Evaluation of severity of delayed graft function in kidney transplant recipients

Soluble DNA Concentration in the Perfusate is a Predictor of Posttransplant Renal Function in Hypothermic Machine Perfused Kidney Allografts

Background

Hypothermic machine perfusion (HMP) has greatly improved kidney allograft preservation. However, tissue damage still occurs during HMP, affecting posttransplant graft function. Therefore, better methods are needed to continuously assess organ quality and to predict posttransplant graft function and survival. We propose that soluble DNA (sDNA) concentration in HMP perfusate can be used as a noninvasive biomarker for this purpose.

Methods

Perfusate samples of kidney grafts placed on HMP were collected 5 min after the initiation of HMP and again at the conclusion of HMP. sDNA of nuclear origin from the perfusate was quantified by real-time polymerase chain reaction and correlated with HMP parameters and posttransplant clinical outcomes.

Results

Kidney grafts from 52 deceased donors placed on HMP were studied. Perfusate sDNA concentration was significantly higher in transplanted kidneys with delayed graft function. Higher concentrations of perfusate sDNA at 5 min and at HMP conclusion were also correlated with lower graft function in the initial posttransplant period, as measured by postoperative day 2, 3, and 4 creatinine reduction ratios. Standard pump parameters such as renal vascular resistance and renal vascular flow were poor indicators of early posttransplant graft function.

Conclusions

sDNA concentration in HMP perfusate of kidney grafts can indicate the quality of kidney graft preservation and predict posttransplant renal function. This biomarker should be explored further to improve renal organ assessment and transplantation outcomes.

Preoperative donor urinary UDP-Glc as an independent risk factor for delayed graft function

Background

Expanded criteria donors (ECD) have the potential to greatly increase the donor organ pool but pose a higher risk of delayed graft function (DGF) post-transplantation. Uridine diphosphate-glucose (UDP-Glc) plays a significant role in extracellular signaling related to tissue damage and retains stability for detection. Donor urinary UDP-Glc level may be an appropriate and effective biomarker for predicting DGF.

Methods

Recipients who underwent successful kidney transplantation, with corresponding collection of donor urine samples, between June 2023 and August 2024 were included. We measured preoperative donor urinary UDP-Glc levels and analyzed their correlation with graft recovery. The study was registered in the Clinical Trial Registry (no. NCT06707272).

Results

Preoperative donor urinary UDP-Glc levels were different between immediated, slowed, and delayed graft function subgroups (7.23 vs. 9.04 vs. 10.13 ug/mL, p < 0.001). Donor urinary UDP-Glc level was an independent risk factor for DGF (odds ratio [OR] = 1.741, 95% confidence interval [CI]: 1.311-2.312, p < 0.001). Furthermore, donor urinary UDP-Glc showed a better predictive value for DGF (AUROC = 0.791, 95% CI: 0.707-0.875, p < 0.001), and combining donor urinary UDP-Glc and donor terminal serum creatinine improved the model predictive value for DGF (AUROC = 0.832, 95% CI: 0.756-0.908, Youden index = 0.56, sensitivity = 0.81, specificity = 0.75, PPV = 0.72, NPV = 0.83, p < 0.001). Additionally, the donor urinary UDP-Glc level was related to the recipient serum creatinine level at 1 month post-transplantation (rs = 0.475, p < 0.001).

Conclusions

Donor urinary UDP-Glc level is an independent risk factor for DGF and can provide surgeons with a novel strategy to predict DGF earlier and more accurately without invasive procedures.

Clinical trial registration

https://clinicaltrials.gov, NCT06707272 identifier.

Protein biomarkers in assessing kidney quality before transplantation‑current status and future perspectives (Review)

To meet the demand for kidney transplants (KTx), organs are frequently retrieved not only from standard criteria donors (SCD; a donor who is aged <50 years and suffered brain death from any number of causes, such as traumatic injuries or a stroke) but also from expanded criteria donors (any donor aged >60 years or donors aged >50 years with two of the following: A history of high blood pressure, a creatinine serum level ≥1.5 mg/dl or death resulting from a stroke). This comes at the cost of a higher risk of primary non‑function (the permanent hyperkalemia, hyperuremia and fluid overload that result in the need for continuous dialysis after KTx), delayed graft function (the need for dialysis session at least once during the first week after KTx), earlier graft loss and urinary complications (vesico‑ureteral reflux, obstruction of the vesico‑ureteral anastomosis, urine leakage). At present, there are no commercially available diagnostic tools for assessing kidney quality prior to KTx. Currently available predictive models based on clinical data, such as the Kidney Donor Profile Index, are insufficient. One promising option is the application of perfusion solutions for protein biomarkers of kidney quality and predictors of short‑ and long‑term outcomes. However, to date, protein markers that can be detected with ELISA, western blotting and cytotoxic assays have not been identified to be a beneficial predictors of kidney quality. These include lactate dehydrogenases, glutathione S‑transferases, fatty acid binding proteins, extracellular histones, IL‑18, neutrophil gelatinase‑associated lipocalin, MMPs and kidney injury molecule‑1. However, novel methods, including liquid chromatography‑mass spectrometry (LC‑MS) and microarrays, allow the analysis of all renal proteins suspended/dissolved in the acellular preservation solution used for kidney storage before KTx (including hypothermic machine perfusion as one of kidney storage methods) e.g. Belzer University of Wisconsin. Recent proteomic studies utilizing LC‑MS have identified complement pathway elements (C3, C1QB, C4BPA, C1S, C1R and C1RL), desmoplakin, blood coagulation pathway elements and immunoglobulin heavy variable 2‑26 to be novel predictors of kidney quality before transplantation. This was because they were found to correlate with estimated glomerular filtration rate at 3 and 12 months after kidney transplantation. However, further proteomic studies focusing on distinct markers obtained from hypothermic and normothermic machine perfusion are needed to confirm their predictive value and to improve kidney storage methods. Therefore, the present literature review from PubMed, Scopus, Embase and Web of Science was performed with the aims of summarizing the current knowledge on the most frequently studied single protein biomarkers. In addition, novel analytical methods and insights into organ injury during preservation were documented, where future directions in assessing organ quality before kidney transplantation were also discussed.

Histopathological Features and Role of Allograft Kidney Biopsy Among Recipients With Prolonged Delayed Graft Function: A Review

Delayed graft function (DGF) is an early posttransplant complication predictive of adverse outcomes. This "acute kidney injury of transplantation" is often defined as allograft dysfunction requiring renal replacement within 7 d posttransplantation. DGF is an important area of study because it is emerging with efforts to expand the donor pool and address the supply-demand gap in kidney transplantation. DGF is often caused by severe kidney injury mechanisms because of multiple donors, recipients, and immunologic factors. The role of kidney biopsy, particularly in prolonged DGF, is an ongoing area of research and inquiry for clinicians and researchers alike to better define, manage, and predict outcomes of this early posttransplant event. This review aims to provide an in-depth, comprehensive summary of the literature to date on the histopathology of DGF and the role of kidney transplant biopsies in prolonged DGF.

Hypothermia for expanded criteria organ donors in kidney transplantation in France (HYPOREME): a multicentre, randomised controlled trial

BACKGROUND

Expanded criteria donors help to increase graft availability, but provide organs with an increased risk of delayed graft function. We aimed to investigate whether donor hypothermia decreases the risk of delayed graft function compared with normothermia.

METHODS

We did this multicentre, randomised, controlled, parallel-arm trial at 53 intensive care units and transplant centres in France. We included expanded criteria donors in whom death was diagnosed based on neurological criteria, in compliance with French law, and the recipients of their kidney grafts. Eligible expanded criteria donors were older than 60 years or were aged 50-59 years and had at least two other risk factors (history of hypertension, creatinine >132 μmol/L, or cerebrovascular cause of death). Donors were randomly assigned to hypothermia (34-35°C) or normothermia (36·5-37·5°C). Machine perfusion was used routinely. Randomisation was done using a computer-generated, interactive, web-response system, in permuted blocks (block size six), stratified by centre. Outcome assessors were masked; investigator masking was not feasible. The primary outcome was the proportion of kidney recipients with delayed graft function, defined as renal replacement therapy within 7 days after transplantation, assessed in the modified intention-to-treat (mITT) population, which included all recipients who received at least one kidney from an expanded criteria donor, with the exception of those under guardianship. Secondary outcomes in expanded criteria donors were the number of organs recovered and transplanted, kidney function, body temperature, total volume of fluids administered, blood pressure and need for vasopressors and inotropes, and adverse events (cardiovascular events, metabolic disturbances, and coagulation disorders). Secondary outcomes in kidney recipients were duration of hospital stay, kidney graft function and vital status at day 7, day 28, 3 months, and 1 year after transplantation, and adverse events (infections, cardiovascular events, and surgical complications). Secondary outcomes were assessed in the mITT population. The trial was registered at ClinicalTrials.gov, NCT03098706.

FINDINGS

Between Nov 9, 2017, and March 3, 2021, 365 donors were randomly assigned, of whom 298 (151 [51%] male, 147 [49%] female) provided kidneys to 526 recipients (323 [61%] male, 203 [39%] female). 251 recipients in the hypothermia group and 275 recipients in the normothermia group were included in the analysis. Graft function was delayed in 40 (16%) of 251 recipients in the hypothermia group and 58 (21%) of 275 recipients in the normothermia group (odds ratio 0·71 [95% CI 0·44-1·13]; p=0·14; absolute difference -5·2% [95% CI 11·8-1·5]). Compared with donors in the normothermia group, donors in the hypothermia group had higher highest mean arterial pressure (115 mm Hg [SD 22] vs 108 mm Hg [20]; p=0·001). 1 year after transplantation, recipients in the hypothermia group had a lower mean creatinine concentration (152·4 μmol/L [SD 59·1] vs 169·7 μmol/L [51·4]; p=0·0351) and a higher mean creatinine clearance (42·3 mL/min/1·73 m2 [15·8] vs 40·5 mL/min/1·73 m2 [17·9]; p=0·0414) than those in the normothermia group. No significant differences between groups were identified for any other secondary outcomes.

INTERPRETATION

Hypothermia in expanded criteria donors whose organs were routinely stored using machine perfusion did not decrease the frequency of delayed kidney graft function. However, hypothermia was associated with a lower serum creatinine concentration and a higher creatinine clearance 1 year after transplantation.

FUNDING

French Ministry of Health and French Intensive Care Society.

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.

Optimal Timing of Serum Creatinine Measurement for KDPI Scoring to Predict Postoperative Renal Function in Deceased Donor Kidney Transplantation

INTRODUCTION

The widely employed Kidney Donor Profile Index (KDPI) scoring system, designed for assessing deceased donors (DD), plays a pivotal role in predicting graft function post kidney transplantation (KT). Given the dynamic nature of renal function, including serum creatinine (sCr), in managing DDs, it remains uncertain optimal timing to use KDPI for assessing postoperative graft function.

METHODS

In this retrospective review, we assessed 246 DDs who were managed within a donor management program from January 2010 to December 2021. We collected sCr values for KDPI scoring at admission, peak, and last measurements before KT. Recipient data included occurrence of slow graft function (SGF), delayed graft function (DGF), and glomerular filtration rate (GFR) at one-year post-transplantation (1 Y). Using Receiver Operating Characteristic (ROC) and Pearson correlation analyses, we explored correlations of KDPI score (admission, peak, last) with graft function (SGF, DGF, GFR 1 Y).

RESULTS

The average age of DDs and recipients was 49.78 ± 13.37 and 52.54 ± 10.49 years, respectively, with mean KDPI values at admission, peak, and last measurements of 62.36 ± 25.44, 66.94 ± 24.73, and 63.75 ± 25.80. After transplantation, SGF was observed in 81 recipients (32.9%) and DGF in 32 (13.0%). For SGF, the Area Under the Curve (AUC) from ROC analysis were 0.684 (95% CI, 0.615-0.753; P < .001) at admission, 0.691 (0.623-0.759; P < .001) at peak, and 0.697 (0.630-0.765; P < .001) at the last measurement. In predicting DGF, the corresponding AUC values were 0.746 (0.661-0.831; P < .001) at admission, 0.724 (0.637-0.810; P < .001) at peak, and 0.721 (0.643-0.809; P < .001) at the last. Moreover, KDPI scores at all time points-admission, peak, and last-moderately correlated with GFR 1 Y (R = -0.426, -0.423, -0.417).

CONCLUSION

KDPI measurements at all time points, particularly admission, would be more effective in predicting DGF in DDKT.

Short-Term, Mid-Term, and Long-Term Outcomes after Deceased Donor Kidney Transplantation in Patients with AKI: A Systematic Review and Meta-Analysis

Key Points

This study reviews the willingness to use kidneys from donors who have experienced AKI during transplantation and provides a thorough analysis of the existing literature. While delayed graft function is more common, primary nonfunction and acute rejection rates appear comparable, as do allograft function and graft survival compared with non-AKI donor kidneys. Considering the shortage of available organs and the high mortality rate of patients on dialysis, the use of donors with AKI as a source for kidney transplantation is a viable alternative.

Background

AKI is a common complication in hospitalized patients and may occur in potential kidney donors. Observational studies have suggested that kidney transplantation in patients with AKI is feasible and safe, but no systematic evaluation has been performed.

Methods

We performed a systematic review and meta-analysis to evaluate the outcomes of kidney transplantation in patients with AKI. We searched MEDLINE, Embase, Cochrane, Google Scholar, and other databases for studies reporting outcomes of donor kidneys with AKI. We included single-center, multicenter, and registry-based studies and analyzed them according to the definition and severity of AKI. End points were primary and delayed graft function (DGF), primary nonfunction (PNF), length of hospital stay, rejection, graft function, and patient and graft survival at 1, 3, 5, and 8–10 years after transplantation. This study was registered in PROSPERO, number CRD42021260088.

Results

We identified 33 single-center, four multicenter, and seven registry studies with more than 100,000 patients published between 2005 and 2022. Recipients from donors with AKI had a higher risk of DGF (relative risk, 1.51; 95% confidence interval [CI], 1.35 to 1.68). Graft function at discharge was worse in the AKI group (MDCrea [95% CI]: 0.96 mg/dl [0.36 to 1.56, I2=96%], MDGFR [95% CI]: −8.88 ml/min per 1.73 m2 [−15.32 to −2.44, I2=93%]), but improved thereafter and was similar in both groups at 3 months after transplantation (MDCrea [95% CI]: −0.05 mg/dl [−0.18 to 0.07, I2=0%], MDGFR [95% CI]: −1.83 ml/min per 1.73 m2 [−5.29 to 1.63, I2=91%]). Primary nonfunction and patient and graft survival were similar at 1, 3, 5, and 8–10 years after transplantation. There were no differences in rejections regardless of AKI definition and severity.

Conclusions

Transplantation of kidneys with AKI is associated with satisfactory short-term and long-term outcomes and should be pursued to increase the donor pool.

Understanding Delayed Graft Function to Improve Organ Utilization and Patient Outcomes: Report of a Scientific Workshop Sponsored by the National Kidney Foundation

Delayed graft function (DGF) is a common complication after kidney transplant. Despite extensive literature on the topic, the extant definition of DGF has not been conducive to advancing the scientific understanding of the influences and mechanisms contributing to its onset, duration, resolution, or long-term prognostic implications. In 2022, the National Kidney Foundation sponsored a multidisciplinary scientific workshop to comprehensively review the current state of knowledge about the diagnosis, therapy, and management of DGF and conducted a survey of relevant stakeholders on topics of clinical and regulatory interest. In this Special Report, we propose and defend a novel taxonomy for the clinical and research definitions of DGF, address key regulatory and clinical practice issues surrounding DGF, review the current state of therapies to reduce and/or attenuate DGF, offer considerations for clinical practice related to the outpatient management of DGF, and outline a prospective research and policy agenda.

Prevention of Delayed Graft Function in Kidney Transplant Recipients through a Continuous Infusion of the Prostaglandin Analogue Iloprost: A Single-Center Prospective Study

BACKGROUND

Delayed graft function (DGF) is common after kidney transplantation from deceased donors and may significantly affect post-transplant outcomes. This study aimed to evaluate whether an innovative approach, based on the administration of the intravenous prostaglandin analogue iloprost, could be beneficial in reducing the incidence of DGF occurring after kidney transplantation from deceased donors.

METHODS

This prospective, randomized (1:1), placebo-controlled study enrolled all consecutive patients who received a kidney transplant from a deceased donor from January 2000 to December 2012 and who were treated in the peri-transplant period with the prostaglandin analogue iloprost at 0.27 μg/min through an elastomeric pump (treatment group) or with a placebo (control group).

RESULTS

A total of 476 patients were included: DGF was reported in 172 (36.1%) patients in the entire cohort. The multivariate analysis showed that the donor's age > 70 years (OR 2.50, 95% confidence interval (CI): 1.40-3.05, p < 0.001), cold ischemia time > 24 h (OR 2.60, 95% CI: 1.50-4.51, p < 0.001), the donor's acute kidney injury (OR 2.71, 95% CI: 1.61-4.52, p = 0.021) and, above all, the recipient's arterial hypotension (OR 5.06, 95% CI: 2.52-10.1, p < 0.0001) were the strongest risk factors for developing post-transplant DGF. The incidence of DGF was 21.4% in the treatment group and 50.9% in the control group (p < 0.001). Interestingly, among patients who developed DGF, those who received iloprost had a shorter duration of post-transplant DGF (10.5 ± 8.3 vs. 13.4 ± 6.7, days, p = 0.016).

CONCLUSIONS

This study showed that the use of a continuous infusion of iloprost could safely and effectively reduce the incidence of DGF in recipients of deceased-donor kidneys, allowing a better graft functionality as well as a better graft survival.

Longitudinal estimated glomerular filtration rate (eGFR) modeling in long-term renal function to inform clinical trial design in kidney transplantation

Kidney transplantation is the preferred treatment for individuals with end-stage kidney disease. From a modeling perspective, our understanding of kidney function trajectories after transplantation remains limited. Current modeling of kidney function post-transplantation is focused on linear slopes or percent decline and often excludes the highly variable early timepoints post-transplantation, where kidney function recovers and then stabilizes. Using estimated glomerular filtration rate (eGFR), a well-known biomarker of kidney function, from an aggregated dataset of 4904 kidney transplant patients including both observational studies and clinical trials, we developed a longitudinal model of kidney function trajectories from time of transplant to 6 years post-transplant. Our model is a nonlinear, mixed-effects model built in NONMEM that captured both the recovery phase after kidney transplantation, where the graft recovers function, and the long-term phase of stabilization and slow decline. Model fit was assessed using diagnostic plots and individual fits. Model performance, assessed via visual predictive checks, suggests accurate model predictions of eGFR at the median and lower 95% quantiles of eGFR, ranges which are of critical clinical importance for assessing loss of kidney function. Various clinically relevant covariates were also explored and found to improve the model. For example, transplant recipients of deceased donors recover function more slowly after transplantation and calcineurin inhibitor use promotes faster long-term decay. Our work provides a generalizable, nonlinear model of kidney allograft function that will be useful for estimating eGFR up to 6 years post-transplant in various clinically relevant populations.

Balanced crystalloid solution versus saline in deceased donor kidney transplantation (BEST-Fluids): a pragmatic, double-blind, randomised, controlled trial

BACKGROUND

Delayed graft function (DGF) is a major adverse complication of deceased donor kidney transplantation. Intravenous fluids are routinely given to patients receiving a transplant to maintain intravascular volume and optimise graft function. Saline (0·9% sodium chloride) is widely used but might increase the risk of DGF due to its high chloride content. We aimed to test our hypothesis that using a balanced low-chloride crystalloid solution (Plasma-Lyte 148) instead of saline would reduce the incidence of DGF.

METHODS

BEST-Fluids was a pragmatic, registry-embedded, multicentre, double-blind, randomised, controlled trial at 16 hospitals in Australia and New Zealand. Adults and children of any age receiving a deceased donor kidney transplant were eligible; those receiving a multi-organ transplant or weighing less than 20 kg were excluded. Participants were randomly assigned (1:1) using an adaptive minimisation algorithm to intravenous balanced crystalloid solution (Plasma-Lyte 148) or saline during surgery and up until 48 h after transplantation. Trial fluids were supplied in identical bags and clinicians determined the fluid volume, rate, and time of discontinuation. The primary outcome was DGF, defined as receiving dialysis within 7 days after transplantation. All participants who consented and received a transplant were included in the intention-to-treat analysis of the primary outcome. Safety was analysed in all randomly assigned eligible participants who commenced surgery and received trial fluids, whether or not they received a transplant. This study is registered with Australian New Zealand Clinical Trials Registry, (ACTRN12617000358347), and ClinicalTrials.gov (NCT03829488).

FINDINGS

Between Jan 26, 2018, and Aug 10, 2020, 808 participants were randomly assigned to balanced crystalloid (n=404) or saline (n=404) and received a transplant (512 [63%] were male and 296 [37%] were female). One participant in the saline group withdrew before 7 days and was excluded, leaving 404 participants in the balanced crystalloid group and 403 in the saline group that were included in the primary analysis. DGF occurred in 121 (30%) of 404 participants in the balanced crystalloid group versus 160 (40%) of 403 in the saline group (adjusted relative risk 0·74 [95% CI 0·66 to 0·84; p<0·0001]; adjusted risk difference 10·1% [95% CI 3·5 to 16·6]). In the safety analysis, numbers of investigator-reported serious adverse events were similar in both groups, being reported in three (<1%) of 406 participants in the balanced crystalloid group versus five (1%) of 409 participants in the saline group (adjusted risk difference -0·5%, 95% CI -1·8 to 0·9; p=0·48).

INTERPRETATION

Among patients receiving a deceased donor kidney transplant, intravenous fluid therapy with balanced crystalloid solution reduced the incidence of DGF compared with saline. Balanced crystalloid solution should be the standard-of-care intravenous fluid used in deceased donor kidney transplantation.

FUNDING

Medical Research Future Fund and National Health and Medical Research Council (Australia), Health Research Council (New Zealand), Royal Australasian College of Physicians, and Baxter.

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 .