Environmentally sustainable kidney care through transplantation: Current status and future challenges.

The environmental impact of healthcare is an issue currently examined with increased scrutiny and on a global scale with multiple stakeholders seeking to identify the appropriate interventions to reduce it. Interestingly, a significant portion of healthcare's environmental impact stems from intensive modalities of treatment for chronic disease. There is no better example than End-Stage Renal Disease (ESRD), where dialysis or transplantation are the modalities of treatment offered to the vast majority of these patients. Kidney transplantation (KTx) offers a longer life expectancy and improved quality of life in comparison to dialysis. Cost-effectiveness analyses have proven its financial superiority, as well. PubMed and EMBASE literature search using keywords "kidney transplantation", "carbon footprint", "sustainability" showed that there is no published work in the field of environmental sustainability in kidney transplantation. Relevant literature was identified for surgical services and applied to transplantation. Assuming its environmental superiority to dialysis, maximising KTx rate would be an important action towards "green" renal care services. That could be achieved through living organ donation, systematic use of machine perfusion for extended criteria deceased donors and individualised immune risk stratification techniques. All these measures aim towards implementing enhanced recovery protocols and two vital steps can be taken towards assessing their value. The first step is a detailed audit of the environmental impact of these novel techniques and secondly their impact in reducing the length of hospital stay and its subsequent environmental impact. Another key element is delivering appropriate post-operative care, substituting allograft biopsy with non-invasive techniques and reducing physical outpatient follow-up, using telemedicine. The gap in quantifying KTx services environmental impact needs to be addressed urgently, with development of strategies within the multidisciplinary transplant team. Introducing novel technologies can lead to donor pool expansion and improved organ utilisation rates, transforming transplant services in "green" hubs.

Delivery of Mesenchymal Stem Cells during Hypothermic Machine Perfusion in a Translational Kidney Perfusion Study.

In transplantation, hypothermic machine perfusion (HMP) has been shown to be superior to static cold storage (SCS) in terms of functional outcomes. Ex vivo machine perfusion offers the possibility to deliver drugs or other active substances, such as Mesenchymal Stem Cells (MSCs), directly into an organ without affecting the recipient. MSCs are multipotent, self-renewing cells with tissue-repair capacities, and their application to ameliorate ischemia- reperfusion injury (IRI) is being investigated in several preclinical and clinical studies. The aim of this study was to introduce MSCs into a translational model of hypothermic machine perfusion and to test the efficiency and feasibility of this method. Methods: three rodent kidneys, six porcine kidneys and three human kidneys underwent HMP with 1-5 × 106 labelled MSCs within respective perfusates. Only porcine kidneys were compared to a control group of 6 kidneys undergoing HMP without MSCs, followed by mimicked reperfusion with whole blood at 37 °C for 2 h for all 12 kidneys. Reperfusion perfusate samples were analyzed for levels of NGAL and IL-ß by ELISA. Functional parameters, including urinary output, oxygen consumption and creatinine clearance, were compared and found to be similar between the MSC treatment group and the control group in the porcine model. IL-1ß levels were higher in perfusate and urine samples in the MSC group, with a median of 285.3 ng/mL (IQR 224.3-407.8 ng/mL) vs. 209.2 ng/mL (IQR 174.9-220.1), p = 0.51 and 105.3 ng/mL (IQR 71.03-164.7 ng/mL) vs. 307.7 ng/mL (IQR 190.9-349.6 ng/mL), p = 0.16, respectively. MSCs could be traced within the kidneys in all models using widefield microscopy after HMP. The application of Mesenchymal Stem Cells in an ex vivo hypothermic machine perfusion setting is feasible, and MSCs can be delivered into the kidney grafts during HMP. Functional parameters during mimicked reperfusion were not altered in treated kidney grafts. Changes in levels of IL-1ß suggest that MSCs might have an effect on the kidney grafts, and whether this leads to a positive or a negative outcome on IRI in transplantation needs to be determined in further experiments.

The Effect of Interleukin-10 Immunotherapy on Renal Ischemia-Reperfusion Injury: A Systematic Review and Meta-Analysis of Preclinical Studies.

Renal ischemia-reperfusion is a common cause of acute kidney injury leading to significant morbidity and mortality. There are no effective treatments available in clinical practice. This meta-analysis aims to assess the effect of IL-10 immunotherapy on renal ischemia-reperfusion injury. Medline, Embase, Cochrane-library, Google Scholar and clinicaltrials.gov were searched up to 31 March 2023. Preclinical and clinical interventional studies investigating IL-10 immunotherapy for renal ischemia-reperfusion were eligible for inclusion. The primary endpoint was renal function (serum creatinine) following ischemia-reperfusion. The secondary endpoints included mitochondrial integrity, cellular proliferation, regulated cell death (TUNEL assay), expression of inflammatory cytokines (TNF-α, IL-6 and IL-1ß), M1/M2 macrophage polarization, tissue integrity (tubular injury score), long-term kidney fibrosis (fibrotic area %) and adverse events (pulmonary toxicity, cardiotoxicity hepatotoxicity). The search returned 861 records. From these, 16 full texts were screened and subsequently, seven animal studies, corresponding to a population of 268 mice/rats, were included. Compared to the control treatment, IL-10 immunotherapy reduced serum creatinine more effectively within 24 h of administration (95% CI: -9.177, -5.601, I2 = 22.42%). IL-10 immunotherapy promoted mitochondrial integrity and cellular proliferation and reduced regulated cell death (95% CI: -11.000, -4.184, I2 = 74.94%). It decreased the expression of TNF-α, IL-6 and IL-1ß, led to M2 polarization of the local macrophages, reduced tubular injury score (95% CI: -8.917, -5.755, I2 = 22.71%), and long-term kidney fibrosis (95% CI: -6.963, -3.438, I2 = 0%). No adverse outcomes were captured. In Conclusion, IL-10 immunotherapy safely improves outcomes in animal models of renal ischemia-reperfusion; the translational potential of IL-10 immunotherapy needs to be further investigated in clinical trials.

A Conceptual Framework for Evaluating National Organ Donation and Transplantation Programs.

Conceptual frameworks are valuable resources that can be used to guide the planning, evaluation, and development of healthcare services. However, there are currently no comprehensive frameworks focused on organ donation and transplantation that identify the critical factors underlying a successful national program. To address this knowledge gap, we developed a conceptual framework that takes into account all major domains of influence, including political and societal aspects as well as clinical implementation. The framework was initially constructed based on a targeted review of the relevant medical literature. Feedback provided by a panel of international experts was incorporated into the framework via an iterative process. The final framework features 16 essential domains that are critical for initiating and maintaining a successful program and improving the health of patients with organ failure. Of particular note, these domains are subject to three overarching health system principles: responsiveness, efficiency, and equity. This framework represents a first attempt to develop a whole-system view of the various factors that contribute to the success of a national program. These findings provide a useful tool that can be adapted to any jurisdiction and used to plan, evaluate, and improve organ donation and transplantation programs.

Ten Lessons From the Spanish Model of Organ Donation and Transplantation.

The organ donation and transplantation program in Spain has long been considered the gold standard worldwide. An in-depth understanding of the Spanish program may promote the development and reform of transplant programs in other countries. Here, we present a narrative literature review of the Spanish organ donation and transplantation program supplemented by expert feedback and presented according to a conceptual framework of best practices in the field. Core features of the Spanish program include its three-tiered governing structure, close and collaborative relationships with the media, dedicated professional roles, a comprehensive reimbursement strategy, and intensive tailored training programs for all personnel. Several more sophisticated measures have also been implemented, including those focused on advanced donation after circulatory death (DCD) and expanded criteria for organ donation. The overall program is driven by a culture of research, innovation, and continuous commitment and complemented by successful strategies in prevention of end-stage liver and renal disease. Countries seeking ways to reform their current transplant systems might adopt core features and may ultimately aspire to include the aforementioned sophisticated measures. Countries intent on reforming their transplant system should also introduce programs that support living donation, an area of the Spanish program with potential for further improvement.

Solid Organ Donation and Transplantation in the United Kingdom: Good Governance is Key to Success.

The United Kingdom (UK) supports a highly successful organ donation and transplantation program. While the UK originally had one of the lowest organ donation rates in Europe, sustained reforms have resulted in steady improvement. Of note, the UK nearly doubled its rate of deceased donations between 2008 and 2018. In this report, we present a case study of the UK organ donation and transplantation program as an example of a complete system with sound and inclusive governing structures that are strongly integrated with critical programs focused on training and research. This study was based on an initial targeted review of the literature led by a UK expert that included guidelines, national reports, and academic papers. Feedback solicited from other European experts was incorporated into our findings via an iterative process. Overall, the study highlights the stepwise evolution of the UK program that ultimately became successful largely due to ongoing collaborative efforts carried out at all levels. Centralized coordination of all aspects of the program remains a key driver of improved rates of organ donation and transplantation. The designation and empowerment of expert clinical leadership have helped to maintain focus and promote ongoing quality improvement.

The National Organ Donation and Transplantation Program in Greece: Gap Analysis and Recommendations for Change.

Greece has fallen far behind many comparable European countries in the field of organ donation and transplantation and has made little progress over the past decade. Despite efforts to improve its organ donation and transplantation program, systemic problems persist. In 2019, the Onassis Foundation commissioned a report to be prepared by the London School of Economics and Political Science that focused on the state of the Greek organ donation and transplantation program and proposed recommendations for its improvement. In this paper, we present our analysis of the Greek organ donation and transplantation program together with an overview of our specific recommendations. The analysis of the Greek program was undertaken in an iterative manner using a conceptual framework of best practices developed specifically for this project. Our findings were further developed via an iterative process with information provided by key Greek stakeholders and comparisons with case studies that featured successful donation and transplantation programs in Croatia, Italy, Portugal, Spain, and the United Kingdom. Because of their overall complexity, we used a systems-level approach to generate comprehensive and far-reaching recommendations to address the difficulties currently experienced by the Greek organ donation and transplantation program.

Organ Donation in Croatia: The Importance of a National Champion, a Comprehensive Plan, and International Collaborations.

The Republic of Croatia is a global leader in organ donation and transplantation despite having fewer resources and more modest healthcare expenditures than other countries in the European Union. The results of an extensive literature review were combined with expert input in an iterative multi-step data collection and evaluation process designed to assess trends in Croatian organ donation and transplantation and identify key elements, policy changes, and drivers of the system that have contributed to its success. Multiple sources of evidence were used in this study, including primary documents, national and international transplantation reports, and insights from critical informants and content experts. The results highlight several key organizational reforms that have substantially improved the performance of the Croatian transplant program. Our findings emphasize the importance of strong central governance led by an empowered national clinical leader acting under the direct auspices of the Ministry of Health and a comprehensive and progressive national plan. The Croatian transplant system is notable for its integrated approach and efficient manner of managing scarce health resources. Collectively, the results suggest that Croatia has become nearly self-sufficient due to its systematic implementation of the guiding principles for organ donation and transplantation.

How to Structure a Successful Organ Donation and Transplantation System in Eight (Not So Easy) Steps: An Italian Case Study.

Valuable information can be obtained from a systematic evaluation of a successful national transplant program. This paper provides an overview of Italy's solid organ transplantation program which is coordinated by the National Transplant Network (Rete Nazionale Trapianti) and The National Transplant Center (Centro Nazionale Trapianti). The analysis is based on a system-level conceptual framework and identifies components of the Italian system that have contributed to improving rates of organ donation and transplantation. A narrative literature review was conducted and the findings were validated iteratively with input from subject matter experts. The results were organized into eight critical steps, including 1) generating legal definitions of living and deceased donation, 2) taking steps to ensure that altruistic donation and transplantation become part of the national culture and a point of pride, 3) seeking out existing examples of successful programs, 4) creating a situation in which it is easy to become a donor, 5) learning from mistakes, 6) working to diminish risk factors that lead to the need for organ donation, 7) increasing the rate of donations and transplantations via innovative strategies and policies, and 8) planning for a system that supports growth.

Lessons From the Portuguese Solid Organ Donation and Transplantation System: Achieving Success Despite Challenging Conditions.

Over the past two decades, Portugal has become one of the world leaders in organ donation and transplantation despite significant financial constraints. This study highlights how Portugal achieved success in organ donation and transplantation and discusses how this information might be used by other countries that are seeking to reform their national programs. To accomplish this goal, we performed a narrative review of relevant academic and grey literature and revised our results after consultation with two national experts. Our findings were then synthesized according to a conceptual framework for organ donation and transplantation programs. Our results revealed several key strategies used by the Portuguese organ donation and transplantation program, including collaboration with Spain and other European nations, a focus on tertiary prevention, and sustained financial commitment. This report also explores how cooperative efforts were facilitated by geographical, governmental, and cultural proximity to Spain, a world leader in organ donation and transplantation. In conclusion, our review of the Portuguese experience provides insight into the development of organ donation and transplantation systems. However, other countries seeking to reform their national transplant systems will need to adapt these policies and practices to align with their unique cultures and contexts.

European Society for Organ Transplantation (ESOT) Consensus Statement on the Role of Pancreas Machine Perfusion to Increase the Donor Pool for Beta Cell Replacement Therapy.

The advent of Machine Perfusion (MP) as a superior form of preservation and assessment for cold storage of both high-risk kidney's and the liver presents opportunities in the field of beta-cell replacement. It is yet unknown whether such techniques, when applied to the pancreas, can increase the pool of suitable donor organs as well as ameliorating the effects of ischemia incurred during the retrieval process. Recent experimental models of pancreatic MP appear promising. Applications of MP to the pancreas, needs refinement regarding perfusion protocols and organ viability assessment criteria. To address the "Role of pancreas machine perfusion to increase the donor pool for beta cell replacement," the European Society for Organ Transplantation (ESOT) assembled a dedicated working group comprising of experts to review literature pertaining to the role of MP as a method of improving donor pancreas quality as well as quantity available for transplant, and to develop guidelines founded on evidence-based reviews in experimental and clinical settings. These were subsequently refined during the Consensus Conference when this took place in Prague.

Microdialysis in Abdominal Organ Transplantation and the Potential for Integration with Dynamic Preservation Platforms and Post Transplant Monitoring.

The perpetual organ shortage crisis worldwide has meant a paradigm shift in global thinking with subsequent expansion of the accepted criteria for an organ donor to meet the demand. Robust pre-transplant organ viability assessment is the next great challenge in the field of transplantation today. Organ preservation in the nature of static cold storage has reached its limits, and machine perfusion both cold and warm offers theoretically superior preservation and the potential to assess organs. Microdialysis is a novel technique with proven ability to allow remote assessment of tissue biochemistry and metabolism. It has been used in various pre-clinical and clinical models of abdominal organ preservation and transplantation. This review focuses on the use of microdialysis in the assessment of the kidney, liver, and pancreas, and where this novel technology is heading in the context of the assessing organ viability prior to and after transplantation.

Risks for donors associated with living kidney donation: meta-analysis.

BACKGROUND: Living kidney donation risk is likely to differ according to donor's demographics. We aimed to analyse the effects of age, sex, body mass index (BMI) and ethnicity. METHODS: A systematic review and meta-analysis was undertaken of the effects of preoperative patient characteristics on donor kidney function outcomes, surgical complications, and hypertension. RESULTS: 5129 studies were identified, of which 31 met the inclusion criteria, mainly from the USA and Europe. The estimated glomerular filtration rate (eGFR) in donors aged over 60 years was a mean of 9.54 ml per min per 1.73 m2 lower than that of younger donors (P < 0.001). Female donors had higher relative short- and long-term survival. BMI of over 30 kg/m2 was found to significantly lower the donor's eGFR 1 year after donation: the eGFR of obese donors was lower than that of non-obese patients by a mean of -2.70 (95 per cent c.i. -3.24 to -2.15) ml per min per 1.73 m2 (P < 0.001). Obesity was also associated with higher blood pressure both before and 1 year after donation, and a higher level of proteinuria, but had no impact on operative complications. In the long term, African donors were more likely to develop end-stage renal disease than Caucasians. CONCLUSION: Obesity and male sex were associated with inferior outcomes. Older donors (aged over 60 years) have a larger eGFR decline than younger donors, and African donors have a higher incidence of ESRD than Caucasians.

Pancreas Transplantation in Black, Asian and Minority Ethnic Patients-Single Centre Experience in the UK.

Ethnic disparities in the outcomes after simultaneous pancreas kidney (SPK) transplantation still exist. The influence of ethnicity on the outcomes of pancreas transplantation in the UK has not been reported and hence we aimed to investigate our cohort. A retrospective analysis of all pancreas transplant recipients (n = 171; Caucasians = 118/Black Asian Ethnic Minorities, BAME = 53) from 2006 to 2020 was done. The median follow-up was 80 months. Patient & pancreas graft survival, rejection rate, steroid free maintenance rate, HbA1c, weight gain, and the incidence of secondary diabetic complications post-transplant were compared between the groups. p < 0.003 was considered significant (corrected for multiple hypothesis testing). Immunosuppression consisted of alemtuzumab induction and steroid free maintenance with tacrolimus and mycophenolate mofetil. Pancreas graft & patient survival were equivalent in both the groups. BAME recipients had a higher prevalence of type-2 diabetes mellitus pre-transplant (BAME = 30.19% vs. Caucasians = 0.85%, p < 0.0001), and waited for a similar time to transplantation once waitlisted, although pre-emptive SPK transplantation rate was higher for Caucasian recipients (Caucasians = 78.5% vs. BAME = 0.85%, p < 0.0001). Despite equivalent rejections & steroid usage, BAME recipients gained more weight (BAME = 7.7% vs. Caucasians = 1.8%, p = 0.001), but had similar HbA1c (functioning grafts) at 3-,12-, 36-, and 60-months post-transplant.

Impact of COVID-19 on Global Kidney Transplantation Service Delivery: Interim Report.

This article gives a personal, historical, account of the impact of the COVID-19 pandemic on transplantation services. The content is based on discussions held at two webinars in November 2020, at which kidney transplantation experts from prestigious institutions in Europe and the United States reflected on how the pandemic affected working practices. The group discussed adaptations to clinical care (i.e., ceasing, maintaining and re-starting kidney transplantations, and cytomegalovirus infection management) across the early course of the pandemic. Discussants were re-contacted in October 2021 and asked to comment on how transplantation services had evolved, given the widespread access to COVID-19 testing and the roll-out of vaccination and booster programs. By October 2021, near-normal life and service delivery was resuming, despite substantial ongoing cases of COVID-19 infection. However, transplant recipients remained at heightened risk of COVID-19 infection despite vaccination, given their limited response to mRNA vaccines and booster dosing: further risk-reduction strategies required exploration. This article provides a contemporaneous account of these different phases of the pandemic from the transplant clinician's perspective, and provides constructive suggestions for clinical practice and research.

The Impact of Cold Ischaemia Time on Outcomes of Living Donor Kidney Transplantation in the UK Living Kidney Sharing Scheme.

OBJECTIVE: To assess the impact of CIT on living donor kidney transplantation (LDKT) outcomes in the UKLKSS versus outside the scheme. BACKGROUND: LDKT provides the best treatment option for end-stage kidney disease patients. end-stage kidney disease patients with an incompatible living donor still have an opportunity to be transplanted through Kidney Exchange Programmes (KEP). In KEPs where kidneys travel rather than donors, cold ischaemia time (CIT) can be prolonged. METHODS: Data from all UK adult LDKT between 2007 and 2018 were analysed. RESULTS: 9969 LDKT were performed during this period, of which 1396 (14%) were transplanted through the UKLKSS, which we refer to as KEP. Median CIT was significantly different for KEP versus non-KEP (339 versus 182 minutes, P < 0.001). KEP LDKT had a higher incidence of delayed graft function (DGF) (2.91% versus 5.73%, P < 0.0001), lower 1-year (estimated Glomerular Filtration Rate (eGFR) 57.90 versus 55.25 ml/min, P = 0.04) and 5-year graft function (eGFR 55.62 versus 53.09 ml/min, P = 0.01) compared to the non-KEP group, but 1- and 5-year graft survival were similar. Within KEP, a prolonged CIT was associated with more DGF (3.47% versus 1.95%, P = 0.03), and lower graft function at 1 and 5-years (eGFR = 55 vs 50 ml/min, P = 0.02), but had no impact on graft survival. CONCLUSION: Whilst CIT was longer in KEP, associated with more DGF and lower graft function, excellent 5-year graft survival similar to non-KEP was found.

Immunomodulatory Properties of Mesenchymal Stromal Cells Can Vary in Genetically Modified Rats.

Mesenchymal Stromal Cells (MSC) have been shown to exhibit immuno-modulatory and regenerative properties at sites of inflammation. In solid organ transplantation (SOT), administration of MSCs might lead to an alleviation of ischemia-reperfusion injury and a reduction of rejection episodes. Previous reports have suggested 'MSC-preconditioning' of macrophages to be partly responsible for the beneficial effects. Whether this results from direct cell-cell interactions (e.g., MSC trans-differentiation at sites of damage), or from paracrine mechanisms, remains unclear. Immunosuppressive capacities of MSCs from donors of different age and from genetically modified donor animals, often used for in-vivo experiments, have so far not been investigated. We conducted an in vitro study to compare paracrine effects of supernatants from MSCs extracted from young and old wild-type Wystar-Kyoto rats (WKY-wt), as well as young and old WKY donor rats positive for the expression of green fluorescent protein (WKY-GFP), on bone marrow derived macrophages (BMDM). Expression levels of Mannose receptor 1 (Mrc-1), Tumor necrosis factor α (TNFα), inducible NO synthase (iNos) and Interleukin-10 (IL-10) in BMDMs after treatment with different MSC supernatants were compared by performance of quantitative PCR. We observed different expression patterns of inflammatory markers within BMDMs, depending on age and genotype of origin for MSC supernatants. This must be taken into consideration for preclinical and clinical studies, for which MSCs will be used to treat transplant patients, aiming to mitigate inflammatory and allo-responses.

Portable Microfluidic Biosensing System for Real-Time Analysis of Microdialysate in Transplant Kidneys.

Currently, there is a severe shortage of donor kidneys that are fit for transplantation, due in part to a lack of adequate viability assessment tools for transplant organs. This work presents the integration of a novel wireless two-channel amperometric potentiostat with microneedle-based glucose and lactate biosensors housed in a 3D printed chip to create a microfluidic biosensing system that is genuinely portable. The wireless potentiostat transmits data via Bluetooth to an Android app running on a tablet. The whole miniaturized system is fully enclosed and can be integrated with microdialysis to allow continuous monitoring of tissue metabolite levels in real time. We have also developed a wireless portable automated calibration platform so that biosensors can be calibrated away from the laboratory and in transit. As a proof of concept, we have demonstrated the use of this portable analysis system to monitor porcine kidneys for the first time from organ retrieval, through warm ischemia, transportation on ice, right through to cold preservation and reperfusion. The portable system is robust and reliable in the challenging conditions of the abattoir and during kidney transportation and can detect clear physiological changes in the organ associated with clinical interventions.

Machine Perfusion and the Pancreas: Will It Increase the Donor Pool?

PURPOSE OF REVIEW: Pancreas transplantation enables complete patient independence from exogenous insulin administration and increases both patient survival and quality of life. Despite this, there has been a decline in pancreas transplantation for the past 20 years, influenced by changing donor demographics with more high-risk extended criteria (ECD) and donation after cardiac death (DCD) donors. This review discusses whether the advent of machine perfusion (MP), if extended to the pancreas, can increase the pool of suitable donor organs. RECENT FINDINGS: Hypothermic and normothermic MP, as forms of preservation deemed superior to cold storage for high-risk kidney and liver donor organs, have opened the avenue for translation of this work into the pancreas. Recent experimental models of porcine and human ex-vivo pancreatic MP are promising. Applications of MP to the pancreas however need refinement-focusing on perfusion protocols and viability assessment tools. Emerging research shows pancreatic MP can potentially offer superior preservation capacity, the ability to both resuscitate and manipulate organs, and assess functional and metabolic organ viability. The future of MP will lie in organ assessment and resuscitation after retrieval, where ultimately organs initially considered high risk and unsuitable for transplantation will be optimised and transformed, making them then available for clinical use, thus increasing the pool of suitably viable pancreata for transplantation.

Allosensitization after transplant failure: the role of graft nephrectomy and immunosuppression - a retrospective study.

There are conflicting data about the role of transplant nephrectomy and immunosuppression withdrawal on the development of allosensitization and the impact on re-transplantation. We divided 109 first graft recipients into two groups according to whether they underwent nephrectomy (NX+, n = 61) or their graft was left in situ (NX-, n = 48). Sera were assessed for HLA-A/B/Cw/DR/DQ antibodies at the time of NX/transplant failure and after 3, 6, 12, 24 months. The NX+ group showed a higher rate of donor specific antibody (DSA) and non-DSA human leukocyte antigen (HLA) antibody production at all the time points. Multivariable analysis showed that nephrectomy was a strong, independent risk factor for the development of DSAs after 12 and 24 months (P = 0.005 and 0.008). In the NX- group, low tacrolimus levels correlated with DSA formation (AUC 0.817, P = 0.002; best cut-off level 2.9 ng/ml). Analysis with a standardized pool of UK donors showed a more difficult grade of HLA matchability following nephrectomy compared with the NX- group. Nephrectomy is followed by the long-term production of DSA and non-DSA HLA antibodies and negatively impacts on the chances of finding a HLA-compatible kidney. Tacrolimus levels ≥3 ng/ml are protective against the development of allosensitization and could facilitate re-transplantation in the NX- group.