The Neglectable Impact of Delayed Graft Function on Long-term Graft Survival in Kidneys Donated After Circulatory Death Associates With Superior Organ Resilience

The differential impact of early graft dysfunction in kidney donation after brain death and after circulatory death: Insights from the Dutch National Transplant Registry

Kidneys donated after circulatory death (DCD) perform similarly to kidneys donated after brain death (DBD). However, the respective incidences of delayed graft function (DGF) differ. This questions the donor type-specific impact of early graft function on long-term outcomes. Using competing risk and Cox-regression analysis, we compared death-censored graft loss between types of early graft function: DGF (temporary dialysis dependency started within 7 days after transplantation), slow graft function (3-day plasma creatinine decline less than 10% per day), and immediate graft function. In 1061 DBD and 1605 DCD graft recipients (January 2014 until January 2023), graft survival was similar. DGF was associated with death-censored graft loss in DBD and DCD (adjusted hazard ratios: DGF in DBD: 1.79 [1.04-2.91], P = .027, DGF in DCD: 1.84 [1.18-2.87], P = .008; Reference: no DGF). Slow graft function was associated with death-censored graft loss in DBD, but not significantly in DCD (adjusted hazard ratios DBD: 2.82 (1.34-5.93), P = .007, and DCD: 1.54 (0.72-3.35), P = .262; Reference: immediate graft function). Early graft dysfunction has a differential impact on graft outcome in DBD and DCD. The differences between DBD and DCD should be accounted for in research and the clinic.

Complement in Kidney Transplantation

Transplantation is the treatment of choice in most patients with kidney failure. The complement system plays a vital role in transplantation. The complement system forms a major part of innate immunity and acts as a bridge between innate and acquired immunity. Many diseases, particularly concerning the kidneys, result from complement system dysregulation, like atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathy (C3GN), systemic lupus erythematosus (SLE and some other immune complex diseases. The complement system activation is a very important part of post-transplant events like ischemia-reperfusion injury (IRI), delayed graft function (DGF), antibody-mediated rejection (ABMR) and thrombotic microangiopathy (TMA). A better understanding of the complement cascade can help to plan strategies to prevent and manage complement-related problems before and after kidney transplantation. Many newer molecules are either being developed or in the pipeline, which target the complement system at various stages. These novel therapeutics are now considered additional measures to improve graft survival. This review summarises the complement cascade, its role in kidney diseases and kidney transplantation, and possible areas of target and novel therapeutics.

Global trends of delayed graft function in kidney transplantation from 2013 to 2023: a bibliometric analysis

Delayed graft function (DGF) is an early complication after kidney transplantation. The literature on DGF has experienced substantial growth. However, there is a lack of bibliometric analysis of DGF. This study aimed to analyze the scientific outputs of DGF and explore its hotspots from 2013 to 2023 by using CiteSpace and VOSviewer. The 2058 pieces of literature collected in the Web of Science Core Collection (WOSCC) from 1 January 2013 to 31 December 2023 were visually analyzed in terms of the annual number of publications, authors, countries, journals, literature co-citations, and keyword clustering by using CiteSpace and VOSviewer. We found that the number of papers published in the past ten years showed a trend of first increasing and then decreasing; 2021 was the year with the most posts. The largest number of papers was published by the University of California System, and the largest number of papers was published by the United States. The top five keyword frequency rankings are: 'delayed graft function', 'kidney transplantation', 'renal transplantation', 'survival', and 'recipients'. These emerging trends include 'brain death donors', 'blood absence re-injection injuries', 'tacrolimus', 'older donors and recipients', and 'artificial intelligence and DGF'. In summary, this study reveals the authors and institutions that could be cooperated with and discusses the research hotspots in the past ten years. It provides a reference and direction for future research and application of DGF.

Diagnostic and Prognostic Value of Machine Perfusion Biomarkers in Kidney Graft Evaluation

BACKGROUND

With the rising prevalence of end-stage kidney disease, the use of expanded criteria donor allografts, seen as essential for meeting organ demand, still proves challenging due to their higher risk of graft loss, delayed function, and rejection. Machine perfusion, a technique in preserving allografts, offers improved allograft outcomes compared to static cold storage while allowing for the noninvasive measurement of kidney injury biomarkers in the perfusate solution. This offers an objective method to assess graft function at various preservation stages.

MATERIALS AND METHODS

We conducted a narrative review of the databases PubMed and Scopus, including studies written in the English language and published after 2010.

RESULTS

In this narrative review, we identified biomarkers, like 4-hydroxyproline, taurine, and glutathione transferase, as predictive markers of delayed graft function. Additionally, biomarkers, like extracellular histone h3, vascular cell adhesion protein, and matrix metalloprotease protein, have shown correlation with decreased graft function, although their predictive ability remains inconclusive.

DISCUSSION

The review outlines various suggestions for potential areas of research focus to enhance future expanded criteria donor allograft utilization. However, limitations exist, including the absence of a singular reliable biomarker and the challenges of validating biomarker effectiveness across diverse outcomes.

Perfusion Techniques in Kidney Allograft Preservation to Reduce Ischemic Reperfusion Injury: A Systematic Review and Meta-Analysis

The limited supply and rising demand for kidney transplantation has led to the use of allografts more susceptible to ischemic reperfusion injury (IRI) and oxidative stress to expand the donor pool. Organ preservation and procurement techniques, such as machine perfusion (MP) and normothermic regional perfusion (NRP), have been developed to preserve allograft function, though their long-term outcomes have been more challenging to investigate. We performed a systematic review and meta-analysis to examine the benefits of MP and NRP compared to traditional preservation techniques. PubMed (MEDLINE), Embase, Cochrane, and Scopus databases were queried, and of 13,794 articles identified, 54 manuscripts were included (n = 41 MP; n = 13 NRP). MP decreased the rates of 12-month graft failure (OR 0.67; 95%CI 0.55, 0.80) and other perioperative outcomes such as delayed graft function (OR 0.65; 95%CI 0.54, 0.79), primary nonfunction (OR 0.63; 95%CI 0.44, 0.90), and hospital length of stay (15.5 days vs. 18.4 days) compared to static cold storage. NRP reduced the rates of acute rejection (OR 0.48; 95%CI 0.35, 0.67) compared to in situ perfusion. Overall, MP and NRP are effective techniques to mitigate IRI and play an important role in safely expanding the donor pool to satisfy the increasing demands of kidney transplantation.

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.

British Transplantation Society guidelines on abdominal organ transplantation from deceased donors after circulatory death

The British Transplantation Society (BTS) 'Guideline on transplantation from deceased donors after circulatory death' has recently been updated and this manuscript summarises the relevant recommendations in abdominal organ transplantation from Donation after Circulatory Death (DCD) donors, encompassing the chapters on liver, kidney, pancreas and islet cell transplantation.

How to Best Protect Kidneys for Transplantation-Mechanistic Target

The increasing number of patients on the kidney transplant waiting list underlines the need to expand the donor pool and improve kidney graft utilization. By protecting kidney grafts adequately from the initial ischemic and subsequent reperfusion injury occurring during transplantation, both the number and quality of kidney grafts could be improved. The last few years have seen the emergence of many new technologies to abrogate ischemia-reperfusion (I/R) injury, including dynamic organ preservation through machine perfusion and organ reconditioning therapies. Although machine perfusion is gradually making the transition to clinical practice, reconditioning therapies have not yet progressed from the experimental setting, pointing towards a translational gap. In this review, we discuss the current knowledge on the biological processes implicated in I/R injury and explore the strategies and interventions that are being proposed to either prevent I/R injury, treat its deleterious consequences, or support the reparative response of the kidney. Prospects to improve the clinical translation of these therapies are discussed with a particular focus on the need to address multiple aspects of I/R injury to achieve robust and long-lasting protective effects on the kidney graft.

Role of post-transplant graft scintigraphy in kidney donation after circulatory death

Background

There is no consensus on how to predict post-transplant function of donation after circulatory death (DCD) kidneys. Thus, we aimed to identify renal scintigraphy parameters that could predict 1-year kidney function.

Methods

In this single center study, we included all consecutive DCD kidney recipients between 2013 and 2021 (n = 29). Patients who did not have a scintigraphy within 10 days of transplantation (n = 3), recipients of multiple organs and less than 18 years old were excluded (n = 1). Primary endpoint was the estimated glomerular filtration rate (eGFR).

Results

Median eGFR and serum creatinine at 1 year were 67 µmol/L (56-81) and 111 ml/min (99-132), respectively. Among parameters tested, the 3rd/2nd-minute activity ratio had the best diagnostic performance (AUC: 0.74 and 0.71, for eGFR and creatinine) 1 year post transplantation. Using 1.21 as the best cut off, the 3rd/2nd-minute activity ratio specificity and sensitivity to predict eGFR >60 ml/min was 0.82 and 0.83. Renal function was significantly better at 1 week, 3, 6, and 12 months after transplantation in patients with 3rd/2nd-minute activity ratios above 1.21.

Conclusion

This study suggests that the 3rd/2nd-minute activity ratio can predict graft function at 1 year. The benefit of post-transplant scintigraphy should be further validated in a prospective cohort.

[Association between controlled circulatory death donor waitlisting and waiting time before kidney transplantation in a French center]

INTRODUCTION

Transplantation from controlled donation after circulatory determination of death (cDCD) is a new practice in France. An additional specific consent is required for registration on the cDCD waiting list. The aim of this study is to evaluate the impact of cDCD acceptance on the waiting time for the registered patients on the transplant list.

METHODS

Patients registered on the kidney transplant waiting list for a Death Brain Donor (DBD) kidney transplant between 2018 and 2019 in our center were included. Patients who were candidates for a second kidney transplant or who had already received an organ transplant were not included. The cDCD waiting list registration was authorized by a signed consent of the patient on the day of DBD registration. The primary endpoint was time to renal transplantation.

RESULTS

Of the 315 patients eligible for a cDCD graft at transplant list registration, 152 were registered on the cDCD waiting list. Time to transplantation for these patients was multiplied by 1.42 (95%CI 1.07-1.87) compared with patients not registered for a cDCD graft. The time to transplantation was 2.59 months (95%CI 0.49-4.69) shorter for a 2-year follow-up for cDCD-listed patients. This represents one additional transplant at 6 months for every seven registered patients.

CONCLUSION

cDCD waiting list registration reduced the time to kidney transplantation in France.

Presence of CD163+ macrophages in DCD kidneys with high DGF reduces the risk for acute cellular rejection in 6 months after kidney transplantation

Acute cellular rejection (ACR) occurs in 10% of renal allograft recipients and is characterized by leukocyte infiltration as observed in needle biopsies. ACR onset is subject to several risk factors, including delayed graft function (DGF). As the impact of DGF on the etiology of ACR remains unclear, this study analyzed the association between presence of leukocyte subsets and ACR onset, in DCD kidney biopsies with extensive DGF following transplantation. Immunohistochemical analysis of protocol biopsies taken 10 days after kidney transplantation revealed that patients with high levels of renal CD163⁺ macrophages have a decreased risk (OR = 0.021, P = 0.008) for ACR in the first 6 months after transplantation. In pre-transplant biopsies of a comparable DCD cohort, with >80% DGF, presence of donor CD163+ macrophages showed no effect on ACR risk. Therefore, leukocyte infiltrate present during the inflammatory response at the time of DGF may contain anti-inflammatory macrophages that exert a protective effect against ACR development.

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.

Causes of Kidney Graft Failure in a Cohort of Recipients With a Very Long-Time Follow-Up After Transplantation

Background

Biopsy-proven causes of graft loss many years after kidney transplantation are scarcely documented.

Methods

Patients transplanted between 1995 and 2005 (n = 737) in a single center were followed on a regular basis until 2021. The recipients were divided according to age at transplantation into 3 groups; 18–39 years (young), 40–55 years (middle age), and older than 55 years (elderly). For cause biopsies of renal transplants were clustered into the categories, rejection, IFTA, return original disease, and diagnosis of de novo kidney disease.

Results

Rejection was the main cause of graft failure censored for death at every time period after transplantation. The incidence of T cell-mediated rejection (TCMR) became rare 6 years after transplantation while the cumulative incidence of antibody-mediated rejection (ABMR) increased over time (1.1% per year). ABMR was not diagnosed anymore beyond 15 years of follow-up in recipients without pre-transplant donor-specific antibodies (DSA). An episode of TCMR was associated with an increased incidence of ABMR diagnosis in the short-term but did not increase the overall incidence of AMBR not in the long-term. Death as a cause of graft failure was an important competitive risk factor long after transplantation and resulted in a significantly lower frequency of rejection-related graft loss in the elderly group (11 vs. 23% in the young group at 15 year follow-up).

Conclusion

Rejection is a major cause of graft loss but recipient’s age, time after transplantation, and the presence of DSA before transplantation determine the relative contribution to overall graft loss and the type of rejection involved.

Duration of delayed graft function and its impact on graft outcomes in deceased donor kidney transplantation

BACKGROUND

There is controversy regarding the impact of delayed graft function (DGF) on kidney transplant outcomes. We hypothesize that the duration of DGF, rather than DGF itself, is associated with long-term kidney graft function.

METHODS

We analyzed all deceased donor kidney transplants (DDKT) done at our center between 2008 to 2020. We determined factors associated with DGF duration. DGF duration was assessed at three 14-day intervals: < 14 DGF days, 14-27 DGF days, > 28 DGF days. We studied the impact of DGF duration on survival and graft function and resource utilization, including hospital length of stay and readmissions.

RESULTS

1714 DDKT recipients were included, 59.4% (n = 1018) had DGF. The median DGF duration was 10 days IQR (6,15). The majority of recipients (95%) had resolution of DGF within 28 days. Donor factors associated with DGF days were longer cold ischemia time, donor on inotropes, older age, donation after circulatory death, higher terminal creatinine, and hypertension. Recipient factors associated with increased DGF duration included male sex, length on dialysis before transplant, and higher body mass index. There were no differences in acute rejection events or interstitial fibrosis progression by 4 months when comparing DGF days. The median length of stay was 3 days. However, readmissions increased with increasing DGF duration. Death-censored graft survival was not associated with the length of DGF except when DGF lasted > 28 days.

CONCLUSIONS

Inferior graft survival was observed only in recipients of DDKT with DGF lasting beyond 28 days. DGF lasting < 28 days had no impact on graft survival. Duration of DGF, rather than DGF itself, is associated with graft survival.

TRIAL REGISTRATION

Retrospective study approved by Mayo Clinic IRB number ID: 20-011561.

Survival Benefit of Donation After Circulatory Death Kidney Transplantation in Children Compared With Remaining on the Waiting List for a Kidney Donated After Brain Death

BACKGROUND

Kidneys donated after circulatory death (DCD) are increasingly being used for transplantation in adults to alleviate organ shortage. Pediatric data on survival benefits of DCD transplantation compared with remaining on the waitlist for a kidney donated after brain death (DBD) offer are lacking.

METHODS

We used Scientific Registry of Transplant Recipients to identify 285 pediatric (<18 y) DCD kidney transplants performed between 1987 and 2017. Propensity score matching was used to create a comparison group of 1132 DBD transplants. We used sequential Cox analysis to evaluate survival benefit of DCD transplantation versus remaining on the waitlist and Cox regression to evaluate patient and graft survival.

RESULTS

DCD transplantation was associated with a higher incidence of delayed graft function (adjusted odds ratio: 3.0; P < 0.001). The risks of graft failure (adjusted hazard ratio [aHR], 0.89; P = 0.46) and death (aHR, 1.2; P = 0.67) were similar between DCD and DBD recipients. We found a significant survival benefit of DCD transplantation compared with remaining on the waitlist awaiting a DBD kidney (aHR, 0.44; P = 0.03).

CONCLUSIONS

Despite a higher incidence of delayed graft function, long-term patient and graft survival are similar between pediatric DCD and DBD kidney transplant recipients. DCD transplantation in children is associated with a survival benefit, despite pediatric priority for organ allocation, compared with remaining on the waitlist.

Kidney transplant outcomes in elderly recipients with controlled donation after circulatory death or donation after brain death donors: a registry cohort study

The number of kidney transplant (KT) procedures with controlled donation after circulatory death (cDCD) donors has exponentially increased in Spain in recent years, with a parallel increase in donor and recipient acceptance criteria. The outcomes of cDCD-KT have been reported to be comparable to those of KT with donation after brain death (DBD) donors. However, studies in elderly recipients have yielded contradictory results. We performed a registry analysis of 852 KT recipients aged ≥65 years (575 in the DBD-KT group, 277 in the cDCD-KT group) in Catalonia, Spain. Clinical outcomes and survival were compared between DBD-KT and cDCD-KT recipients. The donor and recipient ages were similar between the two groups (71.5 ± 8.7 years for donors, 70.8 ± 4.1 years for recipients). Delayed graft function (DGF) was more frequent among cDCD-KT recipients, without a difference in the rate of primary nonfunction. The 3-year patient and death-censored graft survival rates were similar between DBD-KT and cDCD-KT recipients (78.8% vs. 76.4% and 90.3% vs. 86.6%, respectively). In multivariable analysis, previous cardiovascular disease and DGF were independent risk factors for patient death. The type of donation (cDCD vs. DBD) was not an independent risk factor for patient survival or graft loss. cDCD-KT and DBD-KT provide comparable patient and graft survival in elderly recipients.

Effect of delayed graft function on longer-term outcomes after kidney transplantation from donation after circulatory death donors in the United Kingdom: A national cohort study

Kidneys from donation after circulatory death (DCD) donors are utilized variably worldwide, in part due to high rates of delayed graft function (DGF) and putative associations with adverse longer-term outcomes. We aimed to determine whether the presence of DGF and its duration were associated with poor longer-term outcomes after kidney transplantation from DCD donors. Using the UK transplant registry, we identified 4714 kidney-only transplants from controlled DCD donors to adult recipients between 2006 and 2016; 2832 recipients (60·1%) had immediate graft function and 1882 (39·9%) had DGF. Of the 1847 recipients with DGF duration recorded, 926 (50·1%) had DGF < 7 days, 576 (31·2%) had DGF 7-14 days, and 345 (18·7%) had DGF >14 days. After risk adjustment, the presence of DGF was not associated with inferior long-term graft or patient survivals. However, DGF duration of >14 days was associated with an increased risk of death-censored graft failure (hazard ratio 1·7, p = ·001) and recipient death (hazard ratio 1·8, p < ·001) compared to grafts with immediate function. This study suggests that shorter periods of DGF have no adverse influence on graft or patient survival after DCD donor kidney transplantation and that DGF >14 days is a novel early biomarker for significantly worse longer-term outcomes.

Donor-Recipient BSA Matching Is Prognostically Significant in Solitary and En Bloc Kidney Transplantation From Pediatric Circulatory Death Donors

Background.

As the rate of early postoperative complications decline after transplant with pediatric donation after circulatory death (DCD) kidneys, attention has shifted to the long-term consequences of donor–recipient (D-R) size disparity given the pernicious systemic effects of inadequate functional nephron mass.

Methods.

We conducted a retrospective cohort study using Organ Procurement and Transplantation Network data for all adult (aged ≥18 y) recipients of pediatric (aged 0–17 y) DCD kidneys in the United States from January 1, 2004 to March 10, 2020.

Results.

DCD pediatric allografts transplanted between D-R pairs with a body surface area (BSA) ratio of 0.10–0.70 carried an increased risk of all-cause graft failure (relative risk [RR], 1.36; 95% confidence interval [CI], 1.10–1.69) and patient death (RR, 1.32; 95% CI, 1.01–1.73) when compared with pairings with a ratio of >0.91. Conversely, similar graft and patient survivals were demonstrated among the >0.70–0.91 and >0.91 cohorts. Furthermore, we found no difference in death-censored graft survival between all groups. Survival analysis revealed improved 10-y patient survival in recipients of en bloc allografts (P = 0.02) compared with recipients of single kidneys with D-R BSA ratios of 0.10–0.70. A similar survival advantage was demonstrated in recipients of solitary allografts with D-R BSA ratios >0.70 compared with the 0.10–0.70 cohort (P = 0.02).

Conclusions.

Inferior patient survival is likely associated with systemic sequelae of insufficient renal functional capacity in size-disparate DCD kidney recipients, which can be overcome by appropriate BSA matching or en bloc transplantation. We therefore suggest that in DCD kidney transplantation, D-R BSA ratios of 0.10–0.70 serve as criteria for en bloc allocation or alternative recipient selection to optimize the D-R BSA ratio to >0.70.

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.

Implementation of donation after circulatory death kidney transplantation can safely enlarge the donor pool: A systematic review and meta-analysis

BACKGROUND

Donation after circulatory death (DCD) kidney transplantation has been introduced to address organ shortage. However, DCD kidneys are not accepted worldwide due to concerns about inferior quality. To investigate whether these concerns are justified, we performed a systematic review and meta-analysis to investigate DCD graft outcomes compared to donation after brain death (DBD).

MATERIALS AND METHODS

EMBASE, Medline, Cochrane, Web of Science and Google Scholar were searched from database inception until September 2020. Exclusion criteria were studies reporting on pediatric/dual kidney transplants, multi-organ transplants or studies including normothermic perfusion techniques. The primary outcome was graft survival. Secondary outcomes were primary non-function (PNF), delayed graft function (DGF), 3-months biopsy-proven acute rejection (BPAR), 1-year estimated Glomerular Filtration Rate (eGFR), patient survival, and urologic complications. A random-effects model was used for meta-analysis. Meta-regression analysis was performed in case of high between-study heterogeneity.

RESULTS

Fifty-one studies were included, comprising 73,454 DCD and 518,229 DBD recipients. One-year graft loss was increased in DCD recipients (death-censored: risk ratio (RR) 1.10 (95%-confidence interval (CI) 1.04-1.16), all-cause: RR 1.13 (95%-CI 1.08-1.19)). Ten-year graft loss was similar to DBD (death-censored: RR 1.02 (95%-CI 0.92-1.13), all-cause: RR 1.03 (95%-CI 0.94-1.13)). DCD recipients had an increased risk of PNF (RR 1.43 (95%-CI 1.26-1.62)), DGF (RR 2.02 (95%-CI 1.88-2.16)), and 1-year mortality (RR 1.10 (95%-CI 1.01-1.21)). No differences were observed for 3-months BPAR, ureter stenosis/leakage, 1-year eGFR and 10-year mortality.

CONCLUSION

Long-term DCD kidney transplant outcomes are similar to DBD despite a higher risk of PNF, DGF, and a 13% increased risk of graft loss in the first year after transplantation. These results should encourage implementation of DCD programs.

Donation after circulatory death is associated with increased fibrosis on 1-year post-transplant kidney allograft surveillance biopsy

AIM

The use of kidneys donated after circulatory death (DCD) provides an invaluable expansion of the organ supply for transplantation. Here, we investigated the effect of DCD on fibrotic changes on 1 1-year post 1-transplant surveillance kidney allograft biopsy.

METHODS

Recipients of a deceased donor kidney transplant between 2013 and 2017 at a single institution, who survived 1 year and underwent surveillance biopsy, were included in the analysis (n = 333: 87 DCD kidneys, 246 kidneys donated after brain death [DBD]). Banff scores for interstitial fibrosis and tubular atrophy were summed as IFTA and compared between the groups.

RESULTS

DCD and DBD groups were comparable for baseline characteristics. Delayed graft function was 39% in DCD versus 19% in DBD, P = .0002. Patient and graft survival were comparable for DCD and DBD cohorts. IFTA scores were higher in DCD compared to DBD (2.43±..13 vs. 2.01±..08, P = .0054). On multivariate analysis, the odds of IFTA > 2 in the DCD group was 2.5× higher (95%CI: 1.354.63) than in the DBD group. Within the DCD group, kidneys with IFTA > 2 had inferior 5-year graft survival (P = .037).

CONCLUSION

Compared to DBD kidneys, DCD kidneys developed a greater degree of fibrotic changes on 1-year post-transplant surveillance biopsy, which affected graft longevity within the DCD cohort.

Systemic Complement Activation in Donation After Brain Death Versus Donation After Circulatory Death Organ Donors

OBJECTIVES

Complement activation in organs from deceased donors is associated with allograft injury and acute rejection. Because use of organs from donors after circulatory death is increasing, we characterized relative levels of complement activation in organs from donors after brain death and after circulatory death and examined associations between donor complement factor levels and outcomes after kidney and liver transplant.

MATERIALS AND METHODS

Serum samples from 65 donors (55 donations after brain death, 10 donations after circulatory death) were analyzed for classical, lectin, alternative, and terminal pathway components by Luminex multiplex assays. Complement factor levels were compared between groups, and associations with posttransplant outcomes were explored.

RESULTS

Serum levels of the downstream complement activation product C5a were similar in organs from donors after circulatory death versus donors after brain death. In organs from donors after circulatory death, complement activation occurred primarily via the alternative pathway; the classical, lectin, and alternative pathways all contributed in organs from donors after brain death. Donor complement levels were not associated with outcomes after kidney transplant. Lower donor complement levels were associated with need for transfusion, reintervention, hospital readmission, and acute rejection after liver transplant.

CONCLUSIONS

Complement activation occurs at similar levels in organs donated from donors after circulatory death versus those after brain death. Lower donor complement levels may contribute to adverse outcomes after liver transplant. Further study is warranted to better understand how donor complement activation contributes to posttransplant outcomes.

Metabolic needs of the kidney graft undergoing normothermic machine perfusion

Normothermic machine perfusion (NMP) is emerging as a novel preservation strategy. During NMP, the organ is maintained in a metabolically active state that may not only provide superior organ preservation, but that also facilitates viability testing before transplantation, and ex situ resuscitation of marginal kidney grafts. Although the prevailing perfusion protocols for renal NMP are refined from initial pioneering studies concerning short periods of NMP, it could be argued that these protocols are not optimally tailored to address the putatively compromised metabolic plasticity of marginal donor grafts (i.e., in the context of viability testing and/or preservation), or to meet the metabolic prerequisites associated with prolonged perfusions and the required anabolic state in the context of organ regeneration. Herein, we provide a theoretical framework for the metabolic requirements for renal NMP. Aspects are discussed along the lines of carbohydrates, fatty acids, amino acids, and micronutrients required for optimal NMP of an isolated kidney. In addition, considerations for monitoring aspects of metabolic status during NMP are discussed.

Safety and feasibility of 2 h of normothermic machine perfusion of donor kidneys in the Eurotransplant Senior Program

Background

The 5-year graft survival rate of donor kidneys transplanted in the Eurotransplant Senior Program (ESP) is only 47 per cent. Normothermic machine perfusion (NMP) may be a new preservation technique that improves graft outcome. This pilot study aimed to assess safety and feasibility of this technique within the ESP.

Methods

Recipients were eligible for inclusion if they received a donor kidney within the ESP. Donor kidneys underwent 2 h of oxygenated NMP with a red cell-based solution at 37°C, additional to standard-of-care preservation (non-oxygenated hypothermic machine perfusion). The primary outcome was the safety and feasibility of NMP. As a secondary outcome, graft outcome was investigated and compared with that in a historical group of patients in the ESP and the contralateral kidneys.

Results

Eleven patients were included in the NMP group; the function of eight kidneys could be compared with that of the contralateral kidney. Fifty-three patients in the ESP, transplanted consecutively between 2016 and 2018, were included as controls. No adverse events were noted, especially no arterial thrombosis or primary non-function of the transplants. After 120 min of oxygenated NMP, median flow increased from 117 (i.q.r. 80–126) to 215 (170–276) ml/min (P = 0.001). The incidence of immediate function was 64 per cent in the NMP group and 40 per cent in historical controls (P = 0.144). A significant difference in graft outcome was not observed.

Discussion

This pilot study showed NMP to be safe and feasible in kidneys transplanted in the ESP. A well powered study is warranted to confirm these results and investigate the potential advantages of NMP on graft outcome.

Oxygenated versus standard cold perfusion preservation in kidney transplantation (COMPARE): a randomised, double-blind, paired, phase 3 trial

BACKGROUND

Deceased donor kidneys are preserved in cold hypoxic conditions. Providing oxygen during preservation might improve post-transplant outcomes, particularly for kidneys subjected to greater degrees of preservation injury. This study aimed to investigate whether supplemental oxygen during hypothermic machine perfusion (HMP) could improve the outcome of kidneys donated after circulatory death.

METHODS

This randomised, double-blind, paired, phase 3 trial was done in 19 European transplant centres. Kidney pairs from donors aged 50 years or older, donated after circulatory death, were eligible if both kidneys were transplanted into two different recipients. One kidney from each donor was randomly assigned using permuted blocks to oxygenated hypothermic machine perfusion (HMPO2), the other to HMP without oxygenation. Perfusion was maintained from organ retrieval to implantation. The primary outcome was 12-month estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration equation in pairs of donated kidneys in which both transplanted kidneys were functioning at the end of follow-up. Safety outcomes were reported for all transplanted kidneys. Intention-to-treat analyses were done. This trial is registered with the ISRCTN Registry, ISRCTN32967929, and is now closed.

FINDINGS

Between March 15, 2015, and April 11, 2017, 197 kidney pairs were randomised with 106 pairs transplanted into eligible recipients. 23 kidney pairs were excluded from the primary analysis because of kidney failure or patient death. Mean eGFR at 12 months was 50·5 mL/min per 1·73 m2 (SD 19·3) in the HMPO2 group versus 46·7 mL/min per 1·73m2 (17·1) in HMP (mean difference 3·7 mL/min per 1·73m2, 95% CI -1·0 to 8·4; p=0·12). Fewer severe complications (Clavien-Dindo grade IIIb or more) were reported in the HMPO2 group (46 of 417, 11%, 95% CI 8% to 14%) than in the HMP group (76 of 474, 16%, 13% to 20%; p=0·032). Graft failure was lower with HMPO2 (three [3%] of 106) compared with HMP (11 [10%] of 106; hazard ratio 0·27, 95% CI 0·07 to 0·95; p=0·028).

INTERPRETATION

HMPO2 of kidneys donated after circulatory death is safe and reduces post-transplant complications (grade IIIb or more). The 12-month difference in eGFR between the HMPO2 and HMP groups was not significant when both kidneys from the same donor were still functioning 1-year post-transplant, but potential beneficial effects of HMPO2 were suggested by analysis of secondary outcomes.

FUNDING

European Commission 7th Framework Programme.

Food as medicine: targeting the uraemic phenotype in chronic kidney disease

The observation that unhealthy diets (those that are low in whole grains, fruits and vegetables, and high in sugar, salt, saturated fat and ultra-processed foods) are a major risk factor for poor health outcomes has boosted interest in the concept of 'food as medicine'. This concept is especially relevant to metabolic diseases, such as chronic kidney disease (CKD), in which dietary approaches are already used to ameliorate metabolic and nutritional complications. Increased awareness that toxic uraemic metabolites originate not only from intermediary metabolism but also from gut microbial metabolism, which is directly influenced by diet, has fuelled interest in the potential of 'food as medicine' approaches in CKD beyond the current strategies of protein, sodium and phosphate restriction. Bioactive nutrients can alter the composition and metabolism of the microbiota, act as modulators of transcription factors involved in inflammation and oxidative stress, mitigate mitochondrial dysfunction, act as senolytics and impact the epigenome by altering one-carbon metabolism. As gut dysbiosis, inflammation, oxidative stress, mitochondrial dysfunction, premature ageing and epigenetic changes are common features of CKD, these findings suggest that tailored, healthy diets that include bioactive nutrients as part of the foodome could potentially be used to prevent and treat CKD and its complications.

Results of an explorative clinical evaluation suggest immediate and persistent post-reperfusion metabolic paralysis drives kidney ischemia reperfusion injury

Delayed graft function is the manifestation of ischemia reperfusion injury in the context of kidney transplantation. While hundreds of interventions successfully reduce ischemia reperfusion injury in experimental models, all clinical interventions have failed. This explorative clinical evaluation examined possible metabolic origins of clinical ischemia reperfusion injury combining data from 18 pre- and post-reperfusion tissue biopsies with 36 sequential arteriovenous blood samplings over the graft in three study groups. These groups included living and deceased donor grafts with and without delayed graft function. Group allocation was based on clinical outcome. Magic angle NMR was used for tissue analysis and mass spectrometry-based platforms were used for plasma analysis. All kidneys were functional at one-year. Integration of metabolomic data identified a discriminatory profile to recognize future delayed graft function. This profile was characterized by post-reperfusion ATP/GTP catabolism (significantly impaired phosphocreatine recovery and significant persistent (hypo)xanthine production) and significant ongoing tissue damage. Failing high-energy phosphate recovery occurred despite activated glycolysis, fatty-acid oxidation, glutaminolysis and autophagia, and related to a defect at the level of the oxoglutarate dehydrogenase complex in the Krebs cycle. Clinical delayed graft function due to ischemia reperfusion injury associated with a post-reperfusion metabolic collapse. Thus, efforts to quench delayed graft function due to ischemia reperfusion injury should focus on conserving metabolic competence, either by preserving the integrity of the Krebs cycle and/or by recruiting metabolic salvage pathways.

Improving outcomes for donation after circulatory death kidney transplantation: Science of the times

The use of kidneys donated after circulatory death (DCD) remains controversial due to concerns with regard to high incidences of early graft loss, delayed graft function (DGF), and impaired graft survival. As these concerns are mainly based on data from historical cohorts, they are prone to time-related effects and may therefore not apply to the current timeframe. To assess the impact of time on outcomes, we performed a time-dependent comparative analysis of outcomes of DCD and donation after brain death (DBD) kidney transplantations. Data of all 11,415 deceased-donor kidney transplantations performed in The Netherlands between 1990–2018 were collected. Based on the incidences of early graft loss, two eras were defined (1998–2008 [n = 3,499] and 2008–2018 [n = 3,781]), and potential time-related effects on outcomes evaluated. Multivariate analyses were applied to examine associations between donor type and outcomes. Interaction tests were used to explore presence of effect modification. Results show clear time-related effects on posttransplant outcomes. The 1998–2008 interval showed compromised outcomes for DCD procedures (higher incidences of DGF and early graft loss, impaired 1-year renal function, and inferior graft survival), whereas DBD and DCD outcome equivalence was observed for the 2008–2018 interval. This occurred despite persistently high incidences of DGF in DCD grafts, and more adverse recipient and donor risk profiles (recipients were 6 years older and the KDRI increased from 1.23 to 1.39 and from 1.35 to 1.49 for DBD and DCD donors). In contrast, the median cold ischaemic period decreased from 20 to 15 hours. This national study shows major improvements in outcomes of transplanted DCD kidneys over time. The time-dependent shift underpins that kidney transplantation has come of age and DCD results are nowadays comparable to DBD transplants. It also calls for careful interpretation of conclusions based on historical cohorts, and emphasises that retrospective studies should correct for time-related effects.

A systematic review to identify whether perfusate biomarkers produced during hypothermic machine perfusion can predict graft outcomes in kidney transplantation

There is good evidence to support the use of hypothermic machine perfusion (HMP) over static cold storage as the favoured preservation method for deceased donor kidneys. However, the utility of HMP as a tool to assess the viability of kidneys for transplant is unclear. There is a need to determine whether perfusate biomarkers produced during HMP can predict post-transplant outcomes and assess the suitability of organs for transplantation. Three different databases (MEDLINE, Embase, Transplant Library) were screened to 31 May 2019. Articles were included if a relationship was reported between one or more perfusate biomarkers and post-transplant outcomes. Studies were assessed and graded for methodological quality and strength of evidence. Glutathione S-transferase was the most promising biomarker for predicting delayed graft function, but its predictive ability was at best moderate. Analysis of primary nonfunction rates was challenging due to low occurrence rates and small sample sizes. Existing studies are limited in quality and have not yielded biomarkers for kidneys undergoing HMP that are able to predict post-transplant outcomes with sufficient accuracy to support routine clinical use. Further studies with larger samples and more robust methodology are needed. (PROSPERO registration: CRD42019121161).