challenging. While invertebrate activity has been largely investigated, there is limited quantitative data available on vertebrate activity, particularly in Canada. This study aimed to determine which species (vertebrate and invertebrate) belong to the scavenger guilds in southern Quebec, and their potential taphonomic impact on the decomposition process. Two independent trials were conducted in 2020 using pig carcasses: one during summer in a forest habitat and one during fall in a grassland habitat. Each carcass was placed a minimum 100 m apart in semi-rural land. Vertebrate scavenger activity was recorded by continuous surveillance using trail cameras. Carcasses were also regularly visited to monitor the decomposition process and the activity of invertebrate scavengers. Overall, the vertebrate scavenger guilds included a narrow range of corvids, turkey vultures, coyotes, and skunks. The intensity of vertebrate scavengers was greater in the grassland habitat (fall), while the intensity of invertebrate scavengers was greater in the forest habitat (summer). With the exception of invertebrate scavengers, very few species visited during the fresh stage of decomposition, and the probability of body displacement increased as decomposition progressed. These results identify which scavengers have the greatest taphonomic impact and highlight the importance of incorporating scavenger impact when searching for human remains.