Effective and safe implementation of robot-assisted donor nephrectomy by experienced laparoscopic surgeons.

BACKGROUND: In June 2021, the first robot-assisted donor nephrectomy (RADN) was performed at the Leiden University Medical Center (LUMC), the Netherlands. The goal of this study was to investigate whether this procedure has been implemented safely and efficiently. METHODS: RADN was retrospectively compared to laparoscopic donor nephrectomy (LDN) performed during the same time period (June 2021 until November 2022). Patients were assigned to RADN depending on the availability of the da Vinci robot and surgical team. The studied endpoints were postoperative complications, operative time, estimated blood loss, warm ischemic time (WIT), and postoperative pain experience. For analysis, the Student's t-test and Chi-squared test were used for, respectively, continuous and categorical data. RESULTS: Forty RADN were compared to 63 LDN. Total insufflation time was significantly longer in RADN compared to LDN (188 min (169-214) versus 172 min (144-194); p = 0.02). Additionally, WIT was also found to be significantly higher in the robot-assisted group (04:54 min vs. 04:07 min; p < 0.01). No statistical differences were found in postoperative outcomes (eGFR of the recipient at 3-month follow-up, RADN 54.08 mL/min ±18.79 vs. LDN 56.41 mL/min ±16.82; p = 0.52), pain experience, and complication rate. CONCLUSION: RADN was safely and efficiently implemented at the LUMC. It's results were not inferior to laparoscopic donor nephrectomy. Operative time and warm ischemic times were longer in RADN. This may relate to a learning curve effect. No clinically relevant effect on postoperative outcomes was observed.

A cell-free nutrient-supplemented perfusate allows four-day ex vivo metabolic preservation of human kidneys.

The growing disparity between the demand for transplants and the available donor supply, coupled with an aging donor population and increasing prevalence of chronic diseases, highlights the urgent need for the development of platforms enabling reconditioning, repair, and regeneration of deceased donor organs. This necessitates the ability to preserve metabolically active kidneys ex vivo for days. However, current kidney normothermic machine perfusion (NMP) approaches allow metabolic preservation only for hours. Here we show that human kidneys discarded for transplantation can be preserved in a metabolically active state up to 4 days when perfused with a cell-free perfusate supplemented with TCA cycle intermediates at subnormothermia (25 °C). Using spatially resolved isotope tracing we demonstrate preserved metabolic fluxes in the kidney microenvironment up to Day 4 of perfusion. Beyond Day 4, significant changes were observed in renal cell populations through spatial lipidomics, and increases in injury markers such as LDH, NGAL and oxidized lipids. Finally, we demonstrate that perfused kidneys maintain functional parameters up to Day 4. Collectively, these findings provide evidence that this approach enables metabolic and functional preservation of human kidneys over multiple days, establishing a solid foundation for future clinical investigations.

Certification Training and Liver Transplant Experience Improves Liver Procurement Outcomes: The Dutch Approach.

BACKGROUND: This study investigates the impact of certification training and liver transplant experience on procurement outcomes of deceased donor liver procurement in the Netherlands. METHODS: Three groups (trainee, certified, and master) were formed, with further subdivision based on liver transplant experience. Three key outcomes-surgical injury, graft discard after injury, and donor hepatectomy duration-were analyzed. RESULTS: There were no significant differences in surgical graft injury in the three groups (trainee, 16.9%; certified, 14.8%; master, 18.2%; P = 0.357; 2011 to 2018). The only predictor for surgical graft injury was donation after cardiac death (odds ratio [OR], 1.49; 95% confidence interval [CI], 1.10-2.02). Of the three groups, the master group had the highest discard rate after surgical injury (trainee, 0%; certified, 1.3%; master, 2.8%; P = 0.013). Master group without liver transplant experience (OR, 3.16; 95% CI, 1.21-8.27) and male donor sex (OR, 3.58; 95% CI, 1.32-9.73) were independent risk factors for discarding livers after surgical injury. Independent predictors for shorter hepatectomy durations included donors older than 50 years (coefficient [Coeff], -7.04; 95% CI, -8.03 to -3.29; P < 0.001), and master group (Coeff, -9.84; 95% CI, -14.37 to -5.31; P < 0.001) and certified group with liver transplant experience (Coeff, -6.54; 95% CI, -10.83 to -2.26; P = 0.003). On the other hand, master group without liver transplant experience (Coeff, 5.00; 95% CI, 1.03-8.96; P = 0.014) and donation after cardiac death (Coeff, 10.81; 95% CI, 8.32-13.3; P < 0.001) were associated with longer hepatectomy durations. CONCLUSIONS: Training and certification in abdominal organ procurement surgery were associated with a reduced discard rate for surgical injured livers and shorter hepatectomy times. The contrast between master group with and without liver transplant experience underscores the need for specialized training in this field.

Modifying Tacrolimus-related Toxicity After Liver Transplantation Comparing Life Cycle Pharma Tacrolimus Versus Extended-released Tacrolimus: A Multicenter, Randomized Controlled Trial.

Background: The aim of this open-label, multicenter, randomized controlled study was to investigate whether the life cycle pharma (LCP)-tacrolimus compared with the extended-release (ER)-tacrolimus formulation results in a difference in the prevalence of posttransplant diabetes, hypertension and chronic kidney disease (CKD) at 12 mo after liver transplantation. Methods: Patients were 1:1 randomized to either of the 2 tacrolimus formulations. The primary endpoint was defined as a composite endpoint of any of 3 events: sustained (>3 mo postrandomization) posttransplant diabetes, new-onset hypertension, and/or CKD, defined as estimated glomerular filtration rate <60 mL/min/1.73 m2 for >3 m during the follow-up. Results: In total, 105 patients were included. In the intention-to-treat analysis, a statistically significant lower proportion of liver transplant recipients in the LCP-tacrolimus group reached the composite primary endpoint at 12 mo compared with the ER-tacrolimus group (50.9% [27/53], 95% confidence interval [CI], 37.9%-63.9% versus 71.2% [37/52], 95% CI, 57.7%-81.7%; risk difference: 0.202; 95% CI, 0.002-0.382; P = 0.046). No significant difference was found in the per protocol analysis. In the intention-to-treat and per protocol population, fewer liver transplant recipients in the LCP-tacrolimus group developed CKD and new-onset hypertension compared with the ER-tacrolimus group. No differences in rejection rate, graft and patient survival were found. Conclusions: A statistically significant and clinically relevant reduction in the prevalence of the composite primary endpoint was found in the LCP-tacrolimus group compared with the ER-tacrolimus group in the first year after liver transplantation with comparable efficacy.

Red blood cells as oxygen carrier during normothermic machine perfusion of kidney grafts: Friend or foe?

Renal ex vivo normothermic machine perfusion (NMP) is under development as an assessment tool for high-risk kidney grafts and as a means of achieving more physiologically accurate organ preservation. On-going hemolysis has been reported during NMP, as this technique relies on red blood cells for oxygen delivery. In this study, we confirm the occurrence of progressive hemolysis during 6-hour kidney NMP. NMP-associated erythrostasis in the glomeruli and in peri-glomerular vascular networks points to an interaction between the red blood cells and the graft. Continuous hemolysis resulted in prooxidative changes in the perfusate, which could be quenched by addition of fresh frozen plasma. In a cell-based system, this hemolysis induced redox stress and exhibited toxic effects at high concentrations. These findings highlight the need for a more refined oxygen carrier in the context of renal NMP.

Impact of EUS in liver transplantation workup for patients with unresectable perihilar cholangiocarcinoma.

BACKGROUND AND AIMS: For a highly selected group of patients with unresectable perihilar cholangiocarcinoma (pCCA), liver transplantation (LT) is a treatment option. The Dutch screening protocol comprises nonregional lymph node (LN) assessment by EUS, and whenever LN metastases are identified, further LT screening is precluded. The aim of this study is to investigate the yield of EUS in patients with pCCA who are potentially eligible for LT. METHODS: In this retrospective, nationwide cohort study, all consecutive patients with suspected unresectable pCCA who underwent EUS in the screening protocol for LT were included from 2011 to 2021. During EUS, sampling of a "suspicious" nonregional LN was performed based on the endoscopist's discretion. The primary outcome was the added value of EUS, defined as the number of patients who were precluded from further screening because of malignant LNs. RESULTS: A total of 75 patients were included in whom 84 EUS procedures were performed, with EUS-guided tissue acquisition confirming malignancy in LNs in 3 of 75 (4%) patients. In the 43 who underwent surgical staging according to the protocol, nonregional LNs with malignancy were identified in 6 (14%) patients. Positive regional LNs were found in 7 patients in post-LT-resected specimens. CONCLUSIONS: Our current EUS screening for the detection of malignant LNs in patients with pCCA eligible for LT shows a limited but clinically important yield. EUS with systematic screening of all LN stations, both regional and nonregional, and the sampling of suspicious lymph nodes according to defined and set criteria could potentially increase this yield.

Health-related Quality of Life and Fatigue in Liver Transplant Recipients Receiving Tacrolimus Versus Sirolimus-based Immunosuppression: Results From a Randomized Trial.

BACKGROUND: The impact of different immunosuppression regimes on the health-related quality of life (HRQoL) and the severity of fatigue in liver transplant recipients is largely unknown. We investigated the impact of a sirolimus-based regimen compared with a tacrolimus (TAC)-based regimen on the HRQoL and the severity of fatigue. METHODS: In this multicenter, open-label, randomized, controlled trial, 196 patients were randomized 90 d after transplantation to (1) once daily normal-dose TAC or (2) once daily combination therapy of low-dose sirolimus and TAC. HRQoL was measured with the EQ-5D-5L questionnaire, the EQ-visual analog scale, and the severity of fatigue questionnaire Fatigue Severity Score (FSS). The EQ-5D-5L scores were translated to societal values. We examined the HRQoL and the FSS over the course of the study by fitting generalized mixed-effect models. RESULTS: Baseline questionnaires were available for 87.7% (172/196) of the patients. Overall, patients reported the least problems in the states of self-care and anxiety/depression and the most problems in the states of usual activities and pain/discomfort. No significant differences in HrQol and FSS were seen between the 2 groups. During follow-up, the societal values of the EQ-5D-5L health states and the patient's self-rated EQ-visual analog scale score were a little lower than those of the general Dutch population in both study arms. CONCLUSIONS: The HRQoL and FSS were comparable in the 36 mo after liver transplantation in both study groups. The HRQoL of all transplanted patients approximated that of the general Dutch population, suggesting little to no residual symptoms in the long term after transplantation.

Survival benefit from liver transplantation for patients with and without hepatocellular carcinoma.

Background & Aims: In the USA, inequal liver transplantation (LT) access exists between patients with and without hepatocellular carcinoma (HCC). Survival benefit considers survival without and with LT and could equalise LT access. We calculated bias-corrected LT survival benefit for patients with(out) HCC who underwent a transplant, based on longitudinal data in a recent United States cohort. Methods: Adult LT candidates with(out) HCC between 2010 and 2019 were included. Waitlist survival over time was contrasted to post-transplant survival, to estimate 5-year survival benefit from the moment of LT. Waitlist survival was modelled with a bias-corrected Cox regression, and post-transplant survival was estimated through Cox proportional hazards regression. Results: Mean HCC survival without LT was always lower than non-HCC waitlist survival. Below model for end-stage liver disease (sodium) (MELD(-Na)) 30, patients with HCC gained more life-years from LT than patients without HCC at the same MELD(-Na) score. Only patients without HCC below MELD(-Na) 9 had negative benefit. Most patients with HCC underwent a transplant below MELD(-Na) 14, and most patients without HCC underwent a transplant above MELD(-Na) 26. Liver function [MELD(-Na), albumin] was the main predictor of 5-year benefit. Therefore, during 5 years, most patients with HCC gained 0.12 to 1.96 years from LT, whereas most patients without HCC gained 2.48 to 3.45 years. Conclusions: On an individual level, performing a transplant in patients with HCC resulted in survival benefit. However, on a population level, benefit was indirectly decreased, as patients without HCC were likely to gain more survival owing to decreased liver function. For patients who underwent a transplant, a constructed online calculator estimates 5-year survival benefit given specific patient characteristics. Survival benefit scores could serve to equalise LT access. Impact and implications: Benefit is a comparison of the survival with and without liver transplantation, and it is important when deciding who should undergo a transplant. Liver function is most important when predicting possible benefit from transplantation. Patients with liver cancer die sooner on the waiting list than similar patients without liver cancer. However, patients with liver cancer more often have better liver function. Most patients without liver cancer derive more benefit from transplantation than patients with liver cancer.

Primary sclerosing cholangitis and other risk factors for post-transplant lymphoproliferative disease after liver transplantation in adults.

Post-transplant lymphoproliferative disease (PTLD) is a rare but serious complication of liver transplantation (LT) with morbidity and mortality. The risk factors for PTLD in adults are ill-defined. This study aimed to assess the risk factors for PTLD after LT in adults. All adult LT recipients between 1986 and 2016 from 2 centers in the Netherlands were included, with follow-up until 2020. PTLD was diagnosed according to the World Health Organization (WHO) classification. Potential risk factors for PTLD were assessed using multivariate Cox regression analysis. A total of 1281 patients were included, of whom 29 (2.3%) developed PTLD. Results show that independent risk factors for PTLD after LT in adults were no Epstein-Barr virus load monitoring strategy, primary sclerosing cholangitis as an indication for LT, era (historic era linked to more intense long-term immunosuppression), and Epstein-Barr virus-seronegative recipient. No other independent risk factors were identified in this study. Of the 207 patients with primary sclerosing cholangitis as an indication for LT, 13 (6.3%) developed PTLD versus 16 out of 1074 (1.5%) patients with other underlying liver diseases (log-rank p <0.001). The yearly PTLD incidence was higher in the first year than in the later years after LT (2.4%/y vs. 0.6%/y) for primary sclerosing cholangitis, but not for other indications (0.16%/y). In Epstein-Barr virus-seronegative recipients PTLD occurred earlier after LT, while in 97% of seropositive recipients it could occur very late after LT.

Chronic Pancreas Allograft Rejection Followed by Successful HLA-Incompatible Islet Alloautotransplantation: A Novel Strategy?

The purpose of pancreas or islet transplantation is to restore glycemic control in order to mitigate diabetes-related complications and prevent severe hypoglycemia. Complications from chronic pancreas allograft rejection may lead to transplantectomy, even when the endocrine function remains preserved. We present first evidence of a successful HLA incompatible islet re-transplantation with islets isolated from a rejecting pancreas allograft after simultaneous kidney pancreas transplantation. The pancreas allograft was removed because of progressively painful pancreatic panniculitis from clinically uncontrolled chronic rejection. The endocrine function was preserved. Induction treatment for this "islet alloautotransplantation" consisted of plasmapheresis, IVIg and alemtuzumab. At 1 year, the patient retained islet graft function with good glycemic control and absence of severe hypoglycemia, despite persistent low-grade HLA donor-specific antibodies. His panniculitis had resolved completely. In our point of view, islet alloautotransplantation derived from a chronically rejecting pancreas allograft is a potential option to salvage (partial) islet function, despite preformed donor-specific antibodies, in order to maintain stable glycemic control. Thereby it protects against severe hypoglycemia, and it potentially mitigates kidney graft dysfunction and other diabetes-related complications in patients with continued need for immunosuppression and who are otherwise difficult to retransplant.

The role of flavin mononucleotide (FMN) as a potentially clinically relevant biomarker to predict the quality of kidney grafts during hypothermic (oxygenated) machine perfusion.

Hypothermic machine perfusion (HMP) provides preservation superior to cold storage and may allow for organ assessment prior to transplantation. Since flavin mononucleotide (FMN) in perfusate has been proposed as a biomarker of organ quality during HMP of donor livers, the aim of this study was to validate FMN as a biomarker for organ quality in the context of HMP preserved kidneys. Perfusate samples (n = 422) from the paired randomised controlled COPE-COMPARE-trial, comparing HMP with oxygenation (HMPO2) versus standard HMP in kidneys, were used. Fluorescence intensity (FI) was assessed using fluorescence spectroscopy (excitation 450nm; emission 500-600nm) and validated by fluorospectrophotometer and targeted liquid chromatography mass spectrometry (LC-MS/MS). Fluorescence intensity (FI)(ex450;em500-600) increased over time during machine perfusion in both groups (p<0.0001). This increase was similar for both groups (p = 0.83). No correlation, however, was found between FI(ex450;em500-600) and post-transplant outcomes, including day 5 or 7 serum creatinine (p = 0.11; p = 0.16), immediate graft function (p = 0.91), creatinine clearance and biopsy-proven rejection at one year (p = 0.14; p = 0.59). LC-MS/MS validation experiments of samples detected FMN in only one perfusate sample, whilst the majority of samples with the highest fluorescence (n = 37/38, 97.4%) remained negative. In the context of clinical kidney HMP, fluorescence spectroscopy unfortunately appears to be not specific and probably unsuitable for FMN. This study shows that FMN does not classify as a clinically relevant predictive biomarker of kidney graft function after transplantation.

Novel Explanted Human Liver Model to Assess Hepatic Extraction, Biliary Excretion and Transporter Function.

Realistic models predicting hepatobiliary processes in health and disease are lacking. We therefore aimed to develop a physiologically relevant human liver model consisting of normothermic machine perfusion (NMP) of explanted diseased human livers that can assess hepatic extraction, clearance, biliary excretion, and drug-drug interaction (DDI). Eleven livers were included in the study, seven with a cirrhotic and four with a noncirrhotic disease background. After explantation of the diseased liver, NMP was initiated. After 120 minutes of perfusion, a drug cocktail (rosuvastatin, digoxin, metformin, and furosemide; OATP1B1/1B3, P-gp, BCRP, and OCT1 model compounds) was administered to the portal vein and 120 minutes later, a second bolus of the drug cocktail was co-administered with perpetrator drugs to study relevant DDIs. The explanted livers showed good viability and functionality during 360 minutes of NMP. Hepatic extraction ratios close to in vivo reported values were measured. Hepatic clearance of rosuvastatin and digoxin showed to be the most affected by cirrhosis with an increase in maximum plasma concentration (Cmax ) of 11.50 and 2.89 times, respectively, compared with noncirrhotic livers. No major differences were observed for metformin and furosemide. Interaction of rosuvastatin or digoxin with perpetrator drugs were more pronounced in noncirrhotic livers compared with cirrhotic livers. Our results demonstrated that NMP of human diseased explanted livers is an excellent model to assess hepatic extraction, clearance, biliary excretion, and DDI. Gaining insight into pharmacokinetic profiles of OATP1B1/1B3, P-gp, BCRP, and OCT1 model compounds is a first step toward studying transporter functions in diseased livers.

Role of neoadjuvant chemoradiotherapy in liver transplantation for unresectable perihilar cholangiocarcinoma: multicentre, retrospective cohort study.

BACKGROUND: The Mayo protocol for liver transplantation in patients with unresectable perihilar cholangiocarcinoma is based on strict selection and neoadjuvant chemoradiotherapy. The role of neoadjuvant chemoradiotherapy in this scenario remains unclear. The aim of this study was to compare outcomes after transplantation for perihilar cholangiocarcinoma using strict selection criteria, either with or without neoadjuvant chemoradiotherapy. METHODS: This was an international, multicentre, retrospective cohort study of patients who underwent transplantation between 2011 and 2020 for unresectable perihilar cholangiocarcinoma using the Mayo selection criteria and receiving neoadjuvant chemoradiotherapy or not receiving neoadjuvant chemoradiotherapy. Endpoints were post-transplant survival, post-transplant morbidity rate, and time to recurrence. RESULTS: Of 49 patients who underwent liver transplantation for perihilar cholangiocarcinoma, 27 received neoadjuvant chemoradiotherapy and 22 did not. Overall 1-, 3-, and 5-year post-transplantation survival rates were 65 per cent, 51 per cent and 41 per cent respectively in the group receiving neoadjuvant chemoradiotherapy and 91 per cent, 68 per cent and 53 per cent respectively in the group not receiving neoadjuvant chemoradiotherapy (1-year hazards ratio (HR) 4.55 (95 per cent c.i. 0.98 to 21.13), P = 0.053; 3-year HR 2.07 (95 per cent c.i. 0.78 to 5.54), P = 0.146; 5-year HR 1.71 (95 per cent c.i. 0.71 to 4.09), P = 0.229). Hepatic vascular complications were more frequent in the group receiving neoadjuvant chemoradiotherapy compared with the group not receiving neoadjuvant chemoradiotherapy (nine of 27 versus two of 22, P = 0.045). In multivariable analysis, tumour recurrence occurred less frequently in the group receiving neoadjuvant chemoradiotherapy (HR 0.30 (95 per cent c.i. 0.09 to 0.97), P = 0.044). CONCLUSION: In selected patients undergoing liver transplantation for perihilar cholangiocarcinoma, neoadjuvant chemoradiotherapy resulted in a lower risk of tumour recurrence, but was associated with a higher rate of early hepatic vascular complications. Adjustments in neoadjuvant chemoradiotherapy reducing the risk of hepatic vascular complications, such as omitting radiotherapy, may further improve the outcome in patients undergoing liver transplantation for perihilar cholangiocarcinoma.

Three-year results of renal function in liver transplant recipients on low-dose sirolimus and tacrolimus: a multicenter, randomized, controlled trial.

The aim of this study was to investigate whether the combination of low-dose sirolimus (SRL) and low-dose extended-release tacrolimus (TAC) compared to normal-dose extended-release TAC results in a difference in the renal function and comparable rates of rejection, graft and patient survival at 36 months after transplantation. This study was an open-label, multicenter randomized, controlled trial. Patients were randomized to once-daily normal-dose extended-release TAC (control group) or once-daily combination therapy of SRL and low-dose extended-release TAC (interventional group). The primary endpoint was the cumulative incidence of chronic kidney disease (CKD) defined as grade ≥3 (estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2) at 36 months after transplantation. In total, 196 patients were included. CKD at 36 months was not different between the control and interventional group (50.8%, 95% CI: 39.7%-59.9%) vs. 43.7%, 95% CI: 32.8%-52.8%). Only at 6 months after transplantation, the eGFR was higher in the interventional group compared to the control group (mean eGFR 73.1±15 vs. 67.6±16 mL/min/1.73 m2, p=0.02) in the intention-to-treat population. No differences in the secondary endpoints and the number of serious adverse events were found between the groups. Once daily low-dose SRL combined with low-dose extended-release TAC does ultimately not provide less CKD grade ≥3 at 36 months compared to normal-dose extended-release TAC.

Inflammatory conditions play a role in recurrence of PSC after liver transplantation: An international multicentre study.

Background & Aims: Liver transplantation (LT) for primary sclerosing cholangitis (PSC) is complicated by recurrence of PSC (rPSC) in up to 25% of recipients. Recurrence has been shown to be detrimental for both graft and patient survival. For both PSC and rPSC, a medical cure is not available. To predict and ideally to prevent rPSC, it is imperative to find risk factors for rPSC that can be potentially modified. Therefore, we aimed to identify such factors for rPSC in a large international multicentre study including 6 centres in PSC-prevalent countries. Methods: In this international multicentre, retrospective cohort study, 531 patients who underwent transplantation for PSC were included. In 25% of cases (n = 131), rPSC was diagnosed after a median follow-up of 6.72 (3.29-10.11) years post-LT. Results: In the multivariable competing risk model with time-dependent covariates, we found that factors representing an increased inflammatory state increase the risk for rPSC. Recurrent cholangitis before LT as indication for LT (hazard ratio [HR] 3.6, 95% CI 2.5-5.2), increased activity of inflammatory bowel disease after LT (HR 1.7, 95% CI 1.08-2.75), and multiple acute cellular rejections (HR: non-linear) were significantly and independently associated with an increased risk of rPSC. In contrast to the findings of previous studies, pretransplant colectomy was not found to be independently protective against the development of rPSC. Conclusions: An increased inflammatory state before and after LT may play a causal and modifiable role in the development of rPSC. Pretransplant colectomy did not reduce the risk of rPSC per se. Recurrent cholangitis as indication for LT was associated with an increased risk of rPSC. Impact and implications: Recurrence of PSC (rPSC) negatively affects survival after liver transplant (LT). Modifiable risk factors could guide clinical management and prevention of rPSC. We demonstrate that an increased inflammatory state both before and after LT increases the incidence of rPSC. As these are modifiable factors, they could serve as targets for future studies and therapies. We also added further evidence to the ongoing debate regarding preventive colectomy for rPSC by reporting that in our multicenter study, we could not find an independent association between colectomy and risk of rPSC.

Complement Is Activated During Normothermic Machine Perfusion of Porcine and Human Discarded Kidneys.

Background: The gap between demand and supply of kidneys for transplantation necessitates the use of kidneys from extended criteria donors. Transplantation of these donor kidneys is associated with inferior results, reflected by an increased risk of delayed graft function. Inferior results might be explained by the higher immunogenicity of extended criteria donor kidneys. Normothermic machine perfusion (NMP) could be used as a platform to assess the quality and function of donor kidneys. In addition, it could be useful to evaluate and possibly alter the immunological response of donor kidneys. In this study, we first evaluated whether complement was activated during NMP of porcine and human discarded kidneys. Second, we examined the relationship between complement activation and pro-inflammatory cytokines during NMP. Third, we assessed the effect of complement activation on renal function and injury during NMP of porcine kidneys. Lastly, we examined local complement C3d deposition in human renal biopsies after NMP. Methods: NMP with a blood-based perfusion was performed with both porcine and discarded human kidneys for 4 and 6 h, respectively. Perfusate samples were taken every hour to assess complement activation, pro-inflammatory cytokines and renal function. Biopsies were taken to assess histological injury and complement deposition. Results: Complement activation products C3a, C3d, and soluble C5b-9 (sC5b-9) were found in perfusate samples taken during NMP of both porcine and human kidneys. In addition, complement perfusate levels positively correlated with the cytokine perfusate levels of IL-6, IL-8, and TNF during NMP of porcine kidneys. Porcine kidneys with high sC5b-9 perfusate levels had significantly lower creatinine clearance after 4 h of NMP. In line with these findings, high complement perfusate levels were seen during NMP of human discarded kidneys. In addition, kidneys retrieved from brain-dead donors had significantly higher complement perfusate levels during NMP than kidneys retrieved from donors after circulatory death. Conclusion: Normothermic kidney machine perfusion induces complement activation in porcine and human kidneys, which is associated with the release of pro-inflammatory cytokines and in porcine kidneys with lower creatinine clearance. Complement inhibition during NMP might be a promising strategy to reduce renal graft injury and improve graft function prior to transplantation.

Salvage of Declined Extended-criteria DCD Livers Using In Situ Normothermic Regional Perfusion.

OBJECTIVE: This study investigates whether liver grafts donated after circulatory death (DCD) that are declined by the entire Eurotransplant region can be salvaged with abdominal normothermic regional perfusion (aNRP). BACKGROUND: aNRP is increasingly used for DCD liver grafts because it prevents typical complications. However, it is unclear whether aNRP is capable to rescue pretransplant declined liver grafts by providing the opportunity to test function during donation. METHODS: Donor livers from DCD donors, declined by all centers in the Eurotransplant region, were included for this study. The comparator cohort included standard DCD livers and livers donated after brain death, transplanted in the same time period. RESULTS: After the withdrawal of life-sustaining treatment, 28 from the 43 donors had a circulatory death within 2 hours, in which case aNRP was initiated. Of these 28 cases, in 3 cases perfusion problems occurred, 5 grafts were declined based on liver assessment, and 20 liver grafts were transplanted. The main differences during aNRP between the transplanted grafts and the assessed nontransplanted grafts were alanine transaminase levels of 53 U/L (34-68 U/L) versus 367 U/L (318-488 U/L) ( P =0.001) and bile production in 100% versus 50% of the grafts ( P =0.024). The 12-month graft and patient survival were both 95%, similar to the comparator cohort. The incidence of ischemic cholangiopathy was 11%, which was lower than in the standard DCD cohort (18%). CONCLUSION: aNRP can safely select and thus is able to rescue DCD liver grafts that were deemed unsuitable for transplantation, while preventing primary nonfunction and minimizing ischemic cholangiopathy.

Extracellular Vesicles Released During Normothermic Machine Perfusion Are Associated With Human Donor Kidney Characteristics.

BACKGROUND: Extracellular vesicles (EVs) are tissue-specific particles released by cells containing valuable diagnostic information in the form of various biomolecules. The characterization of EVs released by kidney grafts during normothermic machine perfusion (NMP) may present a promising avenue to assess graft status before transplantation. METHODS: We phenotyped and determined the concentrations of EVs in the perfusate of 8 discarded expanded-criteria donor human kidneys during 6 h of NMP. Perfusate samples were taken at 0/60/180/360 min and examined with nanoparticle tracking analysis and imaging flow cytometry (IFCM). Using IFCM, EVs were identified by their expression of common EV markers CD9, CD63, and CD81 (tetraspanins) in combination with either platelet endothelial cell adhesion molecule (CD31), pan-leukocyte protein (CD45), or carboxyfluorescein succiminidyl ester (CFSE) fluorescence. RESULTS: Nanoparticle tracking analysis measurements revealed the release of nanoparticles <400 nm into the perfusate during NMP. With IFCM, tetraspanin protein signatures of the released nanoparticles were characterized, and the majority (~75%) of CFSE+ EVs were found to be CD81+, whereas ~16% were CD9+ and ~8% CD63+. Correlation analysis of concentrations of identified EV subsets with crude donor characteristics and NMP viability characteristics revealed significant correlations with cold ischemia time, donor age, and renal flow. CONCLUSIONS: Our findings demonstrate that discarded expanded-criteria donor kidney grafts release distinct EV subsets during NMP. Because these subsets correlate with well-established indicators of transplant outcome, EVs might represent new potential candidates for assessment of kidney graft quality.

Quantification of Unmethylated Insulin DNA Using Methylation Sensitive Restriction Enzyme Digital Polymerase Chain Reaction.

Assessment of specific ß-cell death can be used to determine the quality and viability of pancreatic islets prior to transplantation and hence predict the suitability of the pancreas for isolation. Recently, several groups have demonstrated that unmethylated insulin (INS)-DNA is correlated to ß-cell death in type 1 diabetes patients and during clinical islet isolation and subsequent transplantation. Here, we present a step-by-step protocol of our novel developed method for quantification of the relative amount of unmethylated INS-DNA using methylation sensitive restriction enzyme digital polymerase chain reaction This method provides a novel and sensitive way to quantify the relative amount of ß-cell derived unmethylated INS-DNA in cellular lysate. We therefore suggest that this technique can be of value to reliably determine the purity of an islet preparation and may also serve as a measure of the quality of islets prior to transplantation measuring unmethylated INS-DNA as a reflection of the relative amount of lysed ß-cells.

Preclinical models versus clinical renal ischemia reperfusion injury: A systematic review based on metabolic signatures.

Despite decennia of research and numerous successful interventions in the preclinical setting, renal ischemia reperfusion (IR) injury remains a major problem in clinical practice, pointing toward a translational gap. Recently, two clinical studies on renal IR injury (manifested either as acute kidney injury or as delayed graft function) identified metabolic derailment as a key driver of renal IR injury. It was reasoned that these unambiguous metabolic findings enable direct alignment of clinical with preclinical data, thereby providing the opportunity to elaborate potential translational hurdles between preclinical research and the clinical context. A systematic review of studies that reported metabolic data in the context of renal IR was performed according to the PRISMA guidelines. The search (December 2020) identified 35 heterogeneous preclinical studies. The applied methodologies were compared, and metabolic outcomes were semi-quantified and aligned with the clinical data. This review identifies profound methodological challenges, such as the definition of IR injury, the follow-up time, and sampling techniques, as well as shortcomings in the reported metabolic information. In light of these findings, recommendations are provided in order to improve the translatability of preclinical models of renal IR injury.