Ex-Vivo Kidney Perfusion With Hemoglobin-Based Oxygen Carriers, Red Blood Cells, or No Oxygen Carrier.

INTRODUCTION: Normothermic machine perfusion (NMP) of donor kidneys provides the opportunity to assess and improve organ viability prior to transplantation. This study explored the necessity of an oxygen carrier during NMP and whether the hemoglobin-based oxygen carrier (HBOC-201) is a suitable alternative to red blood cells (RBCs). METHODS: Porcine kidneys were perfused with a perfusion solution containing either no-oxygen carrier, RBCs, or HBOC-201 for 360 min at 37°C. RESULTS: Renal flow and resistance did not differ significantly between groups. NMP without an oxygen carrier showed lower oxygen consumption with higher lactate and aspartate aminotransferase levels, indicating that the use of an oxygen carrier is necessary for NMP. Cumulative urine production and creatinine clearance in the RBC group were significantly higher than in the HBOC-201 group. Oxygen consumption, injury markers, and histology did not differ significantly between these two groups. However, methemoglobin levels increased to 45% after 360 min in the HBOC-201 group. CONCLUSIONS: We conclude that HBOC-201 could be used as an alternative for RBCs, but accumulating methemoglobin levels during our perfusions indicated that HBOC-201 is probably less suitable for prolonged NMP. Perfusion with RBCs, compared to HBOC-201, resulted in more favorable renal function during NMP.

KIDNEY-PAGER: analysis of circulating tumor DNA as a biomarker in renal cancer - an observational trial. Study protocol.

BACKGROUND: Management of localized renal cell carcinoma (RCC) is challenged by inaccurate methods to assess the risk of recurrence and deferred detection of relapse and residual disease after radical or partial nephrectomy. Circulating tumor DNA (ctDNA) has been proposed as a potential biomarker in RCC. PURPOSE: Conduction of an observational study to evaluate the validity of ctDNA as a biomarker of the risk of recurrence and subclinical residual disease to improve postoperative surveillance. MATERIAL AND METHODS: Urine and blood will be prospectively collected before and after surgery of the primary tumor from up to 500 patients until 5 years of follow-up. ctDNA analysis will be performed using shallow whole genome sequencing and cell-free methylated DNA immunoprecipitation sequencing. ctDNA levels in plasma and urine will be correlated to oncological outcomes. Residual blood and urine as well as tissue biopsies will be biobanked for future research. INTERPRETATION: Results will pave the way for future ctDNA-guided clinical trials aiming to improve RCC management.

Pulmonary embolisms and infections after renal trauma.

INTRODUCTION: The objective of this study was to describe and evaluate the management of patients with renal trauma and their complications at the Department of Urology at Aarhus University Hospital (AUH), Denmark. METHODS: All patients diagnosed with renal injury due to trauma and with contact to the Department of Urology at the AUH, Denmark, between March 2016 and March 2021 were included. Patients were identified by the International Classification of Diseases, Tenth version, code and data obtained from electronic patient records. RESULTS: A total of 58 patients were identified. The median age was 33 years (7-95 years) and the median length of hospitalisation was five days (range: 0-52 days). All patients were evaluated with a multiphase computed tomography upon admission. Injuries to the kidney were graded using the American Association for the Surgery of Trauma kidney injury scale. Twelve percent had grade I injury, 26% had grade II injury, 26% had grade III injury, 36% had grade IV injury and 3% had grade V injury. In the acute phase, all patients were managed non-operatively. Early complications were found in 24% of patients. Pulmonary embolism was diagnosed in 7%. Furthermore, 7% had an infection as a late complication and all of these patients had also had an early infection. A total of 60% were followed up with a renal-scintigraphy three months after their renal trauma. This examination had no consequence for any of the patients. CONCLUSIONS: No patients died due to the renal trauma. However, many experienced complications in terms of infections and pulmonary embolisms. These data support earlier findings and suggest that a renal scintigraphy after renal traumas may be obsolete. FUNDING: None. TRIAL REGISTRATION: Not relevant.

Dosing Limitation for Intra-Renal Arterial Infusion of Mesenchymal Stromal Cells.

The immunomodulatory and regenerative properties of mesenchymal stromal cells (MSCs) make MSC therapy a promising therapeutic strategy in kidney disease. A targeted MSC administration via the renal artery offers an efficient delivery method with limited spillover to other organs. Although local administration alleviates safety issues with MSCs in systemic circulation, it introduces new safety concerns in the kidneys. In a porcine model, we employed intra-renal arterial infusion of ten million allogenic adipose tissue-derived MSCs. In order to trigger any potential adverse events, a higher dose (hundred million MSCs) was also included. The kidney function was studied by magnetic resonance imaging after the MSC infusion and again at two weeks post-treatment. The kidneys were assessed by single kidney glomerular filtration rate (skGFR) measurements, histology and inflammation, and fibrosis-related gene expression. None of the measured parameters were affected immediately after the administration of ten million MSCs, but the administration of one hundred million MSCs induced severe adverse events. Renal perfusion was reduced immediately after MSC administration which coincided with the presence of microthrombi in the glomeruli and signs of an instant blood-mediated inflammatory reaction. At two weeks post-treatment, the kidneys that were treated with one hundred million MSCs showed reduced skGFR, signs of tissue inflammation, and glomerular and tubular damage. In conclusions, the intra-renal administration of ten million MSCs is well-tolerated by the porcine kidney. However, higher concentrations (one hundred million MSCs) caused severe kidney damage, implying that very high doses of intra-renally administered MSCs should be undertaken with caution.

Corticomedullary shunting after ischaemia and reperfusion in the porcine kidney?

BACKGROUND: Renal perfusion may redistribute from cortex to medulla during systemic hypovolaemia and after renal ischaemia for other reasons, but there is no consensus on this matter. We studied renal perfusion after renal ischaemia and reperfusion. METHODS: Renal perfusion distribution was examined by use of 153Gadolinium-labeled microspheres (MS) after 2 h (hrs) and 4 h ischaemia of the pig kidney followed by 4 h of reperfusion. Intra-arterial injected MS are trapped in the glomeruli in renal cortex, which means that MS are not present in the medulla under normal physiological conditions. RESULTS: Visual evaluation after reperfusion demonstrated that MS redistributed from the renal cortex to the medulla in 6 out of 16 pigs (38%) subjected to 4 h ischaemia and in one out of 18 pigs subjected to 2 h ischaemia. Central renal uptake of MS covering the medullary/total renal uptake was significantly higher in kidneys subjected to 4 h ischaemia compared with pigs subjected to 2 h ischaemia (69 ± 5% vs. 63 ± 1%, p < 0.001), and also significantly higher than in the contralateral kidney (69 ± 5% vs. 63 ± 2%, p < 0.001). Analysis of blood and urine demonstrated no presence of radioactivity. CONCLUSION: The study demonstrated the presence of MS in the renal medulla in response to renal ischaemia and reperfusion suggesting that severe ischaemia and reperfusion of the pig kidney leads to opening of functional shunts bypassing glomeruli.

Complications after scrotal surgery - still a major issue?

OBJECTIVE: Gold standard treatment of symptomatic hydrocele or spermatocele is surgery. Despite a minor procedure, complications such as bleeding and infections leading to reoperations may be devastating for the patients. In autumn 2018, an accumulation of complications was seen in our department. The aim of this study was to investigate the rate and grade of complications and to identify potential means to reduce these. MATERIALS AND METHODS: Patient records of all patients undergoing surgical repair of hydrocele or spermatocele from December 2017 to November 2018 were examined. Results were audited to identify potential causes of complications. The focus was on the perioperative hemostasis and postoperative activity restrictions. The outcome was compared to a consecutive patient series operated the following year. RESULTS: Sixty-five men were operated on during the first period. Twenty-two patients contacted the department postoperatively due to swelling or pain, 19 patients were examined at the hospital and six patients were re-operated 1-9 times. The following year, 69 patients were operated on. Of these, 16 patients contacted the department postoperatively (p = 0.17), 13 patients were examined at the hospital, and five patients were re-operated (p = 0.68). There was the same complication rate in patients operated by specialist urologists or supervised younger doctors. However, patients preoperatively examined and informed by a specialized urologist had significantly fewer complications compared to those informed by urological residents and interns (p = 0.012). CONCLUSION: Despite the change in patient information and increased awareness of possible complications, a high proportion of patients still were in need of unplanned contact to the department and reoperation.

Improved Normothermic Machine Perfusion After Short Oxygenated Hypothermic Machine Perfusion of Ischemically Injured Porcine Kidneys.

BACKGROUND: In an era where global kidney shortage has pushed the field of transplantation towards using more marginal donors, modified kidney preservation techniques are currently being reviewed. Some techniques require further optimization before implementation in full scale transplantation studies. Using a porcine donation after circulatory death kidney model, we investigated whether initial kidney hemodynamics improved during normothermic machine perfusion if this was preceded by a short period of oxygenated hypothermic machine perfusion (oxHMP) rather than static cold storage (SCS). METHODS: Kidneys subjected to 75 minutes of warm ischemia were randomly assigned to either SCS (n = 4) or SCS + oxHMP (n = 4), with a total cold storage time of 240 minutes. Cold preservation was followed by 120 minutes of normothermic machine perfusion with continuous measurement of hemodynamic parameters and renal function. RESULTS: oxHMP preserved kidneys maintained significantly lower renal resistance throughout the normothermic machine perfusion period compared to SCS kidneys (P < 0.001), reaching lowest levels at 60 minutes with means of 0.71 ± 0.35 mm Hg/mL/min/100 g (SCS) and 0.45 ± 0.15 mm Hg/mL/min/100 g (oxHMP). Accordingly, the oxHMP group had a higher mean renal blood flow versus SCS kidneys (P < 0.001). oxHMP kidneys had higher oxygen consumption during normothermic machine perfusion compared to SCS preserved kidneys (P < 0.001). Creatinine clearance remained similar between groups (P = 0.665). CONCLUSIONS: Preceding oxHMP significantly improved initial normothermic machine perfusion hemodynamics and increased total oxygen consumption. With the long period of warm ischemia, immediate kidney function was not observed, reflected by the findings of low creatinine clearance in both groups.

Ex Vivo Administration of Mesenchymal Stromal Cells in Kidney Grafts Against Ischemia-reperfusion Injury-Effective Delivery Without Kidney Function Improvement Posttransplant.

BACKGROUND: Mesenchymal stromal cell (MSC) therapy may improve renal function after ischemia-reperfusion injury in transplantation. Ex vivo renal intraarterial administration is a targeted delivery method, avoiding the lung vasculature, a known barrier for cellular therapies. In a randomized and blinded study, we tested the feasibility and effectiveness of MSC therapy in a donation after circulatory death autotransplantation model to improve posttransplant kidney function, using an ex vivo MSC delivery method similar to the clinical standard procedure of pretransplant cold graft flush. METHODS: Kidneys exposed to 75 minutes of warm ischemia and 16 hours of static cold storage were intraarterially infused ex vivo with 10 million male porcine MSCs (Tx-MSC, n = 8) or vehicle (Tx-control, n = 8). Afterwards, the kidneys were autotransplanted after contralateral nephrectomy. Biopsies an hour after reperfusion confirmed the presence of MSCs in the renal cortex. Animals were observed for 14 days. RESULTS: Postoperatively, peak plasma creatinine was 1230 and 1274 µmol/L (Tx-controls versus Tx-MSC, P = 0.69). During follow-up, no significant differences over time were detected between groups regarding plasma creatinine, plasma neutrophil gelatinase-associated lipocalin, or urine neutrophil gelatinase-associated lipocalin/creatinine ratio. At day 14, measured glomerular filtration rates were 40 and 44 mL/min, P = 0.66. Renal collagen content and fibrosis-related mRNA expression were increased in both groups but without significant differences between the groups. CONCLUSIONS: We demonstrated intraarterial MSC infusion to transplant kidneys as a safe and effective method to deliver MSCs to the graft. However, we could not detect any positive effects of this cell treatment within 14 days of observation.

A Pilot Study of Postoperative Animal Welfare as a Guidance Tool in the Development of a Kidney Autotransplantation Model With Extended Warm Ischemia.

This pilot study aimed to maintain acceptable animal welfare in the development of a porcine autotransplantation model with severe and incremental renal ischemic injury, a model for usage in future intervention studies. Secondary aims were to develop and test methods to collect blood and urine without the need to restrain or use sedative and avoid transportation to optimize welfare of the pig. METHODS: Kidneys from 7 female pigs were subjected to incremental durations of warm ischemia (WI) 30, 45, or 75 minutes by left renal artery and vein clamping. After static cold storage, contralateral nephrectomy was performed, and the injured graft was autotransplanted and animals observed for 14 days. Animal welfare was assessed and recorded using a structured scoring sheet before and 4 days after the kidney autotransplantation. Furthermore, blood samples were drawn daily the first week and every second day the following week using a semi-central venous catheter. An ostomy bag around the genitals was tested for urine collection. Measured glomerular filtration rate was calculated using renal clearance of chromium-51-labeled ethylenediamine tetraacetic acid on day 14. RESULTS: None of the 7 animals died during the follow-up. The animal welfare was moderately affected when applying 75 minutes of WI (n = 2), and for that reason WI was not further increased. Pigs with lower WI had no observed welfare issues. With 75 minutes of WI peak, plasma creatinine was 1486 and 1317 µmol/L, reached on day 4. Lowest glomerular filtration rate levels were observed in the pigs with 75 minutes of WI. CONCLUSIONS: WI up to 75 minutes caused the intended severely impaired renal function without significantly compromising animal welfare. Blood and urine was collected postoperatively without sedation of the pigs or use of a metabolic cage.

Voided urine versus bladder washing cytology for detection of urothelial carcinoma: which is better?

OBJECTIVE: Cytology is recommended as part of the follow-up of high-grade non-muscle-invasive bladder cancer (NMIBC). However, currently there are no solid guideline recommendations regarding the use of voided urine versus bladder washing for cytology as part of the diagnosis or follow-up of NMIBC. The aim of this study was to investigate whether the cytological outcome was equal regarding the two techniques. MATERIALS AND METHODS: The authors reviewed all outpatient flexible cystoscopies carried out in their department in 2013. Patient records in the registry of pathology were examined and those with simultaneous urine and bladder washing cytology were included. Previous urothelial disease and positive histology within 3 months after the cystoscopy were registered. RESULTS: A total of 1458 patients had both voided urine and bladder washing cytology and were included in the study, of whom 643 (44%) had a history of urothelial disease. An equal outcome of urine and bladder washing cytology was found in 1447 patients (99.2%). For the remaining 11 patients, only four patients underwent further examinations based on cytology findings in addition to what had already been planned after cystoscopy. Of the included patients, 100 (6.9%) had a positive histological outcome within 3 months. CONCLUSIONS: In most patients, no relevant difference between voided urine and bladder washing cytology was observed. Therefore, if cytology is indicated, it is recommended to use the test that is most readily available locally. The additional gain in using both urine and bladder wash is minimal, and can therefore be discarded.

Identification of risk factors for vascular thrombosis may reduce early renal graft loss: a review of recent literature.

Renal graft survival has improved over the past years, mainly owing to better immunosuppression. Vascular thrombosis, though rare, therefore accounts for up to one third of early graft loss. We assess current literature on transplantation, identify thrombosis risk factors, and discuss means of avoiding thrombotic events and saving thrombosed grafts. The incidence of arterial thrombosis was reported to 0.2-7.5% and venous thrombosis 0.1-8.2%, with the highest incidence among children and infants, and the lowest in living donor reports. The most significant risk factors for developing thrombosis were donor-age below 6 or above 60 years, or recipient-age below 5-6 years, per- or postoperative hemodynamic instability, peritoneal dialysis, diabetic nephropathy, a history of thrombosis, deceased donor, or >24 hours cold ischemia. Multiple arteries were not a risk factor, and a right kidney graft was most often reported not to be. Given the thrombosed kidney graft is diagnosed in time, salvage is possible by urgent reoperation and thrombectomy. Despite meticulous attentions to reduce thrombotic risk factors, thrombosis cannot be entirely prevented and means to an early detection of this complication is desirable in order to save the kidneys through prompt reoperation. Microdialysis may be a new tool for this.

Microdialysis for detection of renal ischemia after experimental renal transplantation.

PURPOSE: We designed an experimental renal transplantation model and evaluated microdialysis as a detector of induced postoperative ischemia, a feared complication that when caused by vascular thrombosis most often causes renal graft loss. MATERIALS AND METHODS: Two microdialysis catheters were placed in the left kidney in 16 pigs, including 1 superficially in the renal cortex and 1 fixed on the renal capsule. Two-hour baseline measurements were made at steady state, after which the kidney was removed and subjected to warm and cold ischemia. It was subsequently re-anastomosed end to end in situ and reperfused for 5 hours. Pigs were then randomized into a total renal artery occlusion and a control group. RESULTS: At baseline there were no changes in local metabolites (glucose, glutamate, glycerol and lactate) and no significant difference between the groups. Glycerol increased 4-fold in each group during cold ischemia but there were no pivotal alterations in other metabolites. After kidney reperfusion glycerol decreased and all metabolites were in steady state after 1 hour. At 30 minutes after postoperative ischemia was introduced there were significant increases in all kidneys in ischemia vs steady state reperfusion levels of cortical lactate, glutamate, glycerol and the lactate-to-glucose ratio (each rank sum test p <0.001). No metabolic changes were seen in controls. CONCLUSIONS: Microdialysis detected significant metabolic changes after postoperative ischemia in pigs with experimental renal transplantation, while no metabolic changes were observed in controls. In the future microdialysis may become a valuable tool for postoperative observation of transplanted kidneys, most probably with major impact on early graft survival.

Early detection of renal ischemia by in situ microdialysis: an experimental study.

PURPOSE: Acute vascular thrombosis of the renal artery or vein is a feared and devastating complication after renal operations, especially transplantation. We evaluated microdialysis as a possible new tool for the rapid and reliable detection of renal ischemia in a porcine model. MATERIALS AND METHODS: A total of 20 healthy anesthetized pigs were randomized to experiments on the left or right kidney and into 3 groups, including arterial ischemia in 8, venous ischemia in 8 and 4 controls. One microdialysis catheter was inserted superficially in the renal cortex and 1 was placed outside on the renal capsule. The contralateral kidney was removed. After 2 hours of baseline measurements ischemia was introduced by clamping the renal artery or vein in the first 2 groups. Microdialysis samples were taken every 30 minutes during baseline and the following 5 hours. The samples were analyzed for glucose, lactate, glutamate and glycerol. The mean change from baseline was analyzed for each metabolite in all groups. RESULTS: At 30 minutes after the introduction of arterial or venous ischemia there was a significant increased mean change from baseline of glutamate, glycerol and lactate in the cortex and of glutamate extracapsularly. The mean change from baseline of glucose in the cortex decreased significantly 60 minutes after venous ischemia and 90 minutes after arterial ischemia. In controls these metabolites did not change significantly from baseline with time. CONCLUSIONS: Microdialysis from just outside the renal capsule is a reliable tool for the early detection of acute renal ischemia. It may be used to detect acute vascular complications in the first days after renal transplantation.

Reproducibility of contrast enhanced magnetic resonance renography in adolescents.

PURPOSE: We sought to determine the reproducibility of magnetic resonance imaging renography using 3 different mathematical models and 2 different approaches to convert the relative signal intensity into quantitative indices. Furthermore, we wanted to examine the influence of fluid intake on the obtained renal parameters. MATERIALS AND METHODS: A total of 10 healthy volunteers 13 to 16 years old were subjected to magnetic resonance imaging 3 times within 10 weeks, including an examination where fluid intake was increased. At each examination 0.1 mmol/kg gadolinium diethylenetriamine pentaacetic acid was administrated intravenously as a rapid bolus during a fast magnetic resonance renography sequence. Images were acquired in the coronal plan, and 1,200 images were recorded during approximately 7 minutes. Cortical data were analyzed to estimate absolute and differential function of renal parameters by converting signal intensities into quantitative units. RESULTS: Using the simple approach that a change in magnetic resonance imaging signal is linearly related to the change in gadolinium diethylenetriamine pentaacetic acid concentration, we found reproducibility in the range of 1% to 5% of all estimations of the differential renal function. The relative glomerular ultrafiltration (ml per minute per cm(3) kidney cortex) was calculated and a reproducibility of 7% was observed for relative glomerular ultrafiltration (using the model based on deconvolution). Increased hydration caused a significant change in most parameters. CONCLUSIONS: Contrast enhanced magnetic resonance renography is reproducible in the normal human kidney but excessive water intake has a significant influence on these parameters. Further studies are required to elucidate whether similar measurements can be applied to a kidney with impaired function.