INTRODUCTION:Solid organ transplantation is a cornerstone of care for end-stage organ disease and a critical consideration for all doctors managing chronic conditions such as chronic kidney disease. Transplantation is wholly dependent on organ donation (both living and deceased), with shortages directly limiting access to life-saving therapy and resulting in preventable mortality for patients on waiting lists. Yet undergraduate exposure to organ donation and transplantation (ODT) across UK medical schools is anecdotally poor and not mapped nationally. The most substantive UK evidence is more than two decades old and demonstrates limited exposure and significant knowledge gaps among final-year medical students.We here describe a protocol for two coordinated national surveys: U-KNOW-RT (Understanding and Knowledge of Renal Transplantation; final-year students) and U-TEACH-ODT (Undergraduate Teaching in ODT; educator leads). Together, these will provide the first UK-wide mapping of undergraduate ODT education, generating contemporary evidence on teaching provision, student exposure, knowledge, attitudes and career intentions. This work will directly inform the design of a standardised national ODT teaching module to ensure that all UK medical graduates attain a core level of literacy in ODT. Survey distribution is scheduled for January 2026, with completion expected by summer 2026. METHODS AND ANALYSIS:We will conduct two parallel cross-sectional online surveys. U-KNOW-RT will recruit final-year medical students from all 44 UK medical schools via social media, institutional channels and student societies. U-TEACH-ODT will invite deans and senior curriculum leads. The student target is ~1200 responses (≥10 per school) to enable national mapping and triangulation with educator reports. Analyses will follow the Consensus-Based Checklist for Reporting of Survey Studies and the Checklist for Reporting Results of Internet E-Surveys reporting frameworks. Prespecified outcomes include student knowledge, exposure and attitudes alongside educator-reported curricular provision. Primary analyses will use mixed-effects regression with school-level clustering, agreement between student and educator reports will be quantified and selected items will be readministered to allow 20-year comparisons with legacy surveys. ETHICS AND DISSEMINATION:This study involves human participants and was granted ethical approval by the University of Sheffield Ethics Department (reference 070914) on 25 November 2025. Participants provided informed consent before taking part. This manuscript reports a study protocol only; no results will be reported. Findings will be disseminated through peer-reviewed publications, conferences and feedback to medical schools and national bodies. De-identified data, questionnaires and analysis code will be shared openly on Open science framework. TRIAL REGISTRATION NUMBER:OSF preregistration (DOI 10.17605/OSF.IO/38W5N).

BackgroundGiven the increasing age and frailty of kidney transplant candidates, there is an emerging drive to optimise patients before transplantation. Lack of exercise has been linked with poor outcomes at all stages of the transplant pathway. The aim of this study was to evaluate the attitudes and perception to exercise in such patients and assess how these practises vary by demographics.MethodsA single-centre, prospective, survey-based study was conducted on consecutive adult patients being assessed for activation on the deceased-donor kidney transplant waiting list.ResultsA total of 103 patients (65% male; 56% White ethnicity; mean age: 47.8 years) completed the survey. Of these, 42% were on haemodialysis and 24% on peritoneal dialysis. Most patients agreed/strongly agreed that exercise was important (86%) and that they would be willing to do so to optimise their health (97%). Despite this, only 56% of patients reported exercising on a regular basis. Most patients stated that they would be willing to wear exercise monitoring devices (81%). Younger (Spearman's rho: 0.20, p = 0.047) and Black/Asian ethnicity (p = 0.038) patients reported performing significantly less exercise activity than their older and White counterparts.ConclusionWhilst kidney transplant candidates have generally positive attitudes toward exercise, only around half of those surveyed reported exercising regularly. The findings of this study, including differences across age and ethnicity, would be useful to consider when designing patient-centred prehabilitation interventions to encourage exercise in this cohort.

Ischemia-reperfusion injury is a significant complication in kidney transplantation, often affecting the viability and function of organs. Normothermic machine perfusion is a technique used to improve the addition of organs prior to transplantation. In this study, we show that incorporating antioxidant poly(propylene sulfide) nanoparticles during cold-storage and normothermic machine perfusion significantly enhances its efficacy in reducing ischemia-reperfusion injury upon porcine kidney transplantation. We found that by scavenging reactive oxygen species, poly(propylene sulfide) nanoparticles reduced oxidative stress and inflammation that occur during ischemia-reperfusion with oxidized DNA reduced 5.3x and both TNF-α and complement activation approximately halved. Our studies show that this approach led to significantly improved hemodynamics, better renal function, and tissue health compared to normothermic machine perfusion alone. The results suggest that incorporating poly(propylene sulfide) nanoparticles into transplantation protocols may expand the pool of kidneys suitable for transplantation and enhance overall transplantation success rates. The broader impact of this work could extend to other organ transplants, suggesting a wider application of nanoantioxidant technologies in organ preservation.

BACKGROUND:Deceased donor kidney transplants often face delays, leading to prolonged cold ischemia time (CIT), yet data on post-allograft arrival delays are scarce. OBJECTIVES:This audit aims to identify and characterize the delays contributing to CIT prolongation after allograft arrival at the implanting center. DESIGN:Data was collected prospectively from 14 UK centers between February and September 2022. Timelines from allograft arrival to the implanting center to implantation were recorded for adult deceased donor kidney-only transplants. RESULTS:The median CIT for all 446 allografts [(donation after cardiac death (DCD), 48.2% and donation after brain death (DBD), 51.6%)] was 11:08 h (interquartile range (IQR): 08:15-15:12). A total of 42% of DCD and 15% of DBD allografts exceeded the national recommended duration of 12 and 18 h, respectively. CIT was prolonged in centers with dedicated transplant theaters, with a median CIT of 13:41 (IQR: 08:11-15:13) compared to a median CIT of 09:43 (IQR: 07:36-12:29) hours (p < 0.005, 95% CI: -4.40, -2.60) in centers without dedicated transplant theaters. Compared to full cross-match (FXM) results, a higher proportion of Virtual cross-match (VXM) results (75.2% vs. 89.4%, Odds Ratio (OR): 2.79, CI: 1.57-5.0, p < 0.005) were available before the allograft arrived at the implanting center. The proportion of crossmatch results available before the recipient's arrival at the implanting center was 31.7% (46.6% for VXM vs. 4.9% for FXM, OR: 16.76, CI: 7.50, 44.17, p < 0.005). However, no difference was found in CIT between the VXM (median: 11:06, IQR: 08:14-15:20) and FXM (median: 11:00, IQR: 08:34-14:56) groups (p = 0.75, CI: -0.75, 1.02). Qualitative analysis identified theater and staff unavailability as common reasons for delay. CONCLUSION:Internal center practices have a significant impact on CIT, necessitating intervention to optimize transplant outcomes.

The aim of this analysis was to explore mortality outcomes for kidney transplant candidates receiving older living donor kidneys (age ≥60 years) versus younger deceased donors or remaining on dialysis. From 2000 to 2019, all patients on dialysis listed for their first kidney-alone transplant were included in a retrospective cohort analysis of UK transplant registry data. The primary outcome was all-cause mortality, with survival analysis conducted by intention-to-treat principle. Time-to-death from listing was modelled using nonproportional hazard Cox regression models with transplantation handled as a time-dependent covariate. A total of 32,978 waitlisted kidney failure patients formed the primary study cohort, of whom 18,796 (58.5%) received a kidney transplant (1,557 older living donor kidneys and 18,062 standard criteria donor kidneys). Older living donor kidney transplantation constituted only 17.0% of all living donor kidney transplant activity (overall cohort; n = 9,140). Recipients of older living donor kidneys had reduced all-cause mortality compared to receiving SCD kidneys (HR 0.904, 95% CI 0.845–0.967, p = 0.003) and much lower all-cause mortality versus remaining on the waiting list (HR 0.160, 95% CI 0.149–0.172, p < 0.001). Older living kidney donors should be actively explored to expand the living donor kidney pool and are an excellent treatment option for waitlisted kidney transplant candidates.

Introduction Ischaemia-reperfusion injury (IRI) results in the pathophysiological generation of reactive oxygen species (ROS) with concurrent activation of the complement cascade. This manifests as delayed graft function, which has a significant impact on the longevity of the graft. We aimed to evaluate if ROS scavenging nanoparticles can be used to mitigate IRI related injury during normothermic machine perfusion (NMP).Methods A randomised, two-stage, preclinical trial was used to assess the impact of poly(propylene sulfide) (polysulfide) nanoparticles (PPS-NPs) on parameters associated with IRI in a renal NMP system (experiment 1, n=6 vs 6). Paired porcine kidneys were randomised to receive either an NP-preservation flush followed by 6 hours of NMP with NP-perfusate, or control preservation flush and standard NMP. Following this, an allogeneic transplant-reperfusion model was used to evaluate if treatment with PPS-NPs improved renal haemodynamics post-transplantation (experiment 2, n=6 vs 6). Kidneys were perfused for 3 hours with or without NP, before being reperfused on a circuit primed with matched blood from genetically different donor pigs for 6 hours, without immunosuppression.Results In experiment 1, all kidneys perfused well for 6 hours with physiological renal haemodynamics and biochemistry. Kidneys perfused with PPS-NPs had improved regional tissue perfusion on infra-red imaging. In experiment 2, renal haemodynamics were significantly improved during allogeneic reperfusion (post-transplant) after treatment with NP. Complement activation remained significantly lower in treated kidneys with a diminished TNF-α response. This translated into an improvement in tissue integrity.Conclusion IRI was ameliorated following treatment with NPs during preservation and NMP. This was evidenced by an improvement in renal haemodynamics and diminished inflammatory markers upon reperfusion with allogeneic blood.### Competing Interest StatementThe authors have declared no competing interest.* DGF : Delayed graft function GTN : Glyceryl trinitrate IRI : Ischaemia-reperfusion injury IRR : Intra-renal resistance NMP : Normothermic machine perfusion NP : Nanoparticles PPS-NP : Poly(propylene sulfide) (polysulfide) nanoparticles RBF : Renal blood flow ROS : Reactive oxygen species SCS : Static cold storage

Survival outcomes for kidney transplant candidates based on expanded criteria donor (ECD) kidney type is unknown. A retrospective cohort study was undertaken of prospectively collected registry data of all waitlisted kidney failure patients receiving dialysis in the United Kingdom. All patients listed for their first kidney-alone transplant between 2000–2019 were included. Treatment types included; living donor; standard criteria donor (SCD); ECD60 (deceased donor aged ≥60 years); ECD50–59 (deceased donor aged 50–59 years with two from the following three; hypertension; raised creatinine and/or death from stroke) or remains on dialysis. The primary outcome was all-cause mortality, with time-to-death from listing analyzed using time-dependent non-proportional Cox regression models. The study cohort comprised 47,917 waitlisted kidney failure patients, of whom 34,558 (72.1%) received kidney transplantation. ECD kidneys (n = 7,356) were stratified as ECD60 (n = 7,009) or ECD50–59 (n = 347). Compared to SCD, both ECD60 (Hazard Ratio 1.126, 95% CI 1.093–1.161) and ECD50–59 (Hazard Ratio 1.228, 95% CI 1.113–1.356) kidney recipients have higher all-cause mortality. However, compared to dialysis, both ECD60 (Hazard Ratio 0.194, 95% CI 0.187–0.201) and ECD50–59 (Hazard Ratio 0.218, 95% CI 0.197–0.241) kidney recipients have lower all-cause mortality. ECD kidneys, regardless of definition, provide equivalent and superior survival benefits in comparison to remaining waitlisted.

The American Transplant Congress 2022, which took place between June 4th and June 8th of 2022, was a hybrid meeting with in-person attendance in Boston-MA and a real-time virtual experience via an online platform. First, we identified abstracts discussing machine perfusion preservation for all organs, a hot topic and approach that may develop into the new gold standard of organ preservation in the near future. A total of 39 abstracts on organ machine preservation were presented at the meeting. Next, we selected abstracts which focus on advances including new approaches to organ preservation, promising biomarkers, ex-situ treatment including cellular therapies, and novel research areas. Here, we summarized the latest developments on machine perfusion preservation in both experimental and clinical studies.

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

Introduction: Recent experimental evidence suggests normothermic machine perfusion of the vascularized composite allograft results in improved preservation compared to static cold storage, with less reperfusion injury in the immediate post-operative period. However, metabolic acidosis is a common feature of vascularized composite allograft perfusion, primarily due to the inability to process metabolic by-products. We evaluated the impact of combined limb-kidney perfusion on markers of metabolic acidosis and inflammation in a porcine model. Methods: Ten paired pig forelimbs were used for this study, grouped as either limb-only (LO, n = 5) perfusion, or limb-kidney (LK, n = 5) perfusion. Infrared thermal imaging was used to determine homogeneity of perfusion. Lactate, bicarbonate, base, pH, and electrolytes, along with an inflammatory profile generated via the quantification of cytokines and cell-free DNA in the perfusate were recorded. Results: The addition of a kidney to a limb perfusion circuit resulted in the rapid stabilization of lactate, bicarbonate, base, and pH. Conversely, the LO circuit became progressively acidotic, correlating in a significant increase in pro-inflammatory cytokines. Global perfusion across the limb was more homogenous with LK compared to LO. Conclusion: The addition of a kidney during limb perfusion results in significant improvements in perfusate biochemistry, with no evidence of metabolic acidosis.

Coronavirus disease 2019 (COVID-19) has caused many units to suspend or reduce transplantation. As transplantation activity resumes, guidelines on screening have developed, with active COVID-19 generally a contraindication for transplantation.1 We report a case of a kidney transplant recipient who likely was infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the time of transplant. A 37-year-old man was admitted for a preemptive living donor kidney transplant. Both donor and recipient were reviewed in a COVID-secure outpatient clinic 14 days pretransplant. Neither reported COVID-19 symptoms or confirmed or suspected contact with anyone with COVID-19. SARS-CoV-2 nasopharyngeal swabs 14 and 3 days pretransplant were negative. Both patients were instructed to self-isolate until admission. The transplant proceeded with no intraoperative complications. Postoperatively he was admitted to a COVID-secure ward specifically for elective surgical patients who had self-isolated and negative SARS-CoV-2 tests within 3 days preadmission. He had immediate graft function, with good urine output and a 136 µmol/L fall in creatinine on postoperative day 1. Routine SARS-CoV-2 nasopharyngeal swabs were taken on admission and postoperative day 3. The first result was negative, but he tested positive on day 3. He remained asymptomatic, blood tests revealed no evidence of severe disease, and a chest radiograph was unremarkable. The immunosuppressive regime of tacrolimus, mycophenolate mofetil, and prednisolone was unchanged as his creatinine was static at 160 µmol/L, causing concerns about rejection. On postoperative day 7, his creatinine increased to 191 µmol/L. A kidney biopsy was performed, showing significant lymphocytic infiltrate causing subtle tubilitis. With the rising creatinine, this was considered significant for Banff’s borderline rejection. He was treated with 3 doses of methylprednisolone and the tacrolimus dose was increased. He remained asymptomatic and was discharged on postoperative day 11. His inflammatory markers were never significantly raised, with a normal white cell count throughout and a peak C-reactive protein 27 mg/L on postoperative day 5. COVID-19-targeted therapies were considered at multidisciplinary meetings, but as he was asymptomatic throughout, these were not commenced. At 3 weeks, he remains asymptomatic, his creatinine is 160 µmol/L, and repeat SARS-CoV-2 nasopharyngeal swabs remain positive. A SARS-CoV-2 antibody test 10 days after his first positive swab was negative. His COVID-19 was likely pretransplant community acquired. Unknown to the team at the time of surgery, he was noncompliant with self-isolation guidelines. Five days preadmission, without using masks or distancing, he met his sister who subsequently developed symptoms and tested positive for SARS-CoV-2. Noncompliance with self-isolation may expose patients and staff to SARS-CoV-2. There are also exposure risks to other patients via the anesthetic ventilation equipment and theater environment.2 His follow-up was modified to minimize the risk of spread to other immunosuppressed transplant patients. There is limited evidence to guide the management of COVID-19 in acute posttransplant patients. The balance of immunosuppression and stopping mycophenolate mofetil in the context of active COVID-19 and possible rejection was considered at multidisciplinary meetings. A refractory rejection would have posed the dilemma of using antithymocyte globulin although its use in simultaneous pancreas-kidney transplant recipients with recent COVID-19 has been reported.3 Finally, the sensitivity of SARS-CoV-2 tests should be considered, with factors including time from exposure, specimen source, and collection technique influencing results.4 The time between exposure and test positivity remains unclear, and a negative test may not necessarily rule out COVID-19, although the estimated median incubation period is 5 days.5 Following this experience, we have introduced additional counseling by clinical nurse specialists and transplant surgeons regarding the need for strict self-isolation to all patients at pretransplant appointments.

Background: The Karpinski scoring system used to allocate kidneys as single (? 4) or double transplants (5 or 6) has been considered overprotective, excluding potentially suitable organs. It has been proven that double kidney transplants who lost 1 of the 2 grafts maintained acceptable renal function as long as 10 years in 70% of cases. This observation suggested extending the histological allocation criteria for single grafts. Methods/Materials: Among 235 patients who received a single graft from either Standard Criteria Donors (SCD) or Expanded Criteria Donors (ECD) in our renal transplantation program from 2004 and 2014, we analyzed the graft survival, delayed graft function (DGF) and acute rejection rate between a group (48 patients) with histologic Karpinski score? 5 (score 6 in 3 cases) and a control group (187 patients) with score < 5. Results: The mean age of donors were comparable in both groups (67.3 vs 65.2 years) as well as the patient’s age at transplant (58.3 vs 56 years). We recorded a delayed graft function in 27 cases (56.2%) in the high score rate group vs 102 (54.5%) in the control. The actuarial death censored graft survival rate (Kaplan-Meyer) at 5 years was 72.8% in the study group vs 73.5% in the control, while at 10 years was 55.2% vs 56.5%. No differences were recorded in terms of acute rejections 18 patients (37.5%) in the study group vs 75 (40.1%), either clinical or biopsy proven. Conclusion: We found no differences in death censored graft survival rate, suggesting the utilization of score 5 kidneys as single grafts (instead of double transplants) can safely lead to an acceptable long-term renal function, expanding accordingly the donor pool.

BACKGROUNDAn increasing number of patients are requiring multiple retransplants. We assessed outcomes of third and fourth kidney transplants, to aid decision making on the most suitable donor type.METHODSData were collected retrospectively for 2561 transplants, including 69 third and 8 fourth, performed from 2000 to 2017. Demographics and outcomes for the combined third/fourth group were compared to first and second transplants. Within the third/fourth kidney transplant group, comparisons were made between deceased donors (n = 39), live donor HLA-compatible (n = 23) and -incompatible (n = 13) transplants, as well as between standard (n = 25) and extended-criteria (n = 14) deceased donor transplants.RESULTSPatient survival did not differ significantly by transplant number (P = 0.532), whereas death-censored graft survival declined progressively, from 89% at 5 years in first, 85% in second and 74% in the third/fourth transplant group (P < 0.001). Within the combined third/fourth transplant subgroup, 5-year graft survival was found to be 100% in recipients of HLA-compatible live donors, compared to 75% in deceased donors and 53% in HLA-incompatible live donors, although this difference did not reach statistical significance (P = 0.083). No significant difference in patient survival (P = 0.356) or complication rates (P = 0.757) were detected between these groups. For recipients of deceased donors in the third/fourth transplant group, there were no significant differences between standard versus extended-criteria donors for any of the outcomes considered.CONCLUSIONSDespite variable functional outcomes, third and fourth kidney transplant recipients experience comparable patient survival rates to first and second transplants, regardless of the donor type. In selected patients, HLA-incompatible live donors and extended-criteria deceased donors should be considered.

Affiliated to the Association of Surgeons in Training and the British Transplantation Society, the Carrel Club is the transplant trainee surgical society. The Carrel Club held a joint meeting with the Chapter of Transplant Surgeons, a subsidiary organisation of the British Transplantation Society, at the Manchester Hilton Hotel on 31 January and 1 February 2013. As part of the meeting, ten abstracts were presented. A selection is printed below. The winner of the Best Presentation award was Mr Mownah.

A best evidence topic in cardiovascular surgery was written according to a structured protocol. The question addressed was whether administering sodium bicarbonate (NaHCO3) prevents contrast-induced nephropathy (CIN) in cardiovascular patients undergoing contrast imaging. In total, 266 papers were found using the reported search, 16 of which represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. CIN is thought to occur as a result of ischaemic or oxidative injury to the kidney. It is postulated that NaHCO3attenuates this renal damage by alkanizing renal tubular fluid thus reducing the generation of contrast-induced free radicals, which damage the kidney. Of the 16 trials, 15 recruited patients with various degrees of renal dysfunction at baseline. The benefit of using NaHCO3 was demonstrated at all stages of chronic kidney disease. Apart from four studies, 12 studies used low toxicity, low-osmolar contrast. Merten et al. published the first trial of NaHCO3 vs (saline) NaCl in preventing CIN, demonstrated a significantly lower rate in the NaHCO3 group and advocated its widespread use. Subsequent trials using the same regimen have collaborated these results. However, more recently, Gomes et al. concluded that NaHCO3 is not superior to saline-based hydration. Similarly, Brar et al. randomized 323 patients with moderate-to-severe renal insufficiency to receive either an NaHCO3 or an NaCl infusion and observed no difference in CIN rates. Two studies investigated the effects of rapid urine alkanization with bolus injections of NaHCO3 prior to contrast and found significant reductions in CIN rates compared with NaCl-treated groups. One study observed that NaCl is superior to NaHCO3, while all other studies showed a beneficial effect or no difference between NaCl- and NaHCO3-based hydration. The most recent meta-analysis by Jang et al. incorporated 3609 patients across 19 trials and concluded that NaHCO3-based hydration regimens are superior to NaCl-based ones. Based on this review, the authors recommend NaHCO3 alongside an NaCl hydration regimen. The exact regimen will depend on the context within which contrast is being administered and needs further evaluation.