Correlation of histologic findings on preimplant biopsy with kidney graft survival

Decoding the hallmarks of allograft dysfunction with a comprehensive pan-organ transcriptomic atlas

The pathogenesis of allograft (dys)function has been increasingly studied using 'omics'-based technologies, but the focus on individual organs has created knowledge gaps that neither unify nor distinguish pathological mechanisms across allografts. Here we present a comprehensive study of human pan-organ allograft dysfunction, analyzing 150 datasets with more than 12,000 samples across four commonly transplanted solid organs (heart, lung, liver and kidney, n = 1,160, 1,241, 1,216 and 8,853 samples, respectively) that we leveraged to explore transcriptomic differences among allograft dysfunction (delayed graft function, acute rejection and fibrosis), tolerance and stable graft function. We identified genes that correlated robustly with allograft dysfunction across heart, lung, liver and kidney transplantation. Furthermore, we developed a transfer learning omics prediction framework that, by borrowing information across organs, demonstrated superior classifications compared to models trained on single organs. These findings were validated using a single-center prospective kidney transplant cohort study (a collective 329 samples across two timepoints), providing insights supporting the potential clinical utility of our approach. Our study establishes the capacity for machine learning models to learn across organs and presents a transcriptomic transplant resource that can be employed to develop pan-organ biomarkers of allograft dysfunction.

Arteriolar hyalinization at 0-hour biopsy predicts long-term graft function in deceased kidney transplantation

OBJECTIVES

Regarding the relationship between donor kidney quality and renal graft function after deceased kidney transplantation (KTx) following donation after cardiac death (DCD), the evaluation timing varies depending on the study. Evaluation of histology and changes in long-term renal graft function is limited.

METHODS

A retrospective single-center study included 71 recipients who underwent 0-hour biopsy for KTx from DCD. The recipients were divided into two groups to evaluate factors related to renal graft function (study1). The two groups were categorized as stable graft function and poor graft function with the change of estimated glomerular filtration rate (eGFR) after KTx. The recipients were then divided into four groups to assess whether the factors identified in study1 were related to the change in long-term renal graft function (study2). They were categorized as follows: Improved, Stable, Deteriorated, and Primary non-function with the change of eGFR after KTx.

RESULTS

In study1, donor age ≥ 50 years (29.5% vs. 65.2%; p = 0.09), banff arteriolar hyalinosis (ah) score (0.66 ± 0.78 vs. 1.2 ± 1.0; p = 0.018), and presence of glomerulosclerosis (43.2% vs. 76.2%; p = 0.017) were significant risk factors for poor long-term graft function. When the recipients were divided into four groups, the severity of ah correlated well with changes in long-term renal function.

CONCLUSIONS

We can predict the shift in long-term renal graft function after KTx from DCD according to the severity of ah by 0-hour biopsy.

Past, Current, and Future Perspectives on Transplanting Acute Kidney Injury Kidneys

(1) Background: Acute kidney injury (AKI) kidneys have high non-utilization rates due to concerns regarding unfavorable outcomes. In this paper, we aimed to review the past, present, and future opinions on AKI kidneys. (2) Methods: A PubMed search was conducted for topics relevant to AKI kidney transplantation. (3) Results: Current short- and long-term data on AKI kidneys have demonstrated good outcomes including favorable graft function and survival. The role of procurement biopsies is controversial, but they have been shown to be beneficial in AKI kidneys by allowing clinicians to differentiate between reversible tubular injury and irreversible cortical necrosis. Machine perfusion has also been applied to AKI kidneys and has been shown to reduce delayed graft function (DGF). The incidence of DGF increases with AKI severity and its management can be challenging. Strategies employed to counteract this have included early initiation of dialysis after kidney transplantation, early targeting of adequate immunosuppression levels to minimize rejection risk, and establishment of outpatient dialysis. (4) Conclusions: Despite good outcomes, there continue to be barriers that impact AKI kidney utilization. Successful strategies have included use of procurement biopsies or machine perfusion and expectant management of DGF. With increasing experience, better use of AKI kidneys can result in additional opportunities to expand the donor pool.

European Society for Organ Transplantation (ESOT)-TLJ 3.0 Consensus on Histopathological Analysis of Pre-Implantation Donor Kidney Biopsy: Redefining the Role in the Process of Graft Assessment

The ESOT TLJ 3.0. consensus conference brought together leading experts in transplantation to develop evidence-based guidance on the standardization and clinical utility of pre-implantation kidney biopsy in the assessment of grafts from Expanded Criteria Donors (ECD). Seven themes were selected and underwent in-depth analysis after formulation of PICO (patient/population, intervention, comparison, outcomes) questions. After literature search, the statements for each key question were produced, rated according the GRADE approach [Quality of evidence: High (A), Moderate (B), Low (C); Strength of Recommendation: Strong (1), Weak (2)]. The statements were subsequently presented in-person at the Prague kick-off meeting, discussed and voted. After two rounds of discussion and voting, all 7 statements reached an overall agreement of 100% on the following issues: needle core/wedge/punch technique representatively [B,1], frozen/paraffin embedded section reliability [B,2], experienced/non-experienced on-call renal pathologist reproducibility/accuracy of the histological report [A,1], glomerulosclerosis/other parameters reproducibility [C,2], digital pathology/light microscopy in the measurement of histological variables [A,1], special stainings/Haematoxylin and Eosin alone comparison [A,1], glomerulosclerosis reliability versus other histological parameters to predict the graft survival, graft function, primary non-function [B,1]. This methodology has allowed to reach a full consensus among European experts on important technical topics regarding pre-implantation biopsy in the ECD graft assessment.

Influence of organ quality on the observed association between deceased donor kidney procurement biopsy findings and graft survival

Deceased donor kidney procurement biopsies findings are the most common reason for kidney discard. Retrospective studies have found inconsistent associations with post-transplant outcomes but may have been limited by selection bias because kidneys with advanced nephrosclerosis from high-risk donors are typically discarded. We conducted a retrospective cohort study of kidneys transplanted in the United States from 2015 to 2019 with complete biopsy data available, defining "suboptimal histology" as glomerulosclerosis ≥11%, IFTA ≥mild, and/or vascular disease ≥mild. We used time-to-event analyses to determine the association between suboptimal histology and death-censored graft failure after stratification by kidney donor profile index (KDPI) (≤35%, 36%-84%, ≥85%) and final creatinine (<1 mg/dl, 1-2 mg/dl, >2 mg/dl). Among 30 469 kidneys included, 36% had suboptimal histology. In adjusted analyses, suboptimal histology was associated with death-censored graft failure among kidneys with KDPI 36-84% (HR 1.22, 95% CI 1.09-1.36), but not KDPI≤35% (HR 1.24, 0.94-1.64) or ≥ 85% (HR 0.99, 0.81-1.22). Similarly, suboptimal histology was associated with death-censored graft failure among kidneys from donors with creatinine 1-2 mg/dl (HR 1.39, 95% CI 1.20-1.60) but not <1 mg/dl (HR 1.07, 0.93-1.23) or >2 mg/dl (HR 0.95, 0.75-1.20). The association of procurement histology with graft longevity among intermediate-quality kidneys that were likely to be both biopsied and transplanted suggests biopsies provide independent organ quality assessments.

The Independent Effects of Procurement Biopsy Findings on Ten-Year Outcomes of Extended Criteria Donor Kidney Transplants

Introduction

Methods

Results

Conclusion

Impact of the explanting surgeon's impression of donor arteriosclerosis on outcome of kidney transplantations from donors aged ≥65 years

PURPOSE

Careful donor selection is important for kidney transplantations (KT) from suboptimal donors aged ≥65 years. Several tools such as histopathological assessment of preimplant biopsies have been shown to predict allograft survival and can be applied for selection. Whether the explanting surgeon's appraisal is associated with outcomes of KTs from suboptimal donors is unknown.

METHODS

We compared outcomes of KTs from ≥65-year-old deceased donors performed at our centre between 1999 and 2018 for which grading of macroscopic 'donor arteriosclerosis' (n=104) and 'organ quality' (n=208) as judged by the explanting surgeon and documented on the Eurotransplant kidney organ report was available.

RESULTS

No association was observed between degree of macroscopic donor arteriosclerosis and death-censored graft survival in univariable or multivariable regression analyses. Compared to KTs from donors with no/mild arteriosclerosis, KTs from donors with moderate/severe arteriosclerosis were associated with a significantly impaired allograft function 3 months, 1 year and 3 years after transplantation (e.g. at 3 years: 176.8 µmol/l vs 137.0 µmol/l, P=0.003). Following multivariable regression analysis, these differences remained significant at 3 months and 3 years after KT. No association was observed between degree of macroscopic arteriosclerosis and mortality or primary non-function as well as no consistent association with delayed graft function and histological arteriosclerosis. Assessment of 'organ quality' was not associated with outcomes.

CONCLUSION

Our data suggest that the explanting surgeon's assessment of donor arteriosclerosis is associated with allograft function. Larger studies and better standardization of kidney inspection after explantation are required to further explore the impact of surgeon's appraisal in KT.

Association between procurement biopsy findings and deceased donor kidney outcomes: a paired kidney analysis

Unfavourable procurement biopsy findings are the most common reason for deceased donor kidney discard in the United States. We sought to assess the association between biopsy findings and post-transplant outcomes when donor characteristics are accounted for. We used registry data to identify 1566 deceased donors of 3132 transplanted kidneys (2015-2020) with discordant right/left procurement biopsy classification and performed time-to-event analyses to determine the association between optimal histology and hazard of death-censored graft failure or death. We then repeated all analyses using a local cohort of 147 donors of kidney pairs with detailed procurement histology data available (2006-2016). Among transplanted kidney pairs in the national cohort, there were no significant differences in incidence of delayed graft function or primary nonfunction. Time to death-censored graft failure was not significantly different between recipients of optimal versus suboptimal kidneys. Results were similar in analyses using the local cohort. Regarding recipient survival, analysis of the national, but not local, cohort showed optimal kidneys were associated with a lower hazard of death (adjusted HR 0.68, 95% CI 0.52-0.90, P = 0.006). In conclusion, in a large national cohort of deceased donor kidney pairs with discordant right/left procurement biopsy findings, we found no association between histology and death-censored graft survival.

Arterial Intimal Fibrosis in Reperfusion Biopsy Correlates with Graft Function after Kidney Transplant

INTRODUCTION

Alterations to the procurement biopsy are one of the main reasons that kidneys are not suitable for transplant and are discarded. The literature on procurement and reperfusion biopsy is inconsistent and heterogeneous. The objective of this study is to describe the correlation of the different histological characteristics detected by the procurement and reperfusion biopsies in relation to graft function.

METHODS

This is a retrospective cohort study of deceased donor kidney transplants performed from 2013 to 2017. All of the different histological components of procurement and reperfusion biopsies were analyzed with nonparametric tests and multivariate regressions. Graft function was expressed as glomerular filtration rate (GFR) at 1, 3, 6, and 12 months after transplant. All tests were based on a level of significance of α = 0.05.

RESULTS

A comparison of procurement and reperfusion biopsies revealed that 60.4% of the grafts exhibited more arterial intimal fibrosis and 55.6% more arteriolar hyalinosis in the reperfusion biopsy than in the procurement biopsy. Arterial intimal fibrosis in reperfusion biopsy correlated with GFR at all time points, and it was the only histological characteristic of the reperfusion biopsy that remained significant in multivariate analysis. Glomerulosclerosis in the procurement biopsy correlated with graft function and remained significant in multivariate analysis, but only at 6 months. Arterial intimal fibrosis in the reperfusion biopsy is significantly associated with graft function independently of clinical characteristics.

CONCLUSION

Our study highlights the importance of arterial intimal fibrosis in predicting kidney function after transplant. Because arterial intimal fibrosis is a chronic change not related to ischemia-reperfusion injury, the differences between the 2 biopsies may be due to the biopsy technique. In order to increase the prognostic accuracy of the procurement biopsy, the technique should be improved to better evaluate the vasculature.

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

Background

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

Method

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

Results

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

Conclusion

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

Kidney transplantation with donors in severe acute kidney injury. Should we use these organs? Retrospective Case Series

INTRODUCTION

The number of incident and prevalent patients on dialysis has increased, as well as the number of candidates for renal transplantation in Brazil, without a proportional increase in the number of organ donors. The use of expanded kidneys, as to renal function, may be an alternative to increase the supply of organs.

OBJECTIVE

to discuss the feasibility of using expanded kidneys for renal function, which are in severe acute renal injury.

METHODS

All cases of renal transplantation of deceased donors performed at the Hospital das Clínicas de Botucatu of UNESP, from January 2010 to June 2018, totaling 732 cases were evaluated. Cases with final donor creatinine greater than 6 mg/dL were selected.

RESULTS

four patients were selected, of whom all donors were in severe acute kidney injury (AKI). These donors presented rhabdomyolysis as a probable cause of severe AKI, were young, with no comorbidities and had decreased urinary volume in the last 24 hours. The clinical evolution of all the recipients was satisfactory, with a glomerular filtration rate after transplantation ranging from 48 to 98 mL/min/1.73 m2.

CONCLUSION

this series of cases shows the possibility of using renal donors in severe AKI, provided the following are respected: donor age, rhabdomyolysis as the cause of AKI, and implantation-favorable biopsy findings. Additional studies with better designs, larger numbers of patients and longer follow-up times are needed.

Histological and clinical evaluation of marginal donor kidneys before transplantation: Which is best?

Organ shortage represents one of the major limitations to the development of kidney transplantation. To increase the donor pool and to answer the ever increasing kidney request, physicians are recurring to marginal kidneys as kidneys from older donors, from hypertensive or diabetic donors and from non-heart beating donors. These kidneys are known to have frequently a worse outcome in the recipients. To date major problem is to evaluate such kidneys in order to use or to discard them before transplantation. The use of such kidneys create other relevant question as whether to use them as single or dual transplant and to allocate them fairly according transplant programs. The pre-transplant histological evaluation, the clinical evaluation of the donor or both the criteria joined has been used and according the time each criterion prevailed over the others. Aim of this review has been to examine the advantages and the drawbacks of any criterion and how they have changed with time. To date any criterion has several limitations and several authors have argued for the development of new guidelines in the field of the kidney evaluation for transplantation. Several authors argue that the use of omic technologies should improve the organ evaluation and studies are ongoing to evaluate these technologies either in the donor urine or in the biopsies taken before transplantation.

The relation between zero-time pretransplant deceased donor renal biopsy and kidney transplant survival

Introduction

There are several investigations about preimplantation biopsy results in alive donors. However, assessment of the biopsies in deceased donors’ kidney and its correlation with patient survival is limited. In this study, we evaluated the correlation between zero-time pretransplant kidney biopsy and survival of kidney in deceased donors.

Patients and methods

This was a cohort study conducted at Montaserieh Hospital, Mash-had, between January 2016 and December 2017. We included all brain dead patients who were referred to Montaserieh transplantation center. After vascular anastomosis of kidneys in recipient patients, in the operation room, and de-clumping of vessels, biopsies were taken from upper pole of donated kidney. Blocks of biopsies were evaluated by expert pathologists and then reported. We followed patients for 1 year and compared the pathologic findings and renal survival in them.

Results

The mean age of deceased donors was 32.32±1.49 years and that of the recipient patients was 36.33±1.27 years. Thirty-eight recipient patients (45.2%) were female and 46 were male (54.8%). The most pathologic pattern in our study was grade I separation, followed by blebs, dilatation, and loss of attenuation. We showed that most of the transplantations were safe after 1-year follow-up (85.7%) without any complications. We observed thrombosis in two cases (2.4%) and rejection of transplantation in ten patients (11.9%). Cox regression analysis showed that end-stage renal disease grade (HR =3.84, 95% CI =2.315–6.348; P<0.0001) and gender of the deceased donors (HR =0.34, 95% CI =0.145–0.797; P=0.013) were related to graft survival rate.

Conclusion

Only cast feature in pathologic exam was related to graft survival, which is a marker of tissue ischemia. There was no significant correlation between other histological findings and graft survival.

Oxalate deposition in renal allograft biopsies within 3 months after transplantation is associated with allograft dysfunction

BACKGROUND

Calcium oxalate (CaOx) deposition in the kidney may lead to loss of native renal function but little is known about the prevalence and role of CaOx deposition in transplanted kidneys.

METHODS

In patients transplanted in 2014 and 2015, all for-cause renal allograft biopsies obtained within 3 months post-transplantation were retrospectively investigated for CaOx deposition. Additionally, all preimplantation renal biopsies obtained in 2000 and 2001 were studied.

RESULTS

In 2014 and 2015, 388 patients were transplanted, of whom 149 had at least one for-cause renal biopsy. Twenty-six (17%) patients had CaOx deposition. In the population with CaOx deposition: Patients had significantly more often been treated with dialysis before transplantation (89 vs. 64%; p = 0.011); delayed graft function occurred more frequently (42 vs. 23%; p = 0.038); and the eGFR at the time of first biopsy was significantly worse (21 vs. 29 ml/min/1.73m2; p = 0.037). In a multivariate logistic regression analysis, eGFR at the time of first biopsy (OR 0.958, 95%-Cl: 0.924-0.993, p = 0.019), dialysis before transplantation (OR 4.868, 95%-Cl: 1.128-21.003, p = 0.034) and the time of first biopsy after transplantation (OR 1.037, 95%-Cl: 1.013-1.062, p = 0.002) were independently associated with CaOx deposition. Graft survival censored for death was significantly worse in patients with CaOx deposition (p = 0.018). In only 1 of 106 preimplantation biopsies CaOx deposition was found (0.94%).

CONCLUSION

CaOx deposition appears to be primarily recipient-derived and is frequently observed in for-cause renal allograft biopsies obtained within 3 months post-transplantation. It is associated with inferior renal function at the time of biopsy and worse graft survival.

Procurement Biopsies in the Evaluation of Deceased Donor Kidneys

BACKGROUND AND OBJECTIVES

Biopsies taken at deceased donor kidney procurement continue to be cited as a leading reason for discard; however, the reproducibility and prognostic capability of these biopsies are controversial.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We compiled a retrospective, single-institution, continuous cohort of deceased donor kidney transplants performed from 2006 to 2009. Procurement biopsy information-percentage of glomerulosclerosis, interstitial fibrosis/tubular atrophy, and vascular disease-was obtained from the national transplant database. Using univariable, multivariable, and time-to-event analyses for death-censored graft survival, we compared procurement frozen section biopsy reports with reperfusion paraffin-embedded biopsies read by trained kidney pathologists (n=270). We also examined agreement for sequential procurement biopsies performed on the same kidney (n=116 kidneys).

RESULTS

For kidneys on which more than one procurement biopsy was performed (n=116), category agreement was found in only 64% of cases (κ=0.14). For all kidneys (n=270), correlation between procurement and reperfusion biopsies was poor: overall, biopsies were classified into the same category (optimal versus suboptimal) in only 64% of cases (κ=0.25). This discrepancy was most pronounced when categorizing percentage of glomerulosclerosis, which had 63% agreement (κ=0.15). Interstitial fibrosis/tubular atrophy and vascular disease had agreement rates of 82% (κ=0.13) and 80% (κ=0.15), respectively. Ninety-eight (36%) recipients died, and 56 (21%) allografts failed by the end of follow-up. Reperfusion biopsies were more prognostic than procurement biopsies (hazard ratio for graft failure, 2.02; 95% confidence interval, 1.09 to 3.74 versus hazard ratio for graft failure, 1.30; 95% confidence interval, 0.61 to 2.76), with procurement biopsies not significantly associated with graft failure.

CONCLUSIONS

We found that procurement biopsies are poorly reproducible, do not correlate well with paraffin-embedded reperfusion biopsies, and are not significantly associated with transplant outcomes.

Hard-to-place kidney offers: Donor- and system-level predictors of discard

Understanding risk factors for deceased-donor kidney nontransplantation is important since discard rates remain high. We analyzed DonorNet^® data of consecutive deceased-donor nonmandatory share primary kidney-only offers to adult candidates at our center and beyond between July 1, 2015 and March 31, 2016 for donor- and system-level risk factors of discard, defined as nontransplantation at our or subsequent transplant centers. Exclusions were hepatitis C virus/hepatitis B virus core antibody status, blood type AB, and donor <1 year based on low candidate waitlist size. Of 456 individual kidney offers, from 296 donors, 73% were discarded. Most were national (93%) offers from Kidney Donor Profile Index 35-85% (n = 233) or >85% (n = 208) donors late in the allocation sequence with prior refusals logged for numerous candidates. On multivariate regression, factors significantly associated with discard were donor cerebrovascular accident (adjusted odds ratio [aOR]: 3.32), cancer transmission concern (aOR: 6.5), renal artery luminal compromise (aOR: 3.97), biopsy score ≥3 (aOR: 5.09), 2-hour pump resistive index >0.4 (aOR: 3.27), absence of pump (aOR: 2.58), nonspecific kidney abnormality (aOR: 2.76), increasing offer cold ischemia time category 11-15, 16-20, and >21 hours (aOR: 2.07, 2.33, 2.82), nighttime notification (aOR: 2.19), and neither kidney placed at time of offer (aOR: 2.74). Many traditional determinants of discard lack discriminatory value when granular factors are assessed. System-level factors also influence discard and warrant further study.

Association between Reperfusion Renal Allograft Biopsy Findings and Transplant Outcomes

Biopsy findings at the time of procurement of deceased donor kidneys remain the most common reason cited for kidney discard. To determine the value of renal allograft histology in predicting outcomes, we evaluated the significance of histologic findings, read by experienced renal pathologists, in 975 postreperfusion biopsy specimens collected from 2005 to 2009 after living donor (n=427) or deceased donor (n=548) renal transplant. We evaluated specimens for the degree of glomerulosclerosis, interstitial fibrosis and tubular atrophy, and vascular disease; specimens with a score of 0 or 1 (scale, 0-3) for each parameter were considered optimal. Overall, 66.3% of living donor kidneys and 50.7% of deceased donor kidneys received an optimal histology score (P<0.001). Irrespective of donor status, suboptimal kidneys came from older donors with a higher incidence of diabetes mellitus, hypertension, and obesity and a higher mean kidney donor risk index (all P<0.001). Death-censored outcomes after transplant differed significantly between optimal and suboptimal kidneys only in the deceased donor transplants (P=0.02). Regardless of histologic classification, outcomes with deceased donor kidneys were inferior to outcomes with living donor kidneys. However, 73.2% of deceased donor kidneys with suboptimal histology remained functional at 5 years. Our findings suggest that histologic findings on postreperfusion biopsy associate with outcomes after deceased donor but not living donor renal transplants, thus donor death and organ preservation-related factors may be of greater prognostic importance. Discarding donated kidneys on the basis of histologic factors may be inappropriate and merits further study.

Strategies for an Expanded Use of Kidneys From Elderly Donors

The old-for-old allocation policy used for kidney transplantation (KT) has confirmed the survival benefit compared to remaining listed on dialysis. Shortage of standard donors has stimulated the development of strategies aimed to expand acceptance criteria, particularly of kidneys from elderly donors. We have systematically reviewed the literature on those different strategies. In addition to the review of outcomes of expanded criteria donor or advanced age kidneys, we assessed the value of the Kidney Donor Profile Index policy, preimplantation biopsy, dual KT, machine perfusion and special immunosuppressive protocols. Survival and functional outcomes achieved with expanded criteria donor, high Kidney Donor Profile Index or advanced age kidneys are poorer than those with standard ones. Outcomes using advanced age brain-dead or cardiac-dead donor kidneys are similar. Preimplantation biopsies and related scores have been useful to predict function, but their applicability to transplant or refuse a kidney graft has probably been overestimated. Machine perfusion techniques have decreased delayed graft function and could improve graft survival. Investing 2 kidneys in 1 recipient does not make sense when a single KT would be enough, particularly in elderly recipients. Tailored immunosuppression when transplanting an old kidney may be useful, but no formal trials are available.Old donors constitute an enormous source of useful kidneys, but their retrieval in many countries is infrequent. The assumption of limited but precious functional expectancy for an old kidney and substantial reduction of discard rates should be generalized to mitigate these limitations.

Decision Making by Young Transplant Surgeons Regarding Expanded-Criteria Donors With Acute Kidney Injury or Allocation Failure

BACKGROUND

The utilization of expanded-criteria donors (ECDs) has increased to overcome donor shortages. Unfortunately, the discard rate has also increased, especially in ECDs with acute kidney injury (AKI). We evaluated the outcomes of kidney transplantation in ECDs and standard-criteria donors (SCDs) with and without AKI.

METHODS

We reviewed the medical records of patients who underwent kidney transplantation. We used the AKI definition published by the Kidney Disease: Improving Global Outcomes group and reviewed the demographic characteristics of donors and recipients. We analyzed transplantation outcomes.

RESULTS

Twenty-seven patients underwent kidney transplantation from ECDs with AKI (n = 6) or without AKI (n = 5) and SCDs with AKI (n = 6) or without AKI (n = 10). Initial creatinine and estimated glomerular filtration rate (eGFR) were not significantly different between the groups. The incidence of delayed graft function was highest in ECDs with AKI (n = 3; 36.4%), but this was not a significantly difference. There was no difference in the last creatinine and eGFR in ECDs with AKI (1.32 mg/dL, 58.7 mL/min/1.73 m(2)), ECDs without AKI (1.67 mg/dL, 44.2 mL/min/1.73 m(2)), SCDs with AKI (0.94 mg/dL, 81.5 mL/min/1.73 m(2)) and SCDs without AKI (0.97 mg/dL, 81.8 mL/min/1.73 m(2)).

CONCLUSIONS

As the donor pool is extended to ECDs, young transplant surgeons may increasingly face decisions regarding ECDs with AKI or allocation failure. There is no consensus regarding discard criteria. However, if the donor showed initially normal creatinine levels or if dual-kidney transplantation can be performed, young transplant surgeons should not hesitate to use ECDs with AKI or allocation failure.

Wedge Versus Core Biopsy at Time Zero: Which Provides Better Predictive Value for Delayed Graft Function With the Remuzzi Histological Scoring System?

BACKGROUND

Histopathological features on time-zero renal biopsies correlate with graft outcome after renal transplantation. With increasing numbers of marginal donors, assessment of pre-implantation graft quality is essential. The clinician's choice of wedge or core biopsy is performed without evidence of efficacy or safety. This study aims to compare the information derived from wedge biopsy versus core biopsy.

METHODS

Prospective evaluation of 37 wedge biopsies and 30 core biopsies was performed. Histopathological data were collected on number of glomeruli and arterioles observed, and Remuzzi scoring for glomerulosclerosis, tubular atrophy, interstitial fibrosis, and arteriolar narrowing was performed. Clinical data on delayed graft function (DGF) were also collated. Sensitivity, specificity, and positive and negative predictive values for DGF were compared.

RESULTS

Patient demographics between the two cohorts were comparable. No complications of biopsies occurred; 81% of wedge biopsies versus 50% of core biopsies had >10 glomeruli (P = .01), whereas 32% of wedge biopsies and 57% of core biopsies had >2 arterioles (P = .02). Wedge biopsies were more likely to identify pathology with more glomerulosclerosis, tubular atrophy (P < .01), and interstitial fibrosis (P < .01). There was a non-significant trend toward high Remuzzi scores in wedge biopsy (22% versus 7% with Remuzzi ≥ 4; P = .12). The sensitivity and positive predictive value of Remuzzi ≥ 4 for predicting DGF was better on wedge biopsy (45.5% versus 0%; P < .01 and 62.5% versus 0%; P < .01, respectively).

CONCLUSIONS

Wedge biopsies were safe and superior to core biopsies for identifying clinically significant histopathological findings on pre-implantation renal biopsy. We believe that the wedge biopsy is the method of choice for time-zero biopsies.

German recommendations for pretransplantation donor kidney biopsies

PURPOSE

This manuscript reviews the data about the histopathologic and develops recommendations to standardise and improve the biopsy procedure, the biopsy handling, the histopathological evaluation, the communication of results and the collection of data from pretransplantation kidney biopsies of deceased donors in Germany.

METHODS

The recommendations are based on this literature review, on discussions at two workshops held by the German Society of Pathology and the German Organ Transplantation Foundation and on personal experiences of the authors.

RESULTS

These German recommendations advocate the use of punch biopsies, paraffin embedding and detailed descriptive reporting of histopathological findings.

CONCLUSIONS

These recommendations constitute only a starting point. Periodical revisions will help to simplify and optimise the recommendations with the ultimate goal to prospectively gather data for the elaboration of a computer-based algorithm that allows the exact prediction of transplantation outcome for a given match of donor and recipient.

Predicting delayed kidney graft function with gene expression in preimplantation biopsies and first-day posttransplant blood

The purpose of this study was to investigate possible markers for predicting delayed graft function (DGF). To this end we analyzed, in pre-implantation biopsies (PIB) and in first-day post-Tx peripheral blood mononuclear cells (PBMC), the expression of five genes (ACSL4, CUBN, DEFB1, FABP3, GK) through real-time TaqMan PCR assays. These genes were selected from a large scale gene expression study in PIB. DEFB1, FABP3 and GK expression levels in PIB were lower in cases with DGF and, in a multivariate analysis which included these genes and clinical variables, only FABP3 expression remained independently associated with DGF. FABP3 expression lower than -1.32 units of relative expression conferred an odds ratio for DGF of 41.1. Compared to the PBMC of recipients without DGF, recipients with prolonged DGF (pDGF) had lower ACSL4 and higher DEFB1 expression levels. In a multivariate analysis, including PBMC gene expression levels of ACSL4, DEFB1 and TLR4 (data from a previous study with the same patients) and clinical variables, only TLR4 remained independently associated with pDGF. In summary, this study revealed FABP3 expression in PIB as a marker for DGF and disclosed new genes possibly involved in the pathogenesis of DGF.

Expanding the pool of kidney donors: use of kidneys with acute renal dysfunction

Given the shortage of organs transplantation, some strategies have been adopted by the transplant community to increase the supply of organs. One strategy is the use of expanded criteria for donors, that is, donors aged >60 years or 50 and 59 years, and meeting two or more of the following criteria: history of hypertension, terminal serum creatinine >1.5mg/dL, and stroke as the donor´s cause of death. In this review, emphasis was placed on the use of donors with acute renal failure, a condition considered by many as a contraindication for organ acceptance and therefore one of the main causes for kidney discard. Since these are well-selected donors and with no chronic diseases, such as hypertension, renal disease, or diabetes, many studies showed that the use of donors with acute renal failure should be encouraged, because, in general, acute renal dysfunction is reversible. Although most studies demonstrated these grafts have more delayed function, the results of graft and patient survival after transplant are very similar to those with the use of standard donors. Clinical and morphological findings of donors, the use of machine perfusion, and analysis of its parameters, especially intrarenal resistance, are important tools to support decision-making when considering the supply of organs with renal dysfunction.

Pretransplant biopsy in expanded criteria donors: do we really need it?

INTRODUCTION

Renal transplantation is the best treatment for end-stage renal disease, including when using expanded criteria donors (ECD) kidneys. However, these suboptimal kidneys should be evaluated rigorously to meet their usefulness. Opinions differ about the best way to evaluate them.

MATERIALS AND METHODS

We retrospectively reviewed kidneys from ECD harvested by a single academic institution between January 2008 and September 2013. Needle biopsies were performed at the time of the harvest when considered relevant by the transplant team. Two pathologists where responsible for their analysis; the Remuzzi classification has been used in all cases.

RESULTS

We evaluated 560 ECD kidneys. Biopsies were made in 197 (35.2%) organs, 20 of which were considered not usable and 36 good only for double transplantation. Sixty-three kidneys (11.3%) were discarded by the transplant team based on the biopsy result and clinical criteria. Donors who underwent a biopsy were older (P < .001) and had a worse glomerular filtration rate (GFR; P = .001). Comparing donors approved and rejected by the biopsy, the rejected donors were heavier (P = .003) and had a lower GFR (P = .002). Cold ischemia time was longer for the biopsy group (P < .001). Regarding graft function, the biopsy overall score correlated with the transplant outcome in the short and long term. Separately, glomeruli and interstitium scores were correlated with recipient's GFR in the earlier periods (3 months; P = .025 and .037), and the arteries and tubules correlated with GFR in the longer term (at 3 years P = .004 and .010).

CONCLUSION

The decision on the usability of ECD grafts is complex. At our center, we chose a mixed approach based on donor risk. Low-risk ECD do not require biopsy. In more complex situations, especially older donors or those with a lower GFR, prompted a pretransplant biopsy. The biopsy results proved to be useful as they relate to subsequent transplant outcomes, thereby allowing us to exclude grafts whose function would most probably be less than optimal.

Kidney retransplantation: removal or persistence of the previous failed allograft?

A significant percentage of patients with failed renal graft are candidates for retransplantation. The outcomes of retransplantation are poorer than those of primary transplantation and sensitization is documented to be a major reason. The management of a failed allograft that is not immediately symptomatic is still very controversial. The aim of this study was to determine the impact of the failed allograft nephrectomy on a subsequent transplantation and its importance in the sensitization. We performed a retrospective analysis of the local prospective transplantation registry of the outcome of 126 second kidney transplantations among 2438 transplantations performed in our unit between June 1980 and March 2013, comparing those who underwent allograft nephrectomy prior to retransplantation with those who retained the failed graft. Primary endpoints were graft and patient survival. The levels of panel-reactive antibodies (PRA) and rate of acute rejections on retransplantation outcomes were also studied. Among the 126 patients who underwent a second renal transplantation, 76 (60.3%) had a prior graft nephrectomy (Group A), whereas 50 (39.7%) kept their failed graft (Group B). Group A showed significantly more positive PRA levels when compared with the other group (38% vs 10%; P < .001), as measured before the most recent transplantation, and a higher rate of acute rejection (19% vs 5.6%; P = .016). There were 28 (36%) renal allograft losses for Group A and 18 (36%) for those who had not had transplantectomy (P = not significant [NS]). One-, 3-, and 5-year graft survival rates were 96.6%, 90.7%, and 83.4%, respectively, in Group A and 95%, 82%, and 68.4%, respectively, in Group B, with no statistical differences (P = .19). Five-year actuarial patient survival rates in the 2 groups was 89.3% and 82.8%, respectively (P = .55). Multivariate analysis showed that PRA level and delayed graft function (DGF) had a statistically significant influence on graft survival (P = .028; odds ratio [OR] = 1.029; and P = .024; OR = 8.6), irrespective of whether the patient had graft nephrectomy or not. The allosensitization indicated by PRA increases after transplantectomy and leads to a higher incidence of acute rejection after retransplantation. Nephrectomy of failed allograft does not seem to significantly influence the survival of a subsequent graft. The decision to remove or retain a failed graft in the context of retransplantation should thus be based on known clinical indications for the procedure.

Contrast-Enhanced Ultrasound Reveals Masked Post-Baseline Wedge Transplant Biopsy Pseudoaneurysm

Biopsy of the transplanted kidney is known to cause intraparenchymal renal vascular injury. The most common vascular complications include arteriovenous fistula (AVF) and pseudoaneurysm (PA). We report a case of a patient who underwent cadaveric renal transplantation and developed an AVF and a PA after an on-table wedge biopsy. The PA was missed during the standard Doppler sonographic examination because of its small size but was unmasked with the use of contrast-enhanced ultrasound (CEUS). Fourteen days after the first CEUS, the procedure was repeated and showed complete thrombosis of the PA.

The Donor Kidney Biopsy and Its Implications in Predicting Graft Outcomes: A Systematic Review

Despite a growing organ shortage in the United States, many deceased donor kidneys removed for transplantation are discarded. Kidney biopsy findings often play a role in these discards, although it is not clear whether biopsies reliably inform acceptance decisions. Therefore, we carried out a systematic review of the medical literature on the utility of both procurement and implantation biopsies for predicting posttransplant outcomes. Between January 1, 1994 and July 1, 2014, 47 studies were published in the English language literature that examined the association between pretransplant donor biopsy findings from 50 or more donors (with more than half being from deceased donors) and either posttransplant graft failure, delayed graft function, or graft function. In general, study quality was poor. All were retrospective or did not indicate if they were prospective. Results were heterogeneous, with authors as often as not concluding that biopsy results did not predict posttransplant outcomes. The percent glomerular sclerosis was most often examined, and failed to predict graft failure in 7 of 14 studies. Of 15 semiquantitative scoring systems proposed, none consistently predicted posttransplant outcomes across studies. Routine use of biopsies to help determine whether or not to transplant a kidney should be reexamined.

Donor acute kidney injury and short-term graft outcome in renal transplantation

BACKGROUND

With increased waiting times for kidney transplantation, marginal organs from expanded criteria donors (ECD) are increasingly offered for allocation. In addition to ECD status, donors may have suffered from acute kidney injury (AKI) prior to organ procurement.

METHODS

In this retrospective cohort study, we studied short-term allograft function in 517 kidney transplants performed between the years 2008-2014. Recipients of allografts from deceased organ donors were categorized as standard criteria donors (SCD) or ECD with or without AKI defined by RIFLE criteria.

RESULTS

Of 382 deceased donations, 174 (45.5%) were classified as ECD and 63 (16.5%) fulfilled AKI criteria. Donor creatinine on hospital admission was similar, whereas creatinine before organ procurement differed (p < 0.001). Despite these differences, serum creatinine and eGFR at discharge and after one yr showed only minor differences between kidneys with or without AKI. In multivariate linear regression analyses, donor AKI was not a predictor of one-yr allograft function.

CONCLUSIONS

Given the poor prognosis of dialysis patients and the increase in waiting time, kidneys from SCD and ECD donors with AKI should be allocated for transplantation. In case of ECD donors with AKI, recipients should be informed about the possibility of permanent non-function or early graft loss.

Microangiopathy is common in submucosal vessels of the colon in patients with diabetes mellitus

OBJECTIVES

The pathophysiology behind gastrointestinal dysmotility in diabetes mellitus is unknown. Both esophageal dysmotility and gastroparesis have been shown to be associated with retinopathy, suggesting that microangiopathy is important in the common etiology. The aim of the present study was to examine whether patients with diabetes exhibit microangiopathy in the colon, and if present, to correlate microangiopathy with the clinical picture.

METHODS

Consecutive patients subjected to colon surgery were identified in the southernmost districts of Skåne between January 2011 and May 2013. Medical records were scrutinized, and patients with a history of diabetes were noted. Gender, age, type of diabetes, treatment, complications, and other concomitant diseases were registered. Histopathologic re-evaluation of surgical biopsies with morphometric analyses of submucosal vessels in the colon was performed. Morphometric examination and clinical data were compared with non-diabetic patients.

RESULTS

Of 1135 identified patients during the time period studied, 95 patients with diabetes were recognized and included. Fifty-three non-diabetic, randomly chosen patients served as controls. The mean age was 71.8 ± 10.2 and 71.4 ± 9.5 years in diabetic and non-diabetic patients, respectively. Microangiopathy was found in 68.4% of diabetic patients and in 7.5% of non-diabetic patients (p < 0.001). The wall-to-lumen ratio was 0.31 (0.23-0.46) in patients with diabetes compared with 0.16 (0.12-0.21) in non-diabetic patients (p < 0.001). No clinical association with microangiopathy could be verified.

CONCLUSION

Microangiopathy in the colon is more common in diabetic than in non-diabetic patients. The clinical significance of microangopathy has yet to be clarified.

Pre-implant biopsy predicts outcome of single-kidney transplantation independent of clinical donor variables

BACKGROUND

Pre-implant biopsy findings account for the discard of many donor kidneys although their clinical value is not fully understood. We retrospectively investigated the predictive value of pre-implant histology, which in our center was obtained for protocol purposes, not for transplant decisions, on long-term allograft and recipient outcome after single-kidney transplantation.

METHODS

This single-center study included 628 consecutive adult recipients of 174 Expanded Criteria Donor (ECD) and 454 Standard Criteria Donor kidneys. Chronic donor organ injury was assessed applying a chronic lesion score differentiating between mild, moderate, and severe histologic organ injury based on the integration of glomerular, vascular, tubular, and interstitial lesions. Recipients were followed over a median time of 7.8 years.

RESULTS

Donor kidneys exhibiting mild or moderate chronic lesions yielded almost identical graft and recipient survival independent of ECD status or other clinical covariables (HR 1.20, 95% CI 0.83-1.74, P=0.326, and HR 1.27, 95% CI 0.83-1.95, P=0.274, respectively). However, if allograft injury was severe, occurring in 3% of transplanted kidneys, graft and recipient survival was significantly reduced (HR 3.13, 95% CI 1.61-6.07, P<0.001 and HR 2.42, 95% CI 1.16-5.04, P=0.005, respectively).

CONCLUSION

The results suggest that donor kidneys displaying moderate chronic injury can safely be transplanted as single kidneys, while organs displaying severe injury should be discarded. Thus, pre-implant biopsy might offer an effective approach to increase the utilization of renal donor organs, especially from ECD and donors with cerebrovascular accident as cause of death, and to improve overall graft outcome.

The role of procurement biopsies in acceptance decisions for kidneys retrieved for transplant

BACKGROUND AND OBJECTIVES

There is a shortage of kidneys for transplant, and many patients on the deceased donor kidney transplant waiting list would likely benefit from kidneys that are currently being discarded. In the United States, the most common reason given for discarding kidneys retrieved for transplant is procurement biopsy results. This study aimed to compare biopsy results from discarded kidneys with discard attributed to biopsy findings, with biopsy results from comparable kidneys that were successfully transplanted.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective, observational, case-control study, biopsy reports were examined from 83 kidneys discarded in 2010 due to biopsy findings (cases), 83 contralateral transplanted kidneys from the same donor (contralateral controls), and 83 deceased donors randomly matched to cases by donor risk profile (randomly matched controls). A second procurement biopsy was obtained in 64 of 332 kidneys (19.3%).

RESULTS

The quality of biopsy reports was low, with amounts of tubular atrophy, interstitial inflammation, arteriolar hyalinosis, and acute tubular necrosis often not indicated; 69% were wedge biopsies and 94% used frozen tissue. The correlation between first and second procurement biopsies was poor; only 25% of the variability (R(2)) in glomerulosclerosis was explained by biopsies being from the same kidney. The percentages of glomerulosclerosis overlapped substantially between cases, contralateral controls, and randomly matched controls: 17.1%±15.3%, 9.0%±6.6%, and 5.0%±5.9%, respectively. Of all biopsy findings, only glomerulosclerosis>20% was independently correlated with discard (cases versus contralateral controls; odds ratio, 15.09; 95% confidence interval, 2.47 to 92.41; P=0.003), suggesting that only this biopsy result was used in acceptance decisions. One-year graft survival was 79.5% and 90.7% in contralateral and randomly matched controls, respectively, versus 91.6% among all deceased donor transplants in the Scientific Registry of Transplant Recipients.

CONCLUSIONS

Routine use of biopsies could lead to unnecessary kidney discards.

Kidney donor risk index is a good prognostic tool for graft outcomes in deceased donor kidney transplantation with short, cold ischemic time

BACKGROUND

We performed a retrospective cohort study to determine the prognostic value of standard criteria donor/expanded criteria donor (SCD/ECD) designation, with regard to one-yr GFR and graft survival rate, in a region with short, cold ischemic time (CIT), and how this designation compares with the kidney donor risk index (KDRI) and zero-time kidney biopsies.

METHODS

We reviewed 362 cases of deceased donor kidney transplantation (DDKT). Donor kidneys were classified as SCD or ECD. They were also assessed by the KDRI. Zero-time kidney biopsy was performed in 196 patients, and histologic score was assessed.

RESULTS

Median follow-up duration was 46 months. Forty-two cases (11.6%) used ECD kidneys. The mean CIT was only 4.9 ± 2.7 h. Graft survival rates were not significantly different between ECD and SCD groups. The KDRI showed the best correlation with one-yr estimations of glomerular filtration rate (eGFR) (R(2) = 0.230, p < 0.001), and higher KDRI was associated with a higher risk of graft failure (hazard ratio 2.63, 95% confidence interval 1.01-6.87). However, higher histologic score was not associated with a higher risk of graft failure.

CONCLUSION

KDRI has greater predictive value for short-term outcomes in DDKT with short CIT than the SCD/ECD designation or pathology.

The reproducibility and predictive value on outcome of renal biopsies from expanded criteria donors

Reproducibility and predictive value on outcome are the main criteria to evaluate the utility of histological scores. Here we analyze the reproducibility of donor biopsy assessment by different on-call pathologists and the retrospective evaluation by a single renal pathologist blinded to clinical outcomes. We also evaluate the predictive value on graft outcome of both evaluations. A biopsy was performed in donors with any of the following: age≥55 years, hypertension, diabetes, creatinine>1.5 mg/dl, or stroke. Glomerulosclerosis, interstitial fibrosis, tubular atrophy, intimal thickening, and arteriolar hyalinosis evaluated according to the Banff criteria were added to obtain a chronic score. Biopsies were classified as mild (≥3), intermediate (4-5), or advanced (6-7) damage, and unacceptable (≥8) for transplantation of 127 kidneys biopsied. Weighted κ value between both readings was 0.41 (95% CI: 0.28-0.54). Evaluation of biopsies by the renal pathologist was significantly and independently associated with estimated 12-month glomerular filtration rate and a significant composite outcome variable, including death-censored graft survival and time to reach an estimated glomerular filtration rate<30 ml/min per 1.73 m2. Thus, there was no association between readings of on-call pathologists and outcome. The lack of association between histological scores obtained by the on-call pathologists and graft outcome suggests that a specific training on renal pathology is recommended to optimize the use of kidneys retrieved from expanded criteria donors.

Usefulness of Oxford classification in assessing immunoglobulin A nephropathy after transplantation

BACKGROUND

We explored the efficacy of the Oxford classification for assessing native immunoglobulin A nephropathy (IgAN) in posttransplantation patients compared with the glomerular injury score and Haas classification.

METHODS

A total of 125 renal allograft biopsies obtained from 114 patients diagnosed with IgAN regardless of original disease were assessed.

RESULTS

The average time to biopsy was 70.5±45.3 months after transplantation. Glomeruli showed normal histology in 18.4%. Mesangial hypercellularity (M1), endocapillary hypercellularity (E1), segmental glomerulosclerosis (S1), and tubulointerstitial fibrosis (T1-2) were present in 12.8%, 6.4%, 45.6%, and 20.8% of the samples, respectively. There was a significant correlation between Oxford-MEST scores and glomerular injury score or Haas subclass. S1 and T1-2 were correlated with elevated serum creatinine level, proteinuria, and decreased estimated glomerular filtration rate, and E1 was correlated with decreased estimated glomerular filtration rate at the time of biopsy. The 10- and 15-year graft survival rates were 62.9% and 34.3%, respectively. The graft survival rate was significantly lower in the presence of S1 and T1-2. Endocapillary hypercellularity, segmental sclerosis, and tubulointerstitial fibrosis predicted graft survival and endocapillary hypercellularity and tubulointerstitial fibrosis also predicted serum creatinine doubling.

CONCLUSIONS

The Oxford classification scheme is useful for evaluating chronic graft dysfunction in patients with posttransplantation IgAN. In addition to tubulointerstitial fibrosis, the presence of endocapillary hypercellularity and segmental sclerosis should be included in the pathology report.

The predictive value of kidney allograft baseline biopsies for long-term graft survival

The effect of baseline histology and individual histologic lesions at the time of transplantation on long-term graft survival has been evaluated using different scoring systems, but the predictive capacity of these systems has not been adequately validated. All kidney recipients transplanted in a single institution between 1991 and 2009 who underwent a baseline kidney allograft biopsy at transplantation were included in this prospective study (N=548). All baseline biopsies were rescored according to the updated Banff classification, and the relationship between the individual histologic lesions and donor demographics was assessed using hierarchical clustering and principal component analysis. Survival analysis was performed using Cox proportional hazards analysis and log-rank testing. Mean follow-up time was 6.7 years after transplantation. Interstitial fibrosis, tubular atrophy, and glomerulosclerosis associated significantly with death-censored graft survival, whereas arteriolar hyalinosis and vascular intimal thickening did not. Notably, donor age correlated significantly with interstitial fibrosis, tubular atrophy, and glomerulosclerosis and associated independently with graft survival. On the basis of these findings, a novel scoring system for prediction of 5-year graft survival was constructed by logistic regression analysis. Although the predictive performance of previously published histologic scoring systems was insufficient to guide kidney allocation in our cohort (receiver operating characteristic area under the curve ≤0.62 for each system), the new system based on histologic data and donor age was satisfactory for prediction of allograft loss (receiver operating characteristic area under the curve = 0.81) and may be valuable in the assessment of kidney quality before transplantation.

Assessment of donor biopsies

PURPOSE OF REVIEW

To provide an up-to-date overview about the assessment of donor biopsies and to discuss the current problems and chances of preimplantation biopsies for transplant allocation with a focus on the technical work up and the histological variables scored.

RECENT FINDINGS

Preimplantation biopsy results are the major reason for discarding procured extended donor criteria kidneys in the USA. There is neither a consensus on the work up, nor the reporting of preimplantation donor biopsies, nor the importance of the biopsy findings in the process of allocation. The best available data have been collected in the context of single vs. double kidney transplantation. A clinical risk factor score may help to define kidneys when a preimplantation biopsy is warranted. Punch biopsies using a skin punch device appear to be a reasonable alternative for surgeons fearing needle biopsies.

SUMMARY

Donor biopsies are very useful as zero-hour biopsies establishing baseline information for comparison with subsequent transplant biopsies. As none of the histological variables and scores provides perfect prediction, preimplantation biopsy results have to be interpreted in the context of all available donor and recipient information.

Pre-existing arteriosclerotic intimal thickening in living-donor kidneys reflects allograft function

BACKGROUND

Donor shortage is a serious problem worldwide and it is now debated whether kidneys from marginal donors are suitable for renal transplantation. Recent studies have shown that the findings of preimplantation kidney biopsy are useful to evaluate vasculopathy in the donated kidney, and may predict transplant outcomes in deceased- donor kidney transplantation. However, few studies have focused on the pathological findings of preimplantation biopsy in living-donor kidney transplantation. Therefore, we investigated whether arteriosclerotic vasculopathy in living-donor kidneys at the time of transplantation predicts the recipient's kidney function (allograft function) later in life.

METHODS

We retrospectively analyzed 75 consecutive adult living-donor kidney transplants performed at Kagawa University Hospital. Renal arteriosclerotic vasculopathy was defined according to the presence of fibrous intimal thickening in the interlobular artery.

RESULTS

Forty-one kidneys exhibited mild arteriosclerotic vasculopathy on preimplantation kidney biopsies. The decreases in estimated glomerular filtration rate after donation were similar in donors with or without renal arteriosclerotic vasculopathy. Pre-existing arteriosclerotic vasculopathy did not affect graft survival rate, patient survival rate or the incidence of complications. Recipients of kidneys with arteriosclerotic vasculopathy had lower allograft function at 1 and 3 years after transplantation than the recipients of arteriosclerosis-free kidneys with or without donor hypertension. In multivariate analysis, fibrous intimal thickening on preimplantation biopsy was predictive of reduced allograft function at 1 year after transplantation.

CONCLUSIONS

The present study demonstrated that mild arteriosclerotic vasculopathy in the donated kidney is an important pathological factor that reflects future impaired function of renal allografts from marginal donors.

Significance of preimplantation analysis of kidney biopsies from expanded criteria donors in long-term outcome

BACKGROUND

The shortage of organs has led to expanding the criteria for donors. Histologic evaluations before transplantation may enable the identification of organs unsuitable for single implantation. The aim of this study was to evaluate the histologic findings as prognostic factors of allograft survival from expanded criteria donors (ECDs).

METHODS

We included a cohort of 136 single transplantations with kidneys from ECD and correlated the preimplantation pathologic findings with graft failure. Renal structures from ECD older (n=104) or younger (n=32) than 60 years were evaluated histologically for renal senescence and rated with a total histologic score. A multivariate Cox analysis was performed to identify predictors of graft failure.

RESULTS

Glomerulosclerosis was the most prevalent lesion in biopsies from donors older and younger than 60 years (P=0.002); interstitial fibrosis was more severe in biopsies from older donors (P=0.001); older donors showed a higher prevalence of tubular atrophy (P=0.022), and vascular compartment showed no significant differences. Kidney biopsy-based scoring system ranged from 0 to 15 points, indicating the presence of changes in the renal parenchyma. Biopsies with total histologic scores less than or equal to 5 showed significantly better 5-year graft survival than those with scores more than 5 (P<0.001). A preimplantation score more than 5 points remained an independent predictor of graft failure (hazard ratio 6.95; 95% confidence interval 1.57-30).

CONCLUSIONS

Histologic analysis of kidney biopsies before transplantation is a valuable tool for facilitating the selection of viable grafts from ECD donors. When the total score is more than 5, single kidney transplantation from ECD should not be recommended for patients similar to this study population.

Impact of failed allograft nephrectomy on initial function and graft survival after kidney retransplantation

The management of an asymptomatic failed renal graft remains controversial. The aim of our study was to explore the effect of failed allograft nephrectomy on kidney retransplantation by comparing the outcome of recipients who underwent graft nephrectomy prior to retransplantation with those who did not. Retrospective comparison of patients undergoing kidney retransplantation with (group A, n = 121) and without (group B, n = 45) preliminary nephrectomy was performed, including subgroup analysis with reference to patients with multiple (≥2) retransplantations and patients of the European Senior Program (ESP). Nephrectomy leads to increased panel reactive antibody (PRA) levels prior to retransplantation and is associated with significantly increased rates of primary nonfunction (PNF; P = 0.05) and acute rejection (P = 0.04). Overall graft survival after retransplantation was significantly worse in group A compared with group B (P = 0.03). Among the subgroups especially ESP patients showed a shorter graft survival after previous allograft nephrectomy. On the multivariate analysis, pretransplant graft nephrectomy and PRA >70% were independent and significant risk factors associated with graft loss after kidney retransplantation. Nephrectomy of the failed allograft was not beneficial for retransplant outcome in our series. Patients with failed graft nephrectomy tended to have a higher risk of PNF and acute rejection after retransplantation. The possibility that the graft nephrectomy has a negative impact on graft function and survival after retransplantation is worth studying further.

Assessment of kidney organ quality and prediction of outcome at time of transplantation

The critical importance of donor organ quality, i.e., number of surviving nephrons, ability to withstand injury, and capacity for repair in determining short- and long-term outcomes is becoming increasingly clear. This review provides an overview of studies to assess donor kidney quality and subsequent transplant outcomes based on clinical pathology and transcriptome-based variables available at time of transplantation. Prediction scores using clinical variables function when applied to large data sets but perform poorly for the individual patient. Histopathology findings in pre-implantation or post-reperfusion biopsies help to assess structural integrity of the donor kidney, provide information on pre-existing donor disease, and can serve as a baseline for tracking changes over time. However, more validated approaches of analysis and prospective studies are needed to reduce the number of discarded organs, improve allocation, and allow prediction of outcomes. Molecular profiling detects changes not seen by morphology or captured by clinical markers. In particular, molecular profiles provide a quantitative measurement of inflammatory burden or immune activation and reflect coordinated changes in pathways associated with injury and repair. However, description of transcriptome patterns is not an end in itself. The identification of predictive gene sets and the application to an individualized patient management needs the integration of clinical and pathology-based variables, as well as more objective reference markers of transplant function, post-transplant events, and long-term outcomes.

Outcomes and utilization of kidneys from deceased donors with acute kidney injury

Utilization and long-term outcomes of kidneys from donors with elevated terminal serum creatinine (sCr) levels have not been reported. Using data from the Scientific Registry of Transplant Recipients from 1995 to 2007, recipient outcomes of kidneys from adult donors were evaluated stratified by standard criteria (SCD; n = 82 262) and expanded criteria (ECD; n = 16 978) donor type and by sCr </=1.5, 1.6-2.0 and >2.0 mg/dL. Discard rates for SCDs were ascertained. The relative risk of graft loss was similar for recipients of SCD kidneys with sCr of 1.6-2.0 and >2.0 mg/dL, compared to </=1.5 mg/dL. For ECD recipients, the relative risk of graft failure significantly increased with increasing sCr. Of potential SCDs, the adjusted risk of discard was higher with sCr >2.0 mg/dL (adjusted odds ratio [AOR] 7.04, 95% confidence interval [CI] 6.5-7.6) and 1.6-2.0 mg/dL (AOR 2.7; CI 2.5-2.9) relative to sCr </=1.5 mg/dL. Among potential SCDs, elevated terminal creatinine is a strong independent risk factor for kidney discard; yet, when kidney transplantation is performed elevated donor terminal creatinine is not a risk factor for graft loss. Further research is needed to identify safe practices for the optimal utilization of SCD kidneys from donors with acute kidney injury.