DCD donor hemodynamics as predictor of outcome after kidney transplantation

Association of agonal phase duration with heart utilization and post-transplant outcomes in donation after circulatory death heart transplantation

BACKGROUND

This study evaluates the impact of the agonal phase and related hemodynamic measures on post-transplant outcomes and heart utilization in donation after circulatory death (DCD) heart transplantation.

METHODS

United Network for Organ Sharing registry was queried to analyze adult recipients who underwent isolated DCD heart transplantation between January 1, 2019 and September 30, 2023. The recipients were stratified into 2 groups based on donor agonal period: <30 and ≥30 minutes. The primary outcome was 90-day post-transplant survival. Propensity score-matching was performed. Sub-analysis was performed to evaluate the association of agonal period with donor heart utilization. Additionally, the associations between different hemodynamic thresholds used to indicate onset of warm ischemia during the agonal phase with 90-day mortality were compared.

RESULTS

Eight hundred and eighty nine recipients were included, with 179 (20.1%) receiving hearts from donors with an agonal period of ≥30 minutes. Ninety-day survival (88.1% vs. 95.6%, p < 0.001) was significantly lower among the recipients of donors with an agonal period of ≥30 minutes. The lower 90-day survival persisted in a propensity score-matched comparison. Furthermore, longer agonal periods were associated with reduced donor heart utilization. Lastly, a time interval from a systolic blood pressure of 80 ± 5mmHg to death exhibited significantly higher association with 90-day mortality than a time interval from a systemic oxygen saturation 80 ± 5% to death.

CONCLUSIONS

Utilizing DCD donor hearts with agonal periods ≥30 minutes is associated with reduced post-transplant survival and decreased donor heart utilization. When assessing the onset of warm ischemia during the agonal phase, hypotension may serve as a more accurate indicator of myocardial ischemia and provide improved post-transplant prognostic insight than hypoxia.

Clinical and Histologic Risk Factors for the Development of Early Allograft Dysfunction in Donation After Circulatory Death Kidney Transplantation

Transplantation of kidneys from donors after circulatory death (DCD) may help address the severe shortage of donor organs. However, they remain underutilized due to concerns for increased rates of delayed graft function (DGF) and primary nonfunction (PNF), despite similar long-term patient and allograft outcomes compared to kidneys from donors after brain death (DBD). Kidneys that recover from DGF have good long-term outcomes compared to those resulting in PNF. Considering immediate graft function (IGF), DGF, and PNF as a spectrum of renal allograft injury and recovery, we analyzed donor and recipient characteristics and corresponding time-zero biopsy findings for adult DCD kidney transplants at our center from 2016 to 2021. We compared transplants resulting in DGF with subsequent allograft recovery compared to those progressing to PNF as well as to grafts that functioned immediately. We found 344 patients received DCD kidneys with 153 resulting in DGF with renal recovery by 90-days post-transplant. Excluding surgical complications, 22 patients developed PNF and required ongoing maintenance dialysis after 90-days post-transplant and 169 patients had immediate graft function. Kidney Donor Profile Index ≥85% and donor history of diabetes and hypertension were associated with PNF. Cold and warm ischemia time, donor acute kidney injury, and use of hypothermic machine perfusion were not significantly different between the groups. Formalin-fixed paraffin embedded renal allograft time-zero biopsies demonstrated that increasing severity of donor-derived vascular disease present at the time of transplant were associated with the development of early allograft failure. These findings help define clinical characteristics important in kidney allograft selection.

Normothermic Machine Perfusion and Normothermic Regional Perfusion of DCD Kidneys Before Transplantation: A Systematic Review

BACKGROUND

To overcome organ shortages, donation after circulatory death (DCD) kidneys are being increasingly used for transplantation. Prior research suggests that DCD kidneys have inferior outcomes compared with kidneys donated after brain death. Normothermic machine perfusion (NMP) and normothermic regional perfusion (NRP) may enhance the preservation of DCD kidneys and improve transplant outcomes. This study aimed to review the evidence surrounding NMP and NRP in DCD kidney transplantation.

METHODS

Two independent reviewers conducted searches for all publications reporting outcomes for NMP and NRP-controlled DCD kidneys, focusing on delayed graft function, primary nonfunction, graft function, graft survival, and graft utilization. Weighted means were calculated for all relevant outcomes and controls. Formal meta-analyses could not be conducted because of significant heterogeneity.

RESULTS

Twenty studies were included for review (6 NMP studies and 14 NRP studies). Delayed graft function rates seemed to be lower for NRP kidneys (24.6%) compared with NMP kidneys (54.3%). Both modalities yielded similar outcomes with respect to primary nonfunction (NMP 3.3% and NRP 5.6%), graft function (12-mo creatinine 149.3 μmol/L for NMP and 129.9 μmol/L for NRP), and graft utilization (NMP 83.3% and NRP 89%). Although no direct comparisons exist, our evidence suggests that both modalities have good short- and medium-term graft outcomes and high graft survival rates.

CONCLUSIONS

Current literature demonstrates that both NMP and NRP are feasible strategies that may increase donor organ utilization while maintaining acceptable transplant outcomes and likely improved outcomes compared with cold-stored DCD kidneys. Further research is needed to directly compare NRP and NMP outcomes.

Neuroimaging Augments DCD-N Score in Predicting Time from Withdrawal of Life-Sustaining Measures to Death Among Potential Organ Donors

BACKGROUND

Controlled donation after circulatory determination of death (DCD) is feasible only if circulatory arrest occurs soon after withdrawal of life-sustaining measures (WLSM). When organ recovery cannot proceed because this time interval is too long, there are potential negative implications, including perceptions of "secondary loss" for patients' families and significant resource consumption. The DCD-N score is a validated clinical tool for predicting rapid death following WLSM. We hypothesized that neuroimaging evidence of effaced perimesencephalic cisterns improves prediction of time to death compared with the DCD-N score alone.

METHODS

In a retrospective population-based cohort study, DCD-N scores were prospectively determined in patients for whom consent for DCD had been obtained. Perimesencephalic cisterns on last available neuroimaging were assessed in duplicate and classified as normal, partially effaced, or completely effaced. Multivariable logistic regression assessed the capacity of DCD-N score and effaced cisterns to predict death within 1, 2, or 3 h of WLSM.

RESULTS

Of 164 consecutive patients, 49 (30%) progressed to death by neurologic criteria and were excluded. Of the remaining 115 patients, 81 (70%) died within 2 h of WLSM. When perimesencephalic cisterns were patent, this occurred in 48% of patients, compared with 88% and 93%, respectively, of patients with partially and completely effaced cisterns (p < 0.0001). In multivariable analysis, the odds ratio for prediction of death within 2 h was 7.2 (2.8-18.3) for each incremental DCD-N score and 15.4 (4.1-58.1) for the presence of either partially or completely effaced cisterns (c = 0.92 vs. 0.75-0.84 for univariate models). Results were comparable for prediction of death within 1 or 3 h. With patent cisterns, median time to death was 132.5 (21-420) minutes, compared with 23.5 (16-32) and 22 (19-30) minutes, respectively, with partially and completely effaced cisterns (p = 0.0002).

CONCLUSIONS

Cerebral edema with effaced perimesencephalic cisterns predicts rapid death following WLSM in potential DCD organ donors and improves on performance of the DCD-N score alone. Although originally validated for the prediction of death within 1 h, the DCD-N score remains predictive up to 3 h following WLSM.

Identification of Renal Ischemia-Reperfusion Injury Subtypes and Predictive Model for Graft Loss after Kidney Transplantation Based on Programmed Cell Death-Related Genes

Introduction

Ischemia-reperfusion injury (IRI) is detrimental to kidney transplants and may contribute to poor long-term outcomes of transplantation. Programmed cell death (PCD), a regulated cell death form triggered by IRI, is often indicative of an unfavorable prognosis following transplantation. However, given the intricate pathophysiology of IRI and the considerable variability in clinical conditions during kidney transplantation, the specific patterns of cell death within renal tissues remain ambiguous. Consequently, accurately predicting the outcomes for transplanted kidneys continues to be a formidable challenge.

Methods

Eight Gene Expression Omnibus datasets of biopsied transplanted kidney samples post-IRI and 1,548 PCD-related genes derived from 18 PCD patterns were collected in our study. Consensus clustering was performed to identify distinct IRI subtypes based on PCD features (IRI PCD subtypes). Differential enrichment analysis of cell death, metabolic signatures, and immune infiltration across these subtypes was evaluated. Three machine learning algorithms were used to identify PCD patterns related to prognosis. Genes associated with graft loss were screened for each PCD type. A predictive model for graft loss was constructed using 101 combinations of 10 machine learning algorithms.

Results

Four IRI subtypes were identified: PCD-A, PCD-B, PCD-C, and PCD-D. PCD-A, characterized by high enrichment of multiple cell death patterns, significant metabolic paralysis, and immune infiltration, showed the poorest prognosis among the four subtypes. While PCD-D involved the least kind of cell death patterns with the features of extensive activation of metabolic pathways and the lowest immune infiltration, correlating with the best prognosis in the four subtypes. Using various machine learning algorithms, 10 cell death patterns and 42 PCD-related genes were identified as positively correlated with graft loss. The predictive model demonstrated high sensitivity and specificity, with area under the curve values for 0.5-, 1-, 2-, 3-, and 4-year graft survival at 0.888, 0.91, 0.926, 0.923, and 0.923, respectively.

Conclusion

Our study explored the comprehensive features of PCD patterns in transplanted kidney samples post-IRI. The prediction model shows great promise in forecasting graft loss and could aid in risk stratification in patients following kidney transplantation.

Donor Time to Death and Kidney Transplant Outcomes in the Setting of a 3-Hour Minimum Wait Policy

Importance

Lengthening waiting lists for organ transplant mandates the development of strategies to expand the deceased donor pool. Due to concerns regarding organ viability, most organ donation organizations internationally wait no longer than 1 to 2 hours for potential donation after circulatory death (DCD), possibly underutilizing an important organ source; UK policy mandates a minimum 3-hour wait time.

Objective

To assess whether time to death (TTD) from withdrawal of life-sustaining treatment (WLST) is associated with kidney transplant outcomes.

Design, Setting, and Participants

This population-based cohort study used data from the prospectively maintained UK Transplant Registry from all 23 UK kidney transplant centers from January 1, 2013, to December 31, 2021; follow-up was until the date of data extraction (October 2023). Participants comprised 7183 adult recipients of DCD kidney-alone transplants.

Exposure

Duration of TTD, defined as time from WLST to donor mechanical asystole.

Main Outcomes and Measures

Primary outcome was 12-month estimated glomerular filtration rate (eGFR; for the main eGFR model, variables with significant right skew [histogram visual assessment] were analyzed on the log2 scale), with secondary outcomes of delayed graft function and graft survival (censored at death or 5 years).

Results

This study included 7183 kidney transplant recipients (median age, 56 years [IQR, 47-64 years]; 4666 men [65.0%]). Median donor age was 55 years (IQR, 44-63 years). Median TTD was 15 minutes (range, 0-407 minutes), with 885 kidneys transplanted from donors with TTD over 1 hour and 303 kidneys transplanted from donors with TTD over 2 hours. Donor TTD was not associated with recipient 12-month eGFR on adjusted linear regression (change per doubling of TTD, -0.25; 95% CI, -0.68 to 0.19; P = .27), nor with delayed graft function (adjusted odds ratio, 1.01; 95% CI, 0.97-1.06; P = .65) or graft survival (adjusted hazard ratio, 1.00; 95% CI, 0.95-1.07; P = .92). These findings were confirmed with restricted cubic spline models (assessing nonlinear associations) and tests of interaction (including normothermic regional perfusion). In contrast, donor asystolic time, cold ischemic time, and reperfusion time were independently associated with outcomes. Compared with a theoretical 1-hour maximum wait time, the UK policy (minimum 3-hour wait time) has been associated with 885 extra DCD transplants compared with 6298 transplants (14.1% increase).

Conclusions and Relevance

In this cohort study of DCD kidney recipients, donor TTD was not associated with posttransplant outcomes, in contrast to subsequent ischemic times. Altering international transplant practice to mandate minimum 3-hour donor wait times could substantially increase numbers of kidney transplants performed without prejudicing outcomes.

Antecedent Cardiac Arrest Status of Donation After Circulatory Determination of Death (DCDD) Kidney Donors and the Risk of Delayed Graft Function After Kidney Transplantation: A Cohort Study

BACKGROUND

The number of donors from donation after circulatory determination of death (DCDD) has increased by at least 4-fold over the past decade. This study evaluated the association between the antecedent cardiac arrest status of controlled DCDD donors and the risk of delayed graft function (DGF).

METHODS

Using data from the Australia and New Zealand Dialysis and Transplant, the associations between antecedent cardiac arrest status of DCDD donors before withdrawal of cardiorespiratory support, DGF, posttransplant estimated glomerular filtration rate (eGFR), and allograft loss were examined using adjusted logistic, linear mixed modeling, and cox regression, respectively. Among donors who experienced cardiac arrest, we evaluated the association between duration and unwitnessed status of arrest and DGF.

RESULTS

A total of 1173 kidney transplant recipients received DCDD kidneys from 646 donors in Australia between 2014 and 2019. Of these, 335 DCDD had antecedent cardiac arrest. Compared with recipients of kidneys from donors without antecedent cardiac arrest, the adjusted odds ratio (95% confidence interval) for DGF was 0.85 (0.65-1.11) among those with kidneys from donors with cardiac arrest. There was no association between antecedent cardiac arrest and posttransplant eGFR or allograft loss. The duration of cardiac arrest and unwitnessed status were not associated with DGF.

CONCLUSIONS

This focused analysis in an Australian population showed that the allograft outcomes were similar whether DCDD donors had experienced a prior cardiac arrest, with no associations between duration or unwitnessed status of arrest and risk of DGF. This study thus provides important reassurance to transplant programs and the patients they counsel, to accept kidneys from donors through the DCDD pathway irrespective of a prior cardiac arrest.

Potential for organ donation after controlled circulatory death: a retrospective analysis

Objectives

Despite the discrepancy between demand and availability of organs for transplantation, controlled circulatory death donation has not been implemented in Portugal. This study aimed to estimate the potential increase in organ donation from implementing such a program.

Material and Methods

All deceased patients within the intensive care medicine department at Centro Hospitalar Universitário de São João, throughout the year 2019, were subjected to retrospective analysis. Potential gain was estimated comparing the results with the number of donors and organs collected during the same period at this hospital center. Differences in variables between groups were assessed using t tests for independent samples or Mann-Whitney U tests for continuous variables, and chi-squared tests were used for categorical variables.

Results

During 2019, 152 deaths occurred after withdrawal of life-sustaining therapies, 10 of which would have been potentially eligible for donation after controlled circulatory death. We can anticipate a potential increase of 10 prospective donors, a maximum 21% growth in yearly transplantation activity, with a greater impact on kidney transplantation. For most patients, the time between withdrawal of organ support and death surpassed 120 minutes, an outcome explained by variations in withdrawal of life-sustaining measures and insufficient clinical records, underestimating the potential for controlled circulatory arrest donation.

Conclusion

This study effectively highlights public health benefits of controlled circulatory arrest donation. Legislation allowing donation through this method represents a social gain and enables patients who will never meet brain death criteria to donate organs as part of the end-of-life process in intensive care medicine, within a framework of complete ethical alignment.

Can We Predict Kidney Graft Function and Graft Survival Using Hypothermic Machine Perfusion Parameters From Donors After Circulatory Death?

Background

Hypothermic machine perfusion (HMP) reduces renal injury in donation after circulatory death donors with a high Kidney Donor Profile Index (KDPI). This study aims to characterize the correlation between KDPI, HMP parameters, and donor vitals during the withdrawal period in predicting short- and long-term graft outcomes.

Methods

ANOVA with Tukey's honestly significant difference tests compared the relationship between average flow, average resistance, peak resistance, flow slope, and resistance slope on day 30, 1-y, and 3-y eGFR, and days of delayed graft function. Graft and recipient survival rates were assessed using Kaplan-Meier analysis.

Results

The data for 72 grafts were suitable for analysis. Kidneys with KDPI >50% had a significantly higher day 30, and 1-y posttransplant eGFR, if HMP average flow was >150 mL/min, or the average resistance was <0.15 mm Hg/mL/min, compared with kidneys with also KDPI >50% but had not achieved the same pump parameters. There were no significant differences in the Kaplan-Meier analysis, considering recipient or graft survival, regardless of the KPDI score with 3- or 5-y outcomes.

Conclusions

Use of average resistance and average flow from a HMP, in conjunction with KDPI, may be predictive of the short- and long-term function of donation after circulatory death kidney transplants.

The Effect of New Acuity Circle Policy on Simultaneous Liver and Kidney Transplantation in the United States

Background

New deceased donor liver allocation policy using an acuity circle (AC)-based model was implemented on February 4th, 2020. The effect of AC policy on simultaneous liver-kidney transplantation (SLKT) remains unknown. The aim of this study was to assess the effect of AC policy on SLKT waitlist mortality, transplant probability, and post-transplant outcomes.

Methods

Using the United Network for Organ Sharing database, 4908 adult SLKT candidates during two study periods, pre-AC (Aug-2017 to Feb-2020, N = 2770) and post-AC (Feb-2020 to Dec-2021, N = 2138) were analyzed. Outcomes included 90-day waitlist mortality, transplant probability, and post-transplant patient and graft survival.

Results

Compared to pre-AC period, SLKT recipients during post-AC period had higher median model for end-stage liver disease (MELD) score (24 vs 23, P < 0.001), and less percentage of MELD exception (4.6% vs 7.7%, P = 0.001). The 90-day waitlist mortality was same, but the probability of SLKT increased in post-AC period (P < 0.001). Post-AC period also saw increased utilization of donation after cardiac death organs (11% vs 6.4%, P < 0.001) and decreased rates of transplantation among Black candidates (7.9% vs 13%). After risk adjustment, post-AC period was not associated with any significant difference in 90-day waitlist mortality (sub-distribution hazard ratio [sHR] 0.80; 95% CI 0.56-1.16, P = 0.24), and a higher 90-day probability of SLKT (sHR 1.68; 95% CI 1.41-1.99, P < 0.001). During post-transplant period, one-year patient survival, liver and kidney graft survival were comparable between two study periods.

Conclusions

The AC liver allocation policy was associated with increased transplant probability of adult SLKT candidates without decreasing waitlist mortality, post-transplant patient survival, or liver and kidney graft survival.

Waitlist and Transplant Outcomes in Organ Donation After Circulatory Death: Trends in the United States

OBJECTIVES

To summarize waitlist and transplant outcomes in kidney, liver, lung, and heart transplantation using organ donation after circulatory death (DCD).

BACKGROUND

DCD has expanded the donor pool for solid organ transplantation, most recently for heart transplantation.

METHODS

The United Network for Organ Sharing registry was used to identify adult transplant candidates and recipients in the most recent allocation policy eras for kidney, liver, lung, and heart transplantation. Transplant candidates and recipients were grouped by acceptance criteria for DCD versus brain-dead donors [donation after brain death (DBD)] only and DCD versus DBD transplant, respectively. Propensity matching and competing-risks regression was used to model waitlist outcomes. Survival was modeled using propensity matching and Kaplan-Meier and Cox regression analysis.

RESULTS

DCD transplant volumes have increased significantly across all organs. Liver candidates listed for DCD organs were more likely to undergo transplantation compared with propensity-matched candidates listed for DBD only, and heart and liver transplant candidates listed for DCD were less likely to experience death or clinical deterioration requiring waitlist inactivation. Propensity-matched DCD recipients demonstrated an increased mortality risk up to 5 years after liver and kidney transplantation and up to 3 years after lung transplantation compared with DBD. There was no difference in 1-year mortality between DCD and DBD heart transplantation.

CONCLUSIONS

DCD continues to expand access to transplantation and improves waitlist outcomes for liver and heart transplant candidates. Despite an increased risk for mortality with DCD kidney, liver, and lung transplantation, survival with DCD transplant remains acceptable.

Evaluation of functional warm ischemia time during controlled donation after circulatory determination of death using normothermic regional perfusion (ECMO-TT): A prospective multicenter cohort study

BACKGROUND

Controlled donation after circulatory determination of death (cDCD) seems an effective way to mitigate the critical shortage of available organs for transplant worldwide. As a recently developed procedure for organ retrieval, some questions remain unsolved such as the uncertainty regarding the effect of functional warm ischemia time (FWIT) on organs´ viability.

METHODS

We developed a multicenter prospective cohort study collecting all data from evaluated organs during cDCD from 2017 to 2020. All the procedures related to cDCD were performed with normothermic regional perfusion. The analysis included organ retrieval as endpoint and FWIT as exposure of interest. The effect of FWIT on the likelihood for organ retrieval was evaluated with Relative distribution analysis.

RESULTS

A total amount of 507 organs´ related information was analyzed from 95 organ donors. Median donor age was 62 years, and 63% of donors were male. Stroke was the most common diagnosis before withdrawal of life-sustaining therapy (61%), followed by anoxic encephalopathy (21%). This analysis showed that length of FWIT was inversely associated with organ retrieval rates for liver, kidneys, and pancreas. No statistically significant association was found for lungs.

CONCLUSIONS

Results showed an inverse association between functional warm ischemia time (FWIT) and retrieval rate. We also have postulated optimal FWIT's thresholds for organ retrieval. FWIT for liver retrieval remained between 6 and less than 11 min and in case of kidneys and pancreas, the optimal FWIT for retrieval was 6 to 12 min. These results could be valuable to improve organ utilization and for future analysis.

Trajectories of systolic blood pressure decline in kidney transplant donors prior to circulatory death and delayed graft function

BACKGROUND

Kidneys donated after circulatory death suffer a period of functional warm ischaemia before death, which may lead to early ischaemic injury. Effects of haemodynamic trajectories during the agonal phase on delayed graft function (DGF) is unknown. We aimed to predict the risk of DGF using patterns of trajectories of systolic blood pressure (SBP) declines in Maastricht category 3 kidney donors.

METHODS

We conducted a cohort study of all kidney transplant recipients in Australia who received kidneys from donation after circulatory death donors, divided into a derivation cohort (transplants between 9 April 2014 and 2 January 2018 [462 donors]) and a validation cohort (transplants between 6 January 2018 and 24 December 2019 [324 donors]). Patterns of SBP decline using latent class models were evaluated against the odds of DGF using a two-stage linear mixed effects model.

RESULTS

In the derivation cohort, 462 donors were included in the latent class analyses and 379 donors in the mixed effects model. Of the 696 eligible transplant recipients, 380 (54.6%) experienced DGF. Ten different trajectories, with distinct patterns of SBP decline were identified. Compared with recipients from donors with the slowest decline in SBP after withdrawal of cardiorespiratory support, the adjusted odds ratio (aOR) for DGF was 5.5 [95% confidence interval (CI) 1.38-28.0] for recipients from donors with a steeper decline and lowest SBP [mean 49.5 mmHg (standard deviation 12.5)] at the time of withdrawal. For every 1 mmHg/min reduction in the rate of decline of SBP, the respective aORs for DGF were 0.95 (95% CI 0.91-0.99) and 0.98 (95% CI 0.93-1.0) in the random forest and least absolute shrinkage and selection operator models. In the validation cohort, the respective aORs were 0.95 (95% CI 0.91-1.0) and 0.99 (95% CI 0.94-1.0).

CONCLUSION

Trajectories of SBP decline and their determinants are predictive of DGF. These results support a trajectory-based assessment of haemodynamic changes in donors after circulatory death during the agonal phase for donor suitability and post-transplant outcomes.

Normothermic machine perfusion versus static cold storage in donation after circulatory death kidney transplantation: a randomized controlled trial

Kidney transplantation is the optimal treatment for end-stage renal disease, but it is still severely limited by a lack of suitable organ donors. Kidneys from donation after circulatory death (DCD) donors have been used to increase transplant rates, but these organs are susceptible to cold ischemic injury in the storage period before transplantation, the clinical consequence of which is high rates of delayed graft function (DGF). Normothermic machine perfusion (NMP) is an emerging technique that circulates a warmed, oxygenated red-cell-based perfusate through the kidney to maintain near-physiological conditions. We conducted a randomized controlled trial to compare the outcome of DCD kidney transplants after conventional static cold storage (SCS) alone or SCS plus 1-h NMP. A total of 338 kidneys were randomly allocated to SCS (n = 168) or NMP (n = 170), and 277 kidneys were included in the final intention-to-treat analysis. The primary endpoint was DGF, defined as the requirement for dialysis in the first 7 d after transplant. The rate of DGF was 82 of 135 (60.7%) in NMP kidneys versus 83 of 142 (58.5%) in SCS kidneys (adjusted odds ratio (95% confidence interval) 1.13 (0.69-1.84); P = 0.624). NMP was not associated with any increase in transplant thrombosis, infectious complications or any other adverse events. A 1-h period of NMP at the end of SCS did not reduce the rate of DGF in DCD kidneys. NMP was demonstrated to be feasible, safe and suitable for clinical application. Trial registration number: ISRCTN15821205 .

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.

Kidney utilization in the Netherlands - do we optimally use our donor organs?

BACKGROUND

To ensure optimal utilization of deceased donor kidneys, it is important to understand the precise reasons why kidneys are discarded. In this study we aimed to obtain a comprehensive overview of kidney utilization and discard during the entire donation process in the Netherlands.

METHODS

In this retrospective cohort study we analysed kidney utilization of 3856 kidneys in the Netherlands between 1 January 2015 and 31 December 2020. For every kidney that was not transplanted, we determined the moment of and reason for discard through a unique case-by-case assessment.

RESULTS

Kidney discard according to the traditional definition (procured but not transplanted) was 7.8%. However, when kidneys that seemed medically suitable at the beginning of the donation process were also included, many more potential donor kidneys were lost and the total non-utilization was 24.4%. Subjectively presumed impaired organ quality was responsible for 34.2% of all discarded kidneys. Two-thirds of kidneys discarded due to acute kidney injury (AKI) had only AKI stage 1 or 2.

CONCLUSION

The classical definition of organ discard underestimates the non-utilization of deceased donor kidneys. Strategies to improve kidney utilization could be a revision of the maximum allowed agonal time in donation after circulatory death, careful consideration in reporting and accepting kidneys from donors with AKI and a prospectively filled registry of detailed organ discard reasons, including the 'silent' non-utilization before procurement.

Predictive value of the renal resistive index in the immediate postoperative period after kidney transplantation on short- and long-term graft and patient outcomes

INTRODUCTION

During the postoperative stay in the intensive care unit after kidney transplantation, the renal resistive index (RI) is routinely measured. An increased RI, measured months posttransplant, is associated with a higher mortality. We wanted to investigate the value of the RI immediately posttransplant in predicting both short- and long-term outcome.

METHODS

We performed a retrospective single-center study. The RI was collected <48 h posttransplant in patients undergoing kidney transplantations between 2005 and 2014. Short-term outcome was evaluated by delayed graft function (DGF). The long-term endpoints were kidney function and mortality at 30 days, 1 year and 5 years.

RESULTS

We included 478 recipients, 91.4% of whom reached the end of the 5-year follow-up. A higher RI < 48 h posttransplant was significantly associated with DGF. This association was particularly strong in patients receiving grafts from donors after brain death and expanded criteria donors. A higher RI also correlated with mortality and death with functioning graft but not with graft failure. After adjustment for confounders, we found an association between increased RI and DGF, but not with long-term kidney function or mortality.

CONCLUSION

The RI routinely measured <48 h posttransplant is an independent predictor of short-term kidney function.

Ethical Issues Related to Donation and Transplantation of Donation After Circulatory Determination of Death Donors

With the continuing disparity between organ supply to match the increasing demand for kidney transplants in patients with renal failure, donation after the circulatory determination of death (DCDD) has become an important and increasing global source of kidneys for clinical use. The concern that the outcomes of controlled DCDD donor kidney transplants were inferior to those obtained from donors declared dead by neurologic criteria has largely diminished because large-scale registry and single-center reports consistently have reported favorable outcomes. For uncontrolled DCDD kidney transplants, outcomes are correspondingly acceptable, although there is a greater risk of primary nonfunction. The potential of DCDD remains unrealized in many countries because of the ethical concerns and resource implications in the utilization of these donor kidneys for transplantation. In this review, we discuss the origin and definitions of DCDD donors, and examine the long-term outcomes of transplants from DCDD donor kidneys. We discuss the controversies, challenges, and ethical and legal barriers in the acceptance of DCDD, including the complexities of implementing and sustaining controlled and uncontrolled DCDD donor programs. The lessons learned from global leaders will assist a wider international recognition, acceptance, and development of DCDD transplant programs that will noticeably facilitate and address the global shortages of kidneys for transplantation, and ensure the opportunity for people who had indicated their desires to become organ donors fulfill their final wishes.

Does utilization of heart machine perfusion for donation after cardiac death transplantation affect outcomes of other abdominal transplanted organs?

INTRODUCTION

Machine perfusion of heart for donation after circulatory death (DCD) is being increasingly utilized. Current protocols for utilizing heart DCD's machine perfusion might prolong donor warm ischemic time for nonheart organs. The aim of this study was to analyze the effects of utilizing heart machine perfusion on liver and kidney transplants from the same donor.

METHODS

We analyzed data of DCD donors from the United Network for Organ Sharing (UNOS) from January-2020 to September-2021 among two groups: donors with heart machine perfusion (HM) and without heart machine perfusion (NHM). Propensity score (PS) matching was performed to compare the short-term outcomes of liver and kidney transplants between two groups.

RESULTS

Total of 102 liver and 319 kidney transplants were performed using organs from donors with HM. After PS matching, no statistically significant difference was seen in 1-year graft survival (GS) for both liver and kidney transplants between two groups (liver HM 90.6% vs. NHM 90.2%, p = .47; kidney HM 95.2% vs. NHM 92.9%, p = .40). There was no difference in the delayed graft function (DGF) rates in kidney transplantation (KT) (HM 42% vs. NHM 35%, p = .062).

CONCLUSION

Utilization of heart machine perfusion in DCD donors had no significant impact on 1-year outcomes of liver and kidney transplantation.

Impact of Red Blood Cells on Function and Metabolism of Porcine Deceased Donor Kidneys During Normothermic Machine Perfusion

BACKGROUND

Normothermic machine perfusion (NMP) protocols using blood-based solutions are commonly used in the assessment of kidneys before transplantation. This procedure is, nevertheless, limited by blood availability and warrants the search for alternatives. We compared a blood-based solution with a serum-like preservation solution (Aqix) enriched with colloids with and without red blood cells (RBCs).

METHODS

Porcine kidneys retrieved from an abattoir were subjected to 30 min of warm ischemia, followed by 3 h of hypothermic oxygenated machine perfusion at 4 °C. Subsequently, kidneys (n = 6 per group) were evaluated with NMP for 4 h with 5 different solutions: diluted blood, Aqix with BSA ± RBCs, or Aqix with dextran 40 ± RBCs.

RESULTS

Throughout NMP, markers of renal function and tubular metabolism were favorable in groups with RBCs. The addition of RBCs resulted in 4- to 6-fold higher oxygen consumption rates. Controls had significantly higher ATP levels post-NMP, exhibited decreased production of oxidative stress markers, and had the highest creatinine clearance. In conclusion, this study shows that the addition of RBCs during NMP reduced renal injury, improved function, and was associated with increased renal metabolism.

CONCLUSIONS

Although the RBC-BSA-supplemented Aqix solution was also able to support metabolism and renal function, a blood-based perfusion solution remains superior.

Nonutilization of Kidneys From Donors After Circulatory Determinant of Death

Background.

The expansion of donation after circulatory determination of death (DCDD) programs and unmet demands for kidney transplantation indicate that there is a need to improve the efficiency and utilization of these organs.

Methods.

We studied all DCDD donors retrieved for kidney transplantation in Australia between 2014 and 2019 and determined the factors associated with nonutilization using least absolute shrinkage and selection operator and random forest models. Self-organizing maps were used to group these donors into clusters with similar characteristics and features associated with nonutilization were defined.

Results.

Of the 762 DCDD donors, 116 (15%) were not utilized for kidney transplantation. Of the 9 clusters derived from self-organizing map, 2 had the highest proportions of nonutilized kidneys. Factors for nonutilization (adjusted odds ratio [95% confidence interval], per SD increase) were duration from withdrawal of cardiorespiratory support till death (1.38 [1.16-1.64]), admission and terminal serum creatinine (1.43 [1.13-1.85]) and (1.41 [1.16-1.73]). Donor kidney function and duration of warm ischemia were the main factors for clinical decisions taken not to use kidneys from DCDD donors.

Conclusions.

Donor terminal kidney function and the duration of warm ischemia are the key factors for nonutilization of DCDD kidneys. Strategies to reduce the duration of warm ischemia and improve post-transplant recipient kidney function may reduce rates of nonutilization.

Kidney transplant outcome of expanded criteria donors after circulatory death

The increase in the number of patients on the kidney transplant waiting list has led to an attempt to increase the number of potential donors by incorporating candidates that previously would not have been considered optimal, including donors after cardiac death (DCD) and those with "expanded" criteria (ECD). Recipients of controlled DCD (cDCD) grafts suffer more delayed graft function (DGF), but have a long-term evolution comparable to those of brain-dead donors, which has allowed an increase in the number of cDCD transplants in different countries in recent years. In parallel, the use of cDCD with expanded criteria (cDCD/ECD) has increased in recent years in different countries, allowing the waiting list for kidney transplantation to be shortened. The use of these grafts, although associated with a higher frequency of DGF, offers similar or only slightly lower long-term graft survival than those of brain death donors with expanded criteria. Different studies have observed that cDCD/ECD graft recipients have worse kidney function than cDCD/standard and DBD/ECD. Mortality associated with cDCD/ECD graft transplantation mostly relates to the recipient age. Patients who receive a cDCD/≥60 graft have better survival than those who continue on the waiting list, although this fact has not been demonstrated in recipients of cDCD/>65 years. The use of this type of organ should be accompanied by the optimization of surgical times and the shortest possible cold ischemia.

Analysis of risk factors for donation after circulatory death kidney transplantation in Japan

Background

In Japan, donations after circulatory death kidney transplantation are widely performed due to legislation delays. The number of donations after brain death kidney transplantations is increasing, but the target remains unmet. We reviewed the outcomes of donation after circulatory death in Japan.

Methods

We analyzed 2923 deceased kidney transplantations (2239: donation after circulatory death (DCD), 684: donation after brain death (DBD)) performed in Japan from 2000 to 2019. The outcomes of the DCD and DBD groups were compared. We examined the risk factors for graft loss in the DCD group.

Results

The 5-year patient survival and death-censored graft survival rates of the DCD group, obtained by propensity score matching, were 93.6% and 95.2%, respectively, which were equivalent to 94.2% and 93.8%, respectively, obtained in the DBD group. Older donors (≥ 50 years) and prolonged cold ischemia time (≥ 12 h) were risk factors for graft loss; in the presence of these, graft survival was lower in the DCD group.

Conclusions

Older donors and prolonged cold ischemia time reduced graft survival in the DCD group. Proper evaluation of donors and careful preparation for transplant surgery are, therefore, essential to ensure good transplant outcomes.

Perfusion of a Kidney Graft from a Donor After Cardiac Death Based on Immediately Started Machine Perfusion: An Experimental Study on a Big Animal

BACKGROUND

Donation after circulatory death donors are becoming a common source of organs for transplant. Despite good long-term outcomes of grafts from donation after circulatory death, this group is affected by a higher occurrence of delayed graft function and primary nonfunction. Our hypothesis is based on the assumption that washing the kidney grafts in the donor's body using a simple mechanical perfusion pump will result in faster and better perfusion of the parenchyma and more efficient cooling compared with hydrostatic perfusion alone.

METHODS

A total of 7 experimental animals (pigs) were used. The animals were divided into 2 groups: group A (n = 3) and group B (n = 4). After a 30-minute ischemic period for the selected kidney (clamped renal vessels), intra-arterial perfusion was performed. In group A perfusion was performed using hydrostatic pressure; in group B mechanical controlled perfusion was performed. After perfusion, declamping of the renal vessels caused restoration of flow. For graft quality evaluation, biopsy specimens were harvested, and the cooling speed was observed. Laboratory markers or renal failure were determined.

RESULTS

We found no significant differences between temperature drop and total diuresis between groups A and B. A significant difference was found between the groups in both flow parameters (flow maximum and mean flow) (P = .007, respectively P = .019). No laboratory parameters were found to be statistically significantly different. Histopathological analysis strongly supports the hypothesis of better flushing of kidney grafts using mechanical perfusion.

CONCLUSIONS

Based on our results, better kidney graft quality can be expected after immediately started mechanical perfusion in situ.

Hypothermic oxygenated machine perfusion of the human pancreas for clinical islet isolation: a prospective feasibility study

Due to an increasing scarcity of pancreases with optimal donor characteristics, islet isolation centers utilize pancreases from extended criteria donors, such as from donation after circulatory death (DCD) donors, which are particularly susceptible to prolonged cold ischemia time (CIT). We hypothesized that hypothermic machine perfusion (HMP) can safely increase CIT. Five human DCD pancreases were subjected to 6 h of oxygenated HMP. Perfusion parameters, apoptosis, and edema were measured prior to islet isolation. Five human DBD pancreases were evaluated after static cold storage (SCS). Islet viability, and in vitro and in vivo functionality in diabetic mice were analyzed. Islets were isolated from HMP pancreases after 13.4 h [12.9–14.5] CIT and after 9.2 h [6.5–12.5] CIT from SCS pancreases. Histological analysis of the pancreatic tissue showed that HMP did not induce edema nor apoptosis. Islets maintained >90% viable during culture, and an appropriate in vitro and in vivo function in mice was demonstrated after HMP. The current study design does not permit to demonstrate that oxygenated HMP allows for cold ischemia extension; however, the successful isolation of functional islets from discarded human DCD pancreases after performing 6 h of oxygenated HMP indicates that oxygenated HMP may be a useful technology for better preservation of pancreases.

Kidney transplant outcome of expanded criteria donors after circulatory death

The increase in the number of patients on the kidney transplant waiting list has led to an attempt to increase the number of potential donors by incorporating candidates that previously would not have been considered optimal, including donors after cardiac death (DCD) and those with "expanded" criteria (ECD). Recipients of controlled DCD (cDCD) grafts suffer more delayed graft function (DGF), but have a long-term evolution comparable to those of brain-dead donors, which has allowed an increase in the number of cDCD transplants in different countries in recent years. In parallel, the use of cDCD with expanded criteria (cDCD/ECD) has increased in recent years in different countries, allowing the waiting list for kidney transplantation to be shortened. The use of these grafts, although associated with a higher frequency of DGF, offers similar or only slightly lower long-term graft survival than those of brain death donors with expanded criteria. Different studies have observed that cDCD/ECD graft recipients have worse kidney function than cDCD/standard and brain death/ECD. Mortality associated with cDCD/ECD graft transplantation mostly relates to the recipient age. Patients who receive a cDCD/≥60 graft have better survival than those who continue on the waiting list, although this fact has not been demonstrated in recipients of cDCD/>65 years. The use of this type of organ should be accompanied by the optimization of surgical times and the shortest possible cold ischemia.

Assessing Kidney Graft Viability and Its Cells Metabolism during Machine Perfusion

Kidney transplantation is the golden treatment for end-stage renal disease. Static cold storage is currently considered the standard method of preservation, but dynamic techniques, such as machine perfusion (MP), have been shown to improve graft function, especially in kidneys donated by extended criteria donors and donation after circulatory death. With poor organ quality being a major reason for kidneys not being transplanted, an accurate, objective and reliable quality assessment during preservation could add value and support to clinicians' decisions. MPs are emerging technologies with the potential to assess kidney graft viability and quality, both in the hypothermic and normothermic scenarios. The aim of this review is to summarize current tools for graft viability assessment using MP prior to implantation in relation to the ischemic damage.

Evaluation of the - 318C/T (RS5742909) CTLA4 gene polymorphism influence on kidney function after transplantation

Introduction: The protein CTLA-4 (Cytotoxic T Lymphocyte Antigen-4) is a molecule that plays a significant role in maintaining immunological homeostasis. Recent studies demonstrated an unequivocal proof that CTLA-4 has an inhibitory effect on immune response. This gene has been identified with several single nucleotide polymorphisms which could change gene activity, consequently leading to structural protein change. This genetic variability is associated with acute rejection and delayed graft function as important indicators of kidney transplantation success. Aim: The aim of this study was to evaluate the potential association of CTLA4 (rs5742909) polymorphisms with acute rejection and delayed graft function in patients with kidney transplant. Material and methods: A total of 151 patients were included in this cross-sectional cohort study. Real-time polymerase chain reaction was used to determine the genotype which was then evaluated in relation to acute rejection and delayed graft function. Statistical significance was analyzed by Pearson's Chi-square and Fisher's exact test. Results: The most frequent genotype among 151 patient was CC (80.8%), then CT (17.9%) and TT (1.3%). The frequency of C allele is 89.7% whereas the frequency of T allele is 10.3%. There was no statistically significant difference in CTLA4 genotype and allele distribution nor their linkage to acute rejection and delayed graft function. The evaluation of C or T allele carriers showed no statistically significant difference with respect to previously mentioned posttransplant complications. Conclusion: In this study, no statistically significant association between -318C/T (rs5742909) CTLA4 polymorphism and AR/DGF was found.

Donation after circulatory determination of death in western Canada: a multicentre study of donor characteristics and critical care practices

PURPOSE

Donation after circulatory determination of death (DCD) has been performed in Canada since 2006. Numerous aspects of donor management remain controversial.

METHODS

We performed a multicentre cohort study involving potential DCD donors in western Canada (2008-2017), as well as recipients of their organs, to describe donor characteristics and critical care practices, and their relation to one-year recipient and graft survival.

RESULTS

There were 257 patients in four provinces that underwent withdrawal of life-sustaining therapies (WLST) in anticipation of possible DCD. The proportion of patients that died within two hours of WLST ranged from 67% to 88% across provinces (P = 0.06), and was predicted by deeper coma (P = 0.01), loss of pupillary light or corneal reflexes (P = 0.02), and vasopressor use (P = 0.01). There were significant differences between provinces in time intervals from onset of hypotension to death (9-11 min; P = 0.02) and death to vascular cannulation (7-10 min; P < 0.001). There was inconsistency in pre-mortem heparin administration (82-96%; P = 0.03), including timing (before vs after WLST; P < 0.001) and dose (≥ 300 vs < 300 units·kg-1; P < 0.001). Donation after circulatory death provided organs for 321 kidney, 81 liver, and 50 lung transplants. One-year recipient and graft survival did not differ among provinces (range 85-90%, P = 0.45). Predictors of death or graft failure included older recipient age (odds ratio [OR] per year, 1.04; 95% confidence interval [CI],1.01 to 1.07) and male donor sex (OR, 3.35; 95% CI, 1.39 to 8.09), but not time intervals between WLST and cannulation or practices related to heparin use.

CONCLUSION

There is significant variability in critical care DCD practices in western Canada, but this has not resulted in significant differences in recipient or graft survival. Further research is required to guide optimal management of potential DCD donors.

Prediction of kidney transplant outcome based on different DGF definitions in Chinese deceased donation

Background

Delayed graft function (DGF) is an important complication of kidney transplantation and can be diagnosed according to different definitions. DGF has been suggested to be associated with the long-term outcome of kidney transplantation surgery. However, the best DGF definition for predicting renal transplant outcomes in Chinese donations after cardiac death (DCDs) remains to be determined.

Method

A total of 372 DCD kidney transplant recipients from June 2013 to July 2017 in the First Affiliated Hospital of Xi’an Jiaotong University were included in this retrospective study to compare 6 different DGF definitions. The relationships of the DGF definitions with transplant outcome were analyzed, including graft loss (GL) and death-censored graft loss (death-censored GL). Renal function indicators, including one-year estimated glomerular filtration rate (eGFR) and three-year eGFR, and were compared between different DGF groups.

Results

The incidence of DGF varied from 4.19 to 35.22% according to the different DGF diagnoses. All DGF definitions were significantly associated with three-year GL as well as death-censored GL. DGF based on requirement of hemodialysis within the first week had the best predictive value for GL (AUC 0.77), and DGF based on sCr variation during the first 3 days post-transplant had the best predictive value for three-year death-censored GL (AUC 0.79). Combination of the 48-h sCr reduction ratio and classical DGF can improve the AUC for GL (AUC 0.85) as well as the predictive accuracy for death-censored GL (83.3%).

Conclusion

DGF was an independent risk factor for poor transplant outcome. The combination of need for hemodialysis within the first week and the 48-h serum creatinine reduction rate has a better predictive value for patient and poor graft outcome.

Duration of delayed graft function and outcomes after kidney transplantation from controlled donation after circulatory death donors: a retrospective study

The impact of the duration of delayed graft function (DGF) on graft survival is poorly characterized in controlled donation after circulatory death (DCD) donor kidney transplantation. A retrospective analysis was performed on 225 DCD donor kidney transplants between 2011 and 2016. When patients with primary nonfunction were excluded (n = 9), 141 recipients (65%) had DGF, with median (IQR) duration of dialysis dependency of 6 (2-11.75) days. Longer duration of dialysis dependency was associated with lower estimated glomerular filtration rate at 1 year, and a higher rate of acute rejection. On Kaplan-Meier analysis, the presence of DGF was associated with lower graft survival (log-rank test P = 0.034), though duration of DGF was not (P = 0.723). However, multivariable Cox regression analysis found that only acute rejection was independently associated with lower graft survival [HR (95% CI) 4.302 (1.617-11.450); P = 0.003], whereas the presence of DGF and DGF duration were not. In controlled DCD kidney transplantation, DGF duration itself may not be independently associated with graft survival; rather, it may be that acute rejection associated with prolonged DGF is the poor prognostic factor.