Outcome of kidney transplantation using expanded criteria donors and donation after cardiac death kidneys: realities and costs

Cortex kidney tissue partial oxygen pressure depends on percentage of active oxygenation during oxygenated hypothermic machine perfusion

BACKGROUND

Preclinical and clinical studies have demonstrated the advantages of oxygenated hypothermic machine perfusion (HMPO2) during kidney preservation. However, the optimal oxygenation levels during HMPO2 remain undetermined. The aim of this study was to compare different levels of oxygenation (0%, 21%, 50%, and 100%) during 22 h of active oxygenated HMP (HMPO2) using oxygen preloading by bubbling oxygenation in the preservation solution and continuous surface oxygenation during MP in a porcine DCD model.

METHODS

After 60 min of warm ischemia time, both kidneys of an 80 kg pig were procured and randomized to one of the following groups: (1) 22-h static cold storage (n = 6), (2) 22-h HMP without active oxygenation (n = 6), (3) 22-h HMPO2 21% O2 (n = 6), (4) 22-h HMPO2 50% O2 (n = 6), and (5) 22-h HMPO2 100% O2 (n = 6). The primary outcome measure was to compare the different oxygen levels among the different groups assessed by cortex kidney tissue oxygen partial pressures (tpO2).

RESULTS

Continuous HMPO2 resulted in a significant modification of cortex kidney tpO2. In addition, tpO2 was dependent on the percentage of oxygenation. One hundred percent oxygen resulted in a significantly higher tpO2 compared to all other study groups. In line with that, ATP resynthesis was significantly higher in the HMPO2 100% group.

CONCLUSIONS

This study demonstrates that continuous HMPO2 results in a significant modification of tpO2 compared with SCS, and the degree of tpO2 is positively correlated with the percentage of active oxygenation during HMP. Metabolic profile analyses (ATP resynthesis) suggest that the aerobic mechanism is better supported with higher oxygen levels (50% and 100% oxygenation).

Assessment of biological organ age using molecular pathology in pre-transplant kidney biopsies

Organ shortage is a major challenge in kidney transplantation but the use of older donors, often with co-morbidities, is hampered by inconsistent outcomes. Methods of accurately stratifying marginal donor organs by clinical and histological assessment are lacking. To better understand organ variability, we profiled the transcriptomes of 271 kidneys from deceased donors at retrieval. Following correction for biopsy composition, we assessed molecular pathways that associated with delayed, and sub-optimal one-year graft function. Analysis of cortical biopsies identified an adaptive immune gene-rich module that significantly associated with increasing age and worse outcomes. Cellular deconvolution using human kidney reference single cell transcriptomes confirmed an increase in kidney-specific B and T cell signatures, as well as kidney macrophage, myofibroblast and fibroblast gene sets in this module. Surprisingly, innate immune pathway and neutrophil gene signature enrichment was associated with better outcomes. Thus, our work uncovers cellular molecular features of pathological organ ageing, identifiable at kidney retrieval, with translational potential.

The association between hemoglobin levels and renal function parameters during normothermic machine perfusion: A retrospective cohort study using porcine kidneys

BACKGROUND

Ex vivo normothermic machine perfusion (NMP) is a promising tool for assessing an isolated kidney prior to transplantation. However, there is no consensus on the perfusate's optimal oxygen-carrying capacity to support renal function. To investigate the association of hemoglobin levels with renal function parameters, a retrospective analysis of isolated, normothermically, perfused porcine kidneys was performed.

METHODS

Between 2015 and 2021, a total of 228 kidneys underwent 4 h of NMP with perfusates that varied in hemoglobin levels. A generalized linear model was used to determine the association of hemoglobin levels with time-weighted means of renal function markers, such as fractional sodium excretion (FENa) and creatinine clearance (CrCl). Stratified by baseline hemoglobin level (<4.5, 4.5-6, or >6 mmol/L), these markers were modeled over time using a generalized linear mixed-effects model. All models were adjusted for potential confounders.

RESULTS

Until a hemoglobin level of around 5 mmol/L was reached, increasing hemoglobin levels were associated with superior FENa and CrCl. Thereafter, this association plateaued. When hemoglobin levels were categorized, hemoglobin <4.5 mmol/L was associated with worse renal function. Hemoglobin levels were neither significantly associated with proteinuria during NMP nor with ATP levels at the end of NMP. Hemoglobin levels >6 mmol/L showed no additional benefits in renal function.

CONCLUSION

In conclusion, we found an association between baseline hemoglobin levels and superior renal function parameters, but not injury, during NMP of porcine kidneys. Furthermore, we show that performing a retrospective cohort study of preclinical data is feasible and able to answer additional questions, reducing the potential use of laboratory animals.

Delayed Graft Function and the Renin-angiotensin System

Delayed graft function (DGF) is a form of acute kidney injury (AKI) and a common complication following kidney transplantation. It adversely influences patient outcomes increases the financial burden of transplantation, and currently, no specific treatments are available. In developing this form of AKI, activation of the renin-angiotensin system (RAS) has been proposed to play an important role. In this review, we discuss the role of RAS activation and its contribution to the pathophysiology of DGF following the different stages of the transplantation process, from procurement and ischemia to transplantation into the recipient and including data from experimental animal models. Deceased kidney donors, whether during cardiac or brain death, may experience activation of the RAS. That may be continued or further potentiated during procurement and organ preservation. Additional evidence suggests that during implantation of the kidney graft and reperfusion in the recipient, the RAS is activated and may likely remain activated, extrapolating from other forms of AKI where RAS overactivity is well documented. Of particular interest in this setting is the status of angiotensin-converting enzyme 2, a key RAS enzyme essential for the metabolism of angiotensin II and abundantly present in the apical border of the proximal tubules, which is the site of predominant injury in AKI and DGF. Interventions aimed at safely downregulating the RAS using suitable shorter forms of angiotensin-converting enzyme 2 could be a way to offer protection against DGF.

Immune landscape of the kidney allograft in response to rejection

Preventing kidney graft dysfunction and rejection is a critical step in addressing the nationwide organ shortage and improving patient outcomes. While kidney transplants (KT) are performed more frequently, the overall number of patients on the waitlist consistently exceeds organ availability. Despite improved short-term outcomes in KT, comparable progress in long-term allograft survival has not been achieved. Major cause of graft loss at 5 years post-KT is chronic allograft dysfunction (CAD) characterized by interstitial fibrosis and tubular atrophy (IFTA). Accordingly, proactive prevention of CAD requires a comprehensive understanding of the immune mechanisms associated with either further dysfunction or impaired repair. Allograft rejection is primed by innate immune cells and carried out by adaptive immune cells. The rejection process is primarily facilitated by antibody-mediated rejection (ABMR) and T cell-mediated rejection (TCMR). It is essential to better elucidate the actions of individual immune cell subclasses (e.g. B memory, Tregs, Macrophage type 1 and 2) throughout the rejection process, rather than limiting our understanding to broad classes of immune cells. Embracing multi-omic approaches may be the solution in acknowledging these intricacies and decoding these enigmatic pathways. A transition alongside advancing technology will better allow organ biology to find its place in this era of precision and personalized medicine.

Mass spectrometry-based proteomics for advancing solid organ transplantation research

Scarcity of high-quality organs, suboptimal organ quality assessment, unsatisfactory pre-implantation procedures, and poor long-term organ and patient survival are the main challenges currently faced by the solid organ transplant (SOT) field. New biomarkers for assessing graft quality pre-implantation, detecting, and predicting graft injury, rejection, dysfunction, and survival are critical to provide clinicians with invaluable prediction tools and guidance for personalized patients' treatment. Additionally, new therapeutic targets are also needed to reduce injury and rejection and improve transplant outcomes. Proteins, which underlie phenotypes, are ideal candidate biomarkers of health and disease statuses and therapeutic targets. A protein can exist in different molecular forms, called proteoforms. As the function of a protein depends on its exact composition, proteoforms can offer a more accurate basis for connection to complex phenotypes than protein from which they derive. Mass spectrometry-based proteomics has been largely used in SOT research for identification of candidate biomarkers and therapeutic intervention targets by so-called "bottom-up" proteomics (BUP). However, such BUP approaches analyze small peptides in lieu of intact proteins and provide incomplete information on the exact molecular composition of the proteins of interest. In contrast, "Top-down" proteomics (TDP), which analyze intact proteins retaining proteoform-level information, have been only recently adopted in transplantation studies and already led to the identification of promising proteoforms as biomarkers for organ rejection and dysfunction. We anticipate that the use of top-down strategies in combination with new technological advancements in single-cell and spatial proteomics could drive future breakthroughs in biomarker and therapeutic target discovery in SOT.

Intermittent Surface Oxygenation Results in Similar Mitochondrial Protection and Maintenance of Aerobic Metabolism as Compared to Continuous Oxygenation during Hypothermic Machine Kidney Machine Perfusion

Short bubble and subsequent surface oxygenation is an innovative oxygenation technique and alternative for membrane oxygenation during hypothermic machine perfusion (HMP). The metabolic effect of the interruption of surface oxygenation for 4 h (mimicking organ transport) during HMP was compared to continuous surface and membrane oxygenation in a pig kidney ex situ preservation model. After 30 min of warm ischemia by vascular clamping, a kidney of a ±40 kg pig was procured and subsequently preserved according to one of the following groups: (1) 22-h HMP + intermittent surface oxygenation (n = 12); (2) 22-h HMP + continuous membrane oxygenation (n = 6); and (3) 22-h HMP + continuous surface oxygenation (n = 7). Brief perfusate O2 uploading before kidney perfusion was either obtained by direct bubble (groups 1, 3) or by membrane (group 2) oxygenation. Bubble oxygenation during minimum 15 min was as efficient as membrane oxygenation in achieving supraphysiological perfusate pO2 levels before kidney perfusion. Metabolic tissue analysis (i.e., lactate, succinate, ATP, NADH, and FMN) during and at the end of the preservation period demonstrated similar mitochondrial protection between all study groups. Short bubble and subsequent intermittent surface oxygenation of the perfusate of an HMP-kidney might be an effective and cheap preservation strategy to protect mitochondria, eliminating the need/costs of a membrane oxygenator and oxygen source during transport.

Current Evidence and Future Perspectives to Implement Continuous and End-Ischemic Use of Normothermic and Oxygenated Hypothermic Machine Perfusion in Clinical Practice

The use of high-risk renal grafts for transplantation requires the optimization of pretransplant assessment and preservation reconditioning strategies to decrease the organ discard rate and to improve short- and long-term clinical outcomes. Active oxygenation is increasingly recognized to play a central role in dynamic preservation strategies, independent of preservation temperature, to recondition mitochondria and to restore the cellular energy profile. The oxygen-related decrease in mitochondrial succinate accumulation ameliorates the harmful effects of ischemia-reperfusion injury. The differences between normothermic and hypothermic machine perfusion with regard to organ assessment, preservation, and reconditioning, as well as the logistic and economic implications, are factors to take into consideration for implementation at a local level. Therefore, these different techniques should be considered complementary to the perfusion strategy selected depending on functional intention and resource availability. This review provides an overview of the current clinical evidence of normothermic and oxygenated hypothermic machine perfusion, either as a continuous or end-ischemic preservation strategy, and future perspectives.

Early readmissions post kidney transplantation: lessons learned

INTRODUCTION

Kidney transplantation (KT) is the gold standard treatment for end-stage renal disease (ESRD) patients. Hospital readmissions post-transplant is a common complication and can be considered an indication of avoidable morbidity and hospital quality, and there is a significant correlation between EHR and adverse patient outcomes. This study aimed to assess the readmission rate following kidney transplants, the underlying causes, and possible ways to prevent it.

MATERIAL AND METHODS

We retrospectively reviewed the medical records of recipients from January 2016 to December 2021 in a single center. The primary objective of this study is to find the readmission rate for kidney transplants and the variables that contribute to readmission. Post-transplant complications that were resulted in the readmission categorized into surgical complications, graft-related complications, infections, DVT, and other medical complications.

RESULTS

Four hundred seventy-four renal allograft recipients met our inclusion criteria and were included in the study. 248 (52.3%) of the allograft recipients had at least one readmission during the first 90 days after the transplantation. 89 (18.8%) allograft recipients had more than one readmission episode in the first 90 days post-transplant. The perinephric fluid collection was the most common surgical complication (52.4%), and UTI was the most common infection (50%), causing readmission in the first 90 days post-transplant. The readmission odd ratio was significantly higher in patients above 60 years old and in kidneys with KDPI ≥ 85, and in recipients with DGF.

CONCLUSION

Early hospital readmission (EHR) following a kidney transplant is a common complication. Identifying the causes not only helps the transplant centers to take further steps to prevent some incidents and help to improve the patients' morbidities and mortalities, but also it can reduce the unnecessary costs of readmissions.

Normothermic Machine Perfusion in Renal Transplantation

Purpose of Review

Normothermic machine perfusion (NMP) is a promising new tool in kidney transplantation to improve the outcome of marginal donor kidney transplantation. This review examines the current evidence for NMP in clinical practice and considers how the technology may be used in the future.

Recent Findings and Summary

There is emerging evidence to suggest that NMP has the potential to expand the donor pool of transplantable organs. The safety and feasibility of NMP have been established in a number of clinical studies but more research is needed to optimise the perfusion conditions. NMP shows promise as a viability assessment tool with particular focus on biomarkers and imaging techniques which provide real-time information to facilitate transplantation decision-making. Moreover, the exciting development of new potential therapeutics such as cell and gene-based therapies which are deliverable during NMP may also improve and recondition grafts prior to implantation.

Kidney donor profile index and post-transplant health care utilization: Implications for value of transplant care delivery

BACKGROUND

Centers discard high kidney donor profile index (KDPI) allografts, potentially related to delayed graft function and prolonged hospital use by kidney transplant recipients (KTR). We sought to determine whether high KDPI KTRs have excess health care utilization.

METHODS

We conducted a retrospective cohort study from a high-volume center analyzing KTRs from January 3, 2011 to April 12, 2015 (n = 652). We measured differences in hospital use, emergency visits, and outpatient visits within the first 90 days between low (≤85%) versus high KDPI (>85%) KTRs, as well as long-term graft function and patient survival.

RESULTS

High (n = 107) and low KDPI (n = 545) KTRs had similar length of stay (median = 3 days, P = .66), and readmission rates at 7, 30, and 90 days after surgery (all, P > .05). High KDPI kidneys were not associated with excess utilization of the hospital, emergency services, outpatient transplant clinics, or ambulatory infusion visits on univariate or multivariate analysis (all, P > .05). Low KDPI KTRs had significantly better eGFR at 2 years (Low vs. High KDPI: 60.35 vs. 41.54 ml/min, P < .001), but similar 3-year patient and graft survival (both, P > .09).

CONCLUSIONS

High and low KDPI KTRs demonstrated similar 90-day risk-adjusted health care utilization, which should encourage use of high KDPI kidneys.

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.

Perfusate Composition and Duration of Ex-Vivo Normothermic Perfusion in Kidney Transplantation: A Systematic Review

Ex-vivo normothermic perfusion (EVNP) is an emerging strategy in kidney preservation that enables resuscitation and viability assessment under pseudo-physiological conditions prior to transplantation. The optimal perfusate composition and duration, however, remain undefined. A systematic literature search (Embase; Medline; Scopus; and BIOSIS Previews) was conducted. We identified 1,811 unique articles dating from January 1956 to July 2021, from which 24 studies were deemed eligible for qualitative analysis. The perfusate commonly used in clinical practice consisted of leukocyte-depleted, packed red blood cells suspended in Ringer’s lactate solution with Mannitol, dexamethasone, heparin, sodium bicarbonate and a specific nutrient solution supplemented with insulin, glucose, multivitamins and vasodilators. There is increasing support in preclinical studies for non-blood cell-based perfusates, including Steen solution, synthetic haem-based oxygen carriers and acellular perfusates with supraphysiological carbogen mixtures that support adequate oxygenation whilst also enabling gradual rewarming. Extended durations of perfusion (up to 24 h) were also feasible in animal models. Direct comparison between studies was not possible due to study heterogeneity. Current evidence demonstrates safety with the aforementioned widely used protocol, however, extracellular base solutions with adequate oxygenation, supplemented with nutrient and metabolic substrates, show promise by providing a suitable environment for prolonged preservation and resuscitation.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021231381, identifier PROSPERO 2021 CRD42021231381

Doxycycline Alters the Porcine Renal Proteome and Degradome during Hypothermic Machine Perfusion

Ischemia-reperfusion injury (IRI) is a hallmark for tissue injury in donation after circulatory death (DCD) kidneys. The implementation of hypothermic machine perfusion (HMP) provides a platform for improved preservation of DCD kidneys. Doxycycline administration has shown protective effects during IRI. Therefore, we explored the impact of doxycycline on proteolytic degradation mechanisms and the urinary proteome of perfused kidney grafts. Porcine kidneys underwent 30 min of warm ischemia, 24 h of oxygenated HMP (control/doxycycline) and 240 min of ex vivo reperfusion. A proteomic analysis revealed distinctive clustering profiles between urine samples collected at T15 min and T240 min. High-efficiency undecanal-based N-termini (HUNTER) kidney tissue degradomics revealed significantly more proteolytic activity in the control group at T-10. At T240, significantly more proteolytic activity was observed in the doxycycline group, indicating that doxycycline alters protein degradation during HMP. In conclusion, doxycycline administration during HMP led to significant proteomic and proteolytic differences and protective effects by attenuating urinary NGAL levels. Ultimately, we unraveled metabolic, and complement and coagulation pathways that undergo alterations during machine perfusion and that could be targeted to attenuate IRI induced injury.

Shifting Paradigms for Suppressing Fibrosis in Kidney Transplants: Supplementing Perfusion Solutions With Anti-fibrotic Drugs

Great efforts have been made toward addressing the demand for donor kidneys. One of the most promising approaches is to use kidneys from donation after circulatory death donors. These kidneys, however, suffer from more severe ischemia and reperfusion injury than those obtained via donation after brain death and are thus more prone to develop interstitial fibrosis and tubular atrophy. Even though machine perfusion is increasingly used to reduce ischemia and reperfusion injury, there are no effective treatments available to ameliorate interstitial fibrosis and tubular atrophy, forcing patients to resume dialysis, undergo re-transplantation, or suffer from premature death. Safe and effective anti-fibrotic therapies are therefore greatly desired. We propose a new therapeutic approach in which machine perfusion solutions are supplemented with anti-fibrotic compounds. This allows the use of higher concentrations than those used in humans whilst eliminating side effects in other organs. To the authors' knowledge, no one has reviewed whether such an approach could reduce interstitial fibrosis and tubular atrophy; we therefore set out to explore its merit. In this review, we first provide background information on ischemia and reperfusion injury as well as interstitial fibrosis and tubular atrophy, after which we describe currently available approaches for preserving donor kidneys. We then present an evaluation of selected compounds. To identify promising compounds, we analyzed publications describing the effects of anti-fibrotic molecules in precision-cut kidneys slices, which are viable explants that can be cultured ex vivo for up to a few days whilst retaining functional and structural features. LY2109761, galunisertib, imatinib, nintedanib, and butaprost were shown to exert anti-fibrotic effects in slices within a relatively short timeframe (<48 h) and are therefore considered to be excellent candidates for follow-up ex vivo machine perfusion studies.

Marginal allografts in liver transplantation have a limited impact on length of stay

The study of marginal liver transplant outcomes, including post-transplant length of stay (LOS), is necessary for determining the practicality of their use. 50 155 patients who received transplants from 2012 to 2020 were retrospectively analyzed with data from the Scientific Registry of Transplant Recipients database using Kaplan-Meier survival curves and multivariable Cox regression. Six different definitions were used to classify an allograft as being marginal: 90^th percentile Donor Risk Index (DRI) allografts, donation after cardiac death (DCD) donors, national share donors, donors over 70, donors with > 30% macrovesicular steatosis, or 90^th percentile Discard Risk Index donors. 24% (n = 12 124) of subjects received marginal allografts. Average LOS was 15.6 days among those who received standard allografts. Among those who received marginal allografts, LOS was found to be highest in those who received 90^th percentile DRI allografts at 15.6 days, and lowest in those who received DCD allografts at 12.7 days. Apart from fatty livers (95% CI .86-.98), marginal allografts were not associated with a prolonged LOS. We conclude that accounting for experience and recipient matching, transplant centers may be more aggressive in their use of extended criteria donors with limited fear of increasing LOS and its associated costs.

Persufflation—Current State of Play

With the ever-increasing disparity between the number of patients waiting for organ transplants and the number organs available, some patients are unable to receive life-saving transplantation in time. The present, widely-used form of preservation is proving to be incapable of maintaining organ quality during long periods of preservation and meeting the needs of an ever-changing legislative and transplantation landscape. This has led to the need for improved preservation techniques. One such technique that has been extensively researched is gaseous oxygen perfusion or Persufflation (PSF). This method discovered in the early 20th century has shown promise in providing both longer term preservation and organ reconditioning capabilities for multiple organs including the liver, kidneys, and pancreas. PSF utilises the organs own vascular network to provide oxygen to the organ tissue and maintain metabolism during preservation to avoid hypoxic damage. This review delves into the history of this technique, its multiple different approaches and uses, as well as in-depth discussion of work published in the past 15 years. Finally, we discuss exciting commercial developments which may help unlock the potential for this technique to be applied at scale.

Simply Adding Oxygen during Hypothermic Machine Perfusion to Combat the Negative Effects of Ischemia-Reperfusion Injury: Fundamentals and Current Evidence for Kidneys

The use of high-risk renal grafts for transplantation requires optimization of pretransplant preservation and assessment strategies to improve clinical outcomes as well as to decrease organ discard rate. With oxygenation proposed as a resuscitative measure during hypothermic machine preservation, this review provides a critical overview of the fundamentals of active oxygenation during hypothermic machine perfusion, as well as the current preclinical and clinical evidence and suggests different strategies for clinical implementation.

A Comparison of Pulsatile Hypothermic and Normothermic Ex Vivo Machine Perfusion in a Porcine Kidney Model

BACKGROUND

Hypothermic machine perfusion (HMP) is a well-established method for deceased donor kidney preservation. Normothermic machine perfusion (NMP) might offer similar or greater advantages. We compared the 2 methods in an ex vivo perfusion model using 34 porcine kidneys.

METHODS

Thirty kidneys were stored on ice for 24 h before undergoing 4 h of HMP (n = 15) or NMP (n = 15) followed by 2 h of normothermic ex vivo reperfusion with whole blood. Four kidneys underwent 28 h of cold static storage followed by 2 h of normothermic ex vivo reperfusion. During the 2 h of normothermic ex vivo reperfusion, perfusate flow rates, urinary output, and oxygen consumption rates were compared between all groups.

RESULTS

Porcine kidneys after HMP showed significantly higher urinary output (5.31 ± 2.06 versus 2.44 ± 1.19 mL/min; P = 0.002), oxygen consumption (22.71 ± 6.27 versus 11.83 ± 1.29 mL/min; P = 0.0016), and perfusate flow rates (46.24 ± 12.49 versus 26.16 ± 4.57 mL/min; P = 0.0051) than kidneys after NMP. TUNEL staining of tissue sections showed significantly higher rates of apoptosis in kidneys after NMP (P = 0.027).

CONCLUSIONS

In our study, the direct comparison of HMP and NMP kidney perfusion in a translational model demonstrated superiority of HMP; however, further in vivo studies would be needed to validate those results.

Mitochondria and Antibiotics: For Good or for Evil?

The discovery and application of antibiotics in the common clinical practice has undeniably been one of the major medical advances in our times. Their use meant a drastic drop in infectious diseases-related mortality and contributed to prolonging human life expectancy worldwide. Nevertheless, antibiotics are considered by many a double-edged sword. Their extensive use in the past few years has given rise to a global problem: antibiotic resistance. This factor and the increasing evidence that a wide range of antibiotics can damage mammalian mitochondria, have driven a significant sector of the medical and scientific communities to advise against the use of antibiotics for purposes other to treating severe infections. Notwithstanding, a notorious number of recent studies support the use of these drugs to treat very diverse conditions, ranging from cancer to neurodegenerative or mitochondrial diseases. In this context, there is great controversy on whether the risks associated to antibiotics outweigh their promising beneficial features. The aim of this review is to provide insight in the topic, purpose for which the most relevant findings regarding antibiotic therapies have been discussed.

Perioperative risk factors associated with delayed graft function following deceased donor kidney transplantation: A retrospective, single center study

BACKGROUND

There is an abundant need to increase the availability of deceased donor kidney transplantation (DDKT) to address the high incidence of kidney failure. Challenges exist in the utilization of higher risk donor organs into what appears to be increasingly complex recipients; thus the identification of modifiable risk factors associated with poor outcomes is paramount.

AIM

To identify risk factors associated with delayed graft function (DGF).

METHODS

Consecutive adults undergoing DDKT between January 2016 and July 2017 were identified with a study population of 294 patients. The primary outcome was the occurrence of DGF.

RESULTS

The incidence of DGF was 27%. Under logistic regression, eight independent risk factors for DGF were identified including recipient body mass index ≥ 30 kg/m², baseline mean arterial pressure < 110 mmHg, intraoperative phenylephrine administration, cold storage time ≥ 16 h, donation after cardiac death, donor history of coronary artery disease, donor terminal creatinine ≥ 1.9 mg/dL, and a hypothermic machine perfusion (HMP) pump resistance ≥ 0.23 mmHg/mL/min.

CONCLUSION

We delineate the association between DGF and recipient characteristics of pre-induction mean arterial pressure below 110 mmHg, metabolic syndrome, donor-specific risk factors, HMP pump parameters, and intraoperative use of phenylephrine.

Pre-arrest doxycycline protects donation after circulatory death kidneys

Kidney injury during donation after circulatory determination of death (DCDD) includes warm ischemic (WI) injury from around the time of asystole, and cold ischemic (CI) injury during cold preservation. We have previously shown that Matrix Metalloproteinases (MMPs) are involved in CI injury and that Doxycycline (Doxy), an antibiotic and known MMP inhibitor, protects the transplant kidney during CI. The purpose of our study was to determine if Doxy given before asystole can also prevent injury during WI. A rat model of DCDD was used, including Control, Preemptive Doxy (45 mg/kg iv), and Preemptive and Perfusion (100 microM) Doxy groups. Thirty minutes after asystole, both kidneys were removed. The left kidney was perfused at 4 °C for 22 h, whereas the right was used to establish the degree of warm ischemic injury prior to cold preservation. MMP-2 in the perfusate was significantly reduced in both treatment groups [Control 43.7 ± 7.2 arbitrary units, versus Preemptive Doxy group 23.2 ± 5.5 (p = 0.03), and 'Preemptive and Perfusion' group 18.0 ± 5.6 (p = 0.02)]. Reductions in NGAL, LDH, and MMP-9 were also seen. Electron microscopy showed a marked reduction in mitochondrial injury scores in the treatment groups. Pre-arrest Doxy was associated with a reduction in injury markers and morphologic changes. Doxy may be a simple and safe means of protecting transplant kidneys from both WI and CI.

Predictors and one-year outcomes of patients with delayed graft function after deceased donor kidney transplantation

BACKGROUND

Delayed graft function (DGF) is closely associated with the use of marginal donated kidneys due to deficits during transplantation and in recipients. We aimed to predict the incidence of DGF and evaluate its effect on graft survival.

METHODS

This retrospective study on kidney transplantation was conducted from January 1, 2018, to December 31, 2019, at the Second Xiangya Hospital of Central South University. We classified recipients whose operations were performed in different years into training and validation cohorts and used data from the training cohort to analyze predictors of DGF. A nomogram was then constructed to predict the likelihood of DGF based on these predictors.

RESULTS

The incidence rate of DGF was 16.92%. Binary logistic regression analysis showed correlations between the incidence of DGF and cold ischemic time (CIT), warm ischemic time (WIT), terminal serum creatine (Scr) concentration, duration of pretransplant dialysis, primary cause of donor death, and usage of LifePort. The internal accuracy of the nomogram was 83.12%. One-year graft survival rates were 93.59 and 99.74%, respectively, for the groups with and without DGF (P < 0.05).

CONCLUSION

The nomogram established in this study showed good accuracy in predicting DGF after deceased donor kidney transplantation; additionally, DGF decreased one-year graft survival.

Kidney-intrinsic factors determine the severity of ischemia/reperfusion injury in a mouse model of delayed graft function

Delayed graft function due to transplant ischemia/reperfusion injury adversely affects up to 50% of deceased-donor kidney transplant recipients. However, key factors contributing to the severity of ischemia/reperfusion injury remain unclear. Here, using a clinically relevant mouse model of delayed graft function, we demonstrated that donor genetic background and kidney-intrinsic MyD88/Trif-dependent innate immunity were key determinants of delayed graft function. Functional deterioration of kidney grafts directly corresponded with the duration of cold ischemia time. The graft dysfunction became irreversible after cold ischemia time exceeded six hours. When cold ischemia time reached four hours, kidney grafts displayed histological features reflective of delayed graft function seen in clinical kidney transplantation. Notably, kidneys of B6 mice exhibited significantly more severe histological and functional impairment than kidneys of C3H or BALB/c mice, regardless of recipient strains or alloreactivities. Furthermore, allografts of B6 mice also showed an upregulation of IL-6, neutrophil gelatinase-associated lipocalin, and endoplasmic reticulum stress genes, as well as an increased influx of host neutrophils and memory CD8 T-cells. In contrast, donor MyD88/Trif deficiency inhibited neutrophil influx and decreased the expression of IL-6 and endoplasmic reticulum stress genes, along with improved graft function and prolonged allograft survival. Thus, kidney-intrinsic factors involving genetic characteristics and innate immunity serve as critical determinants of the severity of delayed graft function. This preclinical murine model allows for further investigations of the mechanisms underlying delayed graft function.

Urine Injury Biomarkers Are Not Associated With Kidney Transplant Failure

BACKGROUND

Kidneys transplanted from deceased donors with serum creatinine-defined acute kidney injury (AKI) have similar allograft survival as non-AKI kidneys but are discarded at a higher rate. Urine injury biomarkers are sensitive markers of structural kidney damage and may more accurately predict graft outcomes.

METHODS

In the 2010-2013 multicenter Deceased Donor Study of 2430 kidney transplant recipients from 1298 donors, we assessed the association of donor urine injury biomarkers microalbumin, neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, IL-18, and liver-type fatty acid binding protein with graft failure (GF) and death-censored GF (dcGF) using Cox proportional hazard models (median follow-up 4 y). We examined if serum creatinine-defined donor AKI modified this association to assess the relationship between subclinical donor AKI (elevated biomarkers without creatinine-defined AKI) and GF. Through chart review of a subcohort (1137 recipients), we determined associations between donor injury biomarkers and a 3-year composite outcome of GF, mortality, or estimated glomerular filtration rate ≤ 20mL/min/1.73m.

RESULTS

Risk of GF, dcGF, and 3-year composite outcome did not vary with donor injury biomarker concentrations after adjusting for donor, transplant, and recipient characteristics (adjusted hazard ratio ranged from 0.96 to 1.01 per log-2 increase in biomarker). Subclinical injury in transplanted kidneys without AKI was not associated with GF.

CONCLUSIONS

AKI measured using injury biomarkers was not associated with posttransplant graft outcomes (at median 4 y posttransplant). When assessing posttransplant graft viability, clinicians can prioritize other donor and recipient factors over donor kidney injury, measured by either serum creatinine or urine injury biomarkers.

Impact of pre-transplant biopsy on 5-year outcomes of expanded criteria donor kidney transplantation

AIM

Compared to Standard Criteria Donors (SCD), Expanded Criteria Donor (ECD) kidneys are associated with poorer outcomes, although pre-transplant biopsy may mitigate risks. This study assessed 5-year outcomes of deceased-donor kidney transplant recipients, comparing recipients of ECD allografts evaluated histologically to recipients of SCD and ECD kidneys assessed clinically.

METHODS

This is a single-centre retrospective study. From November 2005 to December 2009 (Era 1), donors were assessed clinically for suitability for kidney donation. From December 2009 to October 2017 (Era 2), kidneys from ECDs and diabetics underwent pre-transplant biopsy and were allocated based on Remuzzi score. Outcomes of Era 1 and 2 recipients were compared.

RESULTS

ECD kidney transplantation increased from 30.4% to 40.0% from Era 1 to 2. Univariable Cox regression, stratified by transplant era, found that 5-year graft loss was highest with Era 1 ECD (HR 2.5, 95% CI 1.1-5.5, P = .027) while graft loss for Era 2 ECD recipients was similar to SCD recipients. There was no difference in 5-year recipient survival. Amongst Era 1 ECD recipients, 51.2% experienced rejection compared to 30.8-41.5% for other subgroups. Five-year eGFR was higher with Era 2 ECD at 48.4 (33.3-60.7) ml/min/1.73 m² compared to 42.2 (35.8-57.3) ml/min/1.73 m² for Era 1 ECD. However, these differences were not statistically significant.

CONCLUSION

Introduction of pre-transplant biopsy assessment may be associated with improved outcomes of ECD kidney recipients such that they are now comparable to SCD kidney recipients, with benefits persisting over 5 years.

Kidney transplantation outcomes from elderly donors after circulatory death: a comparison with elderly brain-dead donors

Background

The use of kidneys from elderly controlled donation after circulatory death (cDCD) donors has increased significantly in recent years. Concerns about outcomes achieved with these elderly cDCD kidneys have arisen. We aimed to compare outcomes from elderly cDCD kidney transplant recipients (KTrs) and elderly donation after brain death donors (DBDs) in KTrs.

Methods

We conducted a single-centre retrospective study including 87 cDCD-KTrs (46 from donors ≥65 years of age and 41 from <65 years) and 126 DBD-KTrs from donors ≥65 years of age from 2013 through 2017). Young cDCD-KTrs were used as controls. The median follow-up was 27.1 months for all cDCD-KTrs and 29.7 months for DBD-KTrs ≥65 years of age.

Results

Donors >65 years of age represented more than half of our global cDCD cohort (52.9%). KTs from elderly cDCDs had similar rates of delayed graft function, primary non-function and vascular complications compared with young cDCD-KTrs and elderly DBD-KTrs. Short and medium-term graft survival from elderly cDCD kidneys are excellent and are comparable to those from young cDCD and elderly DBD kidneys (90% young cDCD versus 88% elderly cDCD versus 80% elderly DBD at 36 months, P = 0.962 and 0.180, respectively). Although recipients from cDCDs ≥65 years of age showed lower 3-year patient survival (78% versus 87% in elderly DBD-KTrs; P = 0.01), recipient age was the only determinant of patient survival [hazard ratio 1.10 (95% confidence interval 1.02–1.17); P < 0.01], without any influence of donor characteristics.

Conclusions

The use of kidneys from elderly cDCDs is increasing in Spain. Short- and medium-term graft outcomes are similar when comparing kidneys from elderly cDCDs and DBDs. Recipient age is the only determinant of patient survival. Additional studies are needed to assess long-term outcomes.

Uncontrolled donation after circulatory death improves access to kidney transplantation: A decision analysis

AIM

Uncontrolled donation after cardiac death (uDCD) remains an underutilized source of kidney allografts in the United States. The objective of this study was to estimate the impact of the implementation of a uDCD program on transplantation rates and long-term survival for patients with end-stage renal disease (ESRD) in the United States.

METHODS

A decision-analytic Markov state transition model was created using medical decision-making software (DATA 3.5; TreeAge Software, Inc) to estimate the impact of an uDCD program on transplantation rates and patient survival. Additionally, sensitivity analysis of uDCD donor pool increase was modeled. All model statistic parameters were extracted from the literature.

RESULTS

A uDCD program increased the rate of transplant at 10 years (37.8%, Accept uDCD group, vs 35.9%, Reject uDCD group). At 10 years, overall survival for Accept uDCD was 55.6% compared to 54.8% in the Reject uDCD.

CONCLUSIONS

Uncontrolled DCD improves access to transplant for ESRD patients on the kidney transplant waitlist, thereby improving long-term survival.

Impacto de la perfusión hipotérmica pulsativa en el injerto renal de donante subóptimo: nuestra experiencia inicial

Objetivo: Estudios recientes han demostrado que el mantenimiento de la viabilidad de riñones con criterios expandidos durante su preservación sea un reto. La máquina de perfusión hipotérmica pretende mitigar el efecto del almacenamiento en frío sobre la calidad del órgano cuando el tiempo de isquemia fría es prolongada o el donante subóptimo.Objetivo: Evaluar las complicaciones que presentan los pacientes trasplantados renales con preservación está-tica fría o perfusión hipotérmica pulsátil.Material y Método: Estudio observacional retrospec-tivo durante 2010-2012 donde se incluyeron todos los trasplantes renales realizados en un hospital de tercer nivel. Las variables de estudio: estancia hospitalaria, horas de isquemia, necesidad de diálisis y número de sesiones post trasplante y el dispositivo de almacena-miento, edad y patologías asociadas al donante.Resultados: Se realizaron 175 trasplantes donde 70 procedieron de donantes ≥65 años. Se perfundieron en máquina 30 riñones y en 40 se utilizó la preservación estática. Nuestros hallazgos respecto al uso de la má-quina de perfusión conllevan un descenso en la estancia media hospitalaria y una menor necesidad de hemodiá-lisis postrasplante.Conclusiones: Debido al alto porcentaje de órganos procedentes de donantes de edad avanzada y difíciles de preservar, resulta fundamental buscar técnicas de perfusión intravascular continua para una preservación más efectiva del órgano.

Prediction models for delayed graft function: external validation on The Dutch Prospective Renal Transplantation Registry

Background

Delayed graft function (DGF) is a common complication after kidney transplantation in the era of accepting an equal number of brain- and circulatory-death donor kidneys in the Netherlands. To identify those cases with an increased risk of developing DGF, various multivariable algorithms have been proposed. The objective was to validate the reproducibility of four predictive algorithms by Irish et al. (A risk prediction model for delayed graft function in the current era of deceased donor renal transplantation. Am J Transplant 2010;10:2279-2286) (USA), Jeldres et al. (Prediction of delayed graft function after renal transplantation. Can Urol Assoc J 2009;3:377-382) (Canada), Chapal et al. (A useful scoring system for the prediction and management of delayed graft function following kidney transplantation from cadaveric donors. Kidney Int 2014;86:1130-1139) (France) and Zaza et al. (Predictive model for delayed graft function based on easily available pre-renal transplant variables. Intern Emerg Med 2015;10:135-141) (Italy) according to a novel framework for external validation.

Methods

We conducted a prospective observational study with data from the Dutch Organ Transplantation Registry (NOTR). Renal transplant recipients from all eight Dutch academic medical centers between 2002 and 2012 who received a deceased allograft were included (N = 3333). The four prediction algorithms were reconstructed from donor, recipient and transplantation data. Their predictive value for DGF was validated by c-statistics, calibration statistics and net benefit analysis. Case-mix (un)relatedness was investigated with a membership model and mean and standard deviation of the linear predictor.

Results

The prevalence of DGF was 37%. Despite a significantly different case-mix, the US algorithm by Irish was best reproducible, with a c-index of 0.761 (range 0.756 - 0.762), and well-calibrated over the complete range of predicted probabilities of having DGF. The US model had a net benefit of 0.242 at a threshold probability of 0.25, compared with 0.089 net benefit for the same threshold in the original study, equivalent to correctly identifying DGF in 24 cases per 100 patients (true positive results) without an increase in the number of false-positive results.

Conclusions

The US model by Irish et al. was generalizable and best transportable to Dutch recipients with a deceased donor kidney. The algorithm detects an increased risk of DGF after allocation and enables us to improve individual patient management.

Systematic Surgical Assessment of Deceased-Donor Kidneys as a Predictor of Short-Term Transplant Outcomes

BACKGROUND

Short-term kidney graft dysfunction is correlated with complications and it is associated with a decreased long-term survival; therefore, a scoring system to predict short-term renal transplant outcomes is warranted.

AIM

The aim of this study is to quantify the impression of the organ procurement surgeon in correlation with the following kidney transplant outcomes: immediate graft function (IGF), delayed graft function (DGF), and primary nonfunction (PNF). Results are compared to factors associated with the 1-year outcome.

METHODS

A regional prospective pilot study was performed using deceased-donor organ assessment forms to be filled out by procurement surgeons after procurement. Data were gathered on kidney temperature, perfusion, anatomy, atherosclerosis, and overall quality.

RESULTS

Included were 90 donors who donated 178 kidneys, 166 of which were transplanted. Variables that were significantly more prevalent in the DGF-or-PNF group (n = 65) are: large kidney size (length, p = 0.008; width, p = 0.036), poor perfusion quality (p = 0.037), lower diuresis (p = 0.039), fewer hypotensive episodes (p = 0.003), and donation-after-circulatory-death donors (p = 0.017). Multivariable analysis showed that perfusion quality and kidney width significantly predicted the short-term outcome. However multivariable analysis of long-term outcomes showed that the first measured donor creatinine, kidney donor risk index, IGF vs. DGF+PNG, and kidney length predicted outcomes.

CONCLUSIONS

Results show that short-term graft function and 1-year graft function indeed are influenced by different variables. DGF and PNF occur more frequently in kidneys with poor perfusion and in larger kidneys. A plausible explanation for this is that these kidneys might be insufficiently washed out, or even congested, which may predispose to DGF. These kidneys would probably benefit most from reconditioning strategies, such as machine perfusion. A scoring system including these variables might aid in decision-making towards allocation and potential reconditioning strategies.

Current State of Renal Regenerative Therapies

The worldwide increase in the number of patients with end-stage renal disease leads to a growing waiting list for kidney transplantation resulting from the scarcity of kidney donors. Therefore, alternative treatment options for patients with end-stage renal disease are being sought. In vitro differentiation of stem cells into renal tissue is a promising approach to repair nonfunctional kidney tissue. Impressive headway has been made in the use of stem cells with the use of adult renal progenitor cells, embryonic stem cells, and induced pluripotent stem cells for the development toward primitive kidney structures. Currently, efforts are directed at improving long-term maintenance and stability of the cells. This review aims to provide a comprehensive overview of the cell sources used for the generation of kidney cells and strategies used for transplantation in in vivo models. Furthermore, it provides a perspective on stability and safety during future clinical application of in vitro generated kidney cells.

Limited clinical value of two consecutive post-transplant renal scintigraphy procedures

Objectives

Duration of delayed graft function (DGF) and length of hospital stay (LOS) are outcomes of interest in an era that warrants increased efficacy of transplant care whereas renal allografts originate increasingly from marginal donors. While earlier studies investigate the predictive capability of a single renal scintigraphy, this study focuses on the value for both DGF duration and LOS of consecutively performed scintigraphies.

Methods

From 2011 to 2014, renal transplant recipients referred for a Tc-99m MAG3 renal scintigraphy were included in a single-center retrospective study. Primary endpoints were DGF duration and LOS. Both the first (≤ 3 days) and second scintigraphies (3–7 days after transplantation) were analyzed using a 4-grade qualitative scale and quantitative indices (TFS, cTER, MUC10, average upslope).

Results

We evaluated 200 first and 108 (54%) consecutively performed scintigraphies. The Kaplan-Meier curves for DGF duration and qualitative grading of the first and second scintigraphy showed significant differences between the grades (p < 0.01). The Kaplan-Meier curve for the delta grades between these procedures (lower, equal, or higher grade) did not show significant differences (p = 0.18). Multivariate analysis showed a significant association between the qualitative grades, from the first and second scintigraphy, and DGF duration, HR 1.8 (1.4–2.2, p < 0.01) and 2.8 (1.8–4.3, p < 0.01), respectively.

Conclusions

Qualitative grades of single renal scintigraphies, performed within 7 days after transplantation, can be used to make a reliable image-guided decision on the need for dialysis and to predict LOS. A consecutive renal scintigraphy, however, did not show an additional value in the assessment of DGF.

Key Points

• Post-transplant renal scintigraphy procedures provide information to predict delayed graft function duration and length of hospital stay.

• Performing two consecutive renal scintigraphy procedures within 1 week after transplantation does not strengthen the prediction of delayed graft function duration and length of hospital stay.

• Single renal scintigraphy procedures can be used to provide clinicians and patients with a reliable indication of the need for dialysis after transplantation and the expected duration of hospitalization.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06334-1) contains supplementary material, which is available to authorized users.

Algorithms for mapping kidney tissue oxygenation during normothermic machine perfusion using hyperspectral imaging

The lack of donor grafts is a severe problem in transplantation medicine. Hence, the improved preservation of existing and the usage of organs that were deemed untransplantable is as urgent as ever. The development of novel preservation techniques has come into focus. A promising alternative to traditional cold storage is normothermic machine perfusion (NMP), which provides the benefit of improving the organs' viability and of assessing the organs' status under physiological conditions. For this purpose, methods for evaluating organ parameters have yet to be developed. In a previous study, we determined the tissue oxygen saturation (StO2) of kidneys during NMP with hyperspectral imaging (HSI) based on a discrete wavelength (DW) algorithm. The aim of the current study was to identify a more accurate algorithm for StO2 calculation. A literature search revealed three candidates to test: a DW algorithm and two full spectral algorithms - area under a curve and partial least square regression (PLSR). After obtaining suitable calibration data to train each algorithm, they were evaluated during NMP. The wavelength range from 590 to 800 nm was found to be appropriate for analyzing StO2 of kidneys during NMP. The PLSR method shows good results in analyzing the tissues' oxygen status in perfusion experiments.

Pharmacological Protection of Kidney Grafts from Cold Perfusion-Induced Injury

One of the greatest challenges facing the field of organ transplantation is the shortage of donor organs for transplantation. Renal transplantation increases quality of life and survival of patients suffering from end-stage renal disease. Although kidney transplantation has evolved greatly over the past few decades, a not insignificant amount of injury occurs to the kidney during recovery, preservation, and implantation and leads to the loss of function and loss of years of dialysis-free living for many patients. The use of kidneys from expanded criteria donors (ECD) and donation after circulatory determination of death (DCDD) has been adopted partly in response to the shortage of donor kidneys; however these kidneys are even more susceptible to ischemic injury. It has been shown that matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) are involved in mechanisms of injury to the transplant kidney. There is also some evidence that inhibition of MMP activity and/or ROS production can protect the kidney from injury. We review possible pharmacological strategies for protection of kidney graft from injury during recovery, preservation, and implantation.

Brain death-induced cytokine release is not associated with primary graft dysfunction: a cohort study

OBJECTIVE

To examine the association between donor plasma cytokine levels and the development of primary graft dysfunction of organs transplanted from deceased donors.

METHODS

Seventeen deceased donors and the respective 47 transplant recipients were prospectively included in the study. Recipients were divided into two groups: group 1, patients who developed primary graft dysfunction; and group 2, patients who did not develop primary graft dysfunction. Donor plasma levels of TNF, IL-6, IL-1β, and IFN-γ assessed by ELISA were compared between groups.

RESULTS

Sixty-nine organs were retrieved, and 48 transplants were performed. Donor plasma cytokine levels did not differ between groups (in pg/mL): TNF, group 1: 10.8 (4.3 - 30.8) versus group 2: 8.7 (4.1 - 33.1), p = 0.63; IL-6, group 1: 1617.8 (106.7 - 5361.7) versus group 2: 922.9 (161.7 - 5361.7), p = 0.56; IL-1β, group 1: 0.1 (0.1 - 126.1) versus group 2: 0.1 (0.1 - 243.6), p = 0.60; and IFN-γ, group 1: 0.03 (0.02 - 0.2) versus group 2: 0.03 (0.02 - 0.1), p = 0.93). Similar findings were obtained when kidney transplants were analyzed separately.

CONCLUSION

In this sample of transplant recipients, deceased donor plasma cytokines TNF, IL-6, IL-1β, and IFN-γ were not associated with the development of primary graft dysfunction.

The Benefits of Hypothermic Machine Preservation and Short Cold Ischemia Times in Deceased Donor Kidneys

BACKGROUND

Hypothermic machine perfusion (HMP) of deceased donor kidneys is associated with better outcome when compared to static cold storage (CS). Nevertheless, there is little evidence whether kidneys with short cold ischemia time (CIT) also benefit from HMP and whether HMP can safely extend CIT.

METHODS

We analyzed prospectively collected data from the Machine Preservation Trial, an international randomized controlled trial. Seven hundred fifty-two consecutive renal transplants were included: 1 kidney of each of the 376 donors was preserved by HMP, the contralateral organ was preserved by CS.

RESULTS

The mean CIT was 3:05 PM (SD, 4:58 AM). A subgroup analysis was performed, groups were based on CIT duration: 0 to 10 hours, 10 to 15 hours, 15 to 20 hours, or 20 hours or longer. Delayed graft function (DGF) incidence in the subgroup with up to 10 hours CIT was 6.0% (N = 3/50) in the HMP arm and 28.1% (N = 18/64) in the CS arm (univariable P = 0.002; multivariable odds ratio [OR], 0.02; P = 0.007). Cold ischemia time remained an independent risk factor for DGF for machine perfused kidneys recovered from donation after brain death donors (OR, 1.06; 95% confidence interval [CI], 1.017-1.117; P = 0.008), donation after circulatory death donors (OR, 1.13; 95% CI, 1.035-1.233; P = 0.006) and expanded criteria donors (OR, 1.14; 95% CI, 1.057-1.236; P = 0.001).

CONCLUSIONS

In conclusion, HMP resulted in remarkably lower rates of DGF in renal grafts that were transplanted after a short CIT. Also, CIT remained an independent risk factor for DGF in HMP-preserved kidneys.

Predictive Score Model for Delayed Graft Function Based on Hypothermic Machine Perfusion Variables in Kidney Transplantation

Background:

Hypothermic machine perfusion (HMP) is being used more often in cardiac death kidney transplantation; however, the significance of assessing organ quality and predicting delayed graft function (DGF) by HMP parameters is still controversial. Therefore, we used a readily available HMP variable to design a scoring model that can identify the highest risk of DGF and provide the guidance and advice for organ allocation and DCD kidney assessment.

Methods:

From September 1, 2012 to August 31, 2016, 366 qualified kidneys were randomly assigned to the development and validation cohorts in a 2:1 distribution. The HMP variables of the development cohort served as candidate univariate predictors for DGF. The independent predictors of DGF were identified by multivariate logistic regression analysis with a P < 0.05. According to the odds ratios (ORs) value, each HMP variable was assigned a weighted integer, and the sum of the integers indicated the total risk score for each kidney. The validation cohort was used to verify the accuracy and reliability of the scoring model.

Results:

HMP duration (OR = 1.165, 95% confidence interval [CI ]: 1.008–1.360, P = 0.043), resistance (OR = 2.190, 95% CI: 1.032–10.20, P < 0.001), and flow rate (OR = 0.931, 95% CI: 0.894–0.967, P = 0.011) were the independent predictors of identified DGF. The HMP predictive score ranged from 0 to 14, and there was a clear increase in the incidence of DGF, from the low predictive score group to the very high predictive score group. We formed four increasingly serious risk categories (scores 0–3, 4–7, 8–11, and 12–14) according to the frequency associated with the different risk scores of DGF. The HMP predictive score indicates good discriminative power with a c-statistic of 0.706 in the validation cohort, and it had significantly better prediction value for DGF compared to both terminal flow (P = 0.012) and resistance (P = 0.006).

Conclusion:

The HMP predictive score is a good noninvasive tool for assessing the quality of DCD kidneys, and it is potentially useful for physicians in making optimal decisions about the organs donated.

The role of MR imaging in the assessment of renal allograft vasculature

Renal allograft dysfunction after transplantation is a relatively common occurrence with various potential etiologies. Vascular etiologies are of particular importance as early surgical or minimally invasive intervention can, in some cases, salvage the graft. Diagnosis of vascular pathology resulting in allograft dysfunction requires a thorough workup, of which imaging is a key component. Generally, ultrasound is the first-line imaging modality. More recently, MRI has been shown to be an effective and safe modality for diagnosis of vascular pathology after renal transplantation, particularly for diagnosis of transplant renal artery stenosis. This review will summarize imaging modalities that are most commonly used in evaluating vascular pathology after renal transplantation, with a focus on the various contrast- and non-contrast-enhanced MR techniques described in the literature and used at our institution. Of particular interest is the relatively recent utilization of the non-gadolinium containing iron-based contrast agent, ferumoxytol, in time-resolved contrast-enhanced MR angiography.

Kidney transplantation in older recipients: Preemptive high KDPI kidney vs lower KDPI kidney after varying dialysis vintage

AIM

To evaluate the outcomes of transplanting marginal kidneys preemptively compared to better-quality kidneys after varying dialysis vintage in older recipients.

METHODS

Using OPTN/United Network for Organ Sharing database from 2001-2015, we identified deceased donor kidney (DDK) transplant recipients > 60 years of age who either underwent preemptive transplantation of kidneys with kidney donor profile index (KDPI) ≥ 85% (marginal kidneys) or received kidneys with KDPI of 35%-84% (better quality kidneys that older wait-listed patients would likely receive if waited longer) after being on dialysis for either 1-4 or 4-8 years. Using a multivariate Cox model adjusting for donor, recipient and transplant related factors- overall and death-censored graft failure risks along with patient death risk of preemptive transplant recipients were compared to transplant recipients in the 1-4 and 4-8 year dialysis vintage groups.RESUTLSThe median follow up for the whole group was 37 mo (interquartile range of 57 mo). A total of 6110 DDK transplant recipients above the age of 60 years identified during the study period were found to be eligible to be included in the analysis. Among these patients 350 received preemptive transplantation of kidneys with KDPI ≥ 85. The remaining patients underwent transplantation of better quality kidneys with KDPI 35-84% after being on maintenance dialysis for either 1-4 years (n = 3300) or 4-8 years (n = 2460). Adjusted overall graft failure risk and death-censored graft failure risk in preemptive high KDPI kidney recipients were similar when compared to group that received lower KDPI kidney after being on maintenance dialysis for either 1-4 years (HR 1.01, 95%CI: 0.90-1.14, P = 0.84 and HR 0.96, 95%CI: 0.79-1.16, P = 0.66 respectively) or 4-8 years (HR 0.82, 95%CI: 0.63-1.07, P = 0.15 and HR 0.81, 95%CI: 0.52-1.25, P = 0.33 respectively). Adjusted patient death risk in preemptive high KDPI kidney recipients were similar when compared to groups that received lower KDPI kidney after being on maintenance dialysis for 1-4 years (HR 0.99, 95%CI: 0.87-1.12, P = 0.89) but lower compared to patients who were on dialysis for 4-8 years (HR 0.74, 95%CI: 0.56-0.98, P = 0.037).

CONCLUSION

In summary, our study supports accepting a "marginal" quality high KDPI kidney preemptively in older wait-listed patients thus avoiding dialysis exposure.

Adding to the mounting evidence for geographic inequity in liver transplantation: Hospital length of stay

BACKGROUND

Severe geographic inequities in liver transplantation have persisted for years. Previous investigators have demonstrated 90-day transplant rates varying from 14% to 82% and death rates varying from 18% to 86%. The aim of this analysis was to utilize a robust multivariate analysis to investigate whether geographic inequities affected the length of stay after liver transplantation.

METHODS

We conducted a unique Kaplan-Meier analysis with the event being discharge from the hospital and length of stay as the time to the event, using a cohort of 66 674 recipients listed in the UNOS database from 2002 to 2016. Multivariate Cox regression using 43 covariates was used for time-to-event analysis.

RESULTS

Region 9 (0.82; CI 0.79-0.85), Region 2 (0.85; CI 0.83-0.88), and Region 10 (0.96; CI 0.93-0.99) were statistically significant factors for prolonged hospital stay. The following covariates were the most significant factors for prolonged hospital stay: serum sodium >150 mEq/L (0.70; CI 0.62-0.78), ICU admission (0.77; CI 0.74-0.80), hospital admission (0.81; 0.79-0.83), region 9 (0.82; CI 0.79-0.85), and ventilator dependence (0.82; CI 0.76-0.88).

CONCLUSION

In this analysis, we demonstrate regional disparities in hospital length of stay that are significant in robust multivariable Cox regression analysis. We hope the transplant community will take immediate measures to correct geographic inequities.

Cell cycle arrest and cell death correlate with the extent of ischaemia and reperfusion injury in patients following kidney transplantation - results of an observational pilot study

A prolonged cold ischaemia time (CIT) is suspected to be associated with an increased ischaemia and reperfusion injury (IRI) resulting in an increased damage to the graft. In total, 91 patients were evaluated for a delayed graft function within 7 days after kidney transplantation (48 deceased, 43 living donors). Blood and urine samples were collected before, immediately after the operation, and 1, 3, 5, 7 and 10 days later. Plasma and/or urine levels of total keratin 18 (total K18), caspase-cleaved keratin 18 (cc K18), the soluble receptor for advanced glycation end products (sRAGE), tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein-7 (IGFBP7) were measured. As a result of prolonged CIT and increased IRI, deceased donor transplantations were shown to suffer from a more distinct cell cycle arrest and necrotic cell death. Plasmatic total K18 and urinary TIMP-2 and IGFBP7 were therefore demonstrated to be of value for the detection of a delayed graft function (DGF), as they improved the diagnostic performance of a routinely used clinical scoring system. Plasmatic total K18 and urinary TIMP-2 and IGFBP7 measurements are potentially suitable for early identification of patients at high risk for a DGF following kidney transplantation from deceased or living donors.

Analysis of Distribution of Expanded- and Standard-Criteria Donors and Complications Among Polish Recipients by Kidney Donor Risk Index Value

INTRODUCTION

The approach toward transplanting kidneys from expanded-criteria donors (ECDs) in Poland is largely site-dependent. The Kidney Donor Risk Index (KDRI) allows for obtaining a more precise characteristic of ECDs and further stratification into "better" and "worse" quality grafts.

METHODS

Comparison of the incidence of delayed graft function (DGF) and biopsy-proven acute rejection (BPAR), median of hospitalization time and median of estimated glomerular filtration rate (eGFR) at 1 year after transplantation among kidney graft recipients (n = 468), divided by donor status (ECD/standard-criteria donor [SCD]) and KDRI value (I: 0.67-1.2, II: 1.21-1.6, III: 1.61-2.0, IV: 2.01-3.48).

RESULTS

ECD kidneys have been transplanted to 32.47% of recipients. There were no ECD recipients in KDRI compartment I, 16.55% in compartment II, 79.22% in compartment III, and 100% in IV. In KDRI compartment II, DGF was diagnosed in 34.9% of SCDs and 56% of ECDs (P = .003), BPAR occurred in 7.8% of SCDs and 16% of ECDs (P = .073), median hospital stay was 12 days for SCDs and ECDs (P = 1), and eGFR was 50.7 mL/min for SCDs and 49.4 mL/min for ECDs (P = .734). In KDRI compartment III, DGF was diagnosed in 43.8% of SCDs and 49.2% of ECDs (P = .139), BPAR occurred in 6.3% of SCDs and 31.7% of ECDs (P = .001), median hospital stay was 10 days for SCDs and 12 days for ECDs (P = .634), and eGFR was 49.5 mL/min for SCDs and 45.2 mL/min for ECDs (P = .382). Among ECD recipients, DGF was diagnosed in 56.0%, 49.2%, and 47.7% of patients for KDRI compartments II, III, and IV respectively (P = .776); BPAR occurred in 16% (compartment II), 31.7% (compartment III), and 23.1% (compartment IV) (P = .273); the median hospital stay was 12 days (compartment II), 12 days (compartment III), and 12.5 days (compartment IV) (P = 1); and eGFR was 49.5 mL/min (compartment II), 45.4 mL/min (compartment III), and 36.1 mL/min (compartment IV) (P = .002).

CONCLUSION

Assessment using both the ECD and KDRI systems allows for a more precise evaluation of prognosis and predicting complications among recipients.

Benefits of multimodal enhanced recovery pathway in patients undergoing kidney transplantation

BACKGROUND

Use of enhanced recovery after surgery (ERAS) pathways to accelerate functional recovery and reduce length of stay (LOS) has rarely been investigated in kidney transplantation (KTX).

MATERIALS AND METHODS

Consecutive adult isolated KTXs between July 2015 and July 2016 (ERAS, n = 139) were compared with a historical cohort between January 2014 and July 2015 (HISTORIC, n = 95).

RESULTS

Enhanced recovery after surgery recipients were significantly more likely to receive kidneys that were non-local (56.1% vs 4.2%), higher Kidney Donor Profile Index (36-85, 58.4% vs 45.2%; >85, 15.2% vs 10.7%), cold ischemia time ≥30 h (62.4% vs 4.7%), induced with antithymocyte globulin (97.1% vs 87.4%), and to develop delayed graft function (46.4% vs 25.0%). LOS was shorter by 1 day among ERAS (mean 4.59) compared to HISTORIC patients (mean 5.65) predominantly due to a shift in discharges within 3 days (32.4% vs 4.2%); 30-day readmission to the hospital (27.3% vs 27.4%) or emergency room visit (9.4% vs 7.4%) was similar. There was one 30-day death in the ERAS group and none in the HISTORIC group. Return to bowel function and early meal consumption were significantly associated with ERAS, however, with somewhat higher diarrhea and emesis rates.

CONCLUSION

ERAS following KTX correlated with lower LOS without change in readmissions or ER visits despite higher delayed graft function rates.