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.

Two-particle time-domain interferometry in the fractional quantum Hall effect regime

Quasi-particles are elementary excitations of condensed matter quantum phases. Demonstrating that they keep quantum coherence while propagating is a fundamental issue for their manipulation for quantum information tasks. Here, we consider anyons, the fractionally charged quasi-particles of the Fractional Quantum Hall Effect occurring in two-dimensional electronic conductors in high magnetic fields. They obey anyonic statistics, intermediate between fermionic and bosonic. Surprisingly, anyons show large quantum coherence when transmitted through the localized states of electronic Fabry-Pérot interferometers, but almost no quantum interference when transmitted via the propagating states of Mach-Zehnder interferometers. Here, using a novel interferometric approach, we demonstrate that anyons do keep quantum coherence while propagating. Performing two-particle time-domain interference measurements sensitive to the two-particle Hanbury Brown Twiss phase, we find 53 and 60% visibilities for anyons with charges e/5 and e/3. Our results give a positive message for the challenge of performing controlled quantum coherent braiding of anyons.

Excitations of the fractional quantum Hall states are of great interest because they obey anyonic statistics, but electronic interferometers give contrasting results about their quantum coherence. Here the authors use novel two-particle time-domain interferometry to show that quantum coherence is indeed preserved.

Kidney Transplantation From Deceased Donors With Vaccine-induced Immune Thrombocytopenia and Thrombosis: An Updated Analysis of the UK Experience

BACKGROUND

The emergence and attendant mortality of vaccine-induced immune thrombocytopenia and thrombosis (VITT) as a consequence of vaccination against severe acute respiratory syndrome coronavirus 2 have resulted in some patients with VITT being considered as deceased organ donors. Outcomes after kidney transplantation in this context are poorly described. Because the disease seems to be mediated by antiplatelet factor 4 antibodies, there is a theoretical risk of transmission via passenger leukocytes within the allograft.

METHODS

We analyzed the experience of kidney transplantation from donors with VITT in the United Kingdom between January and June 2021. We followed-up all recipients of kidney-only transplants from donors with VITT to detect major postoperative complications or features of disease transmission and assess graft survival and function.

RESULTS

There were 16 kidney donors and 30 single kidney transplant recipients in our study period. Of 11 preimplantation biopsies, 4 showed widespread glomerular microthrombi. After a median of 5 mo, patient and graft survival were 97% and 90%, respectively. The median 3-mo estimated glomerular filtration rate was 51 mL/min/1.73 m 2 . Two recipients had detectable antiplatelet factor 4 antibodies but no evidence of clinical disease after transplantation. Major hemorrhagic complications occurred in 3 recipients, all of whom had independent risk factors for bleeding, resulting in the loss of 2 grafts. The involvement of VITT could not be completely excluded in one of these cases.

CONCLUSIONS

The UK experience to date shows that favorable outcomes are possible after kidney transplantation from donors with VITT but highlights the need for ongoing vigilance for donor-related complications in these patients.

Uptake, translocation, weathering and speciation of gold nanoparticles in potato, radish, carrot and lettuce crops

Extensive use of nanomaterials in agriculture will inevitably lead to their release to the environment in significant loads. Thus, understanding the fate of nanoparticles in the soil-plant environment, and potential presence and consequent implication of nanoparticles in food and feed products, is required. We study plant uptake of gold nanoparticles from soil, and their distribution, translocation and speciation (in terms of particle size change and release of ionic Au) in the different plant tissues of four important crops (potato, radish, carrot and lettuce). Our new analytical protocol and experiments show the feasibility of determining the presence, concentration and distribution of nanoparticles in different plant parts, which differ from plant to plant. Critically, we identify the evident capacity of plants to break down (or substantially change the properties of) nanoparticles in the rhizosphere prior to uptake, as well as the evident capacity of plants to reorganize ionic metals as nanoparticles in their tissues. This could lead to nanoparticle exposure through consumption of crops.

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.

Macroscopic assessment of the quality of cold perfusion after deceased-donor kidney procurement: A United Kingdom population-based cohort study

Concern regarding the quality of cold perfusion (QOP) during macroscopic assessment of procured kidneys is a common reason for discard. In the UK, QOP is routinely graded by both retrieving and implanting teams during back-bench surgery as: 1 (good), 2 (fair), 3 (poor) or 4 (patchy). We evaluated the association of this grading with organ utilization, graft outcomes, and agreement between teams. Data on all deceased-donor kidneys procured between January 2000 and December 2016 were analyzed for discard rates, while association with graft outcomes was studied in single adult transplants. Of 31,167 kidneys procured, 90.6%, 5.7%, 1.7%, and 2.1% were assigned grades 1, 2, 3, and 4, respectively, at retrieval. QOP was an independent risk factor of discard, with the highest rates observed in grade 3 kidneys (41.8%), compared to 6.5% in grade 1 (aOR 7.67, 95% CI 5.44-10.82, p < .001). Grading at retrieval was an independent predictor of delayed graft function (p = .019) and primary non-function (p = .001), but not long-term graft survival (p = .111). Implanting grade was an independent predictor of all three outcomes (p < .001, p < .001, and p = .002, respectively). Consistency of grading between teams was poor (Kappa = 0.179). QOP influences utilization and predicts outcomes, but a standardized and validated scoring system is required.

Kidney transplantation outcomes for adult recipients of pediatric donor kidneys

Despite a paucity of data assessing transplantation of deceased-donor pediatric donor kidneys into adult recipients, utilization of pediatric organs is declining in the UK, likely due to concerns that such organs may have inferior outcomes. However, we hypothesized that these concerns may be unfounded. As such, the aim of the study was to compare kidney transplant outcomes between adult recipients of pediatric and adult deceased-donor organs. Data were collected from the UK Transplant Registry for all adult (18+ years) deceased-donor single-kidney transplant recipients between January 2000 and January 2016. Univariable and multivariable analyses were undertaken, to compare a range of outcomes between recipients of kidneys from pediatric and adult donors. Transplants were stratified by the donor age (years) as follows: 0-16 (n = 666), 17-18 (n = 465), and 19-44 (n = 7378). Recipients of pediatric donor kidneys were observed to have improved long-term graft function, with a median creatinine at 1 year of 109 vs. 117 μmol/L for recipients of donors aged 0-16 vs. 19-44 years (P < .001). However, on multivariable analysis, this was not found to correspond to a significant difference in patient (P = .914) or graft survival (P = .190) between the donor age groups. Subgroup analysis within the younger donors found no significant differences in recipient outcomes between donors aged 0-6, 7-12, and 13-16 years. In this population cohort study, we identified excellent outcomes among adult recipients of pediatric donor kidneys. Pediatric donors are a valuable source of organs for adult recipients in an era where organ demand is rising.

Recipient Sex Differences in Kidney Graft Survival Are Influenced by Donor Sex and Recipient Age

OBJECTIVES

An age-dependent interaction has been described for the effect of donor-recipient sex mismatch on outcomes after kidney transplant in the United States. However, this has not been verified or tested in a different cohort from another country.

MATERIALS AND METHODS

Data of 25 140 deceased donor kidney transplant recipients (2000-2016) were retro-spectively analyzed at a population-cohort level using the United Kingdom transplant registry. Within sub-groups of donor sex, associations between recipient sex and death-censored graft survival were assessed for the cohort as a whole and within recipient age subgroups.

RESULTS

No differences in graft survival were detected between female versus male recipients of male donor kidneys (adjusted hazard ratio: 1.05; P = .227). However, a significant interaction between the age and sex of recipients was identified (P = .007). Female recipients aged 25 to 44 years had significantly shorter graft survival than male recipients (adjusted hazard ratio: 1.27; P = .003), but this effect was reversed in recipients who were 45 years or older (adjusted hazard ratio: 0.94; P = .258), where there was a nonsignificant tendency for longer graft survival in females. No such effect was observed in the subgroup of female donor transplants, with no significant difference between female versus male recipients overall (adjusted hazard ratio: 1.02; P = .638) and no significant interaction with age (P = .470).

CONCLUSIONS

Graft survival is influenced by the combination of recipient age and sex in recipients of male donor kidneys only. This work demonstrates findings broadly similar to published reports but presents differences in observed effect sizes among certain subgroups. Our research suggests further work is warranted to explore personalized approaches to age- and sex-adapted immunosuppression.

Brief O2 uploading during continuous hypothermic machine perfusion is simple yet effective oxygenation method to improve initial kidney function in a porcine autotransplant model

With oxygenation proposed as a resuscitative measure during hypothermic models of preservation, the aim of this study was to evaluate the optimal start time of oxygenation during continuous hypothermic machine perfusion (HMP). In this porcine ischemia-reperfusion autotransplant model, the left kidney of a ±40 kg pig was exposed to 30 minutes of warm ischemia prior to 22 hours of HMP and autotransplantation. Kidneys were randomized to receive 2 hours of oxygenation during HMP either at the start (n = 6), or end of the perfusion (n = 5) and outcomes were compared to standard, nonoxygenated HMP (n = 6) and continuous oxygenated HMP (n = 8). The brief initial and continuous oxygenated HMP groups were associated with superior graft recovery compared to either standard, nonoxygenated HMP or kidneys oxygenated at the end of HMP. This correlated with significant metabolic differences in perfusate (eg, lactate, succinate, flavin mononucleotide) and tissues (eg, succinate, adenosine triphosphate, hypoxia-inducible factor-1α, nuclear factor erythroid 2-related factor 2) suggesting superior mitochondrial preservation with initial oxygenation. Brief initial O₂ uploading during HMP at procurement site might be an easy and effective preservation strategy to maintain aerobic metabolism, protect mitochondria, and achieve an improved early renal graft function compared with standard HMP or oxygen supply shortly at the end of HMP preservation.

P1651HLA CW12 IN KIDNEY TRANSPLANT RECIPIENTS IS A NOVEL RISK FACTOR FOR THE DEVELOPMENT OF POST-TRANSPLANTATION DIABETES: A SINGLE-CENTRE RETROSPECTIVE STUDY

Background and Aims

Counselling kidney transplant candidates for their personalised risk of developing post-transplantation diabetes mellitus (PTDM) requires an understanding of risk factors. While some risk factors are well defined (e.g. age, ethnicity, body mass index), others like HLA typing are heterogeneously reported and lack consistency. The aim of this study was to investigate the association between HLA alleles and PTDM risk.

Method

Data was retrospectively extracted from hospital informatics systems for all kidney transplant recipients at a single-centre between 2007 and 2018, with patients excluded if they had pre-existing diabetes. Electronic patient records were then manually searched and records linked to various sources (e.g. NHS Blood and Transplant tissue typing, Hospital Episode Statistics, national death registry) to create a well-phenotyped cohort. Standard immunosuppression for all kidney transplant recipients during this study period was basiliximab induction with maintenance immunosuppression consisting tacrolimus, mycophenolate mofetil and low-dose corticosteroids. PTDM classification was aligned with International Consensus recommendations.

Results

Data was extracted for 1,560 kidney allograft recipients, with median follow up 5.4 years (IQR 2.7-8.7 years) up to October 2018. PTDM developed in 243 kidney transplant recipients (incidence 15.6%). A range of HLA alleles were examined (e.g. HLA-A, HLA-B, HLA-Cw, HLA-Bw, HLA-DR and HLA-DQ) but only the presence of HLA-Cw12 allele was associated with risk for PTDM (27.4% versus 14.3%, p&lt;0.001) along with a selection of predominately recipient- and transplant related variables. In a logistic regression model, adjusted for all variables with a p-value &lt;0.15 on univariate analysis, recipient HLA-Cw12 was found to be an independent risk factor associated with development of PTDM (Odds Ratio 1.793 [95% confidence interval 1.070-3.002], p=0.027) along with recipient female sex, recipient age, recipient BMI and recipient non-white ethnicity.

Conclusion

HLA-Cw12 allele in the kidney transplant recipient is independently associated with development of PTDM, although it is important to acknowledge association does not imply causality. This association has not been previously reported and requires validation and further investigation to understand any possible underlying biological mechanisms.

A simple ex vivo model of human renal allograft preservation using the gonadal vein

INTRODUCTION

Hypothermic machine perfusion, an organ preservation modality, involves flow of chilled preservation fluid through an allograft's vasculature. This study describes a simple, reproducible, human model that allows for interrogation of flow effects during ex vivo organ perfusion.

MATERIALS AND METHODS

Gonadal veins from deceased human renal allografts were subjected to either static cold storage or hypothermic machine perfusion for up to 24 hours. Caspase-3, Krüppel-like factor 2 expression and electron microscopic analysis were compared between 'flow' and 'no-flow' conditions, with living donor gonadal vein sections serving as negative controls.

RESULTS

The increase in caspase-3 expression was less pronounced for hypothermic machine-perfused veins compared with static cold storage (median-fold increase 1.2 vs 2.3; P < 0.05). Transmission electron microscopy provided ultrastructural corroboration of endothelial cell apoptosis in static cold storage conditions. For static cold storage preserved veins, Krüppel-like factor 2 expression diminished in a time-dependent manner between baseline and 12 hours (P < 0.05) but was abrogated and reversed by hypothermic machine perfusion (P < 0.05).

CONCLUSIONS

Our methodology is a simple, reproducible and successful model of ex vivo perfusion in the context of human organ preservation. To demonstrate the model's utility, we establish that two widely used markers of endothelial health (caspase-3 and Krüppel-like factor 2) differ between the flow and no-flow conditions of the two predominant kidney preservation modalities. These findings suggest that ex vivo perfusion may mediate the induction of a biochemically favourable endothelial niche which may contribute tohypothermic machine perfusion's association with improved renal transplantation outcomes.

Black Ethnicity is Not a Risk Factor for Mortality or Graft Loss After Kidney Transplant in the United Kingdom

OBJECTIVES

There are conflicting reports in the literature regarding outcomes after kidney transplant for patients of black ethnicity. To investigate further, we compared outcomes for black versus white kidney transplant recipients in a single UK transplant center.

MATERIALS AND METHODS

We analyzed 1066 kidney transplant recipients (80 black patients, 986 white patients) within a single-center cohort (2007-2017) in the United Kingdom, with cumulative 4446 patient-year follow-up. Data were electronically extracted from the Department of Health Informatics database for every study recruit, with manual data linkage to the UK Transplant Registry (for graft survival, delayed graft function, and rejection data) and Office for National Statistics (for mortality data). Primary outcomes of interest were graft/patient survival.

RESULTS

Black recipients have increased baseline risk profiles with longer wait times, difficulty in matching, worse HLA matching, more socioeconomic deprivation, and lower rates of living kidney donors. Postoperatively, black versus white recipients had increased risk for delayed graft function (34.3% vs 10.2%; P < .001), increased 1-year rejection (16.7% vs 7.3%; P = .012), higher 1-year creatinine levels (166 vs 138 mmol/L; P = .003), and longer posttransplant length of stay (14.5 vs 9.5 days; P = .020). Although black recipients did not have increased risk of death versus white recipients (10.0% vs 11.0%, respectively; P = .486), they did have increased risk for death-censored graft loss (23.8% vs 11.1%; P = .002). However, in an adjusted Cox regression model, black ethnicity was not associated with increased risk for death-censored graft loss (hazard ratio of 1.209, 95% confidence interval, 0.660-2.216; P = .539).

CONCLUSIONS

Black kidney transplant recipients in the United Kingdom have increased risk of adverse graft-related outcomes due to high-risk baseline variables rather than their black ethnicity per se.

Hypoalbuminaemia at time of surgery is associated with an increased risk for overall graft loss after kidney transplantation

AIM

The aim of this retrospective cohort study was to investigate whether pre-operative hypoalbuminaemia (<35 g/L) is associated with adverse outcomes post-kidney transplantation.

METHODS

Our retrospective, single-centre analysis included all patients who received their kidney transplant between 2007 and 2017, with documented admission albumin levels prior to surgery. Survival analyses were undertaken to explore the relationship of pre-transplant hypoalbuminaemia versus other baseline variables upon post-transplant outcomes.

RESULTS

We analysed 1131 kidney allograft recipients transplanted at our centre (2007-2017), with median follow-up 746 days (interquartile range 133-1750 days). Kidney transplant recipients with pre-operative hypoalbuminaemia were more likely older, female, recipients of deceased-donor kidneys and to have longer cold ischaemic times. Recipients with pre-operative hypoalbuminaemia had longer hospital admissions post-operatively but no difference in delayed graft function rates. There was no difference in 1 year creatinine but recipients with hypoalbuminaemia had reduced risk for cellular rejection. We observed significantly worse patient survival (83.2% vs 90.7%, P < 0.001) and overall graft survival (72.5% vs 82.0%, P < 0.001) for recipients with hypoalbuminaemia vs normal albumin levels, respectively, but no difference in death-censored graft survival. In a Cox regression model, adjusted for baseline pre-operative variables, hypoalbuminaemia was independently associated with an increased risk for overall graft loss after kidney transplantation (hazard ratio 1.468, 95% confidence interval 1.087-1.982, P = 0.012).

CONCLUSION

Pre-operative hypoalbuminaemia is an independent risk factor for overall graft loss after kidney transplantation. Further work is warranted to investigate the underlying pathophysiology to determine what supportive measures can be undertaken to attenuate adverse post-transplant outcomes.

Outcomes of donation after circulatory death kidneys undergoing hypothermic machine perfusion following static cold storage: A UK population-based cohort study

Evidence is currently lacking regarding the outcomes of kidneys undergoing hypothermic machine perfusion (HMP) in patients in the United Kingdom. Using the National Health Service Blood and Transplant database, the authors compared outcomes for recipients of single-organ donation after circulatory death (DCD) kidneys preserved with HMP with those preserved using only static cold storage (SCS). Between 2007 and 2015, HMP was used in 19.1% (864/4,529) of kidneys. Rates of delayed graft function (DGF) were significantly lower in organs preserved with HMP than for organs preserved with SCS (34.2% vs 42.0%, P < .001), despite a slightly longer cold ischemic time (median: 14.8 vs 14.1 hours, P < .001). Multivariable analysis found the effect of preservation modality to remain significant, with HMP organs having a significantly lower rate of DGF (odds ratio 0.65, 95% confidence interval 0.53-0.80, P < .001) and significantly shorter times to DGF resolution (average: 6.1 vs 7.4 days, P = .003) than SCS organs. The patient (P = .313) and graft (P = .263) survival rates were similar in the 2 preservation groups. HMP was associated with a marginal functional benefit in 1-year creatinine values (P = .044), with adjusted averages of 1.36 mg/dL (HMP) versus 1.40 mg/dL (SCS). This study supports the use of HMP and aids decision-making over its instigation, which may improve short-term patient outcomes.

Deceased-Donor Smoking History Is Associated With Increased Recipient Mortality After Kidney Transplant: A Population-Cohort Study

OBJECTIVES

Historical data have suggested that donor smoking is associated with detrimental clinical outcomes for recipients of kidneys from deceased donors. However, the effects of smoking status of a kidney donor on the outcomes of the recipient in a contemporary setting of immunosuppression and transplant practice have not yet been ascertained.

MATERIALS AND METHODS

This retrospective, population-cohort study analyzed data of all deceased-donor kidney-alone transplant procedures performed in the United Kingdom between April 2001 and April 2013. Our study included 11?199 deceased-donor kidney allograft recipients, with median follow-up of 46 months posttransplant.

RESULTS

In our cohort, 5280 deceased donors (47.1%) had a documented history of smoking. Deceased donors with versus those without smoking history were more likely to be younger (mean age of 48 vs 50 years; P < .001), be of white ethnicity (96.6% vs 95.3%; P < .001), and have brain death before donation (77.1% vs 74.9%; P = .006). On unadjusted survival analyses, overall patient survival was significantly shorter in patients who received kidney allografts from deceased donors with smoking history (hazard ratio of 1.12, 95% confidence interval, 1.00-1.25; P = .044). No significant association was seen for death-censored or overall graft survival. Our multivariate survival analyses showed that, after accounting for confounding factors, the effects of donor smoking status remained significant for patient survival (hazard ratio of 1.16, 95% CI, 1.03-1.29; P =.011) but not graft survival.

CONCLUSIONS

This population-cohort study suggests that deceased-donor kidneys from smokers contribute to an increased risk of death for kidney allograft recipients. These study findings imply donor smoking history should be factored into the risk stratification decision for recipient selection to optimize decision making; however, further clarification and validation of these data are warranted.

Mortality risk after cancer diagnosis in kidney transplant recipients: the limitations of analyzing hospital administration data alone

Administrative data are frequently used for epidemiological studies but its usefulness to analyze cancer epidemiology after kidney transplantation is unclear. In this retrospective population-based cohort study, we identified every adult kidney-alone transplant performed in England (2003-2014) using administrative data from Hospital Episode Statistics. Results were compared to the hospitalized adult general population in England to calculate standardized incidence and mortality ratios. Data were analyzed for 19,883 kidney allograft recipients, with median follow-up 6.0 years' post-transplantation. Cancer incidence was more common after kidney transplantation compared to the general population in line with published literature (standardized incidence ratio 2.47, 95% CI: 2.34-2.61). In a Cox proportional hazards model, cancer development was associated with increasing age, recipients of deceased kidneys, frequent readmissions within 12 months post-transplant and first kidney recipients. All-cause mortality risk for kidney allograft recipients with new-onset cancer was significantly higher compared to those remaining cancer-free (42.0% vs. 10.3%, respectively). However, when comparing mortality risk for kidney allograft recipients to the general population after development of cancer, risk was lower for both cancer-related (standardized mortality ratio 0.75, 95% CI: 0.71-0.79) and noncancer-related mortality (standardized mortality ratio 0.90, 95% CI: 0.85-0.95), which contradicts reported literature. Although some plausible explanations are conceivable, our analysis likely reflects the limitations of administrative data for analyzing cancer data. Future studies require record linkage with dedicated cancer registries to acquire more robust and accurate data relating to cancer epidemiology after transplantation.

Smoking History Is Associated With Adverse Outcomes for Kidney Allograft Recipients

OBJECTIVES

Donor kidney measurements may affect outcomes of transplanted allografts. We tested allograft and recipient measurements on kidney allograft outcomes. In this study, we compared the effects of kidney allograft volumes, which were measured using computed tomographic angiography before transplant, and allograft weight, which was measured during surgery, in relation to the recipient's body weight and body mass index on kidney function at 6 and 12 months after transplant.

MATERIAL AND METHODS

We included 74 patients (40 female and 34 male patients, mean age of 50.42 ±; 9.75 y) in this study.

RESULTS

Intraoperative allograft weight was 182.68 ± 40.33 g (range, 104-266 g). The allograft volume measured using computed tomographic angiography scanning was 123.34 ± 24.26 mL (range, 78-181 mL). The estimated glomerular filtration rates of the recipients at 6 and 12 months after transplant correlated negatively with age and recipient body mass index but correlated positively with allograft volume/recipient body weight, allograft volume/recipient body mass index, allograft weight, allograft weight/recipient body weight, and allograft weight/recipient body mass index values, as concluded by univariate analyses. From multivariate analyses, we found variables of interest presumed to significantly affect the 12-month estimated glomerular filtration rates, including recipient age, allograft volume/recipient body weight, allograft volume/recipient body mass index, allograft weight, allograft weight/recipient body weight, and allograft weight/recipient body mass index.

CONCLUSIONS

Transplanted allograft and recipient body values may be used as predictors of estimated glomerular filtration rates 6 and 12 months after transplant.

Pre-existing diabetes is a risk factor for increased rates of cellular rejection after kidney transplantation: an observational cohort study

AIM

To investigate whether people with diabetes have an elevated risk of kidney allograft rejection in a well characterized clinical cohort in the setting of contemporary immunosuppression.

METHODS

We conducted a retrospective cohort study including all kidney allograft recipients at a single centre between 2007 and 2015, linking clinical, biochemical and histopathological data from electronic patient records.

RESULTS

Data were analysed for 1140 kidney transplant recipients. The median follow-up was 4.4 years post-transplantation, and 117 of the kidney transplant recipients (10.2%) had diabetes at time of transplantation. Kidney allograft recipients with vs without diabetes were older (53 vs 45 years; P<0.001) and more likely to be non-white (41.0% vs 26.4%; P=0.001). Kidney allograft recipients with vs without diabetes had a higher risk of cellular rejection (19.7% vs 12.4%; P=0.024), but not of antibody-mediated rejection (3.4% vs 3.7%; P=0.564). Graft function and risk of death-censored graft loss were similar in the two groups, but kidney allograft recipients with diabetes had a higher risk of death and overall graft loss than those without diabetes. In a Cox regression model of non-modifiable risk factors at time of transplantation, diabetes was found to be an independent risk factor for cellular rejection (hazard ratio 1.445, 95% CI 1.023-1.945; P=0.042).

CONCLUSIONS

Kidney allograft recipients with diabetes at transplantation should be counselled regarding their increased risk of cellular rejection but reassured regarding the lack of any adverse impact on short-to-medium term allograft function or survival.

Do outcomes after kidney transplantation differ for black patients in England versus New York State? A comparative, population-cohort analysis

OBJECTIVES

Inferior outcomes for black kidney transplant recipients in the USA may not be generalisable elsewhere. In this population cohort analysis, we compared outcomes for black kidney transplant patients in England versus New York State.

DESIGN

Retrospective, comparative, population cohort study utilising administrative data registries.

SETTINGS AND PARTICIPANTS

English data were derived from Hospital Episode Statistics, while New York State data were derived from Statewide Planning and Research Cooperative System. All adults receiving their first kidney-alone allograft between 2003 and 2013 were eligible for inclusion.

MEASURES

The primary outcome measure was mortality post kidney transplantation (including inhospital death, 30-day mortality and 1-year mortality). Secondary outcome measures included postoperative admission length of stay, risk of rehospitalisation, development of cardiac events, stroke, cancer or fracture and finally transplant rejection/failure. Cox proportional hazards regression was used to investigate relationship between ethnicity, country and outcome.

RESULTS

Black patients comprised 6.5% of the English cohort (n=1215/18 493) and 23.0% of the New York State cohort (n=2660/11 602). Compared with New York State, black kidney transplant recipients in England were more likely younger, male, living-donor kidney recipients and had dissimilar medical comorbidities. Inpatient mortality was not statistically different, but death within 30 days, 1 year or kidney transplant rejection/failure was lower among black patients in England versus black patients in New York State. In adjusted regression analysis, with black ethnicity the reference group, white patients had reduced risk for 30-day mortality (OR 0.62 (95% CI 0.44 to 0.86)) and 1-year mortality (OR 0.79 (95% CI 0.63 to 0.99)) in New York State but no difference was observed in England. Compared with England, black kidney transplant patients in New York State had increased HR for kidney transplant rejection rejection/failure by median follow-up (HR 2.15, 95% CI 1.91 to 2.43).

CONCLUSIONS

Outcomes after kidney transplantation for black patients may not be translatable between countries.

Detection of Focal Longitudinal Changes in the Brain by Subtraction of MR Images

BACKGROUND AND PURPOSE

The detection of new subtle brain pathology on MR imaging is a time-consuming and error-prone task for the radiologist. This article introduces and evaluates an image-registration and subtraction method for highlighting small changes in the brain with a view to minimizing the risk of missed pathology and reducing fatigue.

MATERIALS AND METHODS

We present a fully automated algorithm for highlighting subtle changes between multiple serially acquired brain MR images with a novel approach to registration and MR imaging bias field correction. The method was evaluated for the detection of new lesions in 77 patients undergoing cardiac surgery, by using pairs of fluid-attenuated inversion recovery MR images acquired 1-2 weeks before the operation and 6-8 weeks postoperatively. Three radiologists reviewed the images.

RESULTS

On the basis of qualitative comparison of pre- and postsurgery FLAIR images, radiologists identified 37 new ischemic lesions in 22 patients. When these images were accompanied by a subtraction image, 46 new ischemic lesions were identified in 26 patients. After we accounted for interpatient and interradiologist variability using a multilevel statistical model, the likelihood of detecting a lesion was 2.59 (95% CI, 1.18-5.67) times greater when aided by the subtraction algorithm (P = .017). Radiologists also reviewed the images significantly faster (P < .001) by using the subtraction image (mean, 42 seconds; 95% CI, 29-60 seconds) than through qualitative assessment alone (mean, 66 seconds; 95% CI, 46-96 seconds).

CONCLUSIONS

Use of this new subtraction algorithm would result in considerable savings in the time required to review images and in improved sensitivity to subtle focal pathology.

Cancer-related outcomes in kidney allograft recipients in England versus New York State: a comparative population-cohort analysis between 2003 and 2013

It is unclear whether cancer‐related epidemiology after kidney transplantation is translatable between countries. In this population‐cohort study, we compared cancer incidence and all‐cause mortality after extracting data for every kidney‐alone transplant procedure performed in England and New York State (NYS) between 2003 and 2013. Data were analyzed for 18,493 and 11,602 adult recipients from England and NYS respectively, with median follow up 6.3 years and 5.5 years respectively (up to December 2014). English patients were more likely to have previous cancer at time of transplantation compared to NYS patients (5.6% vs. 3.5%, P < 0.001). Kidney allograft recipients in England versus NYS had increased cancer incidence (12.3% vs. 5.9%, P < 0.001) but lower all‐cause mortality during the immediate postoperative stay (0.7% vs. 1.0%, P = 0.011), after 30‐days (0.9% vs. 1.8%, P < 0.001) and after 1‐year post‐transplantation (3.0% vs. 5.1%, P < 0.001). However, mortality rates among patients developing post‐transplant cancer were equivalent between the two countries. During the first year of follow up, if patients had an admission with a cancer diagnosis, they were more likely to die in both England (Odds Ratio 4.28 [95% CI: 3.09–5.93], P < 0.001) and NYS (Odds Ratio 2.88 [95% CI: 1.70–4.89], P < 0.001). Kidney allograft recipients in NYS demonstrated higher hazard ratios for developing kidney transplant rejection/failure compared to England on Cox regression analysis. Our analysis demonstrates significant differences in cancer‐related epidemiology between kidney allograft recipients in England versus NYS, suggesting caution in translating post‐transplant cancer epidemiology between countries.

(13)C glucose labelling studies using 2D NMR are a useful tool for determining ex vivo whole organ metabolism during hypothermic machine perfusion of kidneys

Background

The aim of this study is to determine the feasibility of using nuclear magnetic resonance (NMR) tracer studies (¹³C-enriched glucose) to detect ex vivo de novo metabolism in the perfusion fluid and cortical tissue of porcine kidneys during hypothermic machine perfusion (HMP).

Methods

Porcine kidneys (n = 6) were subjected to 24 h of HMP using the Organ Recovery Systems LifePort Kidney perfusion device. Glucose, uniformly enriched with the stable isotope ¹³C ([U-¹³C] glucose), was incorporated into KPS-1-like perfusion fluid at a concentration of 10 mM. Analysis of perfusate was performed using both 1D ¹H and 2D ¹H,¹³C heteronuclear single quantum coherence (HSQC) NMR spectroscopy. The metabolic activity was then studied by quantifying the proportion of key metabolites containing ¹³C in both perfusate and tissue samples.

Results

There was significant enrichment of ¹³C in a number of central metabolites present in both the perfusate and tissue extracts and was most pronounced for lactate and alanine. The total amount of enriched lactate (per sample) in perfusion fluid increased during HMP (31.1 ± 12.2 nmol at 6 h vs 93.4 ± 25.6 nmol at 24 h p < 0.01). The total amount of enriched alanine increased in a similar fashion (1.73 ± 0.89 nmol at 6 h vs 6.80 ± 2.56 nmol at 24 h p < 0.05). In addition, small amounts of enriched acetate and glutamic acid were evident in some samples.

Conclusions

This study conclusively demonstrates that de novo metabolism occurs during HMP and highlights active metabolic pathways in this hypothermic, hypoxic environment. Whilst the majority of the ¹³C-enriched glucose is metabolised into glycolytic endpoint metabolites such as lactate, the presence of non-glycolytic pathway derivatives suggests that metabolism during HMP is more complex than previously thought. Isotopic labelled ex vivo organ perfusion studies using 2D NMR are feasible and informative.

Effect of cold ischaemia time on outcome after living donor renal transplantation

BACKGROUND

The aim of the present study was to determine the effects of cold ischaemia time (CIT) on living donor kidney transplant recipients in a large national data set.

METHODS

Data from the National Health Service Blood and Transplant and UK Renal Registry databases for all patients receiving a living donor kidney transplant in the UK between January 2001 and December 2014 were analysed. Patients were divided into three groups depending on CIT (less than 2 h, 2-4 h, 4-8 h). Risk-adjusted outcomes were assessed by multivariable analysis adjusting for discordance in both donor and recipient characteristics.

RESULTS

Outcomes of 9156 transplants were analysed (CIT less than 2 h in 2662, 2-4 h in 4652, and 4-8 h in 1842). After adjusting for confounders, there was no significant difference in patient survival between CIT groups. Recipients of kidneys with a CIT of 4-8 h had excellent graft outcomes, although these were slightly inferior to outcomes in those with a CIT of less than 2 h, with risk-adjusted rates of delayed graft function of 8·6 versus 4·3 per cent, and 1-year graft survival rates of 96·2 versus 97·1 per cent, respectively.

CONCLUSION

The detrimental effect of prolonging CIT for up to 8 h in living donation kidney transplantation is marginal.

Risk of post-transplantation diabetes mellitus is greater in South Asian versus Caucasian kidney allograft recipients

South Asians have increased risk for type 2 diabetes mellitus compared with Caucasians in the general population, but data for the development of post-transplantation diabetes mellitus (PTDM) is scarce. In this retrospective analysis, data was extracted from electronic patient records at a single centre (2004-2014). Caucasians were more likely to be male, with higher age and BMI than South Asians. Case-control matching was therefore undertaken to remove this bias, resulting in 102 recipient pairs. Median follow-up was 50 months (range 4-127 months). Matched groups had similar baseline characteristics, although South Asians compared with Caucasians received more deceased-donor kidneys (74% vs. 43%, respectively, P < 0.001) and were more likely to be CMV positive (77% vs. 43%, respectively, P < 0.001). PTDM incidence was significantly higher in South Asians versus Caucasians (35% vs. 10%, respectively, subhazard ratio 4.2 [95% CI: 2.1-8.5, P < 0.001]). Donor type had significant interaction with ethnicity, with the observed difference in PTDM rates between ethnicities most visible with receipt of deceased-donor kidneys. No significant difference was detected in allograft function, rejection episodes, adverse cardiovascular events or patient/graft survival. South Asians have increased risk of PTDM, especially recipients of deceased kidneys, and recognition of this allows appropriate patient counselling and development of targeted strategies.

Complex kidneys for complex patients: the risk associated with transplantation of kidneys with multiple arteries into obese patients

Conflicting evidence surrounds clinical outcomes in obese individuals after transplantation; nonetheless, many are denied the opportunity to receive a transplant. Allografts with complex vascular anatomy are regularly used in both deceased and living donor settings. We established the risk of transplanting kidneys with multiple renal arteries into obese recipients. A retrospective analysis of data from 1095 patients undergoing renal transplantation between January 2004 and July 2013 at a single centre was conducted. Of these, 24.2% were obese (body mass index >30 kg/m(2)), whereas 25.1% of kidneys transplanted had multiple arteries, thereby making the transplantation of kidneys of complex anatomy into obese recipients a relatively common clinical occurrence. Vessel multiplicity was associated with inferior 1-year graft survival (85.8.% vs 92.1%, P = .004). Obese patients had worse 1-graft survival compared to those of normal BMI (86.8% vs 93.8%, P = .001). The risk of vascular complications and of graft loss within a year after transplantation were greater when grafts with multiple arteries were transplanted into obese recipients as compared to their nonobese counterparts (RR 2.00, CI 95% 1.07-3.65, and RR 1.95, CI 95% 1.02-3.65). Additionally, obese patients faced significantly higher risk of graft loss if receiving a kidney with multiple arteries compared to one of normal anatomy (RR 1.97, 95% CI 1.02-3.72). Thus, obese patients receiving complex anatomy kidneys face poorer outcomes, which should be considered when allocating organs, seeking consent, and arranging for aftercare.