Improving the Supply and Quality of Deceased-Donor Organs for Transplantation

Promising Results of Kidney Transplantation From Donors Following Euthanasia During 10-Year Follow-Up: A Nationwide Cohort Study

The outcome of kidneys transplanted following organ donation after euthanasia (ODE) remains unclear. This study analyzed all kidney transplantations in the Netherlands from January 2012 to December 2021, comparing the outcomes following ODE, donation after circulatory death (DCD-III), and donation after brain death (DBD). 9,208 kidney transplantations were performed: 148 ODE, 2118 DCD-III, and 1845 DBD. Initial graft function was compared between these categories. Immediate graft function, delayed graft function and primary non-function in ODE kidney recipients were 76%, 22%, and 2%, respectively, 47%, 50% and 3% in DCD-III kidney recipients and 73%, 25%, and 2% in DBD kidney recipients (overall p-value: p < 0.001). The number of kidneys transplanted over a median follow-up period of 4.0 years (IQR 2.0-6.6), was 1810, including 72 ODE, 958 DCD-III and 780 DBD kidneys. In this period, 213 grafts (11.8%) failed [7 grafts (9.7%) from ODE donors, 93 grafts (9.7%) from DCD-III donors, and 113 grafts (14.5%) from DBD donors]. Kidneys transplanted after euthanasia have a good immediate graft function, a comparable longitudinal 10 years eGFR, and similar graft failure hazard to kidneys from DCD-III and DBD. Kidney transplantation following ODE is a valuable and safe contribution to the donor pool.

Impact of deceased-donor characteristics on early graft function: outcome of kidney donor pairs accepted for transplantation

Introduction

The impact of deceased donor characteristics on kidney transplant outcomes is controversial. Correspondingly, the predictive performance of deceased donor scores remains moderate, and many transplant centers lack validated criteria for graft acceptance decisions. To better dissect donor-related risk from recipient and periprocedural variables, we analyzed outcomes of kidney donor pairs transplanted in different individuals.

Methods

This study explored (a)symmetry of early outcomes of 328 cadaveric kidney transplant recipients from 164 donor pairs transplanted at three Eurotransplant centers. The primary discriminatory factor was (a)symmetry of partner graft function, defined as early graft loss or impaired graft function [estimated glomerular filtration rate (eGFR) <30 mL/min] 3 months after transplantation. We reasoned that a relevant impact of donor factors would result in a high concordance rate of limited graft function or failure.

Results

The observed number of symmetric graft failure after transplantation was less than statistically expected (3 months: 1 versus 2, p = 0.89; and 12 months: 3 versus 5, p = 0.26). However, we found a trend toward an impaired 5-year graft survival of grafts with good function 3 months after transplantation but a failed or impaired partner graft compared to symmetrically well-functioning grafts (p = 0.09). Subsequently, we explored the impact of individual donor and recipient variables on early transplant outcomes. Generalized estimating equations after feature selection with LassoGEE bootstrap selected donor age, donor body mass index, and donor eGFR as the relevant risk factors.

Discussion

Our findings indicate that donor factors impact early outcomes in kidney transplantation but may have a limited role in long-term graft survival, once a graft has been accepted for transplantation. Utilizing donor-based clinical scores has the potential to aid clinicians in acceptance decisions, giving them an estimate of individual posttransplant outcomes. However, the ultimate decision for acceptance should rest with clinicians, who must consider the complex interplay of donor factors, as well as recipient and periprocedural characteristics.

Donor Conditioning and Organ Pre-Treatment Prior to Kidney Transplantation: Reappraisal of the Available Clinical Evidence

Therapeutic measures aimed at optimising organ function prior to transplantation-whether by conditioning the donor after determination of brain death or by improving organ preservation after kidney removal-have the potential to enhance outcomes after transplantation. The particular advantage is that, unlike any optimised immunosuppressive therapy, a favourable effect can be achieved without side effects for the organ recipient. In recent years, several such measures have been tested in controlled clinical trials on large patient cohorts following kidney transplantation. Hypothermic pulsatile machine perfusion, in particular, has become the focus of interest, but interventions in the donor prior to organ removal, such as the administration of low-dose dopamine until the start of cold perfusion as an example of conditioning antioxidant therapy and therapeutic donor hypothermia in the intensive care unit after brain death confirmation, have also significantly reduced the frequency of dialysis after transplantation with far less effort and cost. With regard to benefits for graft survival, the database for all procedures is less clear and controversial. The aim of this review article is to re-evaluate the available clinical evidence from large multicentre controlled trials, which have also significantly influenced later meta-analyses, and to assess the significance for use in routine clinical practice.

An image inpainting-based data augmentation method for improved sclerosed glomerular identification performance with the segmentation model EfficientNetB3-Unet

The percent global glomerulosclerosis is a key factor in determining the outcome of renal transfer surgery. At present, the rate is typically computed by pathologists, which is labour intensive and nonstandardized. With the development of Deep Learning (DL), DL-based segmentation models can be used to better identify and segment normal and sclerosed glomeruli. Based on this, we can better quantify percent global glomerulosclerosis to reduce the discard rate of donor kidneys. We used 51 whole slide images (WSIs) from different institutions that are publicly available on the internet. However, the number of sclerosed glomeruli is much smaller than that of normal glomeruli in different WSIs, which can reduce the effectiveness of Deep Learning. For better sclerosed glomerular identification and segmentation performance, we modified and trained a GAN (generative adversarial network)-based image inpainting model to obtain more synthetic sclerosed glomeruli. Our proposed inpainting method achieved an average SSIM (Structural Similarity) of 0.8086 and an average PSNR (Peak Signal-to-Noise Ratio) of 22.8943 dB in the area of generated sclerosed glomeruli. We obtained sclerosed glomerular segmentation performance improvement by adding synthetic sclerosed glomerular images and achieved the best Dice of glomerular segmentation in different test sets based on the modified Unet model.

Evidence-Based Checklist to Delay Cardiac Arrest in Brain-Dead Potential Organ Donors: The DONORS Cluster Randomized Clinical Trial

Importance

The effectiveness of goal-directed care to reduce loss of brain-dead potential donors to cardiac arrest is unclear.

Objective

To evaluate the effectiveness of an evidence-based, goal-directed checklist in the clinical management of brain-dead potential donors in the intensive care unit (ICU).

Design, Setting, and Participants

The Donation Network to Optimize Organ Recovery Study (DONORS) was an open-label, parallel-group cluster randomized clinical trial in Brazil. Enrollment and follow-up were conducted from June 20, 2017, to November 30, 2019. Hospital ICUs that reported 10 or more brain deaths in the previous 2 years were included. Consecutive brain-dead potential donors in the ICU aged 14 to 90 years with a condition consistent with brain death after the first clinical examination were enrolled. Participants were randomized to either the intervention group or the control group. The intention-to-treat data analysis was conducted from June 15 to August 30, 2020.

Interventions

Hospital staff in the intervention group were instructed to administer to brain-dead potential donors in the intervention group an evidence-based checklist with 13 clinical goals and 14 corresponding actions to guide care, every 6 hours, from study enrollment to organ retrieval. The control group provided or received usual care.

Main Outcomes and Measures

The primary outcome was loss of brain-dead potential donors to cardiac arrest at the individual level. A prespecified sensitivity analysis assessed the effect of adherence to the checklist in the intervention group.

Results

Among the 1771 brain-dead potential donors screened in 63 hospitals, 1535 were included. These patients included 673 males (59.2%) and had a median (IQR) age of 51 (36.3-62.0) years. The main cause of brain injury was stroke (877 [57.1%]), followed by trauma (485 [31.6%]). Of the 63 hospitals, 31 (49.2%) were assigned to the intervention group (743 [48.4%] brain-dead potential donors) and 32 (50.8%) to the control group (792 [51.6%] brain-dead potential donors). Seventy potential donors (9.4%) at intervention hospitals and 117 (14.8%) at control hospitals met the primary outcome (risk ratio [RR], 0.70; 95% CI, 0.46-1.08; P = .11). The primary outcome rate was lower in those with adherence higher than 79.0% than in the control group (5.3% vs 14.8%; RR, 0.41; 95% CI, 0.22-0.78; P = .006).

Conclusions and Relevance

This cluster randomized clinical trial was inconclusive in determining whether the overall use of an evidence-based, goal-directed checklist reduced brain-dead potential donor loss to cardiac arrest. The findings suggest that use of such a checklist has limited effectiveness without adherence to the actions recommended in this checklist.

Trial Registration

ClinicalTrials.gov Identifier: NCT03179020.

Association of postoperative length of stay with outcomes following orthotopic heart transplantation-A national analysis

BACKGROUND

In the absence of standardized recovery protocols, there is little evidence to guide postoperative care to ensure optimal in-hospital and long-term outcomes following heart transplantation (HT). Using two national databases, we examined the association between postoperative length of stay (LOS) with patient/graft survival, index hospitalization costs, and non-elective readmissions.

METHODS

Adult HT recipients from 2010 to 2019 were identified and analyzed within the Organ Procurement and Transplantation Network (OPTN) Database and Nationwide Readmissions Database (NRD). The risk-adjusted relationship between 1-year mortality and LOS was assessed with restricted cubic splines and subsequently used to stratify patients into Expedited (7-11 days), Routine (12-16 days), and Delayed (>16) discharge groups. Survival outcomes were analyzed using Restricted Means Survival Time analysis (RMST) and multivariable Cox models.

RESULTS

Of 9995 HT recipients within the OPTN, 3777 (38%) were categorized as Expedited, and 3040 (30%) as Routine. After adjustment, expedited discharge was not associated with inferior 90-day (ΔRMST -.01, p = .91) and 1-year patient survival (ΔRMST -.02, p = .53). Additionally, expedited was not associated with increased odds of non-elective readmission at 90-days (HR 1.04, CI .77-1.43) relative to Routine discharge. Counterfactual analysis revealed an estimated cost saving of $50 million if all Routine patients received an expedited discharge.

CONCLUSION

Expedited discharge after HT seems to be cost-effective and is not associated with inferior outcomes. Institutional-level outcome analyses should be performed to identify patients that would benefit from expedited discharge, and future studies should analyze the feasibility of implementing standardized discharge protocols following HT.

High RIPK3 expression is associated with a higher risk of early kidney transplant failure

Renal ischemia-reperfusion injury (IRI) is associated with reduced allograft survival, and each additional hour of cold ischemia time increases the risk of graft failure and mortality following renal transplantation. Receptor-interacting protein kinase 3 (RIPK3) is a key effector of necroptosis, a regulated form of cell death. Here, we evaluate the first-in-human RIPK3 expression dataset following IRI in kidney transplantation. The primary analysis included 374 baseline biopsy samples obtained from renal allografts 10 minutes after onset of reperfusion. RIPK3 was primarily detected in proximal tubular cells and distal tubular cells, both of which are affected by IRI. Time-to-event analysis revealed that high RIPK3 expression is associated with a significantly higher risk of one-year transplant failure and prognostic for one-year (death-censored) transplant failure independent of donor and recipient associated risk factors in multivariable analyses. The RIPK3 score also correlated with deceased donation, cold ischemia time and the extent of tubular injury.

MiR-132-3p activation aggravates renal ischemia-reperfusion injury by targeting Sirt1/PGC1alpha axis

The pathogenesis of renal ischemic diseases remains unclear. In this study, we demonstrate the induction of microRNA-132-3p (miR-132-3p) in ischemic acute kidney injury (AKI) and cultured renal tubular cells under oxidative stress. miR-132-3p mimic increased apoptosis in renal tubular cells and enhanced ischemic AKI in mice, whereas miR-132-3p inhibition offered protective effects. We analyzed miR-132-3p target genes through bioinformatic analysis and Sirt1 was predicted as the target gene of miR-132-3p. Luciferase microRNA target reporter assay further verified Sirt1 as a direct target of miR-132-3p. In cultured tubular cells and mouse kidneys, IRI and H2O2 treatment repressed Sirt1 and PGC-1α/NRF2/HO-1 expression, whereas anti-miR-132-3p preserved Sirt1 and PGC-1α/NRF2/HO-1 expression. In renal tubular, Sirt1 inhibitor suppressed PGC1-1α/NRF2/HO-1 expression and aggravated tubular apoptosis. Together, the results suggest that miR-132-3p induction aggravates ischemic AKI and oxidative stress by repressing Sirt1 expression, and miR-132-3p inhibition offers renal protection and may be a potential therapeutic target.

A Spectrofluorometric Method for Real-Time Graft Assessment and Patient Monitoring

Biomarkers are powerful clinical diagnostics and predictors of patient outcome. However, robust measurements often require time and expensive laboratory equipment, which is insufficient to track rapid changes and limits direct use in the operating room. Here, this study presents a portable spectrophotometric device for continuous real-time measurements of fluorescent and non-fluorescent biomarkers at the point of care. This study measures the mitochondrial damage biomarker flavin mononucleotide (FMN) in 26 extended criteria human liver grafts undergoing hypothermic oxygenated perfusion to guide clinical graft assessment. Real-time data identified seven organs unsuitable for transplant that are discarded. The remaining grafts are transplanted and FMN values correlated with post-transplant indicators of liver function and patient recovery. Further, this study shows how this device can be used to monitor dialysis patients by measuring creatinine in real-time. Our approach provides a simple method to monitor biomarkers directly within biological fluids to improve organ assessment, patient care, and biomarker discovery.

miR-147 Represses NDUFA4, Inducing Mitochondrial Dysfunction and Tubular Damage in Cold Storage Kidney Transplantation

SIGNIFICANCE STATEMENT

Cold storage-associated transplantation (CST) injury occurs in renal transplant from deceased donors, the main organ source. The pathogenesis of CST injury remains poorly understood, and effective therapies are not available. This study has demonstrated an important role of microRNAs in CST injury and revealed the changes in microRNA expression profiles. Specifically, microRNA-147 (miR-147) is consistently elevated during CST injury in mice and in dysfunctional renal grafts in humans. Mechanistically, NDUFA4 (a key component of mitochondrial respiration complex) is identified as a direct target of miR-147. By repressing NDUFA4, miR-147 induces mitochondrial damage and renal tubular cell death. Blockade of miR-147 and overexpression of NDUFA4 reduce CST injury and improve graft function, unveiling miR-147 and NDUFA4 as new therapeutic targets in kidney transplantation.

BACKGROUND

Kidney injury due to cold storage-associated transplantation (CST) is a major factor determining the outcome of renal transplant, for which the role and regulation of microRNAs remain largely unclear.

METHODS

The kidneys of proximal tubule Dicer (an enzyme for microRNA biogenesis) knockout mice and their wild-type littermates were subjected to CST to determine the function of microRNAs. Small RNA sequencing then profiled microRNA expression in mouse kidneys after CST. Anti-microRNA-147 (miR-147) and miR-147 mimic were used to examine the role of miR-147 in CST injury in mouse and renal tubular cell models.

RESULTS

Knockout of Dicer from proximal tubules attenuated CST kidney injury in mice. RNA sequencing identified multiple microRNAs with differential expression in CST kidneys, among which miR-147 was induced consistently in mouse kidney transplants and in dysfunctional human kidney grafts. Anti-miR-147 protected against CST injury in mice and ameliorated mitochondrial dysfunction after ATP depletion injury in renal tubular cells in intro . Mechanistically, miR-147 was shown to target NDUFA4, a key component of the mitochondrial respiration complex. Silencing NDUFA4 aggravated renal tubular cell death, whereas overexpression of NDUFA4 prevented miR-147-induced cell death and mitochondrial dysfunction. Moreover, overexpression of NDUFA4 alleviated CST injury in mice.

CONCLUSIONS

microRNAs, as a class of molecules, are pathogenic in CST injury and graft dysfunction. Specifically, miR-147 induced during CST represses NDUFA4, leading to mitochondrial damage and renal tubular cell death. These results unveil miR-147 and NDUFA4 as new therapeutic targets in kidney transplantation.

The Sigma-1 Receptor Is a Novel Target for Improving Cold Preservation in Rodent Kidney Transplants

Kidney transplantation is the preferred treatment for patients with end-stage kidney disease. Maintaining organ viability between donation and transplantation, as well as minimizing ischemic injury, are critically important for long-term graft function and survival. Moreover, the increasing shortage of transplantable organs is a considerable problem; thus, optimizing the condition of grafts is a pivotal task. Here, rodent models of kidney transplantation and cold storage were used to demonstrate that supplementation of a preservation solution with Sigma-1 receptor (S1R) agonist fluvoxamine (FLU) reduces cold and warm ischemic injury. Post-transplant kidney function was improved, histological injury was mitigated, and mRNA expression of two tubular injury markers-kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin-was robustly reduced. In addition, renal inflammation was diminished, as shown by reduced leukocyte infiltration and pro-inflammatory cytokine expression. In the cold ischemia model, FLU ameliorated structural injury profoundly after 2 h as well as 24 h. The reduced number of TUNEL-positive and Caspase 3-positive cells suggests the anti-apoptotic effect of FLU. None of these beneficial effects of FLU were observed in S1R^-/- mice. Of note, organ damage in FLU-treated kidneys after 24 h of cold storage was similar to just 2 h without FLU. These results indicate that S1R agonists can prolong storage time and have great potential in improving organ preservation and in alleviating the problem of organ shortages.

Histological, Laboratorial, and Clinical Benefits of an Optimized Maintenance Strategy of a Potential Organ Donor-A Rabbit Experimental Model

INTRODUCTION

Most transplanted organs are obtained from brain-dead donors. Inflammation results in a higher rate of rejection. Objectives: The objective of this animal model of brain death (BD) was to evaluate the effect of the progressive institution of volume expansion, norepinephrine, and combined hormone therapy on clinical, laboratory, and histological aspects. Methods: Twenty rabbits were divided: A (control), B (induction of BD + infusion of crystalloid), C (BD + infusion of crystalloid and noradrenaline (NA)), and D (BD + infusion of crystalloid + vasopressin + levothyroxine + methylprednisolone + NA). The animals were monitored for four hours with consecutives analysis of vital signs and blood samples. The organs were evaluated by a pathologist. Results: In Group D, we observed fewer number and lesser volume of infusions (p = 0.032/0.014) when compared with groups B and C. Mean arterial pressure levels were higher in group D when compared with group B (p = 0.008). Group D had better glycemic control when compared with group C (p = 0.016). Sodium values were elevated in group B in relation to groups C and D (p = 0.021). In Group D, the organ perfusion was better. Conclusion: The optimized strategy of management of BD animals is associated with better hemodynamic, glycemic, and natremia control, besides reducing early signs of ischemia.

Development and validation of the lung donor (LUNDON) acceptability score for pulmonary transplantation

There is a chronic shortage of donor lungs for pulmonary transplantation due, in part, to low lung utilization rates in the United States. We performed a retrospective cohort study using data from the Scientific Registry of Transplant Recipients database (2006-2019) and developed the lung donor (LUNDON) acceptability score. A total of 83 219 brain-dead donors were included and were randomly divided into derivation (n = 58 314, 70%) and validation (n = 24 905, 30%) cohorts. The overall lung acceptance was 27.3% (n = 22 767). Donor factors associated with the lung acceptance were age, maximum creatinine, ratio of arterial partial pressure of oxygen to fraction of inspired oxygen, mechanism of death by asphyxiation or drowning, history of cigarette use (≥20 pack-years), history of myocardial infarction, chest x-ray appearance, bloodstream infection, and the occurrence of cardiac arrest after brain death. The prediction model had high discriminatory power (C statistic, 0.891; 95% confidence interval, 0.886-0.895) in the validation cohort. We developed a web-based, user-friendly tool (available at https://sites.wustl.edu/lundon) that provides the predicted probability of donor lung acceptance. LUNDON score was also associated with recipient survival in patients with high lung allocation scores. In conclusion, the multivariable LUNDON score uses readily available donor characteristics to reliably predict lung acceptability. Widespread adoption of this model may standardize lung donor evaluation and improve lung utilization rates.

Hypothermic Oxygenated Machine Perfusion Promotes Mitophagy Flux against Hypoxia-Ischemic Injury in Rat DCD Liver

Hypothermic oxygenated machine perfusion (HOPE) can enhance organ preservation and protect mitochondria from hypoxia-ischemic injury; however, an understanding of the underlying HOPE mechanism that protects mitochondria is somewhat lacking. We hypothesized that mitophagy may play an important role in HOPE mitochondria protection. Experimental rat liver grafts were exposed to 30 min of in situ warm ischemia. Then, grafts were procured, followed by cold storage for 3 or 4 h to mimic the conventional preservation and transportation time in donation after circulatory death (DCD) in clinical contexts. Next, the grafts underwent hypothermic machine perfusion (HMP) or HOPE for 1 h through portal vein only perfusion. The HOPE-treated group showed a better preservation capacity compared with cold storage and HMP, preventing hepatocyte damage, nuclear injury, and cell death. HOPE can increase mitophagy marker expression, promote mitophagy flux via the PINK1/Parkin pathway to maintain mitochondrial function, and reduce oxygen free radical generation, while the inhibition of autophagy by 3-methyladenine and chloroquine could reverse the protective effect. HOPE-treated DCD liver also demonstrated more changes in the expression of genes responsible for bile metabolism, mitochondrial dynamics, cell survival, and oxidative stress. Overall, HOPE attenuates hypoxia-ischemic injury in DCD liver by promoting mitophagy flux to maintain mitochondrial function and protect hepatocytes. Mitophagy could pave the way for a protective approach against hypoxia-ischemic injury in DCD liver.

Predicting older-donor kidneys' post-transplant renal function using pre-transplant data

This paper provides a methodology for predicting post-transplant kidney function, that is, the 1-year post-transplant estimated Glomerular Filtration Rate (eGFR-1) for each donor-candidate pair. We apply customized machine-learning algorithms to pre-transplant donor and recipient data to determine the probability of achieving an eGFR-1 of at least 30 ml/min. This threshold was chosen because there is insufficient survival benefit if the kidney fails to generate an eGFR-1 ≥ 30 ml/min. For some donor-candidate pairs, the developed algorithm provides highly accurate predictions. For others, limitations of previous transplants' data results in noisier predictions. However, because the same kidney is offered to many candidates, we identify those pairs for whom the predictions are highly accurate. Out of 6977 discarded older-donor kidneys that were a match with at least one transplanted kidney, 5282 had one or more identified candidate, who were offered that kidney, did not accept any other offer, and would have had ≥80% chance of achieving eGFR-1 ≥ 30 ml/min, had the kidney been transplanted. We also show that transplants with ≥80% chance of achieving eGFR-1 ≥ 30 ml/min and that survive 1 year have higher 10-year death-censored graft survival probabilities than all older-donor transplants that survive 1 year (73.61% vs. 70.48%, respectively).

Extracellular histone release by renal cells after warm and cold ischemic kidney injury: Studies in an ex-vivo porcine kidney perfusion model

Extracellular histones are cytotoxic molecules involved in experimental acute kidney injury. In patients receiving a renal transplant from donors after circulatory death, who suffer from additional warm ischemia, worse graft outcome is associated with higher machine perfusate extracellular histone H3 concentrations. We now investigated temperature-dependent extracellular histone release in an ex vivo porcine renal perfusion model, and subsequently studied histone release in the absence and presence of non-anticoagulant heparin. Seven pairs of ischemically damaged porcine kidneys were machine perfused at 4°C (cold ischemia) or 28°C (warm ischemia). Perfusate histone H3 concentration was higher after warm as compared to cold ischemia (median (IQR) = 0.48 (0.20-0.83) μg/mL vs. 0.02 (0.00-0.06) μg/mL; p = .045, respectively). Employing immune-electron microscopy (EM), histone containing cytoplasmic protrusions of tubular and endothelial cells were found after warm ischemic injury. Furthermore, abundant histone localization was detected in debris surrounding severely damaged glomerular cells, in a "buck shot" pattern. In vitro, histones were cytotoxic to endothelial and kidney epithelial cells in a temperature-dependent manner. In a separate ex vivo experiment, addition of heparin did not change the total histone H3 levels observed in the perfusate but revealed a continuous increase in the level of a lower molecular weight histone H3 variant. Our findings show that ischemically damaged kidneys release more extracellular histones in warm ischemia, which by EM was due to histone release by renal cells. Blocking of histone-mediated damage during transplantation may be beneficial in prevention of renal injury.

Cardiology Assessment of Patients Undergoing Evaluation for Orthotopic Liver Transplantation

Orthotopic liver transplantation (OLT) is a viable treatment option for end-stage liver disease. Significant perioperative stress is placed on the cardiovascular system because of hemodynamic changes and the length of the operation. Diagnosis and treatment of cardiovascular disease before OLT are imperative to ensure favorable outcomes. Considerable variability exists among practitioners caring for these patients. Institutions tailor their protocols on the basis of local and historical practices, the preferences of the cardiologists, and the OLT team, and algorithms are not often revised or updated on the basis of the available evidence. In collaboration with cardiology and hepatology experts from leading OLT centers, we sought to examine the diagnostic cardiovascular workup of OLT candidates, including a review of the available literature on the diagnostic modalities used to screen cardiovascular disease before OLT. We advocate an emphasis on noninvasive methods to assess cardiovascular risk with reserved use of invasive risk stratification in select patients.

MiR-20a-5p alleviates kidney ischemia/reperfusion injury by targeting ACSL4-dependent ferroptosis

Ischemia/reperfusion injury (IRI) is prone to occur after kidney transplantation, leading to delayed graft function (DGF). MicroRNAs play a crucial role in the pathogenesis of ischemia/reperfusion-induced acute kidney injury, and miR-20a-5p was found to be the most significantly upregulated gene in a DGF patient cohort. However, the roles of microRNAs in transplanted kidneys remain largely unknown. In this study, we found that miR-20a-5p was upregulated in the kidneys of acute kidney injury mice and in patients with DGF. We identified early growth response-1 as a critical upstream target and verified the binding of early growth response-1 to a predicted sequence in the promoter region of the miR-20a-5p gene. Functionally, the miR-20a-5p mimic attenuated IRI and postischemic renal fibrosis, whereas the miR-20a-5p inhibitor delivery aggravated IRI and fibrosis. Importantly, delivery of the miR-20a-5p mimic or inhibitor in the donor kidneys attenuated or aggravated renal loss and structural damage in cold storage transplantation injury. Furthermore, our study identified miR-20a-5p as a negative regulator of acyl-CoA synthetase long-chain family member 4 (ACSL4) by targeting the 3' untranslated region of ACSL4 mRNA, thereby inhibiting ACSL4-dependent ferroptosis. Our results suggest a potential therapeutic application of miR-20a-5p in kidney transplantation through the inhibition of ACSL4-dependent ferroptosis.

Application of polymerized porcine hemoglobin in the ex vivo normothermic machine perfusion of rat livers

Background: In contrast to traditional static cold preservation of donor livers, normothermic machine perfusion (NMP) may reduce preservation injury, improve graft viability and potentially allows ex vivo assessment of graft viability before transplantation. The polymerized porcine hemoglobin is a kind of hemoglobin oxygen carrier prepared by crosslinking porcine hemoglobin by glutaraldehyde to form a polymer. The pPolyHb has been proved to have the ability of transporting oxygen which could repair the organ ischemia-reperfusion injury in rats. Objective: In order to evaluate the effectiveness of rat liver perfusion in vitro based on pPolyHb, we established the NMP system, optimized the perfusate basic formula and explored the optimal proportion of pPolyHb and basal perfusate. Methods: The liver was removed and perfused for 6 h at 37°C. We compared the efficacy of liver perfusion with different ratios of pPolyHb. Subsequently, compared the perfusion effect using Krebs Henseleit solution and pPolyHb perfusate of the optimal proportion, and compared with the liver preserved with UW solution. At 0 h, 1 h, 3 h and 6 h after perfusion, appropriate samples were collected for blood gas analysis and liver injury indexes detection. Some tissue samples were collected for H&E staining and TUNEL staining to observe the morphology and detect the apoptosis rate of liver cells. And we used Western Blot test to detect the expression of Bcl-2 and Bax in the tissues. Results: According to the final results, the optimal addition ratio of pPolyHb was 24%. By comparing the values of Bcl-2/Bax, the apoptosis rate of pPolyHb group was significantly reduced. Under this ratio, the results of H&E staining and TUNEL staining showed that the liver morphology was well preserved without additional signs of hepatocyte ischemia, biliary tract injury, or hepatic sinusoid injury, and hepatocyte apoptosis was relatively mild. Conclusion: Through the above-mentioned study we show that within 6 h of perfusion based on pPolyHb, liver physiological and biochemical activities may essentially be maintained in vitro. This study demonstrates that a pPolyHb-based perfusate is feasible for NMP of rat livers. This opens up a prospect for further research on NMP.

Diabetes-free survival among living kidney donors and non-donors with obesity: A longitudinal cohort study

BACKGROUND

Approval of living kidney donors (LKD) with end-stage kidney disease (ESKD) risk factors, such as obesity, has increased. While lifetime ESKD development data are lacking, the study of intermediate outcomes such as diabetes is critical for LKD safety. Donation-attributable diabetes risk among persons with obesity remains unknown. The purpose of this study was to evaluate 10-year diabetes-free survival among LKDs and non-donors with obesity.

METHODS

This longitudinal cohort study identified adult, LKDs (1976-2020) from 42 US transplant centers and non-donors from the Coronary Artery Risk Development in Young Adults (1985-1986) and the Atherosclerosis Risk in Communities (1987-1989) studies with body mass index ≥30 kg/m2. LKDs were matched to non-donors on baseline characteristics (age, sex, race, body mass index, systolic and diastolic blood pressure) plus diabetes-specific risk factors (family history of diabetes, impaired fasting glucose, smoking history). Accelerated failure time models were utilized to evaluate 10-year diabetes-free survival.

FINDINGS

Among 3464 participants, 1119 (32%) were LKDs and 2345 (68%) were non-donors. After matching on baseline characteristics plus diabetes-specific risk factors, 4% (7/165) LKDs and 9% (15/165) non-donors developed diabetes (median follow-up time 8.5 (IQR: 5.6-10.0) and 9.1 (IQR: 5.9-10.0) years, respectively). While not significant, LKDs were estimated to live diabetes-free 2 times longer than non-donors (estimate 1.91; 95% CI: 0.79-4.64, p = 0.15).

CONCLUSIONS

LKDs with obesity trended toward living longer diabetes-free than non-donors with obesity, suggesting within the decade following donation there was no increased diabetes risk among LKDs. Further work is needed to evaluate donation-attributable diabetes risk long-term.

2021 Clinical Update in Liver Transplantation

In 2021, the United States performed 9,236 liver transplantations, an increase of 3.7% from 2020. As the specialty of transplant anesthesiologist continues to grow, so does the body of evidence-based research to improve patient care. New technology in organ preservation offers the possibility of preserving marginal organs for transplant or improving the graft for transplantation. The sequalae of end-stage liver disease have wide-ranging consequences that affect neurologic outcomes of patients both during and after transplantation that anesthesiologists should monitor. Obesity presents several challenges for anesthesiologists. As an increasing number of patients with nonalcoholic steatohepatitis are listed for transplant, managing their multiple comorbidities can be challenging. Finally, the rebalanced hemostasis of end-stage liver disease can cause both bleeding and thrombus. Often, bleeding risks predominate as a concern, but anesthesiologists should be aware of risks of intracardiac thrombus and review therapeutic options for prevention and treatment.

Preserving and rejuvenating old organs for transplantation: novel treatments including the potential of senolytics

PURPOSE OF REVIEW

Older donors have the potential to close the gap between demand and supply in solid organs transplantation. Utilizing older organs, at the same time, has been associated with worse short- and long-term outcomes. Here, we introduce potential mechanisms on how treatments during machine perfusion (MP) may safely improve the utilization of older organs.

RECENT FINDINGS

Consequences of ischemia reperfusion injury (IRI), a process of acute, sterile inflammation leading to organ injury are more prominent in older organs. Of relevance, organ age and IRI seem to act synergistically, leading to an increase of damage associated molecular patterns that trigger innate and adaptive immune responses. While cold storage has traditionally been considered the standard of care in organ preservation, accumulating data support that both hypothermic and normothermic MP improve organ quality, particularly in older organs. Furthermore, MP provides the opportunity to assess the quality of organs while adding therapeutic agents. Experimental data have already demonstrated the potential of applying treatments during MP. New experimental show that the depletion of senescent cells that accumulate in old organs improves organ quality and transplant outcomes.

SUMMARY

As the importance of expanding the donor pool is increasing, MP and novel treatments bear the potential to assess and regenerate older organs, narrowing the gap between demand and supply.

Recommendations for Evaluation and Selection of Deceased Organ Donor: Position Statement of ISCCM

There is a wide gap between patients who need transplants and the organs that are available in India. Extending the standard donation criterion is certainly important to address the scarcity of organs for transplantation. Intensivists play a major role in the success of deceased donor organ transplants. Recommendations for deceased donor organ evaluation are not discussed in most intensive care guidelines. The purpose of this position statement is to establish current evidence-based recommendations for multiprofessional critical care staff in the evaluation, assessment, and selection of potential organ donors. These recommendations will give "real-world" criteria that are acceptable in the Indian context. The aim of this set of recommendations is to both increase the number and enhance the quality of transplantable organs.

How to cite this article

Zirpe KG, Tiwari AM, Pandit RA, Govil D, Mishra RC, Samavedam S, et al. Recommendations for Evaluation and Selection of Deceased Organ Donor: Position Statement of ISCCM. Indian J Crit Care Med 2022;26(S2):S43-S50.

Donor characteristics and their impact on kidney transplantation outcomes: Results from two nationwide instrumental variable analyses based on outcomes of donor kidney pairs accepted for transplantation

BACKGROUND

Donor-characteristics and donor characteristics-based decision algorithms are being progressively used in the decision process whether or not to accept an available donor kidney graft for transplantation. While this may improve outcomes, the performance characteristics of the algorithms remains moderate. To estimate the impact of donor factors of grafts accepted for transplantation on transplant outcomes, and to test whether implementation of donor-characteristics-based algorithms in clinical decision-making is justified, we applied an instrumental variable analysis to outcomes for kidney donor pairs transplanted in different individuals.

METHODS

This analysis used (dis)congruent outcomes of kidney donor pairs as an instrument and was based on national transplantation registry data for all donor kidney pairs transplanted in separate individuals in the Netherlands (1990-2018, 2,845 donor pairs), and the United Kingdom (UK, 2000-2018, 11,450 pairs). Incident early graft loss (EGL) was used as the primary discriminatory factor. It was reasoned that a scenario with a dominant impact of donor variables on transplantation outcomes would result in high concordance of EGL in both recipients, whilst dominance of asymmetrical outcomes could indicate a more complex scenario, involving an interaction of donor, procedural and recipient factors.

FINDINGS

Incidences of congruent EGL (Netherlands: 1·2%, UK: 0·7%) were slightly lower than the arithmetical (stochastic) incidences, suggesting that once a graft has been accepted for transplantation, donor factors minimally contribute to incident EGL. A long-term impact of donor factors was explored by comparing outcomes for functional grafts from donor pairs with asymmetrical vs. symmetrical outcomes. Recipient survival was similar for both groups, but a slightly compromised graft survival was observed for grafts with asymmetrical outcomes in the UK cohort: (10-years Hazard Ratio for graft loss: 1·18 [1·03-1·35] p<0·018); and 5 years eGFR (48·6 [48·3-49·0] vs. 46·0 [44·5-47·6] ml/min in the symmetrical outcome group, p<0·001).

INTERPRETATION

Our results suggest that donor factors for kidney grafts deemed acceptable for transplantation impact minimally on transplantation outcomes. A strong reliance on donor factors and/or donor-characteristics-based decision algorithms could result in unjustified rejection of grafts. Future efforts to optimize transplant outcomes should focus on a better understanding of the recipient factors underlying transplant outcomes.

FUNDING

None.

Cellular senescence and senolytics: the path to the clinic

Interlinked and fundamental aging processes appear to be a root-cause contributor to many disorders and diseases. One such process is cellular senescence, which entails a state of cell cycle arrest in response to damaging stimuli. Senescent cells can arise throughout the lifespan and, if persistent, can have deleterious effects on tissue function due to the many proteins they secrete. In preclinical models, interventions targeting those senescent cells that are persistent and cause tissue damage have been shown to delay, prevent or alleviate multiple disorders. In line with this, the discovery of small-molecule senolytic drugs that selectively clear senescent cells has led to promising strategies for preventing or treating multiple diseases and age-related conditions in humans. In this Review, we outline the rationale for senescent cells as a therapeutic target for disorders across the lifespan and discuss the most promising strategies-including recent and ongoing clinical trials-for translating small-molecule senolytics and other senescence-targeting interventions into clinical use.

The Kidney Donor Profile Index (KDPI) Correlates With Histopathologic Findings in Post-reperfusion Baseline Biopsies and Predicts Kidney Transplant Outcome

Background

The increasing organ shortage in kidney transplantation leads to the necessity to use kidneys previously considered unsuitable for transplantation. Numerous studies illustrate the need for a better decision guidance rather than only the classification into kidneys from standard or expanded criteria donors referred to as SCD/ECD-classification. The kidney donor profile index (KDPI) exhibits a score utilizing a much higher number of donor characteristics. Moreover, graft biopsies provide an opportunity to assess organ quality.

Methods

In a single center analysis 383 kidney transplantations (277 after deceased and 106 after living donation) performed between January 1st, 2006, and December 31st, 2016, retrospectively underwent SCD/ECD and KDPI scoring. Thereby, the quality of deceased donor kidneys was assessed by using the KDPI and the living donor kidneys by using the living KDPI, in the further analysis merged as (L)KDPI. Baseline biopsies taken 10 min after the onset of reperfusion were reviewed for chronic and acute lesions. Survival analyses were performed using Kaplan-Meier analysis and Cox proportional hazards analysis within a 5-year follow-up.

Results

The (L)KDPI correlated with glomerulosclerosis (r = 0.30, p < 0.001), arteriosclerosis (r = 0.33, p < 0.001), interstitial fibrosis, and tubular atrophy (r = 0.28, p < 0.001) as well as the extent of acute tubular injury (r = 0.20, p < 0.001). The C-statistic of the (L)KDPI concerning 5-year death censored graft survival was 0.692. Around 48% of ECD-kidneys were classified as (L)KDPI<85%. In a multivariate Cox proportional hazard analysis including (preformed) panel reactive antibodies, cold ischemia time, (L)KDPI, and SCD/ECD-classification, the (L)KDPI was significantly associated with risk of graft loss (hazard ratio per 10% increase in (L)KDPI: 1.185, 95% confidence interval: 1.033–1.360, p = 0.025). Survival analysis revealed decreased death censored (p < 0.001) and non-death censored (p < 0.001) graft survival in kidneys with an increasing (L)KDPI divided into groups of <35, 35–85, and >85%, respectively.

Conclusion

With a higher granularity compared to the SCD/ECD-classification the (L)KDPI is a promising tool to judge graft quality. The correlation with chronic and acute histological lesions in post-reperfusion kidney biopsies underlines the descriptive value of the (L)KDPI. However, its prognostic value is limited and underlines the urgent need for a more precise prognostic tool adopted to European kidney transplant conditions.

Epigenetic Regulation in Kidney Transplantation

Kidney transplantation is a standard care for end stage renal disease, but it is also associated with a complex pathogenesis including ischemia-reperfusion injury, inflammation, and development of fibrosis. Over the past decade, accumulating evidence has suggested a role of epigenetic regulation in kidney transplantation, involving DNA methylation, histone modification, and various kinds of non-coding RNAs. Here, we analyze these recent studies supporting the role of epigenetic regulation in different pathological processes of kidney transplantation, i.e., ischemia-reperfusion injury, acute rejection, and chronic graft pathologies including renal interstitial fibrosis. Further investigation of epigenetic alterations, their pathological roles and underlying mechanisms in kidney transplantation may lead to new strategies for the discovery of novel diagnostic biomarkers and therapeutic interventions.

Can adequate hemodynamic management of brain-dead donors improve donor organ procurement?

There is increasing evidence that adequate donor management with a goal of optimization of organ function is essential to maximize the number of organs that can be procured. Therefore, identification of the cause of hemodynamic instability is crucial in order to direct the right therapy. Several donor management goals for better hemodynamic management including serial echocardiography can guide hemodynamic management in potential donors to increase both number and quality of donor hearts.

Renal Normothermic Machine Perfusion: The Road Toward Clinical Implementation of a Promising Pretransplant Organ Assessment Tool

The increased utilization of high-risk renal grafts for transplantation requires optimization of pretransplant organ assessment strategies. Current decision-making methods to accept an organ for transplantation lack overall predictive power and always contain an element of subjectivity. Normothermic machine perfusion (NMP) creates near-physiological conditions, which might facilitate a more objective assessment of organ quality before transplantation. NMP is rapidly gaining popularity, with various transplant centers developing their own NMP protocols and renal viability criteria. However, to date, no validated sets of on-pump viability markers exist nor are there unified NMP protocols. This review provides a critical overview of the fundamentals of current renal NMP protocols and proposes a framework to approach further development of ex vivo organ evaluation. We also comment on the potential logistical implications of routine clinical use of NMP, which is a more complex procedure compared with static cold storage or even hypothermic machine perfusion.

Inhibition of HDAC3 protects against kidney cold storage/transplantation injury and allograft dysfunction

Cold storage/rewarming is an inevitable process for kidney transplantation from deceased donors, which correlates closely with renal ischemia-reperfusion injury (IRI) and the occurrence of delayed graft function. Histone deacetylases (HDAC) are important epigenetic regulators, but their involvement in cold storage/rewarming injury in kidney transplantation is unclear. In the present study, we showed a dynamic change of HDAC3 in a mouse model of kidney cold storage followed by transplantation. We then demonstrated that the selective HDAC3 inhibitor RGFP966 could reduce acute tubular injury and cell death after prolonged cold storage with transplantation. RGFP966 also improved renal function, kidney repair and tubular integrity when the transplanted kidney became the sole life-supporting graft in the recipient mouse. In vitro, cold storage of proximal tubular cells followed by rewarming induced remarkable cell death, which was suppressed by RGFP966 or knockdown of HDAC3 with shRNA. Inhibition of HDAC3 decreased the mitochondrial pathway of apoptosis and preserved mitochondrial membrane potential. Collectively, HDAC3 plays a pathogenic role in cold storage/rewarming injury in kidney transplantation, and its inhibition may be a therapeutic option.

The potential of Senolytics in transplantation

Older organs provide a substantial unrealized potential with the capacity to close the gap between demand and supply in organ transplantation. The potential of senolytics in improving age-related conditions has been shown in various experimental studies and early clinical trials. Those encouraging data may also be of relevance for transplantation. As age-differences between donor and recipients are not uncommon, aging may be accelerated in recipients when transplanting older organs; young organs may, at least in theory, have the potential to 'rejuvenate' old recipients. Here, we review the relevance of senescent cells and the effects of senolytics on organ quality, alloimmune responses and outcomes in solid organ transplantation. This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

Endocrine Management and Hormone Replacement Therapy in Cardiac Donor Management: A Retrospective Observational Study

BACKGROUND

Pituitary dysfunction after brainstem death can cause various hormone deficiencies in potential heart donors. The aim of this study was to evaluate the relationship between hormone replacement therapy (HRT; including antidiuretic hormone analog, thyroid hormone, and methylprednisolone) in heart donors and the recipients' outcomes after heart transplantation (HTx).

METHODS

We retrospectively analyzed HTxs performed between January 2012 and October 2018. Donor and recipient characteristics were retrieved with a focus on endocrine parameters and HRT. The primary outcome was primary graft dysfunction (PGD). Secondary outcomes were the 30-day and 2-year mortality of the recipients. Univariate and multivariate Cox regression analyses were applied.

RESULTS

The study included 297 HTxs. PGD occurred in 56 recipients (18.9%). In the multivariable Cox analysis, methylprednisolone and thyroxine treatment in donors were associated with a lower odds for PGD (odds ratio [OR], 0.43; 95% CI, 0.19-1.01; P = .052; and OR,: 0.34; 95% CI, 0.15-0.76; P = .009, respectively). In multivariate analysis, thyroxine treatment in donors was associated with a lower odds of PGD (OR, 0.38; 95% CI, 0.17-0.86; P = .020). Donor thyroxine supplementation also had a beneficial effect on recipients' 2-year survival (OR, 0.53; 95% CI, 0.29-0.96; P = .036).

CONCLUSIONS

Combined thyroxine and methylprednisolone treatment could be a protective factor against PGD. Thyroxine administration was associated with better 2-year survival in recipients.

Chronic Allograft Injury

With the incremental improvements in long-term kidney transplant survival, there is renewed focus on what causes failure of the transplanted allograft. Over the past decade, our understanding of the injuries that lead to loss of graft function over time has evolved. Chronic allograft injury includes both immune-mediated and nonimmune-mediated injuries, which may involve the organ donor, the recipient, or both. The targets of injury include the kidney tubular epithelium, the endothelium, and the glomerulus. As a response to injury, there are the expected tissue remodeling and repair processes. However, if inflammation persists, which is not uncommon in the transplant setting, the resulting maladaptive response is matrix deposition and/or fibrosis. This ultimately leads to declining graft function and, finally, failure. With our advancing knowledge of the multiple etiologies and mechanisms, enhanced by more recent cohort studies in humans, there is an opportunity to identify those at greater risk to initiate new strategies to ameliorate the process. Although the most recent studies focus on immune-mediated injuries, there is a critical need to identify both markers of injury and mechanisms of injury. In this review, we highlight the findings of recent studies, highlight the potential therapeutic targets, and identify the continued unmet need for understanding the mechanisms of late graft failure.

Proximal Tubule p53 in Cold Storage/Transplantation-Associated Kidney Injury and Renal Graft Dysfunction

Kidney injury associated with cold storage/transplantation is a primary factor for delayed graft function and poor outcome of renal transplants. p53 contributes to both ischemic and nephrotoxic kidney injury, but its involvement in kidney cold storage/transplantation is unclear. Here, we report that p53 in kidney proximal tubules plays a critical role in cold storage/transplantation kidney injury and inhibition of p53 can effectively improve the histology and function of transplanted kidneys. In a mouse kidney cold storage/transplantation model, we detected p53 accumulation in proximal tubules in a cold storage time-dependent manner, which correlated with tubular injury and cell death. Pifithrin-α, a pharmacologic p53 inhibitor, could reduce acute tubular injury, apoptosis and inflammation at 24 h after cold storage/transplantation. Similar effects were shown by the ablation of p53 from proximal tubule cells. Notably, pifithrin-α also ameliorated kidney injury and improved the function of transplanted kidneys in 6 days when it became the sole life-supporting kidney in recipient mice. in vitro, cold storage followed by rewarming induced cell death in cultured proximal tubule cells, which was accompanied by p53 activation and suppressed by pifithrin-α and dominant-negative p53. Together, these results support a pathogenic role of p53 in cold storage/transplantation kidney injury and demonstrate the therapeutic potential of p53 inhibitors.

Effluent Molecular Analysis Guides Liver Graft Allocation to Clinical Hypothermic Oxygenated Machine Perfusion

Hypothermic-oxygenated-machine-perfusion (HOPE) allows assessment/reconditioning of livers procured from high-risk donors before transplantation. Graft referral to HOPE mostly depends on surgeons' subjective judgment, as objective criteria are still insufficient. We investigated whether analysis of effluent fluids collected upon organ flush during static-cold-storage can improve selection criteria for HOPE utilization. Effluents were analyzed to determine cytolysis enzymes, metabolites, inflammation-related mediators, and damage-associated-molecular-patterns. Molecular profiles were assessed by unsupervised cluster analysis. Differences between "machine perfusion (MP)-yes" vs. "MP-no"; "brain-death (DBD) vs. donation-after-circulatory-death (DCD)"; "early-allograft-dysfunction (EAD)-yes" vs. "EAD-no" groups, as well as correlation between effluent variables and transplantation outcome, were investigated. Livers assigned to HOPE (n = 18) showed a different molecular profile relative to grafts transplanted without this procedure (n = 21, p = 0.021). Increases in the inflammatory mediators PTX3 (p = 0.048), CXCL8/IL-8 (p = 0.017), TNF-α (p = 0.038), and ANGPTL4 (p = 0.010) were observed, whereas the anti-inflammatory cytokine IL-10 was reduced (p = 0.007). Peculiar inflammation, cell death, and coagulation signatures were observed in fluids collected from DCD livers compared to those from DBD grafts. AST (p = 0.034), ALT (p = 0.047), and LDH (p = 0.047) were higher in the "EAD-yes" compared to the "EAD-no" group. Cytolysis markers and hyaluronan correlated with recipient creatinine, AST, and ICU stay. The study demonstrates that effluent molecular analysis can provide directions about the use of HOPE.

The use of normothermic machine perfusion to rescue liver allografts from expanded criteria donors

The use of expanded criteria donors is one of the strategies used to overcome the gap between the demand for organs and the number of donors. Physicians debate the extent to which marginal grafts can be used. In recent years, normothermic machine perfusion (NMP) has been used to test liver viability before transplantation. Grafts underwent NMP whenever histological steatosis was > 40% or there were at least three Eurotransplant criteria for expanded criteria donor (ECD). We used NMP to test 19 grafts, 3 from donation after type 3 controlled cardiac death (DCD), and 16 from donation after brain death (DBD). Only two grafts from DBD were not transplanted, because perfusion proved they were not suitable (total of 17 transplanted grafts of 19 tested grafts). Kaplan-Meier survival estimates at 30, 90, 180, and 1 year after transplant were all 94% (95% CI 84-100%); estimated 3-years survival was 82% (95% CI 62-100%). Overall survival rates did not differ from those of patients transplanted with non-perfused grafts from an ECD. In our experience, the use of very marginal grafts preventively tested by NMP does not negatively influence the patient's outcome, and increases the number of transplants in low donation areas.

Mitochondrial DNA may act as a biomarker to predict donor-kidney quality

Kidney transplantation is the best therapy for end-stage renal disease. Demand for kidney transplantation rises year-on-year, and the gap between kidney supply and demand remains large. To meet this clinical need, a gradual expansion in the supply of donors is required. However, clinics lack appropriate tools capable of quickly and accurately predicting post-transplant renal allograft function, and thus assess donor-kidney quality before transplantation. Mitochondrial DNA (mtDNA) is a key component of damage-associated molecular patterns (DAMPs) and plays an important part in ischemia-reperfusion injury (IRI), accelerating the progression of IRI by inducing inflammation and type I interferon responses. mtDNA is known to be closely involved in delayed graft function (DGF) and acute kidney injury (AKI) after transplantation. Thus, mtDNA is a potential biomarker able to predict post-transplant renal allograft function. This review summarizes mtDNA biology, the role mtDNA plays in renal transplantation, outlines advances in detecting mtDNA, and details mtDNA's able to predict post-transplant renal allograft function. We aim to elucidate the potential value of mtDNA as a biomarker in the prediction of IRI, and eventually provide help for predicting donor-kidney quality.

Association Between Deceased Donor Acute Kidney Injury Assessed Using Baseline Serum Creatinine Back-Estimation and Graft Survival: Results From the French National CRISTAL Registry

RATIONALE & OBJECTIVE

Deceased donor acute kidney injury (AKI) frequently leads to kidney discards, but its impact on long-term graft survival in kidney transplant recipients remains unclear. We investigated the association between deceased donor AKI assessed using back-estimation of baseline serum creatinine (Scr) and graft survival.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

Adult patients represented within the French CRISTAL registry who received a single kidney allograft from brain-dead deceased donors between January 2006 and December 2017.

EXPOSURE

A back-estimated Scr baseline value was derived for an assumed glomerular filtration rate at 75mL/min/1.73m², using the MDRD Study equation. A refined classification system for donor AKI was implemented as follows: no AKI, undetermined AKI/chronic kidney disease (CKD), recovery from AKI, and ongoing AKI.

OUTCOME

Death-censored graft survival.

ANALYTICAL APPROACH

Multivariable Cox models using a robust variance estimator for paired kidneys from the same donor.

RESULTS

We classified 26,786 recipients as follows: no AKI (n=19,276); undetermined AKI/CKD (n=1,745); recovery from AKI (n=2,392); and ongoing AKI (n=3,373). We observed 4,458 kidney graft losses during a median follow-up period of 5.7 years. Compared with no AKI, ongoing AKI was associated with an increased risk of graft failure (hazard ratio [HR], 1.24 [95% CI, 1.13-1.35]). The HRs for graft failure in the undetermined AKI/CKD and recovery from AKI groups (1.22 [95% CI, 1.07-1.38] and 1.18 [95% CI, 1.06-1.31], respectively) were similar to those observed in the ongoing AKI group. The adverse effect of deceased donor AKI was no longer evident when relying either on the admission or the lowest Scr throughout the procurement procedure as baseline Scr.

LIMITATIONS

No measurement of urine output in donors.

CONCLUSIONS

Deceased donor ongoing AKI, undetermined AKI/CKD, and recovery from AKI according to back-estimated baseline Scr are associated with decreased graft survival. The definition of baseline Scr as the first value measured on admission would have led to a misclassification bias and erroneous estimates.

Fresh and cryopreserved ovarian tissue from deceased young donors yields viable follicles

OBJECTIVE

Ovarian tissue cryopreservation is one of the crucial options for fertility preservation. Transplantation of cryopreserved ovarian tissue was proven to restore ovarian endocrine function in patients with premature ovarian insufficiency. Ovaries from deceased donors potentially serve as an excellent and readily available tissue for the translational and basic research. In this study, we used ovaries obtained from 5 deceased donors aged 18-26 years, to evaluate the number and quality of ovarian follicles isolated before and after cryopreservation.

DESIGN

Preclinical.

SETTING

Academic biomedical research laboratory.

PATIENTS

De-identified deceased human donors.

INTERVENTIONS

Slow-freeze cryopreservation and thawing.

MAIN OUTCOME MEASURES

Follicle count, follicle density, follicle viability using immunohistochemical staining (TUNEL).

RESULTS

The follicle density negatively correlated with age in both cryopreserved/thawed and fresh group. A total of 2803 follicles from fresh and 1608 follicles from cryopreserved tissues were classified and analyzed using Hematoxylin and eosin staining. There was no significant difference in the percent of morphologically normal follicles between two groups. TUNEL assay indicated no higher DNA damage in the follicles and the stroma cells after cryopreservation. Morphologically normal preantral follicles were enzymatically isolated from both fresh and cryopreserved tissue with 88.51 ± 5.93% (mean ± SD) of the isolated follicles confirmed viable using LIVE/DEAD evaluation.

CONCLUSIONS

Our results indicate the ovarian tissue from deceased donors maintain high quality after long time extracorporeal circulation and transportation from the hospital to the laboratory. High survival rate of follicles at different developmental stages suggested tolerance to the cryopreservation process. Human ovarian tissues obtained from deceased donors is an ample source tissue and can be applied to promoting research and future clinical applications.

Whole Blood Thiamine in Organ Donors After the Neurologic Determination of Death

INTRODUCTION

Metabolic resuscitation of organ donors and the attenuation of oxidative stress incurred by organs following brain death and transplantation have the potential to improve organ yield and allograft function. Thiamine (vitamin B1) is a vital coenzyme in both energy metabolism and the production of antioxidants that has not been studied in the donor population.

RESEARCH AIM

To determine the frequency of subclinical thiamine deficiency in brain-dead organ donors and its correlation with demographics, length of hospitalization, donor management, lactic acidosis, and the requirement for vasoactive support.

DESIGN

Prospective cohort study of brain-dead donors managed at a single organ procurement organization's organ recovery facility.

RESULTS

A total 64 donors were enrolled; 24 donors had thiamine levels drawn upon arrival and 40 donors had levels drawn at the time of organ procurement. Whole blood thiamine levels were inversely correlated with the time from death (P = .007) and 20% (8/40) of donors had levels below the normal range at the time of organ procurement. Demographic features of the donor were not associated with thiamine levels although longer hospital stays prior to death were associated with lower levels (P < .05). The presence and resolution of lactic acidosis was not associated with whole blood thiamine level. Higher thiamine levels were associated with earlier discontinuation of vasoactive support (P = .04).

DISCUSSION

Whole blood thiamine deficiency was not uncommon at the time of organ procurement. Thiamine may be associated with the requirement for hemodynamic support.

Impaired renal function before kidney procurement has a deleterious impact on allograft survival in very old deceased kidney donors

As the use of elderly kidney donors for transplantation is increasing with time, there is a need to understand which factors impact on their prognosis. No data exist on the impact of an impaired renal function (IRF) in such population. 116 kidney recipients from deceased kidney donors over 70 years were included from 2005 to 2015 in a single-center retrospective study. IRF before organ procurement was defined as a serum creatinine above 1.0 mg/dl or a transient episode of oligo-anuria. Mean ages for donors and recipients were respectively 74.8 ± 3.5 and 66.7 ± 8.0. Graft survival censored for death at 5 years was of 77%. Using a multivariate analysis by Cox model, the only predictor of graft loss present in the donor was IRF before organ procurement (HR 4.2 CI95[1.8–9.7]). IRF was also associated with significant lower estimated glomerular filtration rates up to 1 year post-transplantation. By contrast, KDPI score (median of 98 [96–100]), was not associated with the risk of graft failure. Then, IRF before kidney procurement may define a risk subgroup among very-old deceased kidney donors, in whom pre-implantatory biopsies, dual kidney transplantation or calcineurin inhibitor-free immunosuppressive regimen could help to improve outcomes.

Hypothermic Machine Perfusion in Liver Transplantation - A Randomized Trial

BACKGROUND

Transplantation of livers obtained from donors after circulatory death is associated with an increased risk of nonanastomotic biliary strictures. Hypothermic oxygenated machine perfusion of livers may reduce the incidence of biliary complications, but data from prospective, controlled studies are limited.

METHODS

In this multicenter, controlled trial, we randomly assigned patients who were undergoing transplantation of a liver obtained from a donor after circulatory death to receive that liver either after hypothermic oxygenated machine perfusion (machine-perfusion group) or after conventional static cold storage alone (control group). The primary end point was the incidence of nonanastomotic biliary strictures within 6 months after transplantation. Secondary end points included other graft-related and general complications.

RESULTS

A total of 160 patients were enrolled, of whom 78 received a machine-perfused liver and 78 received a liver after static cold storage only (4 patients did not receive a liver in this trial). Nonanastomotic biliary strictures occurred in 6% of the patients in the machine-perfusion group and in 18% of those in the control group (risk ratio, 0.36; 95% confidence interval [CI], 0.14 to 0.94; P = 0.03). Postreperfusion syndrome occurred in 12% of the recipients of a machine-perfused liver and in 27% of those in the control group (risk ratio, 0.43; 95% CI, 0.20 to 0.91). Early allograft dysfunction occurred in 26% of the machine-perfused livers, as compared with 40% of control livers (risk ratio, 0.61; 95% CI, 0.39 to 0.96). The cumulative number of treatments for nonanastomotic biliary strictures was lower by a factor of almost 4 after machine perfusion, as compared with control. The incidence of adverse events was similar in the two groups.

CONCLUSIONS

Hypothermic oxygenated machine perfusion led to a lower risk of nonanastomotic biliary strictures following the transplantation of livers obtained from donors after circulatory death than conventional static cold storage. (Funded by Fonds NutsOhra; DHOPE-DCD ClinicalTrials.gov number, NCT02584283.).

Development and Validation of a Deep Learning Model to Quantify Glomerulosclerosis in Kidney Biopsy Specimens

IMPORTANCE

A chronic shortage of donor kidneys is compounded by a high discard rate, and this rate is directly associated with biopsy specimen evaluation, which shows poor reproducibility among pathologists. A deep learning algorithm for measuring percent global glomerulosclerosis (an important predictor of outcome) on images of kidney biopsy specimens could enable pathologists to more reproducibly and accurately quantify percent global glomerulosclerosis, potentially saving organs that would have been discarded.

OBJECTIVE

To compare the performances of pathologists with a deep learning model on quantification of percent global glomerulosclerosis in whole-slide images of donor kidney biopsy specimens, and to determine the potential benefit of a deep learning model on organ discard rates.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study used whole-slide images acquired from 98 hematoxylin-eosin-stained frozen and 51 permanent donor biopsy specimen sections retrieved from 83 kidneys. Serial annotation by 3 board-certified pathologists served as ground truth for model training and for evaluation. Images of kidney biopsy specimens were obtained from the Washington University database (retrieved between June 2015 and June 2017). Cases were selected randomly from a database of more than 1000 cases to include biopsy specimens representing an equitable distribution within 0% to 5%, 6% to 10%, 11% to 15%, 16% to 20%, and more than 20% global glomerulosclerosis.

MAIN OUTCOMES AND MEASURES

Correlation coefficient (r) and root-mean-square error (RMSE) with respect to annotations were computed for cross-validated model predictions and on-call pathologists' estimates of percent global glomerulosclerosis when using individual and pooled slide results. Data were analyzed from March 2018 to August 2020.

RESULTS

The cross-validated model results of section images retrieved from 83 donor kidneys showed higher correlation with annotations (r = 0.916; 95% CI, 0.886-0.939) than on-call pathologists (r = 0.884; 95% CI, 0.825-0.923) that was enhanced when pooling glomeruli counts from multiple levels (r = 0.933; 95% CI, 0.898-0.956). Model prediction error for single levels (RMSE, 5.631; 95% CI, 4.735-6.517) was 14% lower than on-call pathologists (RMSE, 6.523; 95% CI, 5.191-7.783), improving to 22% with multiple levels (RMSE, 5.094; 95% CI, 3.972-6.301). The model decreased the likelihood of unnecessary organ discard by 37% compared with pathologists.

CONCLUSIONS AND RELEVANCE

The findings of this prognostic study suggest that this deep learning model provided a scalable and robust method to quantify percent global glomerulosclerosis in whole-slide images of donor kidneys. The model performance improved by analyzing multiple levels of a section, surpassing the capacity of pathologists in the time-sensitive setting of examining donor biopsy specimens. The results indicate the potential of a deep learning model to prevent erroneous donor organ discard.

Self-advocacy is associated with lower likelihood of living donor kidney transplantation

BACKGROUND

The Living Donor Navigator (LDN) Program pairs kidney transplant candidates (TC) with a friend or family member for advocacy training to help identify donors and achieve living donor kidney transplantation (LDKT). However, some TCs participate alone as self-advocates.

METHODS

In this retrospective cohort study of TCs in the LDN program (04/2017-06/2019), we evaluated the likelihood of LDKT using Cox proportional hazards regression and rate of donor screenings using ordered events conditional models by advocate type.

RESULTS

Self-advocates (25/127) had lower likelihood of LDKT compared to patients with an advocate (adjusted hazard ratio (aHR): 0.22, 95% confidence interval (CI): 0.03-1.66, p = 0.14). After LDN enrollment, rate of donor screenings increased 2.5-fold for self-advocates (aHR: 2.48, 95%CI: 1.26-4.90, p = 0.009) and 3.4-fold for TCs with an advocate (aHR: 3.39, 95%CI: 2.20-5.24, p < 0.0001).

CONCLUSIONS

Advocacy training was beneficial for self-advocates, but having an independent advocate may increase the likelihood of LDKT.

Early Graft Loss after Deceased-Donor Kidney Transplantation: What Are the Consequences?

BACKGROUND

Decreasing kidney discards continues to be of paramount importance for improving organ transplant access, but transplantation of nonideal deceased donor kidneys may have higher inherent risks of early graft loss (EGL). Patients with EGL (defined as graft failure within 90 days after transplant) are allowed reinstatement of waiting time according to United Network for Organ Sharing (UNOS) policy. The purpose of this study was to examine outcomes for patients experiencing EGL.

STUDY DESIGN

We performed a single center retrospective review of adult deceased donor kidney transplant (DDKT)-alone recipients from 2001 to 2018, comparing those with EGL (including primary nonfunction [PNF]) to those without.

RESULTS

EGL occurred in 103 (5.5%) of 1,868 patients, including 57 (55%) PNF, 25 (24%) deaths, 16 (16%) thrombosis, 3 (3%) rejection, and 2 (2%) disease recurrence. Kidney Donor Profile Index (KDPI) > 85% and donation after circulatory death (DCD) DDKTs did not increase risk of either EGL or PNF unless combined with prolonged cold ischemic time (CIT). For KDPI >85% with CIT >24 hours, the risk of EGL or PNF was tripled (EGL odds ratio [OR] 2.9, 95% CI 1.6-5.2; PNF OR3.6, 95% CI1.7-7.7). For DCD with CIT > 24 hours, increased risks were likewise seen for EGL (OR 2.4, 95% CI 1.3-4.3), and PNF (OR 3.2, 95% CI 1.5-7). One-year and 5-year patient survival rates were 60% and 50% after EGL, 80% and 73% after PNF, and 99% and 87% for controls, respectively. Only 24% of either EGL or PNF patients underwent retransplantation.

CONCLUSIONS

EGL and PNF were associated with low retransplantation rates and inferior patient survival. Prolonged CIT compounds risks associated with KDPI > 85% and DCD donor kidneys. Therefore, policies promoting rapid allocation and increased local use of these kidneys should be considered.

Development and external validation study combining existing models and recent data into an up-to-date prediction model for evaluating kidneys from older deceased donors for transplantation

With a rising demand for kidney transplantation, reliable pre-transplant assessment of organ quality becomes top priority. In clinical practice, physicians are regularly in doubt whether suboptimal kidney offers from older donors should be accepted. Here, we externally validate existing prediction models in a European population of older deceased donors, and subsequently developed and externally validated an adverse outcome prediction tool. Recipients of kidney grafts from deceased donors 50 years of age and older were included from the Netherlands Organ Transplant Registry (NOTR) and United States organ transplant registry from 2006-2018. The predicted adverse outcome was a composite of graft failure, death or chronic kidney disease stage 4 plus within one year after transplantation, modelled using logistic regression. Discrimination and calibration were assessed in internal, temporal and external validation. Seven existing models were validated with the same cohorts. The NOTR development cohort contained 2510 patients and 823 events. The temporal validation within NOTR had 837 patients and the external validation used 31987 patients in the United States organ transplant registry. Discrimination of our full adverse outcome model was moderate in external validation (C-statistic 0.63), though somewhat better than discrimination of the seven existing prediction models (average C-statistic 0.57). The model's calibration was highly accurate. Thus, since existing adverse outcome kidney graft survival models performed poorly in a population of older deceased donors, novel models were developed and externally validated, with maximum achievable performance in a population of older deceased kidney donors. These models could assist transplant clinicians in deciding whether to accept a kidney from an older donor.