A simple clinico-histopathological composite scoring system is highly predictive of graft outcomes in marginal donors

A single-center experience with 200 dual kidney transplantations

This study reports on a large series of 200 dual kidney transplantations (DKTs) from expanded criteria donors (ECDs) and proposes specific ways to optimize outcomes. Data concerning 200 DKTs performed in the last 14 yr were retrospectively analyzed. Kidneys from high-risk ECD were allocated for use in DKTs on an old-for-old basis after histological assessment. Different surgical techniques and immunosuppressant regimens were used over time, and the outcomes are discussed. Donors and recipients were a median 73 (70-77) and a 62 (58-67) yr old, respectively. Delayed graft function occurred in 31.5% of cases, and acute rejection in 13.5%. Patient and graft survival at five yr were 90.4% and 85.8%, respectively. Unilateral kidney placement was preferred for 75% of patients, and was associated with a low rate of surgical complications. Our current standard therapy comprising low-dose calcineurin inhibitors (CNIs) associated with mammalian target of rapamycin inhibitors (mTOR) and steroids appears to offer the best risk/benefit profile for elderly patients undergoing DKT. In our experience, outcomes after DKT can be improved by: (i) kidney clinical-histological assessment; (ii) unilateral kidney placement; (iii) minimal use of CNI associated with mTOR.

Spanish consensus document for acceptance and rejection of kidneys from expanded criteria donors

In the recent years, more than 60% of available deceased donors are either older than 50 yr or have significant vascular comorbidities. This makes the acceptance and rejection criteria of renal allografts very rigorous, especially in cases of younger recipients, and at the same time encourages live donations. In our country, there is a lack of homogeneity in the percentages of use of expanded criteria donor (ECD) allografts between the different autonomous communities. Furthermore, the criteria vary greatly, and in some cases, great importance is given to the biopsy while in others very little. In this study, we present a unified and homogenous criteria agreed upon by consensus of a 10-member Panel representing major scientific societies related to renal transplantation in Spain. The criteria are to be used in accepting and/or rejecting kidneys from the so-called ECDs. The goal was to standardize the use of these organs, to optimize the results, and most importantly to provide for the maximum well being of our patients. Finally, we believe that after taking into account the Panel's thorough review of specific scientific literature, this document will be adaptable to other national renal transplant programmes.

Donor Kidney Evaluation

In patients with end-stage renal disease, kidney transplantation is the best means to extend survival and offer a better quality of life. The current shortage of organs available for transplantation has led to an effort to expand the kidney donor pool, including the use of nonideal donor kidneys. Assessment of the quality of the donated kidney is essential, and would facilitate the decision to transplant a potential organ or discard it. Multiple clinical and histologic parameters have been examined to evaluate the donor kidney and relate the findings to the graft outcome, but clear-cut criteria are yet to be defined.

Improved access to histopathology using a digital system could increase the organ donor pool and improve allocation

Improvements in digital slide scanners have reached a stage that digital whole slide images (WSIs) can be used for diagnostic purposes. A digital system for histopathology, analogous to the systems used in radiology, would allow the establishment of networks of subspecialist histopathologists to provide a regional, national or even international rota to support out of hours histopathology for emergency frozen sections, urgent paraffin sections and to generally improve efficiencies with the provision of histopathology services. Such a system would promote appropriate organ utilization by allowing rapid characterization of unexpected lesions in the donor to determine whether donation should occur and further characterization of the organ, such as the degree of fibrosis in the kidney or steatosis in the liver, to determine whether the organ should be used. If introduced across Europe, this would promote safe and effective exchange of organs and support a cost efficient use of pathologist expertise. This review article outlines current issues with the provision of an urgent out of hours histopathology service and focuses on how such a service has the potential to increase organ donors, improve allocation, sharing and the use of available donor organs.

The marginal kidney donor

PURPOSE OF REVIEW

The current era of organ shortage has necessitated a widening of criteria for donation, considering donors who would have been considered unsuitable before. This review summarizes the recent advances in strategies to maximize the use of marginal kidneys without compromising the outcomes.

RECENT FINDINGS

Various strategies have been studied and implemented to optimize procurement and allocation of marginal kidneys, and to preserve their function. In particular, a growing number of transplant centers are using donors after circulatory death. Whereas normothermic ex-vivo and postmortem perfusion are promising procedures to improve the outcomes of marginal grafts in the future, dual-kidney transplantation is a viable approach which is at present potentially underutilized. Despite active research on new strategies to evaluate organ quality, pretransplant biopsy assessment currently remains the most reliable method. The practice of using living donors with advanced age is supported by available evidence, whereas the use of young living donors with minor medical abnormalities needs further investigation.

SUMMARY

Progress has been made in the recent years, clarifying the best criteria for evaluating, recovering, and allocating marginal kidney donors. However, further research is needed, with special regards to the criteria for using marginal living-kidney donors.

Preoperative assessment of the deceased-donor kidney: from macroscopic appearance to molecular biomarkers

Variation in deceased-donor kidney quality can significantly affect outcomes after kidney transplantation. Suboptimal organ selection for a given recipient can result in primary nonfunction, premature graft failure, or inappropriate discard of a suitable organ. Appraisal and appropriate selection of deceased-donor kidneys for use in transplantation is therefore critical. A number of predictive tools have been developed to assist the transplant team in evaluating the suitability of a deceased-donor kidney for transplantation to a given recipient. These include stratification of donors into "standard-" or "expanded-criteria" categories based on clinical parameters, pre-implantation biopsy scores, donor risk scores, machine perfusion characteristics, functional kidney weight, donor biomarkers and molecular diagnostic tools, ex vivo viability assessment using postmortem normothermic perfusion, and overall macroscopic appraisal by the surgical team. Consensus as to the role and predictive value of each of these tools is lacking and clinical practice regarding evaluation and selection of kidneys varies considerably.In this review, we seek to critically appraise the literature and evaluate the levels of evidence for tools used to assess deceased-donor kidneys. Although a plethora of appraisal tools exist, very few demonstrate desirable predictive power to be useful in clinical decision-making. Further research using large, well-designed prospective studies is urgently needed to advance this important field of transplantation science.

The Interplay between inflammation and fibrosis in kidney transplantation

Serial surveillance renal allograft biopsies have shown that early subclinical inflammation constitutes a risk factor for the development of interstitial fibrosis. More recently, it has been observed that persistent inflammation is also associated with fibrosis progression and chronic humoral rejection, two histological conditions associated with poor allograft survival. Treatment of subclinical inflammation with steroid boluses prevents progression of fibrosis and preserves renal function in patients treated with a cyclosporine-based regimen. Subclinical inflammation has been reduced after the introduction of tacrolimus based regimens, and it has been shown that immunosuppressive schedules that are effective in preventing acute rejection and subclinical inflammation may prevent the progression of fibrosis and chronic humoral rejection. On the other hand, minimization protocols are associated with progression of fibrosis, and noncompliance with the immunosuppressive regime constitutes a major risk factor for chronic humoral rejection. Thus, adequate immunosuppressive treatment, avoiding minimization strategies and reinforcing educational actions to prevent noncompliance, is at present an effective approach to combat the progression of fibrosis.

The impact of time-zero biopsy on early graft outcomes after living donor kidney transplantation

BACKGROUND

In contrast with deceased donor transplantation, the clinical significance of pathologic findings in time-zero biopsies after living donor kidney transplantation are rarely reported, due to the expectation that histologic findings and renal function are normal. The aim of this study was to identify subclinical pathologic findings in living donors and examine the effect on early graft renal function.

METHODS

Between December 2006 and July 2011, 146 living-donor kidney transplant recipients were enrolled in this study. We retrospectively analyzed donor and recipient-related clinical parameters, and post-transplant 6 months and 1 year estimated glomerular filtration rate (eGFR) as early graft renal function. Time-zero biopsies were evaluated using the 2007 Banff criteria.

RESULTS

Most abnormal histologic findings were of mild degree as determined by Banff scores. Global glomerulosclerosis (GS, 35.6%), tubular atrophy (CT, 36.3%), interstitial fibrosis (CI, 20.5%), vascular fibrous intimal thickening (CV, 4.1%), arteriolar hyaline thickening (AH, 14.4%), interstitial inflammation (I, 3.4%) were pathologic findings in time-zero biopsies. The univariate analysis revealed that donor age and gender were significantly associated with eGFR at post-transplant 6 months and at 1 year (P < .05). Furthermore, GS and CT were significantly associated with early graft renal function (P < .05). However, multivariate linear regression analysis showed only donor age was significantly associated with early graft renal function (P = .001).

CONCLUSION

A mild degree of subclinical, pathologic findings on time-zero biopsy did not affect early graft renal function in living-donor kidney transplantation.

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.

Expanding the use of expanded criteria donors in kidney transplantation

PURPOSE

Although the use of kidney allografts from expanded criteria donors (ECD) has increased in recent years, the reported discard rates are also growing. The influence of ECD characteristics on transplant outcomes is still underevaluated.

METHODS

This retrospective study investigated the influence of preimplantation biopsy findings and delayed graft function (DGF) on patient and graft survivals and renal function at 36 months in a cohort of 372 ECD kidney transplant recipients.

RESULTS

Patient and graft survivals were 91.6 and 68.9 %. The incidence of biopsy-proven acute rejection was 31 %. There were no differences in patient (88.6 vs. 91.1 vs. 94.7 vs. 78.6 %, p = 0.10) or graft (78.1 vs. 72.2 vs. 60.5 vs. 62.6 %, p = 0.14) survivals and renal function (41.7 ± 25.6 vs. 39.9 ± 29.9 vs. 38.1 ± 30.6 vs. 37.4 ± 29.2 mL/min, p = 0.79) comparing ECD kidneys with mild, moderate, and severe histological changes or with no preimplantation biopsy, respectively. However, severe scored transplants had the worst death-censored graft survival (OR 3.1, 95 % CI 1.4-6.9, p = 0.007). No significant differences in patient (86.2 vs. 83.4 %, p = 0.17) or graft (73.7 vs. 65.9 %, p = 0.06) survivals and renal function (38.9 ± 28.6 vs. 39.9 ± 28.4 mL/min, p = 0.72) were observed comparing patients with or without DGF. Multivariable analysis found diabetes history as the only independent risk factor for graft loss (OR 2.1, 95 % CI 1.3-3.3, p = 0.003) or patient death (OR 3.1, 95 % CI 1.5-5.8, p < 0.001).

CONCLUSIONS

Within the limitations of sample size and short follow-up time, in this cohort of ECD kidney transplant recipients the severity of histological changes observed in preimplantation biopsies was independently associated with graft loss.

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.

Kidneys at higher risk of discard: expanding the role of dual kidney transplantation

Half of the recovered expanded criteria donor (ECD) kidneys are discarded in the United States. A new kidney allocation system offers kidneys at higher risk of discard, Kidney Donor Profile Index (KDPI)>85%, to a wider geographic area to promote broader sharing and expedite utilization. Dual kidney transplantation (DKT) based on the KDPI is a potential option to streamline allocation of kidneys which otherwise would have been discarded. To assess the clinical utility of the KDPI in kidneys at higher risk of discard, we analyzed the OPTN/UNOS Registry that included the deceased donor kidneys recovered between 2002 and 2012. The primary outcomes were allograft survival, patient survival and discard rate based on different KDPI categories (<80%, 80-90% and >90%). Kidneys with KDPI>90% were associated with increased odds of discard (OR=1.99, 95% CI 1.74-2.29) compared to ones with KDPI<80%. DKTs of KDPI>90% were associated with lower overall allograft failure (HR=0.74, 95% CI 0.62-0.89) and better patient survival (HR=0.79, 95% CI 0.64-0.98) compared to single ECD kidneys with KDPI>90%. Kidneys at higher risk of discard may be offered in the up-front allocation system as a DKT. Further modeling and simulation studies are required to determine a reasonable KDPI cutoff percentile.

Identification of expanded-criteria donor kidney grafts at lower risk of delayed graft function

BACKGROUND

Organ shortage leads to the increased use of expanded-criteria donor (ECD) kidneys, which contribute to a higher risk of delayed graft function (DGF) after transplantation. The aim of this study was to determine factors that may better predict the risk of DGF.

METHODS

Histologic assessments of donor renal biopsy were used with other clinical variables to predict the risk of DGF after kidney transplantation. The total Banff score equaled the sum of interstitial fibrosis (CI), tubular atrophy, arteriolar hyaline thickening, fibrous intimal thickening (CV), and fraction of sclerotized glomeruli.

RESULTS

In total, 126 of 344 patients developed DGF after kidney transplantation. The histologic score for CI, tubular atrophy, and CV and the total Banff score were increased in patients with DGF. Only CI and CV were independent predictors of DGF (P<0.01). A CIV score (CI+CV; odds ratio, 2.68; 95% confidence interval, 1.55-4.66; P<0.001) was superior to the combination of the total Banff score (odds ratio, 1.48; 95% confidence interval, 0.85-2.55; P=NS). A CIV score≥1, donor age more than 51 years, and anoxia donor brain injury were associated with the highest risk of DGF. A CIV<1 identified a subgroup of ECDs at a lower risk of DGF comparable with standard-criteria donors (29.3% vs. 28.4%).

CONCLUSIONS

Composite CIV score better identifies ECD kidneys with a lower risk of developing DGF. Morphologic evaluation of ECD kidneys and donor characteristics may improve kidney allocation.

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.

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.

Optimizing utilization of kidneys from deceased donors over 60 years: five-year outcomes after implementation of a combined clinical and histological allocation algorithm

This 5 year observational multicentre study conducted in the Nord Italian Transplant programme area evaluated outcomes in patients receiving kidneys from donors over 60 years allocated according to a combined clinical and histological algorithm. Low-risk donors 60-69 years without risk factors were allocated to single kidney transplant (LR-SKT) based on clinical criteria. Biopsy was performed in donors over 70 years or 60-69 years with risk factors, allocated to Single (HR-SKT) or Dual kidney transplant (HR-DKT) according to the severity of histological damage. Forty HR-DKTs, 41 HR-SKTs and 234 LR-SKTs were evaluated. Baseline differences generally reflected stratification and allocation criteria. Patient and graft (death censored) survival were 90% and 92% for HR-DKT, 85% and 89% for HR-SKT, 88% and 87% for LR-SKT. The algorithm appeared user-friendly in daily practice and was safe and efficient, as demonstrated by satisfactory outcomes in all groups at 5 years. Clinical criteria performed well in low-risk donors. The excellent outcomes observed in DKTs call for fine-tuning of cut-off scores for allocation to DKT or SKT in high-risk patients.

Do protocol transplant biopsies improve kidney transplant outcomes?

PURPOSE OF REVIEW

The research undertaken on 'protocol' renal transplant biopsies has provided a rich, if not the richest, approach to better understanding of the immune and nonimmune impacts upon the transplant. The purpose of this review is to detail how the direct benefit to the patient also lies in these renamed 'surveillance' biopsies.

RECENT FINDINGS

Undertaken at fixed time points after transplantation, biopsy provides individual diagnoses with which the clinician can vary immunosuppression both in intensity and in the type of agent used to modify pathological processes early in their course. Initial nonfunction from acute tubular necrosis, subclinical cellular and humoral rejection, calcineurin inhibitor nephrotoxicity, BK virus nephropathy and recurrent glomerulonephritis are all important diagnoses for which early intervention provides better therapeutic outcomes than delaying until they are clinically evident.

SUMMARY

This review provides the recent evidence that has convinced many transplant units to embark upon surveillance programmes for their patients in order to individualize their immunosuppression and thus gain better outcomes.

Association between peritransplant kidney injury biomarkers and 1-year allograft outcomes

BACKGROUND AND OBJECTIVES

Current tools to predict outcomes after kidney transplantation are inadequate. The objective of this study was to determine the association of perioperative urine neutrophil gelatinase-associated lipocalin and IL-18 with poor 1-year allograft function (return to dialysis or estimated GFR<30 ml/min per 1.73 m(2)).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Neutrophil gelatinase-associated lipocalin and IL-18 from early post-transplant urine was measured in this prospective, multicenter study of deceased-donor kidney transplant recipients. The outcome of poor allograft function at 1 year relative to these biomarkers using multivariable logistic regression and net reclassification improvement was examined. Also, the interaction between delayed graft function and the biomarkers on the outcome were evaluated, and the change in biomarkers over consecutive days related to the outcome using trend tests was examined.

RESULTS

Mean age for the 153 recipients was 54 ± 13 years. Delayed graft function occurred in 42%, and 24 (16%) recipients had the 1-year outcome. Upper median values for neutrophil gelatinase-associated lipocalin and IL-18 on the first postoperative day had adjusted odds ratios (95% confidence interval) of 6.0 (1.5-24.0) and 5.5 (1.4-21.5), respectively. Net reclassification improvement (95% confidence interval) was significant for neutrophil gelatinase-associated lipocalin and IL-18 at 36% (1%-71%) and 45% (8%-83%), respectively. There was no significant interaction between biomarkers and delayed graft function on the outcome. Change in biomarkers moderately trended with the outcome.

CONCLUSIONS

Perioperative urine neutrophil gelatinase-associated lipocalin and IL-18 are associated with poor 1-year allograft function, suggesting their potential for identifying patients for therapies that minimize the risk of additional injury.

With respect to elderly patients: finding kidneys in the context of new allocation concepts

The elderly have benefited from increased access to renal transplantation in recent years. New allocation concepts would shift distribution of kidneys to younger recipients, making expanded criteria and living donor kidneys more relevant for seniors. Current issues impacting expanded criteria donor kidney availability and living donor transplant opportunities for the elderly are explored. It is hoped that the kidney donor profile index will improve risk assessment and utilization of marginal kidneys. The usefulness of procurement biopsy remains controversial. Dual kidney transplantation and machine perfusion appear to be effective mechanisms to increase organ availability. "Old-for-old" allocation systems, donation service area variation and regulatory and reimbursement issues highlight disparities and disincentives affecting expanded criteria donor organ utilization, and considerations for the way forward are discussed. Living donor transplantation, even with older donors, may provide the best option for elderly recipients, and careful expansion of the living donor pool appears appropriate. In light of new allocation concepts, it will be important to understand issues pertinent to seniors and develop effective strategies to maintain or improve their access to the benefits of transplantation.

Deceased-donor kidney perfusate and urine biomarkers for kidney allograft outcomes: a systematic review

BACKGROUND

Accurate and reliable assessment of kidney quality before transplantation is needed to predict recipient outcomes and to optimize management and allocation of the allograft. The aim of this study was to systematically review the published literature on biomarkers in two mediums (the perfusate from deceased-donor kidneys receiving machine perfusion and deceased-donor urine) that were evaluated for their possible association with outcomes after kidney transplantation.

METHODS

We searched the Ovid Medline and Scopus databases using broad keywords related to deceased-donor biomarkers in kidney transplantation (limited to humans and the English language). Studies were included if they involved deceased-donor kidneys, measured perfusate or urine biomarkers and studied a possible relationship between biomarker concentrations and kidney allograft outcomes. Each included article was assessed for methodological quality.

RESULTS

Of 1430 abstracts screened, 29 studies met the inclusion criteria. Of these, 23 were studies of perfusate (16 biomarkers examined) and 6 were studies of urine (18 biomarkers examined). Only 3 studies (two perfusate) met the criteria of 'good' quality and only 12 were published since 2000. Perfusate lactate dehydrogenase, glutathione-S-transferase (GST) and aspartate transaminase were all found to be significantly associated with delayed graft function in a majority of their respective studies (6/9, 4/6 and 2/2 studies, respectively). Urine neutrophil gelatinase-associated lipocalin, GST, Trolox-equivalent antioxidant capacity and kidney injury molecule-1 were found to be significantly associated with allograft outcomes in single studies that examined diverse end points.

CONCLUSION

Higher quality studies are needed to investigate modern kidney injury biomarkers, to validate novel biomarkers in larger donor populations and to determine the incremental predictive value of biomarkers over traditional clinical variables.

Immunosuppressive regimen and interstitial fibrosis and tubules atrophy at 12 months postrenal transplant

BACKGROUND AND OBJECTIVES

Chronic renal transplant dysfunction is histopathologically characterized by interstitial fibrosis and tubular atrophy. This study investigated the relative contribution of baseline donor, recipient, and transplant characteristics to interstitial fibrosis and tubular atrophy score at month 12 after renal transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective study includes all 109 consecutive recipients with adequate implantation and month 12 biopsies transplanted between April of 2003 and February of 2007. Immunosuppression regimen was tacrolimus and steroids (10 days) plus either sirolimus or mycophenolate mofetil.

RESULTS

Average interstitial fibrosis and tubular atrophy score increased from 0.70 to 1.65 (P<0.001). In an adjusted multiple linear regression analysis, interstitial fibrosis and tubular atrophy score at month 12 was significantly related to donor type (donors after cardiac death versus living donor had interstitial fibrosis and tubular atrophy score+0.41, 95% confidence interval=0.05-0.76, P=0.02), baseline interstitial fibrosis and tubular atrophy, and immunosuppression regimen. Because of interaction between the latter two variables (P=0.002), results are given separately: recipients with a baseline interstitial fibrosis and tubular atrophy score of zero had a 0.60 higher score at month 12 (95% confidence interval=0.09-1.10, P=0.02) when mycophenolate mofetil-treated, whereas recipients with a baseline interstitial fibrosis and tubular atrophy score more than zero had a 0.38 higher score at month 12 (95% confidence interval=0.01-0.74, P=0.04) when sirolimus-treated. A higher score at month 12 correlated with a lower estimated GFR (ρ=-0.45, P<0.001).

CONCLUSIONS

These findings suggest that histologic assessment of a preimplantation biopsy may guide choice of immunosuppresion to maximize transplant survival and its interaction with type of immunosuppression.

Monitoring and managing graft health in the kidney transplant recipient

Ongoing monitoring of kidney transplants is a widely accepted and practiced part of posttransplantation management. One reason to monitor is to evaluate whether the transplant is stable. The transplant community evaluates stability by checking kidney function. Despite problems with sensitivity and specificity, obtaining serial serum creatinine levels is the most common approach to assessing kidney function. Some programs supplement serial serum creatinine levels with surveillance kidney biopsies. Although not uniformly accepted as beneficial, surveillance biopsies are useful in select subsets of patients such as highly sensitized recipients. Recent biopsy studies shed light on which histopathology findings portend poor prognoses. The Long-Term Deterioration of Kidney Allograft Function Study (DeKAF) and similar studies that will prospectively evaluate therapeutic interventions should help the transplant community better define how to monitor and manage the kidney transplant optimally. In the meantime, Kidney Diseases: Improving Global Outcomes (KDIGO) provides an evidence-based approach toward monitoring and managing the kidney transplant.

Surveillance protocol kidney transplant biopsies: their evolving role in clinical practice

Protocol renal allograft biopsies at fixed time points from transplantation have aided research and provided insights into the pathogenesis of early and late allograft injury. Their role is evolving from research to a clinical management tool needed to detect subclinical pathology requiring treatment adjustment. They frequently reveal unexpected findings and influence therapy in the majority of patients. Detection of subclinical rejection (SCR) remains important despite declining prevalence with triple therapy, the evidence favors treatment, if found. Surveillance biopsies in steroid avoidance and calcineurin inhibitor (CNI) withdrawal programs provide an important safety net against the increased rates of late acute and SCR. Individualization of therapy in high-risk patients and safe reduction of immunosuppression in standard risk individuals becomes possible. Other potentially reversible chronic pathologies that may be detected, include chronic T-cell or antibody-mediated rejection, recurrent disease, BK virus-associated nephropathy, interstitial fibrosis and tubular atrophy and CNI nephrotoxicity, allowing modifications of therapy to limit ongoing graft injury. Biopsy is safe and inexpensive compared with costs of earlier graft failure and return to dialysis. This review summarizes current evidence on use of surveillance histology for the clinical practice of renal transplantation.

Interstitial fibrosis evolution on early sequential screening renal allograft biopsies using quantitative image analysis

Screening renal biopsies (RB) may assess early changes of interstitial fibrosis (IF) after transplantation. The aim of this study was to quantify IF by automatic color image analysis on sequential RB. We analyzed RB performed at day (D) 0, month (M) 3 and M12 from 140 renal transplant recipients with a program of color segmentation imaging. The mean IF score was 19 ± 9% at D0, 27 ± 11% at M3 and 32 ± 11% at M12 with a 8% progression during the first 3 months and 5% between M3 and M12. IF at M3 was correlated with estimated glomerular rate (eGFR) at M3, 12 and 24 (p < 0.02) and IF at M12 with eGFR at M12 and 48 (p < 0.05). Furthermore, IF evolution between D0 and M3 (ΔIFM3-D0) was correlated with eGFR at M24, 36 and 48 (p < 0.03). IF at M12 was significantly associated with male donor gender and tacrolimus dose (p = 0.03). ΔIFM3-D0 was significantly associated with male donor gender, acute rejection episodes (p = 0.04) and diabetes mellitus (p = 0.02). Thus, significant IF is already present before transplantation. IF evolution is more important during the first 3 months and has some predictive ability for change in GFR. Intervention to decrease IF should be applied early, i.e. before 3 months, after transplantation.

Graft quality assessment in kidney transplantation: not an exact science yet!

PURPOSE OF REVIEW

The enduring donor shortage necessitates the development of tools capable of objectively assessing kidney graft quality and thereby allowing the safer and wider use of expanded criteria donors and kidneys donated after cardiac death. We summarize current assessment tools available prior to procurement and during preservation.

RECENT FINDINGS

Several donor risk scores, combining donor and recipient risk factors of inferior graft outcome, exist but all lack predictive power. Histological scoring of glomerulosclerosis, tubular atrophy, interstitial fibrosis, and vascular damage in pretransplantation kidney biopsies can supply reliable, reproducible data on the actual kidney state but prospective data on their use in graft assessment are lacking. Renal resistance and certain perfusate biomarker concentrations during machine perfusion are independent risk factors of delayed graft function, but neither method has sufficient predictive power to allow kidney discard.

SUMMARY

Available tools for graft quality assessment have their intrinsic value but none offer the necessary power to predict graft outcome for a specific donor-recipient pair. This is probably due to the multitude of donor, preservation, and recipient factors at stake. Only combining these factors might improve prediction of graft outcome and allow safer use of expanded criteria donors and kidneys donated after cardiac death.

Early loss of peritubular capillaries after kidney transplantation

Inflammation, interstitial fibrosis (IF), and tubular atrophy (TA) precede chronic transplant dysfunction, which is a major cause of renal allograft loss. There is an association between IF/TA and loss of peritubular capillaries (PTCs) in advanced renal disease, but whether PTC loss occurs in an early stage of chronic transplant dysfunction is unknown. Here, we studied PTC number, IF/TA, inflammation, and renal function in 48 patients who underwent protocol biopsies. Compared with before transplantation, there was a statistically significant loss of PTCs by 3 months after transplantation. Fewer PTCs in the 3-month biopsy correlated with high IF/TA and inflammation scores and predicted lower renal function at 1 year. Predictors of PTC loss during the first 3 months after transplantation included donor type, rejection, donor age, and the number of PTCs at the time of implantation. In conclusion, PTC loss occurs during the first 3 months after renal transplantation, associates with increased IF and TA, and predicts reduced renal function.

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.

Consequences of transplant quality on chronic allograft nephropathy

Using kidneys from expanded-criteria donors to alleviate organ shortage has raised concern on reduced transplant outcomes. In this paper, we review how critical donor-related factors such as donor age, brain death, and consequences of ischemia-reperfusion injury (IRI) determine graft quality and impact chronic allograft nephropathy. We propose that combinatorial effects of organ-intrinsic features associated with increasing age and unspecific injuries related to brain death and IRI will impact innate and adaptive immune responses. Future research will need to explore avenues to optimize donor management, organ preservation, adapted immunosuppressive strategies, as well as modifications of the allocation of suboptimal allografts.

Development and evaluation of a composite risk score to predict kidney transplant failure

BACKGROUND

Although risk factors for kidney transplant failure are well described, prognostic risk scores to estimate risk in prevalent transplant recipients are limited.

STUDY DESIGN

Development and validation of risk-prediction instruments.

SETTING & PARTICIPANTS

The development data set included 2,763 prevalent patients more than 12 months posttransplant enrolled into the LOTESS (Long Term Efficacy and Safety Surveillance) Study. The validation data set included 731 patients who underwent transplant at a single UK center.

PREDICTOR

Estimated glomerular filtration rate (eGFR) and other risk factors were evaluated using Cox regression.

OUTCOME

Scores for death-censored and overall transplant failure were based on the summed hazard ratios for baseline predictor variables. Predictive performance was assessed using calibration (Hosmer-Lemeshow statistic), discrimination (C statistic), and clinical reclassification (net reclassification improvement) compared with eGFR alone.

RESULTS

In the development data set, 196 patients died and another 225 experienced transplant failure. eGFR, recipient age, race, serum urea and albumin levels, declining eGFR, and prior acute rejection predicted death-censored transplant failure. eGFR, recipient age, sex, serum urea and albumin levels, and declining eGFR predicted overall transplant failure. In the validation data set, 44 patients died and another 101 experienced transplant failure. The weighted scores comprising these variables showed adequate discrimination and calibration for death-censored (C statistic, 0.83; 95% CI, 0.75-0.91; Hosmer-Lemeshow χ(2)P = 0.8) and overall (C statistic, 0.70; 95% CI, 0.64-0.77; Hosmer-Lemeshow χ(2)P = 0.5) transplant failure. However, the scores failed to reclassify risk compared with eGFR alone (net reclassification improvements of 7.6% [95% CI, -0.2 to 13.4; P = 0.09] and 4.3% [95% CI, -2.7 to 11.8; P = 0.3] for death-censored and overall transplant failure, respectively).

LIMITATIONS

Retrospective analysis of predominantly cyclosporine-treated patients; limited study size and categorization of variables may limit power to detect effect.

CONCLUSIONS

Although the scores performed well regarding discrimination and calibration, clinically relevant risk reclassification over eGFR alone was not evident, emphasizing the stringent requirements for such scores. Further studies are required to develop and refine this process.

Post-transplant nuclear renal scans correlate with renal injury biomarkers and early allograft outcomes

BACKGROUND

Clinical- and histopathology-based scores are limited predictors of allograft outcome. In addition, more objective markers of early transplant function are needed to identify and validate biomarkers and predictive scores. We evaluated existing scores and transcriptome biomarkers of kidney injury as predictors of early transplant function measured by renal scan.

METHODS

Clinical, histopathologic and transcriptome data were collected in 143 consecutive kidney transplant recipients. A post-operative renal scan was performed within 48 h. Prediction scores for early outcomes were calculated.

RESULTS

Patients were stratified into three groups by renal scan: normal, mild-to-moderate or severe dysfunction. Kidneys with severe dysfunction were more often from deceased donors (P < 0.001), had greater HLA antigen mismatches (P < 0.001), were transplanted into older recipients (P = 0.040), had lower urine output during the first 8 h (P < 0.001), higher Day 7 serum creatinine (P < 0.001) and higher incidence of delayed graft function (P < 0.001). Clinical- and pathology-based scores did not discriminate between scan groups. In contrast, the overall transcriptome (P < 0.001) and transcripts of preselected acute kidney injury (AKI) genes were significantly different between the groups, with kidney injury molecule 1 (P = 0.001) and neutrophil gelatinase-associated lipocalin (P = 0.002) being most highly expressed and genes associated with glutathione metabolism (GSTA1, 3 and 4) most down-regulated in kidneys with subsequent severe dysfunction.

CONCLUSIONS

Renal scans reflect early transplant function and allow for a more objective assessment of scores predicting early outcome and for identification of biomarkers. The study shows that transcript levels of AKI genes correlate better with renal scans than clinical- or histopathology-based scores.

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.

Analysis of four scoring systems and monocentric experience to optimize criteria for marginal kidney transplantation

There is a strong need among the transplantation community to identify common criteria to utilize the pool of expanded criteria donors (ECD), considering the disparity between organ demand and supply as well as the benefits of transplantation on long-term mortality compared with survival on dialysis, also in patients transplanted with these organs. The purpose of this article was to analyze scoring systems proposed in literature by Nyberg, Anglicheau, Rao (Kidney Donor Risk Index), and Schold, seeking to verify whether our clinical and histological allocation strategy matched the Nyberg score. Herein we have reported the results of a preliminary retrospective study on the 5-year outcomes of organs from 60 marginal donors, who were older than 50 years and histologically evaluated before implantation. The donors matched Nyberg class C and D, that is, marginal donors. We noted a tendency toward an association between global and vascular scores with class D (odds ratio 2.2 and 4.3, respectively). Kaplan-Meier graft survival curves were similar to Nyberg data: 83% for class C versus 73% for class D at 5 years. Without any comparison to the Nyberg score, the only feature that was predictive of renal function at 5 years in our population was hypertension in the donor. Further studies are required to identify which of the scoring systems--clinical and/or histological--is more suitable to allocate ECD kidneys and to predict recipient outcomes.

Novel markers in zero-hour kidney biopsies indicate graft quality and clinical outcome

BACKGROUND

In renal transplantation, allograft biopsies provide valuable diagnostic information indicating adverse allograft outcome posttransplantation. To uncover novel candidate markers characteristic of subtle inflammation and immune activation present during the intraoperative period, we investigated messenger RNA (mRNA) gene expression profiles in renal zero biopsies.

METHODS

Transcription profiles from deceased donors (n=63) and living donors (n=26) were investigated for inflammation-associated markers in zero-hour biopsies by real-time reverse-transcriptase polymerase chain reaction.

RESULTS

We observed a significant induction of the chemokine receptor 7 ligands [C-C motif] ligand 19/21 in the deceased donor group (P<0.001). Additionally, along with the induction of the activation marker CD69 (P<0.01), we further detected significant elevated mRNA levels of the inducible immunoproteasome subunits PSMB8, PSMB9, and PSMB10 (P<0.001, respectively). Candidate markers were further tested for posttransplantation clinical outcomes showing the potential to predict the development of delayed graft function, acute rejection, and renal function after 6 months. For instance, by combining mRNA gene expression profiles with clinical patient data, the analysis revealed high sensitivity (95%) and specificity (84%, area under the curve=0.93) for the prediction of acute rejection.

CONCLUSIONS

Zero-hour biopsies of renal allografts may provide useful information on subclinical pathological changes in the grafted kidney. The identification of CCL19/21 or PSMB8/9/10 makes these molecules particularly suitable as potential candidate targets for therapeutic interventions.

Histological assessment of pre-transplant kidney biopsies is reproducible and representative

AIMS

Histological examination of pre-transplant renal biopsy specimens can be used to select grafts from older donors after cardiac death (DCD) with a satisfactory transplant outcome. The aim was to determine whether such biopsy specimens can be reproducibly scored between pathologists and are representative of the whole kidney.

METHODS AND RESULTS

In renal biopsy specimens from DCD aged >or=60 years (n = 44), globally sclerosed glomeruli, vascular narrowing, tubular atrophy and interstitial fibrosis were scored by three independent pathologists according to the Pirani scoring system. Interobserver agreement on the sum of scores improved considerably with the introduction of a combined tubulo-interstitial scoring system (intraclass correlation coefficient increased from 0.38 to 0.64). In small needle biopsy specimens (n = 144) obtained at autopsy, estimates of the proportion of globally sclerosed glomeruli were more precise with increasing sample size. Reasonably precise estimates may be obtained from specimens with at least seven glomeruli.

CONCLUSIONS

It is feasible to implement pre-transplant renal biopsy specimen analysis as a selection criterion in clinical practice in order to accept kidneys from marginal donors for transplantation.

Banff '09 meeting report: antibody mediated graft deterioration and implementation of Banff working groups

The 10th Banff Conference on Allograft Pathology was held in Banff, Canada from August 9 to 14, 2009. A total of 263 transplant clinicians, pathologists, surgeons, immunologists and researchers discussed several aspects of solid organ transplants with a special focus on antibody mediated graft injury. The willingness of the Banff process to adapt continuously in response to new research and improve potential weaknesses, led to the implementation of six working groups on the following areas: isolated v-lesion, fibrosis scoring, glomerular lesions, molecular pathology, polyomavirus nephropathy and quality assurance. Banff working groups will conduct multicenter trials to evaluate the clinical relevance, practical feasibility and reproducibility of potential changes to the Banff classification. There were also sessions on quality improvement in biopsy reading and utilization of virtual microscopy for maintaining competence in transplant biopsy interpretation. In addition, compelling molecular research data led to the discussion of incorporation of omics-technologies and discovery of new tissue markers with the goal of combining histopathology and molecular parameters within the Banff working classification in the near future.

Donor-estimated GFR as an appropriate criterion for allocation of ECD kidneys into single or dual kidney transplantation

It has been suggested that dual kidney transplantation (DKT) improves outcomes for expanded criteria donor (ECD) kidneys. However, no criteria for allocation to single or dual transplantation have been assessed prospectively. The strategy of DKT remains underused and potentially eligible kidneys are frequently discarded. We prospectively compared 81 DKT and 70 single kidney transplant (SKT) receiving grafts from ECD donors aged >65 years, allocated according to donor estimated glomerular filtration rate (eGFR): DKT if eGFR between 30 and 60 mL/min, SKT if eGFR greater than 60 mL/min. Patient and graft survival were similar in the two groups. In the DKT group, 13/81 patients lost one of their two kidneys due to hemorrhage, arterial or venous thrombosis. Mean eGFR at month 12 was similar in the DKT and SKT groups (47.8 mL/min and 46.4 mL/min, respectively). Simulated allocation of kidneys according to criteria based on day 0 donor parameters such as those described by Remuzzi et al., Andres et al. and UNOS, did not indicate an improvement in 12-month eGFR compared to our allocation based on donor eGFR.