Donor risk score and baseline biopsy CADI value predict kidney graft outcome

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.

Deep learning identified pathological abnormalities predictive of graft loss in kidney transplant biopsies

Interstitial fibrosis, tubular atrophy, and inflammation are major contributors to kidney allograft failure. Here we sought an objective, quantitative pathological assessment of these lesions to improve predictive utility and constructed a deep-learning-based pipeline recognizing normal vs. abnormal kidney tissue compartments and mononuclear leukocyte infiltrates. Periodic acid- Schiff stained slides of transplant biopsies (60 training and 33 testing) were used to quantify pathological lesions specific for interstitium, tubules and mononuclear leukocyte infiltration. The pipeline was applied to the whole slide images from 789 transplant biopsies (478 baseline [pre-implantation] and 311 post-transplant 12-month protocol biopsies) in two independent cohorts (GoCAR: 404 patients, AUSCAD: 212 patients) of transplant recipients to correlate composite lesion features with graft loss. Our model accurately recognized kidney tissue compartments and mononuclear leukocytes. The digital features significantly correlated with revised Banff 2007 scores but were more sensitive to subtle pathological changes below the thresholds in the Banff scores. The Interstitial and Tubular Abnormality Score (ITAS) in baseline samples was highly predictive of one-year graft loss, while a Composite Damage Score in 12-month post-transplant protocol biopsies predicted later graft loss. ITASs and Composite Damage Scores outperformed Banff scores or clinical predictors with superior graft loss prediction accuracy. High/intermediate risk groups stratified by ITASs or Composite Damage Scores also demonstrated significantly higher incidence of estimated glomerular filtration rate decline and subsequent graft damage. Thus, our deep-learning approach accurately detected and quantified pathological lesions from baseline or post-transplant biopsies and demonstrated superior ability for prediction of post-transplant graft loss with potential application as a prevention, risk stratification or monitoring tool.

Polymorphisms in vasoactive eicosanoid genes of kidney donors affect biopsy scores and clinical outcomes in renal transplantation

Cytochrome P450 (CYP) enzymes metabolize arachidonic acid to vasoactive eicosanoids such as epoxyeicosatrienoic acids (EETs) and 20-Hydroxyeicosatetraenoic acid (20-HETE), whilst soluble epoxide hydrolase, encoded by the EPHX2 gene, is in charge of EETs degradation. We aimed to analyze the influence of common, functional polymorphisms in four genes of the donor on the renal biopsy scores independently assigned by pathologists. Additionally, we examined whether this score or the presence of these SNPs were independent risk factors of clinical outcomes in the first year after grafting. A cohort of 119 recipients and their corresponding 85 deceased donors were included in the study. Donors were genotyped for the CYP4F2 V433M, CYP2C8*3, CYP2J2*7, EPHX2 3’UTR A>G, EPHX2 K55R and EPHX2 R287Q polymorphisms. The association of the donors’ SNPs with the biopsy scores and clinical outcomes was retrospectively evaluated by multivariate regression analysis. The CYP2C8*3 polymorphism in the donor was significantly associated with higher scores assigned to pretransplant biopsies [OR = 3.35 (1.03–10.93), p = 0.045]. In turn, higher scores were related to an increased risk of acute rejection [OR = 5.28 (1.32–21.13), p = 0.019] and worse glomerular filtration rate (eGFR) (45.68±16.05 vs. 53.04±16.93 ml/min in patients whose grafts had lower scores, p = 0.010) one year after transplant. Patients whose donors carried the CYP4F2 433M variant showed lower eGFR values (48.96±16.89 vs. 55.94±18.62 ml/min in non-carriers, p = 0.038) and higher risk of acute rejection [OR = 6.18 (1.03–37.21), p = 0.047]. The CYP2J2*7 SNP in the donor was associated with elevated risk of delayed graft function [OR = 25.68 (1.52–43.53), p = 0.025]. Our results taken together suggest that donor genetic variability may be used as a predictor of tissue damage in the graft as well as to predict clinical outcomes and graft function in the recipient.

SDF‑1/CXCR4 induces epithelial‑mesenchymal transition through activation of the Wnt/β‑catenin signaling pathway in rat chronic allograft nephropathy

Epithelial-mesenchymal transition (EMT) has been demonstrated to serve a crucial role in the progression of interstitial fibrosis, which is one of the principal pathological features of chronic allograft nephropathy (CAN). However, to the best of our knowledge, the mechanisms of EMT in CAN have not been investigated. In the present study, the effect of stromal cell-derived factor 1 (SDF-1) and the Wnt signaling pathway on the progression of EMT following kidney transplantation was investigated. The CAN model was established using Fisher 344 and Lewis rats, treated with low-dose cyclosporine with or without AMD3100. CAN was confirmed by the pathological alterations and chronic allograft damage index scoring, and EMT was confirmed by western blotting and reverse transcription-quantitative polymerase chain reaction. In the AMD3100 group, there were lower expression levels of α-SMA and higher expression levels of E-cadherin, which indicated that CAN and EMT were ameliorated by AMD3100. The kidney tissue was analyzed using an mRNA + long noncoding (lnc)RNA microarray. A total of 506 mRNAs and 404 lncRNAs were demonstrated to be significantly differentially expressed between the two groups, which revealed the involvement of SDF-1/CXC chemokine receptor 4 (CXCR4) and the Wnt pathway. SDF-1 was demonstrated to induce EMT in vitro through the upregulation of α-SMA, downregulation of E-cadherin and the wound healing assay, and in the rat renal tubular epithelial cells via the nuclear accumulation of β-catenin, which were all inhibited by either AMD3100 or DKK-1. CXXC finger protein 5 (CXXC5), a negative regulator of the Wnt pathway, was downregulated following treatment with SDF-1, which was inhibited by AMD3100 but not by DKK-1. Thus, CXXC5 may be a regulator downstream of SDF-1/CXCR4 in EMT. In conclusion, SDF-1/CXCR4 induces EMT of renal tubular epithelial cells with the involvement of the Wnt pathway, which may be a novel mechanism and therapeutic target in kidney allograft fibrosis of rats.

Fifteen-Year Analysis of Deceased Kidney Donation: A Single Transplant Center Experience in a Region of Northern Italy

Background

The rising number of patients on waiting lists for kidney transplant and the shortage of available organs has intensified efforts to increase the number of potential donors.

Material/Methods

This study investigated changes in clinical parameters among potential deceased donors in the 15-year period between 1999 and 2013 and their impact on transplantation procedure and outcomes. A total of 1634 potential deceased donors were examined and divided into 2 groups: 707 of them identified from 1999 to 2005 (Group A), and 927 from 2006 to 2013 (Group B).

Results

The comparison between the potential donors in Group A vs. Group B revealed an increase over time in donor age (54.6±17.2 vs. 58.8±16.3, p<0.001), a reduction in the percentage of standard donors (52.3% vs. 39.8%, p<0.001), a broader utilization of organs from expanded criteria donors, and a greater number of comorbidities, particularly cardiovascular disease and dyslipidemia. However, renal function parameters and the bioptic scores did not change significantly over the years.

Conclusions

These results suggest the usefulness of strategies to increase the number of potential donors suitable for organ donation, especially among elderly and marginal donors.

Gene expression in the twilight of death: The increase of thousands of transcripts has implications to transplantation, cancer, and forensic research

After a vertebrate dies, many of its organ systems, tissues, and cells remain functional while its body no longer works as a whole. We define this state as the "twilight of death" - the transition from a living body to a decomposed corpse. We claim that the study of the twilight of death is important to ethical, legal and medical science. We examined gene expression at the twilight of death in the zebrafish and mouse reaching the conclusion that apparently thousands of transcripts significantly increase in abundance from life to several hours/days postmortem relative to live controls. Transcript dynamics of different genes provided "proof-of-principle" that models accurately predict an individual's elapsed-time-of-death (i.e. postmortem interval). While many transcripts were associated with survival and stress compensation, others were associated with epigenetic factors, developmental control, and cancer. Future studies are needed to determine whether the high incidence of cancer in transplant recipients is due to the postmortem processes in donor organs.

Biomarkers for the detection of renal fibrosis and prediction of renal outcomes: a systematic review

Background

Fibrosis is the unifying pathway leading to chronic kidney disease. Identifying biomarkers of fibrosis may help predict disease progression.

Methods

We performed a systematic review to evaluate the reliability of blood and urine biomarkers in identifying fibrosis on biopsy as well as predicting renal outcomes. Using MEDLINE and EMBASE, a two-stage search strategy was implemented. Stage I identified a library of biomarkers correlating with fibrosis on biopsy. Stage II evaluated the association between biomarkers identified in stage I, and renal outcomes. Only biomarkers with moderate positive correlation with fibrosis (r > 0.40) or acceptable area under the curve (AUC >0.65) advanced to stage II.

Results

Stage I identified 17 studies and 14 biomarkers. Five biomarkers met criteria to advance to stage II, but only three were independently associated with renal outcomes. Transforming growth factor β (TGF-β) correlated with fibrosis (r = 0.60), and was associated with 1.7–3.9 times the risk of worsening renal function in 426 patients. Monocyte chemoattractant protein-1 (MCP-1) diagnosed fibrosis with AUC of 0.66 and was associated with 2.3–11.0 times the risk of worsening renal function in 596 patients. Matrix metalloproteinase-2 (MMP-2) correlated with fibrosis (r = 0.41), and was associated with 2.5 times the risk of worsening renal function.

Conclusions

Given the heterogeneity of the data due to diverse patient populations along with differing renal outcomes, a meta-analysis could not be conducted. Nonetheless we can conclude from the published data that TGF-β, MCP-1 and MMP-2 may identify patients at risk for renal fibrosis and hence worse renal outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0490-0) contains supplementary material, which is available to authorized users.

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.

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.

Poor organ quality and donor-recipient age mismatch rather than poor donation rates account for the decrease in deceased kidney transplantation rates in a Germany Transplant Center

Kidney transplantation is limited not by technical or immunological challenges but by lack of donor organs. Whereas the number of patients on waiting list increased, the transplantation rate decreased. We analyzed the development of decline rates and reasons as well as the fate of declined organs. In total, 1403 organs offered to 1950 patients between 2001 and 2010 were included. Of 440 organs offered between 2009 and 2011 that were declined, we investigated whether these organs were transplanted elsewhere and requested delayed graft function, creatinine, graft and patient survival. Data were compared to results of transplantations at the same time at our center. Decline rate increased from 47% to 87%. Main reasons were poor organ quality and donor-recipient age or size mismatch. Of the rejected organs, 55% were transplanted at other centers with function, graft and patient survival equivalent to patients transplanted at our center during that period. The number of decline has increased over time mainly due to a growing number of marginal donors accounting for poor organ quality or a mismatch of donor and recipient. If proper donor-recipient selection is performed, many organs that would otherwise be discarded can be transplanted successfully.

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.

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.

Prediction of three-year outcome of renal transplantation from optimal donors versus expanded criteria donors

BACKGROUND/AIMS

The shortage in organ supply has required the use of expanded criteria donors (ECD) for kidney transplantation. Current pre-transplant evaluations of ECD organs are based on histological, clinical or mixed criteria. This monocentric study investigates the predictivity of Karpinski's histological score on 3-year graft function in renal transplant. Ex-post classification using Nyberg's score was carried out to assess the reliability of a purely clinical score and its applicability for organ allocation.

METHODS

We evaluated 407 deceased donors (251 optimal and 156 ECD) for renal transplants performed between 2001 and 2006. The differences in creatinine levels and MDRD-GFR at transplant and 1, 2 and 3 years post-transplant between optimal donors and ECD were recorded. Amongst ECD organs, the effect of different Karpinski score classes (0-1, 2, 3, 4, double transplants) on 3-year graft outcomes was analyzed. We then compared renal function over time across the Nyberg grades (A, B, C, and D).

RESULTS

Karpinski scores 0-1 and 2 and double transplants were associated with improved graft function compared to scores 3 and 4. Nyberg's clinical score shows a good fit with medium-term outcome and Karpinski's score, but among the donors with a high Nyberg grade (C and D), it fails to differentiate between allocable or non-allocable organs (due to Karpinski's score ≥7).

CONCLUSIONS

Our data demonstrate a correlation of histological damage at the time of transplant with 3-year graft function, but at present we are unable to provide any supposition on the possible outcome of the discarded kidneys.

The cutting (w)edge--comparative evaluation of renal baseline biopsies obtained by two different methods

BACKGROUND

The assessment of donor-derived damage of transplanted kidneys might be instrumental for estimating donor organ quality and for predicting short- and long-term organ outcome. In the present study, we report a new standardized method for obtaining pre-transplant kidney biopsy specimens. Instead of taking wedge biopsies (WBs), a skin punch biopsy (PB) tool was utilized to obtain standardized biopsy samples that also represented deeper cortical zones.

METHODS

We compared 147 PB specimens and 114 WBs with respect to the number of glomeruli and arterial vessels they contained. The performance of the two biopsy methods in detecting glomerular damage, interstitial fibrosis/tubular atrophy (IF/TA) and arteriosclerosis was determined by evaluation of subsequent transplant core biopsies of the patients. Statistical comparison employed Kruskal-Wallis and kappa (κ) tests.

RESULTS

Significantly more PB samples (89%) than WBs (66%) were diagnostically adequate according to the Banff criteria. Despite a higher number of glomeruli in WBs (34.6 versus 21.7 in punch biopsies), arteries were present in only 68% of WBs but could be found in 93% of punch biopsies. The comparison of findings in pre-transplant biopsies with lesions in corresponding post-transplant core biopsies revealed a superior diagnostic concordance for IF/TA and arteriosclerosis for punch biopsies than for WBs, reaching kappa values of 0.823 versus 0.729 and 0.661 versus 0.516, respectively.

CONCLUSION

The use of skin PB tools for obtaining baseline biopsies from transplanted kidneys is a safe and effective method for assessment of donor-derived damage of the organ.

Approach to the pretransplant evaluation of the living kidney donor

Evaluation of the potential kidney donor is a complex activity that differs substantially from other types of preoperative assessments. The well being of the donor, who derives no medical benefit from this surgery, must be assured in both the short term and long term, and the potential adverse consequences to the recipient must be determined as well. The criteria that must be met for a person to donate a kidney are rigorous and include medical, social, psychosocial, ethical, and legal issues. Donor evaluation can be divided into assessments to protect the health and safety of the donor and assessments to protect the health and safety of the recipient. This article provides an approach to evaluating a donor, focusing on the complex issues that an evaluator is faced with. A careful assessment of risks and benefits to both the donor and recipient can lead to favorable outcomes.