Vasoreactivity as a Measure of Kidney Viability During ExVivo Normothermic Machine Perfusion.

Mesenchymal stromal cell treatment of donor kidneys during ex vivo normothermic machine perfusion: A porcine renal autotransplantation study.

Liver transplantation has become an immense success; nevertheless, far more recipients are registered on waiting lists than there are available donor livers for transplantation. High-risk, extended criteria donor livers are increasingly used to reduce the discrepancy between organ demand and supply. Especially for high-risk livers, dynamic preservation using machine perfusion can decrease post-transplantation complications and may increase donor liver utilisation by improving graft quality and enabling viability testing before transplantation. To further increase the availability of donor livers suitable for transplantation, new strategies are required that make it possible to use organs that are initially too damaged to be transplanted. With the current progress in experimental liver transplantation research, (long-term) normothermic machine perfusion may be used in the future as a dynamic platform for regenerative medicine approaches, enabling repair and regeneration of injured donor livers. Currently explored therapeutics such as defatting cocktails, RNA interference, senolytics, and stem cell therapy may assist in the repair and/or regeneration of injured livers before transplantation. This review will provide a forecast of the future utility of normothermic machine perfusion in decreasing the imbalance between donor liver demand and supply by enabling the repair and regeneration of damaged donor livers.

Normothermic Acellular Machine Perfusion and Bile Duct Injury in Pig Livers Retrieved After Cardiac Death

Normothermic liver machine perfusion as a dynamic platform for assessment and treatment of organs from septic donors

Secondary Cold Ischemia After Normothermic Machine Perfusion: A Drawback to Centralized Organ Perfusion Centers?

Role of normothermic machine perfusion in liver transplantation: Current trends and outcomes.

Coagulation factors may inform on liver function during normothermic machine perfusion (NMP). We investigated whether graft ischemic injury impairs the accumulation of anticoagulation factors during NMP of porcine and human livers. Dynamics of FV, FVII, FVIII, FIX, and FX during NMP and their correlation with graft injury was investigated in porcine livers with minimal (no warm ischemia, n = 5) or severe injury (60 min warm ischemia, n = 5). Next, FV, FVIII, FIX, fibrinogen, and antithrombin were measured in 35 matched human liver NMPs from the COPE trial. Correlation of these factors with outcomes was explored. Livers were categorized in to 4 groups depending on donor type and posttransplant peak aspartate aminotransferase (AST) as surrogate of minimal (peak < 500 IU/L) or moderate injury (peak > 1000 IU/L). Factor concentrations increased significantly during NMP regardless of severity of injury. In porcine livers, factor concentrations were 2- to 6-fold lower in severely injured grafts (all P < 0.05). All factors negatively correlated with AST (coefficient range: from -0.50 to -0.93; all P < 0.05) and lactate (range: from -0.51 to -0.67; all P < 0.05). In human livers, no difference in factor accumulation rates and no correlation with other markers were observed. One graft with primary nonfunction had low rate of factor accumulation. Anticoagulation factors accumulate during NMP regardless of donor type and severity of injury. In pigs, severe ischemic injury resulted in significantly lower factor concentrations. In human livers with life-sustaining function, they do not correlate with hepatic injury. Whether low concentrations predict nonfunction in high-risk livers with severe injury requires further investigation.

The application of normothermic machine perfusion (NMP) machine technology as an assessment device may help to increase the utility of kidneys from uncontrolled donation after circulatory death (uDCD) donors. Here, we describe a case in which NMP perfusion characteristics were misleading and failed to predict primary nonfunction in 2 kidneys from a uDCD. The donor was a 37-y-old man who died of an intracerebral hemorrhage. Before withdrawal of life supporting treatment the donor had a cardiac arrest. He was rapidly transferred to the operating room and the abdominal organs cold perfused in situ with University of Wisconsin solution at 4°C. The first warm ischemic time was 27 min. Both kidneys appeared very poorly perfused and were further flushed on the back table with 4 L of hyperosmolar citrate solution over a period of 90 min. The appearance of both kidneys improved but they still remained patchy. The kidneys underwent a 1-h period of NMP as previously described.1,2 During NMP, the macroscopic appearance, renal blood flow, and urine output of both kidneys met our published criteria for transplantation2 (Table 1). The kidneys were transplanted into 2 separate nonsensitized recipients (Table 1). Immunological cross-matching was negative for both transplants. Both kidneys had a single renal artery and vein and these were anastomosed to the external iliac vessels. There was no intraoperative hypotension. A baseline biopsy taken from the left kidney 30 min after transplantation showed severe ischemic/reperfusion injury with almost all glomerular and peritubular capillaries filled with sludged red cells. Percutaneous needle core biopsies of both kidneys at day 8 showed infarction of the entire specimen. Computerized tomography angiography demonstrated patency of the main renal arteries and veins but diffuse poor parenchymal enhancement. In the absence of any improvement in renal function, primary nonfunction (PNF) was diagnosed in both kidneys at 3 mo. TABLE 1. - Recipient characteristics, preservation times, and normothermic machine perfusion parameters of the left and right kidney Left kidney Right kidney Recipient characteristics Gender/age Male 44 y Male 43 y Cause of ESRF APCKD Membranous GN Dialysis Predialysis Predialysis eGFR (mL/min) 9 10 HLA mismatch 1-0-1 1-0-1 Preservation times CIT (first) min 177 291 NMP min 67 60 CIT (second) min 158 433 Anastomosis min 47 55 Total CIT min 335 724 NMP parameters Macroscopic appearance 2 1 Mean RBF (mL/min/100g) 65.6 112.8 Total urine output (mL) 45 65 Oxygen consumption (mL/min/g) 36.6 48.0 Pre-NMP Post-NMP Pre-NMP Post-NMP pH 7.42 7.43 7.51 7.53 Potassium (mmol/L) 10.8 15.4 8.4 13.2 Lactate (mmol/L) 10.4 8.2 7.3 7.5 Glucose (mmol/L) 10.6 7.2 10.4 5.2 Recipient characteristics; gender/age, cause of ESRF, dialysis, eGFR, and HLA mismatch. Preservation times; CIT, NMP, second CIT, and anastomosis time. NMP parameters; macroscopic appearance (1, excellent; 2, patchy; 3, poor), mean RBF, total urine output, oxygen consumption after 60 min, prearterial and postarterial NMP levels of pH, potassium, lactate, and glucose. APCKD and membranous GN.APCKD, autosomal dominant polycystic kidney disease; CIT, cold ischemic time; eGFR, estimated glomeruli filtration rate; ESRF, end-stage renal failure; membranous GN, membranous glomerulonephritis; NMP, normothermic machine perfusion; RBF, renal blood flow. Extensive red cell plugging at revascularization led to cortical necrosis and allograft quality assessment by NMP failed to predict PNF. The young age of the donor and the short ischemic times were favorable factors. However, inadequate clearance of the microcirculation after in situ and back-table flushing is a well-described complication of prolonged warm-ischemic injury in uDCD organs.3,4 NMP theoretically offers a more accurate pretransplant viability assessment, because it restores cellular metabolism.2 We have used NMP to successfully assess and salvage kidneys from controlled donation after circulatory death donors because of inadequate clearance of the microcirculation after in situ cooling.2 This is the first report of applying the same principle to uDCD kidneys, and the adverse outcome is admonitory. The failure of NMP to predict PNF in these cases may be related to the duration and nature of the perfusion protocol. A 1-h period of NMP has been the standard in our practice and its effect on delayed graft function is currently being trialed in donation after circulatory death kidneys.5 However, cortical necrosis takes some hours to evolve and a more extended period of NMP might have been more predictive of the outcome. Furthermore, NMP conditions are designed to be protective and could mask the actual level of ischemic injury within a short timeframe. In conclusion, NMP strategies need to be further developed to reliably salvage and assess kidneys with severe ischemic injury complicated by poor clearance of the microvasculature.

Introduction:Ageing of the general population has led to an increase in the use of suboptimal kidneys from expanded criteria donation after brain death (ECD-DBD) and donation after circulatory death (DCD) donors. However, these kidneys have inferior graft outcomes and lower rates of immediate function. Normothermic machine perfusion (NMP) may improve outcomes of these suboptimal donor kidneys. Previous non-randomized studies have shown the safety of this technique and suggested its efficacy in improving the proportion of immediate functioning kidneys compared to static cold storage (SCS). However, its additional value to hypothermic machine perfusion (HMP), which has already been proved superior to SCS, has not yet been established.Methods and analysis:This single-center, open-label, randomized controlled trial aims to assess immediate kidney function after 120 minutes additional, end-ischemic NMP compared to HMP alone. Immediate kidney function is defined as no dialysis treatment in the first week after transplant. Eighty recipients on dialysis at the time of transplant who receive an ECD-DBD or DCD kidney graft are eligible for inclusion. In the NMP group, the donor kidney is taken of HMP upon arrival in the recipient hospital and thereafter put on NMP for 120 minutes at 37 degrees Celsius followed by transplantation. In the control group, donor kidneys stay on HMP until transplantation. The primary outcome is immediate kidney function.Ethics and dissemination:The protocol has been approved by the Medical Ethical Committee of Erasmus Medical Center (2020-0366). Results of this study will be submitted to peer-reviewed journals.Registration:registered in clinicaltrials.gov (NCT04882254).Highlights:This is the first RCT to compare additional NMP to HMP alone.Extensive sampling will offer in-depth analysis of kidney physiology during NMP.This RCT may help identify biomarkers to predict clinical outcomes during NMP.Biomarkers can help develop NMP as assessment tool for declined kidneys.

Machine Perfusion as "Comfort Zone": What Are Key Challenges of Liver Viability Assessment Today?

Transcriptomic signatures during normothermic liver machine perfusion correspond with graft quality and predict the early graft function

Normothermic machine perfusion (NMP) aims to reduce ischemia-reperfusion injury in donor livers and its clinical manifestation, early allograft dysfunction (EAD) by maintaining perfusion and oxygenation. However, there is limited data on which NMP perfusate biomarkers might be associated with such EAD and the role of perfusate hemoglobin has not been assessed. We performed a pilot retrospective analysis of adult donor livers undergoing NMP between 2020 and 2022 at our center. NMP was commenced at the recipient hospital after initial static cold storage. All NMP circuits were primed in the same manner according to the manufacturer's instructions. Livers were stratified by initial perfusate hemoglobin below (≤5.2 mmol/L) or above (>5.2 mmol/L) the median. The association between hemoglobin levels and EAD or recipient peak transaminase levels was assessed. Among 23 livers, eight were considered unsuitable for transplantation, leaving 15 livers for assessment. Higher initial hemoglobin was associated with a lower risk of EAD (0% vs. 55.6%, p = 0.04). Perfusate hemoglobin decreased after NMP initiation (p = 0.003) and negatively correlated with recipient peak transaminase levels (ALT: ρ = -0.72, p = 0.002; AST: ρ = -0.79, p < 0.001). Consistently, higher hemoglobin livers also demonstrated lower perfusate liver enzymes. Perfusate hemoglobin levels decreased during NMP, and lower perfusate hemoglobin levels were associated with a higher incidence of EAD and higher levels of liver injury markers. Maintaining higher hemoglobin levels during NMP may help reduce ischemia-reperfusion injury and prevent or attenuate EAD. Larger prospective studies are needed to validate the findings of this pilot study.

The gap between the demand and supply of donor livers is still a considerable challenge. Since static cold storage is not sufficient in marginal livers, machine perfusion is being explored as an alternative. The objective of this study was to assess (dual) hypothermic oxygenated machine perfusion (HOPE/D-HOPE) and normothermic machine perfusion (NMP) in contrast to static cold storage (SCS). Three databases were searched to identify studies about machine perfusion. Graft and patient survival and postoperative complications were evaluated using the random effects model. the incidence of biliary complications was lower in HOPE vs. SCS (OR: 0.59, 95% CI: 0.36-0.98, p = 0.04, I2: 0%). There was no significant difference in biliary complications between NMP and SCS (OR: 0.76, 95% CI: 0.41-1.40, p = 0.38, I2: 55%). Graft and patient survival were significantly better in HOPE than in SCS (HR: 0.40, 95% CI: 0.23-0.71, p = 0.002, I2: 0%) and (pooled HR: 0.43, 95% CI: 0.20-0.93, p = 0.03, I2: 0%). Graft and patient survival were not significantly different between NMP and SCS. HOPE/D-HOPE and NMP are promising alternatives to SCS for donor liver preservation. They may help address the widening gap between the demand for and availability of donor livers by enabling the rescue and transplantation of marginal livers.

Strategies in Organ Preservation-A New Golden Age.

Lohmann 1/M. Pool 2, K. Rozenberg 3, M. Eijken 4, U. Møldrup 5, B.K. Møller 6, J.M. Sierra Parraga 7, M. Hoogduijn 7, L. Lo Faro 3, C. Moers 2, J. Hunter 3, A.K. Keller 1, H. Leuvenink 2, C.C. Baan 7, R.J. Ploeg 3, B. Jespersen 1 Department of Clinical Medicine, Aarhus University, Aarhus, Denmark Department of Surgery, University Medical Center Groningen, Groningen, The Netherlands Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark Department of Urology, Aarhus University Hospital, Aarhus, Denmark Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark Department of Internal Medicine, Nephrology and Transplantation, Erasmus MC, University Medical Center, Rotterdam, the Netherlands Introduction Marginal kidneys are increasingly being accepted to decrease waiting time for a transplant. Normothermic machine perfusion (NMP) is a technique that allows delivery of therapies that may help condition or repair the organ prior to transplantation. Mesenchymal stromal cells (MSC) may be able to ameliorate ischaemia reperfusion injury as they possess potent anti-inflammatory and regenerative properties. We investigated the safety and effect of MSCs administered during ex vivo NMP prior to transplantation in a pig auto-transplant model of donation after circulatory death. Methods Porcine kidneys subjected to 75 min warm ischaemia were retrieved and preserved for 14h by oxygenated HMP (oxHMP) and 4h NMP and then auto-transplantation. Kidneys were randomised to three different intervention strategies (n=7 per group): following 1h NMP, either a vehicle (NMP), 10 million pig MSC (NMP+pMSC) or 10 million human MSC (NMP+hMSC) were intra-arterially infused. The NMP groups were all compared to a control group, where kidneys were only preserved with oxHMP. The pig was re-anaesthetised, the contralateral kidney was removed and the treated kidney was auto-transplanted and the animals were recovered for 14 days. Results Renal blood flow during NMP was no different between the groups (p=0.0685). Post-transplant plasma creatinine increased in all groups but there were no significant differences between the groups (p=0.517). Plasma kidney injury biomarker NGAL was significantly higher in the NMP+pMSC group compared to the NMP (p=0.003) and NMP+hMSC (p=0.017) groups at day 14. On day 14, mGFR significantly improved in the NMP group compared to the control (55 ± 3 vs 42 ± 12 ml/min, p=0.025). No differences in GFR were observed on day 14 in the other groups (NMP+pMSC, p=0.090 and NMP+hMSC, p=0.387). MSC were detectable in biopsies of MSC treated kidney after NMP and post-transplantation. Conclusion NMP alone improved renal graft function compared to oxHMP of DCD kidneys post-transplant. The method of MSC administration during NMP proved to be safe, however in this model MSC treatment did not improve renal function. Nevertheless viable MSC remained detectable in the transplanted kidney at postoperative day 14 which may have an effect on longer term outcomes.