Improved outcomes in cadaveric renal allografts with pulsatile preservation

Renal Transplantation in the Elderly: Are They All the Same? A Multicenter, Comorbidity-Based Study

INTRODUCTION

The age for kidney transplantation (KT) is no longer a limitation and several studies have shown benefits in the survival of elderly patients. The aim of this study was to examine the relationship of the baseline Charlson comorbidity index (CCI) score to morbidity and mortality after transplantation.

METHODS

In this multicentric observational retrospective cohort study, we included patients older than 60 years admitted on the waiting list (WL) for deceased donor KT from January 01, 2006, to December 31, 2016. The CCI score was calculated for each patient at inclusion on the WL.

RESULTS

Data for analysis were available of 387 patients. The patients were divided in tertiles of CCI: group 1 (CCI: 1-2) n = 117, group 2 (CCI: 3-4) n = 158, and group 3 (CCI: ≥5) n = 112. Patient survival was significantly different between CCI groups at 1, 3, and 5 years, respectively: 90%, 88%, and 84% for group 1, 88%, 80%, and 72% for group 2, and 87%, 75%, and 63% for group 3 (p < 0.0001). Variables associated with mortality were CCI score (p < 0.0001), HLA mismatch (p = 0.014), length of hospital stay (p < 0.0001), surgical complications (p = 0.048).

CONCLUSION

Individualized strategies to modify these variables may improve patient's morbidity and mortality after KT.

Evaluating the Performance of a Nonelectronic, Versatile Oxygenating Perfusion System across Viscosities Representative of Clinical Perfusion Solutions Used for Organ Preservation

Introduction: On the United States' Organ Transplantation Waitlist, approximately 17 people die each day waiting for an organ. The situation continues to deteriorate as the discrepancy between harvested organs and the number of patients in need is increasing. Static cold storage is the clinical standard method for preserving a harvested organ but is associated with several drawbacks. Machine perfusion of an organ has been shown to improve preservation quality as well as preservation time over static cold storage. While there are machine perfusion devices clinically available, they are costly and limited to specific organs and preservation solutions. This study presents a versatile oxygenating perfusion system (VOPS) that supplies oxygen and pulsatile perfusion. Materials and Methods: Experiments evaluated the system's performance with a human kidney mimicking hydraulic analog using multiple compressed oxygen supply pressures and aqueous solutions with viscosities ranging from 1 to 6.5 cP, which simulated viscosities of commonly used organ preservation solutions. Results and Conclusions: The VOPS produced mean flow rates ranging from 0.6 to 28.2 mL/min and perfusion pressures from 4.8 to 96.8 mmHg, which successfully achieved the desired perfusion parameters for human kidneys. This work provides evidence that the VOPS described herein has the versatility to perfuse organs using many of the clinically available preservation solutions.

Retroperitoneal kidney transplantation with liver and native kidney mobilization: a safe technique for pediatric recipients

BACKGROUND

Pediatric kidney transplant (KT) using larger, deceased or living donor adult kidneys can be challenging in the pediatric population due to limited space in the retroperitoneum. Liver and native kidney (L/NK) mobilization techniques can be used in smaller and younger transplant recipients to aid in retroperitoneal placement of the renal allograft. Here, we compare the clinical outcomes of pediatric retroperitoneal KT with and without L/NK mobilization.

METHODS

We retrospectively analyzed pediatric renal transplant recipients treated between January 2015 and May 2021. Donor and recipient demographics, intraoperative data, and recipient outcomes were included. Recipients were divided into two groups according to the surgical technique utilized: with L/NK mobilization (Group 1) and without L/NK mobilization (Group 2). Baseline variables were described using frequency distributions for categorical variables and means and standard errors for continuous variables. Tests of association with the likelihood of using L/NK mobilization were performed using standard χ² tests, t tests, and the log-rank test.

RESULTS

Forty-six pediatric recipients were evaluated and categorized into Group 1 (n = 26) and Group 2 (n = 20). Recipients in Group 1 were younger (6.7 ± 0.8 years vs. 15. 3 ± 0.7, P < 0.001), shorter (109.5 ± 3.7 vs. 154.2 ± 3.8 cm, P < 0.001) and weighed less (21.4 ± 2.0 vs. 48.6 ± 3.4 kg, P < 0.001) than those in Group 2. Other baseline characteristics did not differ between Groups 1 and 2. One urologic complication was encountered in Group 2; no vascular or surgical complications were observed in either group. Additionally, no stents or drains were used in any of the patients. There were no cases of delayed graft function or graft primary nonfunction. The median follow-up of the study was 24.6 months post-transplant. Two patients developed death-censored graft failure (both in Group 2, P = 0.22), and there was one death with a functioning graft (in Group 2, P = 0.21).

CONCLUSIONS

Retroperitoneal liver/kidney mobilization is a feasible and safe technique that facilitates implantation of adult kidney allografts into pediatric transplant recipients with no increased risk of developing post-operative complications, graft loss, or mortality.

Factors Associated With the Use of Hypothermic Machine Perfusion in Kidney Transplant Recipients: A Multicenter Retrospective Cohort Study

Background:

Delayed graft function (DGF) is associated with an increased risk of graft loss. The use of cold hypothermic machine perfusion (HMP) has been shown to reduce the incidence of DGF in kidney transplant recipients (KTRs), especially when extended-criteria donors (ECDs) are used. HMP can also improve graft survival. However, there is a paucity of data on the determinants of HMP use in clinical practice.

Objective:

We aimed to determine the factors associated with the use of HMP in a cohort of donors and KTRs.

Design:

Multicenter retrospective cohort study.

Setting:

5 transplant centers in Quebec.

Patients:

159 neurologically deceased donors (NDD) and 281 KTR.

Measurements:

Use of HMP.

Methods:

We collected data on consecutive NDD admitted to a dedicated donor unit in a single university-affiliated center and their KTRs between June 2013 and December 2018 in 5 adult transplant centers across the province of Quebec, Canada. All organs were recovered in a single hospital center where a HMP device was available for every organ recovered and the decision to use HMP was left at the discretion of the procurement surgeon. Generalized estimating equations were used to predict the use of HMP.

Results:

The cohort included 159 NDDs and their 281 KTRs. Thirty-three percent of donors were ECDs, and 59% of KTRs received organs placed on HMP. The median cold ischemia time (CIT) was 12.5 (IQR 7.9-16.3) hours. In univariate analysis, none of the donors’ characteristics were associated with the use of HMP. ECD represented 33% of KTR on HMP vs 35% of those not placed on HMP (P = .77). In univariate analysis, the use of HMP was associated with KTR race (non-Caucasian), longer CIT, use of basiliximab/alemtuzumab, year of transplant, and transplant center. The use of HMP varied largely across transplant centers, ranging from 15% to 82%. In multivariate analysis, use of HMP was associated with longer CIT (odds ratio [OR] 1.15, 95% confidence interval [CI] = 1.07-1.25), transplant center as well as transplantations performed after 2013.

Limitations:

One dedicated donor unit including NDD only, absence of specific data on surgeons’ experience and personal or logistic reasons for using or not HMP.

Conclusions:

We found that use of HMP remains low and varies largely across transplant centers. The use of HMP was strongly associated with the transplant center where the surgeons practiced, suggesting that surgeon preference/training plays an important role in determining the use of HMP. Availability of HMP at the time of organ procurement might also be limited by logistic issues such as difficulty in returning the device. Further studies aimed at determining the reasons underlying the barriers precluding the use of HMP could help increasing its use and improve transplant outcomes.

Vectisol Formulation Enhances Solubility of Resveratrol and Brings Its Benefits to Kidney Transplantation in a Preclinical Porcine Model

Current organ shortages have led centers to extend the acceptance criteria for organs, increasing the risk for adverse outcomes. Current preservation protocols have not been adapted so as to efficiently protect these organs. Herein, we target oxidative stress, the key mechanism of ischemia reperfusion injury. Vectisol^® is a novel antioxidant strategy based on the encapsulation of resveratrol into a cyclodextrin, increasing its bioavailability. We tested this compound as an additive to the most popular static preservation solutions and machine perfusion (LifePort) in a preclinical pig model of kidney autotransplantation. In regard to static preservation, supplementation improved glomerular filtration and proximal tubular function early recovery. Extended follow-up confirmed the higher level of protection, slowing chronic loss of function (creatininemia and proteinuria) and the onset of histological lesions. Regarding machine perfusion, the use of Vectisol^® decreased oxidative stress and apoptosis at the onset of reperfusion (30 min post declamping). Improved quality was confirmed with decreased early levels of circulating SOD (Superoxide Dismutase) and ASAT (asparagine amino transferase). Supplementation slowed the onset of chronic loss of function, as well as interstitial fibrosis and tubular atrophy. The simple addition of Vectisol^® to the preservation solution significantly improved the performance of organ preservation, with long-term effects on the outcome. This strategy is thus a key player for future multi-drug therapy aimed at ischemia reperfusion in transplantation.

Comparative Assessment of uNGAL, uNAG and Cystatin C As Early Biomarkers in Renal Post-Transplant Patients

Urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary N-acetyl-bd-glucosaminidase (NAG), urinary α1-microglobulin/creatinine ratio and cystatin C have been suggested as potential early markers of delayed graft function (DGF) following kidney transplantation. We conducted a prospective study in 50 consecutive kidney transplant recipients to evaluate serial changes of these biomarkers within the first week after transplantation and assess their performance in predicting DGF (dialysis requirement during initial post-transplant week) and graft function throughout the first year. Urine samples were collected on post-transplantation days 0, 1, 2, 4, and 7. Statistical analysis: Linear mixed and multivariable regression models, receiver-operating characteristic (ROC), and areas under ROC curves were used. At all-time points, mean urinary NGAL levels were significantly higher in patients developing DGF. Shortly after transplantation (3-6 h), uNGAL and uNAG values were higher in DGF recipients (on average +242 ng/mL; NAG – 6.8 U/mmol creatinine, considering mean dialysis time of 4.1 years) and rose further in the following days, contrasting with prompt function recipients. On Day-1 uNGAL levels accurately predicted DGF (AUC-ROC = 0.93), with a performance higher than serum creatinine (AUC-ROC = 0.76), and similar to cystatin C (AUC-ROC = 0.95). Multivariable analyses revealed that uNGAL levels at days 4 and 7 were strongly associated with one-year serum creatinine level. Urinary NGAL, serum cystatin C is an early marker of graft injury and is independently associated with dialysis requirement within one week after transplantation and one-year graft function.

Machine perfusion and long-term kidney transplant recipient outcomes across allograft risk strata

Background

The use of machine perfusion (MP) in kidney transplantation lowers delayed graft function (DGF) and improves 1-year graft survival in some, but not all, grafts. These associations have not been explored in grafts stratified by the Kidney Donor Profile index (KDPI).

Methods

We analyzed 78 207 deceased-donor recipients using the Scientific Registry of Transplant Recipients data from 2006 to 2013. The cohort was stratified using the standard criteria donor/expanded criteria donor (ECD)/donation after cardiac death (DCD)/donation after brain death (DBD) classification and the KDPI scores. In each subgroup, MP use was compared with cold storage.

Results

The overall DGF rate was 25.4% and MP use was associated with significantly lower DGF in all but the ECD-DCD donor subgroup. Using the donor source classification, the use of MP did not decrease death-censored graft failure (DCGF), except in the ECD-DCD subgroup from 0 to 1 year {adjusted hazard ratio [aHR] 0.56 [95% confidence interval (CI) 0.32-0.98]}. In the ECD-DBD subgroup, higher DCGF from 1 to 5 years was noted [aHR 1.15 (95% CI 1.01-1.31)]. Also, MP did not lower all-cause graft failure except in the ECD-DCD subgroup from 0 to 1 year [aHR = 0.59 (95% CI 0.38-0.91)]. Using the KDPI classification, MP did not lower DCGF or all-cause graft failure, but in the ≤70 subgroup, higher DCGF [aHR 1.16 (95% CI 1.05-1.27)] and higher all-cause graft failure [aHR 1.10 (95% CI 1.02-1.18)] was noted. Lastly, MP was not associated with mortality in any subgroup.

Conclusions

Overall, MP did not lower DCGF. Neither classification better risk-stratified kidneys that have superior graft survival with MP. We question their widespread use in all allografts as an ideal approach to organ preservation.

Methods for the evaluation of biomarkers in patients with kidney and liver diseases: multicentre research programme including ELUCIDATE RCT

Background

Protein biomarkers with associations with the activity and outcomes of diseases are being identified by modern proteomic technologies. They may be simple, accessible, cheap and safe tests that can inform diagnosis, prognosis, treatment selection, monitoring of disease activity and therapy and may substitute for complex, invasive and expensive tests. However, their potential is not yet being realised.

Design and methods

The study consisted of three workstreams to create a framework for research: workstream 1, methodology – to define current practice and explore methodology innovations for biomarkers for monitoring disease; workstream 2, clinical translation – to create a framework of research practice, high-quality samples and related clinical data to evaluate the validity and clinical utility of protein biomarkers; and workstream 3, the ELF to Uncover Cirrhosis as an Indication for Diagnosis and Action for Treatable Event (ELUCIDATE) randomised controlled trial (RCT) – an exemplar RCT of an established test, the ADVIA Centaur® Enhanced Liver Fibrosis (ELF) test (Siemens Healthcare Diagnostics Ltd, Camberley, UK) [consisting of a panel of three markers – (1) serum hyaluronic acid, (2) amino-terminal propeptide of type III procollagen and (3) tissue inhibitor of metalloproteinase 1], for liver cirrhosis to determine its impact on diagnostic timing and the management of cirrhosis and the process of care and improving outcomes.

Results

The methodology workstream evaluated the quality of recommendations for using prostate-specific antigen to monitor patients, systematically reviewed RCTs of monitoring strategies and reviewed the monitoring biomarker literature and how monitoring can have an impact on outcomes. Simulation studies were conducted to evaluate monitoring and improve the merits of health care. The monitoring biomarker literature is modest and robust conclusions are infrequent. We recommend improvements in research practice. Patients strongly endorsed the need for robust and conclusive research in this area. The clinical translation workstream focused on analytical and clinical validity. Cohorts were established for renal cell carcinoma (RCC) and renal transplantation (RT), with samples and patient data from multiple centres, as a rapid-access resource to evaluate the validity of biomarkers. Candidate biomarkers for RCC and RT were identified from the literature and their quality was evaluated and selected biomarkers were prioritised. The duration of follow-up was a limitation but biomarkers were identified that may be taken forward for clinical utility. In the third workstream, the ELUCIDATE trial registered 1303 patients and randomised 878 patients out of a target of 1000. The trial started late and recruited slowly initially but ultimately recruited with good statistical power to answer the key questions. ELF monitoring altered the patient process of care and may show benefits from the early introduction of interventions with further follow-up. The ELUCIDATE trial was an ‘exemplar’ trial that has demonstrated the challenges of evaluating biomarker strategies in ‘end-to-end’ RCTs and will inform future study designs.

Conclusions

The limitations in the programme were principally that, during the collection and curation of the cohorts of patients with RCC and RT, the pace of discovery of new biomarkers in commercial and non-commercial research was slower than anticipated and so conclusive evaluations using the cohorts are few; however, access to the cohorts will be sustained for future new biomarkers. The ELUCIDATE trial was slow to start and recruit to, with a late surge of recruitment, and so final conclusions about the impact of the ELF test on long-term outcomes await further follow-up. The findings from the three workstreams were used to synthesise a strategy and framework for future biomarker evaluations incorporating innovations in study design, health economics and health informatics.

Trial registration

Current Controlled Trials ISRCTN74815110, UKCRN ID 9954 and UKCRN ID 11930.

Funding

This project was funded by the NIHR Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 6, No. 3. See the NIHR Journals Library website for further project information.

Impact of machine perfusion after long static cold storage on delayed graft function incidence and duration and time to hospital discharge

Delayed graft function (DGF) is very high in our center (70%-80%), and we usually receive a kidney for transplant after more than 22 hours of static cold ischemia time (CIT). Also, there is an inadequate care of the donors, contributing to a high rate of DGF. We decided to test whether machine perfusion (MP) after a CIT improved the outcome of our transplant patients. We analyzed the incidence of DGF, its duration, and the length of hospital stay (LOS) in patients who received a kidney preserved with MP after a CIT (hybrid perfusion-HP). We included 54 deceased donors kidneys preserved with HP transplanted from Feb/13 to Jul/14, and compared them to 101 kidney transplants preserved by static cold storage (CS) from Nov/08 to May/12. The median pumping time was 11 hours. DGF incidence was 61.1% vs 79.2% (P = .02), median DGF duration was 5 vs 11 days (P < .001), and median LOS was 13 vs 18 days (P < .011), for the HP compared to CS group. The observed reduction of DGF with machine perfusion did not occur in donors over 50 years old. In the multivariate analysis, risk factors for DGF, adjusted for CIT, were donor age (OR, 1.04; P = .005) and the absence of use of MP (OR, 1.54; P = .051). In conclusion, the use of HP contributed to faster recovery of renal function and to a shorter length of hospital stay.

Factors Associated With Delayed Graft Function and Their Influence on Outcomes of Kidney Transplantation

BACKGROUND

One of the main postoperative complications of kidney transplant is delayed graft function (DGF), which means absence of graft function after transplant or the need for dialysis during the first week post procedure. The occurrence of DGF currently in our hospital is high and has been attributed to a combination of many factors. The aim of this study was to evaluate the factors associated to DGF and their influence in the outcome of kidney transplants.

METHODS

Historical cohort of 150 patients transplanted with live or deceased donor kidneys from 2011 to 2013.

RESULTS

DGF was associated to time in dialysis and the number of recipient pre-transplant transfusions, donors age, serum creatinine level, use of vasoactive drugs in the donor, distance from place of organ retrieval and transplant center, and duration of cold ischemia time. DGF influenced post-transplantation outcome in regard to length of stay in intensive care, length of hospital stay, acute rejection episodes, and higher creatinine levels at discharge. Patients and graft survival were shorter in the DGF group.

CONCLUSIONS

There are multiple factors related to DGF, the most important being those related to donors, and organ storage. The most important factor related to the recipient was the dialysis vintage. We did not find a correlation between DGF and HLA-compatibility. DGF consequences are important, including worse graft function and survival, as well as impact in recipient morbidity and mortality.

Maximizing kidneys for transplantation using machine perfusion: from the past to the future: A comprehensive systematic review and meta-analysis

BACKGROUND

The two main options for renal allograft preservation are static cold storage (CS) and machine perfusion (MP). There has been considerably increased interest in MP preservation of kidneys, however conflicting evidence regarding its efficacy and associated costs have impacted its scale of clinical uptake. Additionally, there is no clear consensus regarding oxygenation, and hypo- or normothermia, in conjunction with MP, and its mechanisms of action are also debated. The primary aims of this article were to elucidate the benefits of MP preservation with and without oxygenation, and/or under normothermic conditions, when compared with CS prior to deceased donor kidney transplantation.

METHODS

Clinical (observational studies and prospective trials) and animal (experimental) articles exploring the use of renal MP were assessed (EMBASE, Medline, and Cochrane databases). Meta-analyses were conducted for the comparisons between hypothermic MP (hypothermic machine perfusion [HMP]) and CS (human studies) and normothermic MP (warm (normothermic) perfusion [WP]) compared with CS or HMP (animal studies). The primary outcome was allograft function. Secondary outcomes included graft and patient survival, acute rejection and parameters of tubular, glomerular and endothelial function. Subgroup analyses were conducted in expanded criteria (ECD) and donation after circulatory (DCD) death donors.

RESULTS

A total of 101 studies (63 human and 38 animal) were included. There was a lower rate of delayed graft function in recipients with HMP donor grafts compared with CS kidneys (RR 0.77; 95% CI 0.69-0.87). Primary nonfunction (PNF) was reduced in ECD kidneys preserved by HMP (RR 0.28; 95% CI 0.09-0.89). Renal function in animal studies was significantly better in WP kidneys compared with both HMP (standardized mean difference [SMD] of peak creatinine 1.66; 95% CI 3.19 to 0.14) and CS (SMD of peak creatinine 1.72; 95% CI 3.09 to 0.34). MP improves renal preservation through the better maintenance of tubular, glomerular, and endothelial function and integrity.

CONCLUSIONS

HMP improves short-term outcomes after renal transplantation, with a less clear effect in the longer-term. There is considerable room for modification of the process to assess whether superior outcomes can be achieved through oxygenation, perfusion fluid manipulation, and alteration of perfusion temperature. In particular, correlative experimental (animal) data provides strong support for more clinical trials investigating normothermic MP.

Evaluation of renal transplantations performed in the Transplantation Center at Sanko University Medical School

INTRODUCTION

Renal transplantation is the optimum treatment to improve the quality and length of life in end-stage renal disease. The aim of this study is to evaluate patients who underwent renal transplantation in our transplantation center and to present our clinical experience.

METHODS

Living donor and cadaveric renal transplants performed in the Transplantation Center of Sanko University Medical School between 2011 and 2014 were evaluated retrospectively. In our study, important parameters, such as delayed graft function, early and late phase infections and urologic complications after the operation, results of renal transplants with marginal donors with high creatinine levels, and increase in posttransplant body mass index were evaluated regarding to the living donor and cadaveric renal transplants performed in our transplantation center.

RESULTS

We included 136 patients were (92 males [68%] and 44 females [32%]), with an average age of 38.9 ± 9.8 years (range, 17-67). There were 63 living donor renal transplantations (43%) and 73 cadaveric renal transplantations (57%). The youngest cadaveric donor was 3 years old, and the oldest was 86. Fifteen of the cadaveric donors had blood creatinine levels around 1.5 g/dL. The highest level of creatinine from cadaveric donors was 5.1 g/dL.

CONCLUSIONS

Living donor renal transplantations have higher success rate than cadaveric renal transplantations. Ureteroneocystostomy and native ureteropyelostomy seem to be safe and efficient treatment methods for ureteral complications. High creatinine levels in marginal donors do not affect graft function in early stages.

Metabolomic perfusate analysis during kidney machine perfusion: the pig provides an appropriate model for human studies

INTRODUCTION

Hypothermic machine perfusion offers great promise in kidney transplantation and experimental studies are needed to establish the optimal conditions for this to occur. Pig kidneys are considered to be a good model for this purpose and share many properties with human organs. However it is not established whether the metabolism of pig kidneys in such hypothermic hypoxic conditions is comparable to human organs.

METHODS

Standard criteria human (n = 12) and porcine (n = 10) kidneys underwent HMP using the LifePort Kidney Transporter 1.0 (Organ Recovery Systems) using KPS-1 solution. Perfusate was sampled at 45 minutes and 4 hours of perfusion and metabolomic analysis performed using 1-D 1H-NMR spectroscopy.

RESULTS

There was no inter-species difference in the number of metabolites identified. Of the 30 metabolites analysed, 16 (53.3%) were present in comparable concentrations in the pig and human kidney perfusates. The rate of change of concentration for 3-Hydroxybutyrate was greater for human kidneys (p<0.001). For the other 29 metabolites (96.7%), there was no difference in the rate of change of concentration between pig and human samples.

CONCLUSIONS

Whilst there are some differences between pig and human kidneys during HMP they appear to be metabolically similar and the pig seems to be a valid model for human studies.

Neutrophil gelatinase-associated lipocalin in kidney transplantation is an early marker of graft dysfunction and is associated with one-year renal function

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) has been suggested as potential early marker of delayed graft function (DGF) following kidney transplantation (KTx). We conducted a prospective study in 40 consecutive KTx recipients to evaluate serial changes of uNGAL within the first week after KTx and assess its performance in predicting DGF (dialysis requirement during initial posttransplant week) and graft function throughout first year. Urine samples were collected on post-KTx days 0, 1, 2, 4, and 7. Linear mixed and multivariable regression models, receiver-operating characteristic (ROC), and areas under ROC curves were used. At all-time points, mean uNGAL levels were significantly higher in patients developing DGF (n = 18). Shortly after KTx (3–6 h), uNGAL values were higher in DGF recipients (on average +242 ng/mL, considering mean dialysis time of 4.1 years) and rose further in following days, contrasting with prompt function recipients. Day-1 uNGAL levels accurately predicted DGF (AUC-ROC = 0.93), with a performance higher than serum creatinine (AUC-ROC = 0.76), and similar to cystatin C (AUC-ROC = 0.95). Multivariable analyses revealed that uNGAL levels at days 4 and 7 were strongly associated with one-year serum creatinine. Urinary NGAL is an early marker of graft injury and is independently associated with dialysis requirement within one week after KTx and one-year graft function.

Hypothermic machine preservation reduces molecular markers of ischemia/reperfusion injury in human liver transplantation

Hypothermic machine perfusion (HMP) is in its infancy in clinical liver transplantation. Potential benefits include diminished preservation injury (PI) and improved graft function. Molecular data to date has been limited to extrapolation of animal studies. We analyzed liver tissue and serum collected during our Phase 1 trial of liver HMP. Grafts preserved with HMP were compared to static cold stored (SCS) transplant controls. Reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry and transmission electron microscopy (TEM) were performed on liver biopsies. Expression of inflammatory cytokines, adhesion molecules and chemokines, oxidation markers, apoptosis and acute phase proteins and the levels of CD68 positive macrophages in tissue sections were evaluated. RT-PCR of reperfusion biopsy samples in the SCS group showed high expression of inflammatory cytokines, adhesion molecules and chemokines, oxidative markers and acute phase proteins. This upregulation was significantly attenuated in livers that were preserved by HMP. Immunofluorescence showed larger numbers of CD68 positive macrophages in the SCS group when compared to the HMP group. TEM samples also revealed ultrastructural damage in the SCS group that was not seen in the HMP group. HMP significantly reduced proinflammatory cytokine expression, relieving the downstream activation of adhesion molecules and migration of leukocytes, including neutrophils and macrophages when compared to SCS controls.

Early renal transplantation after donor renal angiography affects initial graft function

BACKGROUND

Renal angiography of a living donor is a common radiologic examination before transplantation. However, the contrast agent used during this procedure can cause contrast nephropathy. There are insufficient data regarding whether this radiocontrast exposure detoriates renal function and survival after transplantation. In this study, we analyzed the effects of radiocontrast exposure to donors before transplant surgery on the incidence of delayed graft function (DGF) and on the outcomes of recipients at 1 year posttransplantation.

METHODS

We divided 80 living donor transplantations according to the duration between the renal angiography and the transplantation procedure: Group 1 as early transplantation at ≤ 20 days (n = 42) versus group 2 of late transplantation at ≥ 20 days (n = 38). We retrospectively collected acute rejection episodes and graft survival at 1 year, monthly serum creatinine values of, DGF, proteinuria at 1 month, GFR at posttransplant day 3 month 1, and 1 year.

RESULTS

There were 10 group 1 recipients (23.8%) and 2 group 2 (5.3%) subjects who experienced ≥ 1 acute rejection episode in the 1st posttransplant year (P = .02); 1 patient in each group experienced graft loss at 1 year (P = .941). DGF was observed in 9 (22%) versus 1 patient (2.6%) in group 2 (P = .009). Posttransplant day 3 creatinine values were significantly higher (P = .005) with significantly lower GFR values (P = .043) in group 1. However, creatinine and GFR levels were similar at 1 month and 1 year. Month 1 proteinuria levels were significantly higher in group 1 (P = .014). There was a significant negative correlation between renal angiography time and month 1 proteinuria (P = .014).

CONCLUSIONS

Early renal transplantation (within 2 weeks after renal angiography) in living kidney donors can detoriate initial graft function and cause DGF.

Associations of pre-transplant anemia management with post-transplant delayed graft function in kidney transplant recipients

BACKGROUND

Delayed graft function (DGF) complicates kidney allograft outcomes in the immediate post-transplantation period. We hypothesized that in hemodialysis patients more severe anemia, iron deficiency, the requirement for higher doses of erythropoietin-stimulating agents (ESA), or blood transfusions prior to transplantation are associated with higher risk of DGF.

METHODS

Linking five-yr hemodialysis patient data of a large dialysis organization to the Scientific Registry of Transplant Recipients, we identified 11 836 hemodialysis patients. Using logistic regression analyses we examined the association between pre-transplant parameters and post-transplant DGF.

RESULTS

Patients were 49 ± 14 (mean ± SD) yr old and included 38% women, 27% blacks, and 26% diabetics. After adjusting for relevant covariates, pre-transplant blood transfusion was associated with 33% higher DGF risk (odds ratio [OR] = 1.33; 95% confidence interval [CI]: 1.19-1.48); and each 5000 U/wk increase of pre-transplant ESA dose with 5% higher DGF (OR = 1.05; 95% CI: 1.02-1.09). Compared to pre-transplant blood hemoglobin of 12-12.99 g/dL, there was 25% higher risk of DGF with blood hemoglobin 10-10.99 g/dL (OR = 1.25; 95% CI: 1.01-1.55), whereas blood hemoglobin ≥13 g/dL exhibited 15% higher risk of DGF (OR = 1.15; 95% CI: 0.98-1.34).

CONCLUSIONS

Pre-transplant blood transfusion, higher ESA dose, and either high or low blood hemoglobin but not iron markers are associated with higher risk of DGF.

Reduced expression of inflammatory genes in deceased donor kidneys undergoing pulsatile pump preservation

BACKGROUND

The use of expanded criteria donor kidneys (ECD) had been associated with worse outcomes. Whole gene expression of pre-implantation allograft biopsies from deceased donor kidneys (DDKs) was evaluated to compare the effect of pulsatile pump preservation (PPP) vs. cold storage preservation (CSP) on standard and ECD kidneys.

METHODOLOGY/PRINCIPAL FINDINGS

99 pre-implantation DDK biopsies were studied using gene expression with GeneChips. Kidneys transplant recipients were followed post transplantation for 35.8 months (range = 24-62). The PPP group included 60 biopsies (cold ischemia time (CIT) = 1,367+/-509 minutes) and the CSP group included 39 biopsies (CIT = 1,022+/-485 minutes) (P<0.001). Donor age (42.0±14.6 vs. 34.1±14.2 years, P = 0.009) and the percentage of ECD kidneys (PPP = 35% vs. CSP = 12.8%, P = 0.012) were significantly different between groups. A two-sample t-test was performed, and probe sets having a P<0.001 were considered significant. Probe set level linear models were fit using cold ischemia time and CSP/PPP as independent variables to determine significant probe sets (P<0.001) between groups after adjusting for cold ischemia time. Thus, 43 significant genes were identified (P<0.001). Over-expression of genes associated with inflammation (CD86, CD209, CLEC4, EGFR2, TFF3, among others) was observed in the CSP group. Cell-to-cell signaling and interaction, and antigen presentation were the most important pathways with genes significantly over-expressed in CSP kidneys. When the analysis was restricted to ECD kidneys, genes involved in inflammation were also differentially up-regulated in ECD kidneys undergoing CSP. However, graft survival at the end of the study was similar between groups (P = 0.2). Moreover, the incidence of delayed graft function was not significant between groups.

CONCLUSIONS/SIGNIFICANCE

Inflammation was the most important up-regulated pattern associated with pre-implantation biopsies undergoing CSP even when the PPP group has a larger number of ECD kidneys. No significant difference was observed in delayed graft function incidence and graft function post-transplantation. These findings support the use of PPP in ECD donor kidneys.

Protective effects of hypothermic ex vivo perfusion on ischemia/reperfusion injury and transplant outcomes

Hypothermic machine preservation (HMP) has been used in renal transplantation since the late 1960s with recent robust prospective, multicenter data showing lower rates of delayed graft function and improved graft survival. Although now clearly beneficial for renal transplantation, extrarenal machine perfusion has remained predominantly in preclinical investigations. Pancreatic HMP has drawn little clinical interest because HMP has been suggested to cause graft edema and congestion, which is associated with early venous thrombosis and graft failure. Early investigation showed no benefit of HMP in whole-organ pancreas transplant. One report did show that HMP increases islet cell yield after isolation. Preclinical work in liver HMP has been promising. Short- and long-term HMP has been shown to improve graft viability and reduce preservation injury, even in animal models of steatotic and donation after cardiac death. The first clinical study of liver HMP using a centrifugal dual perfusion technique showed excellent results with lower hepatocellular injury markers and no adverse perfusion-related outcomes. In addition, a dramatic attenuation of proinflammatory cytokine expression was observed. Further studies of liver HMP are planned with focus on developing a reproducible and standard protocol that will allow the widespread availability of this technology. Future research and clinical trials of novel organ preservation techniques, solutions, and interventions are likely to bring about developments that will allow further reduction of preservation-related ischemia/reperfusion injury and improved outcomes and allow safer utilization of the precious and limited resource of donor organs.

Pulsatile perfusion preservation for expanded-criteria donors kidneys: Impact on delayed graft function rate

PURPOSE

Expanded criteria donors (ECD) kidneys are a potential solution to organ shortage, but exhibit more delayed graft function (DGF). We conducted a prospective controlled study aiming to evaluate the impact of pulsatile perfusion preservation (PPP) on DGF rate.

METHODS

Inclusion criteria were: 1) ECD definition (any brain-dead donor aged > 60 years or aged 50-60 years with at least 2 of the following: history of hypertension, terminal serum creatinin level = 1.5 mg/dL, death resulting from a cerebrovascular accident; 2) Donor prolonged circulatory arrest (> 20 mn); 3) previsible cold ischemia time longer than 24 hours. In each pair of kidneys, one organ was preserved with PPP and the other organ was preserved in static cold storage.

RESULTS

From February 2007 to September 2009, a total of 22 donors (44 recipients) were included. Recipients were comparable in the two groups with respect to demographic and immunological data. The rate of DGF was significantly lower (9% vs. 31.8%, p = 0.021) in the PPP group. At 1, 3, and 12 months, renal function was comparable in the two groups.

CONCLUSIONS

Pulsatile perfusion preservation significantly reduced DGF rate in ECD kidney transplantation.

Molecular expression of acute phase mediators is attenuated by machine preservation in human liver transplantation: preliminary analysis of effluent, serum, and liver biopsies

BACKGROUND

Hypothermic machine perfusion (HMP) mitigates the effects of ischemia/reperfusion injury (IRI) in renal transplantation and preclinical work with livers. In liver transplantation, IRI increases the likelihood of primary graft dysfunction and is associated with significant morbidity. We recently completely the first phase 1 clinical trial of liver HMP at our center, and demonstrated improved clinical parameters and shorter duration of stay for patients who received grafts stored by HMP than patients who received grafts preserved in cold storage. Biomarker analysis of venous effluent collected from the hepatic veins during HMP may yield predictive information reflecting the condition of the donor liver, such as graft injury sustained during brain death and graft preservation. The aim of this study was to characterize biomarkers released into the effluent during HMP.

METHODS

Effluent was collected every 30 minutes during liver HMP during our phase 1 clinical trial. Serum was extracted from blood samples obtained at incision, before explantation, and at 1, 2, and 3 hours after reperfusion. The effluent and serum samples were assayed in multiplex to determine the concentration of inflammatory cytokines and growth factors. Tissue obtained from liver biopsies was processed for either downstream reverse transcription-polymerase chain reaction or immunofluorescence. Statistical significance was determined by a two-tailed t-test.

RESULTS

Growth factors and most cytokines were not readily detectable in levels above baseline with this technique; however, interleukin-1 (IL-1) receptor antagonist and monocyte chemotactic protein-1 were present in significant concentrations in the effluent at all time points. This finding was confirmed with serum samples and mRNA expression obtained from liver biopsies. The concentrations of these proteins decreased from their initial values over the course of HMP, and mRNA expression levels were decreased by the use of HMP.

CONCLUSION

IL-1β and tumor necrosis factor (TNF)-α are key mediators of inflammation in IRI. Although difficult to measure because of short half-lives, their downstream effectors indicate their levels of activity. IL-1 receptor antagonist is secreted in response to IL-1β, and monocyte chemotactic protein in response to TNF-α. Their decreased production over the course of HMP suggests that interruption of acute-phase inflammation in the graft may attenuate reperfusion-related graft injury. Further cDNA studies and effluent analyses are required to confirm this hypothesis.

Associations of pretransplant serum albumin with post-transplant outcomes in kidney transplant recipients

The association between pretransplant serum albumin concentration and post-transplant outcomes in kidney transplant recipients is unclear. We hypothesized that in transplant-waitlisted hemodialysis patients, lower serum albumin concentrations are associated with worse post-transplant outcomes. Linking the 5-year patient data of a large dialysis organization (DaVita) to the Scientific Registry of Transplant Recipients, we identified 8961 hemodialysis patients who underwent first kidney transplantation. Mortality or graft failure and delayed graft function (DGF) risks were estimated by Cox regression (hazard ratio [HR]) and logistic regression (Odds ratio [OR]), respectively. Patients were 48 ± 13 years old and included 37% women and 27% diabetics. The higher pretransplant serum albumin was associated with lower mortality, graft failure and DGF risk even after multivariate adjustment for case-mix, malnutrition-inflammation complex and transplant related variable. Every 0.2 g/dL higher pretransplant serum albumin concentration was associated with 13% lower all-cause mortality (HR = 0.87 [95% confidence interval: 0.82-0.93]), 17% lower cardiovascular mortality (HR = 0.83[0.74-0.93]), 7% lower combined risk of death or graft failure (HR = 0.93[0.89-0.97]) and 4% lower DGF risk (OR = 0.96[0.93-0.99]). Hence, lower pretransplant serum albumin level is associated with worse post-transplant outcomes. Clinical trials to examine interventions to improve nutritional status in transplant-waitlisted hemodialysis patients and their impacts on post-transplant outcomes are indicated.

Higher recipient body mass index is associated with post-transplant delayed kidney graft function

To examine whether a higher body mass index (BMI) in kidney recipients is associated with delayed graft function (DGF), we analyzed data from 11,836 hemodialysis patients in the Scientific Registry of Transplant Recipients who underwent kidney transplantation. The patient cohort included women, blacks, and diabetics; the average age was 49 years; and the mean BMI was 26.8 kg/m(2). After adjusting for relevant covariates, multivariate logistic regression analyses found that one standard deviation increase in pretransplant BMI was associated with a higher risk of DGF (odds ratio (OR) 1.35). Compared with patients with a pretransplant BMI of 22-24.99 kg/m(2), overweight patients (BMI 25-29.99 kg/m(2)), mild obesity patients (BMI 30-34.99 kg/m(2)), and moderate-to-severe obesity patients (BMI 35 kg/m(2) and over) had a significantly higher risk of DGF, with ORs of 1.30, 1.42, and 2.18, respectively. Similar associations were found in all subgroups of patients. Hence, pretransplant overweight or obesity is associated with an incrementally higher risk of DGF.

Pulsatile perfusion of kidney allografts with Celsior solution

BACKGROUND

Use of pulsatile perfusion (PP) to optimize outcomes in deceased donor renal transplantation remains controversial. This prospective analysis describes all cadaveric renal allografts transplanted at our center that were preserved with PP using Celsior solution.

METHODS

We used the LifePort Kidney Transporter (Organ Recovery Systems) perfusion machine. Study outcomes included 1-year graft and patient survivals as well as rates of delayed graft function and need for posttransplant dialysis.

RESULTS

Graft survival for PP was 90% and patient survival 100%. The incidences of delayed graft function was 10% and of posttransplant dialysis, 10%.

CONCLUSION

These data support the use of PP with Celsior solution.

Favorable outcomes with machine perfusion and longer pump times in kidney transplantation: a single-center, observational study

BACKGROUND

Hypothermic machine perfusion (MP) preservation is used for all deceased donor kidney transplants at our center. Kidneys are placed in cold storage at retrieval, then transferred to MP on arrival. Because a lack of consensus regarding optimal use of MP still exists, we evaluated the overall impact of using MP at our center and the prognostic value of MP (Pump) time.

METHODS

We retrospectively analyzed 339 adult, primary deceased donor kidney transplant recipients who were pooled across three prospective, randomized immunosuppression trials (since 2000) at our center. In addition to providing overall results for delayed graft function (DGF) (requirement for dialysis in the first week), slow graft function (SGF), first biopsy-proven acute rejection (BPAR), and graft failure, stepwise logistic and Cox regression analyses were used to determine the prognostic value of pump time, particularly after controlling for other significant prognosticators.

RESULTS

Mean cold storage and pump times were 6.6 and 26.7 hr, consistent across immunosuppression protocols. Overall DGF and SGF rates were 4.4% (15/339) and 12.1% (41/339). DGF was equally low for pump time less than 24 vs. more than or equal to 24 hr, 5.2% (6/116) vs. 4.0% (9/223) (P=0.63), with similar results after adjusting for known DGF predictors. A significantly lower first BPAR rate was observed for longer pump time (as a continuous variable) among more immunologically active recipients (those having more risk factors: DGF, age <50 yr, and non-white) (univariable P=0.005; multivariable P=0.009), with an estimated hazard ratio of 0.43 (P=0.006) favoring pump time more than or equal to 24 hr among those with more than or equal to two risk factors. CONCLUSIONS.: In this single-center, observational study, MP with prolonged pump times was associated with low DGF/SGF and first BPAR rates, supporting continued use of MP.

The risk factors of delayed graft function and comparison of clinical outcomes after deceased donor kidney transplantation: single-center study

INTRODUCTION

The aim of this study was to analyze risk factors for delayed graft function (DGF) after deceased donor kidney transplantation and to compare the clinical outcomes of non-DGF versus DGF recipients.

PATIENTS AND METHODS

From January 2004 to June 2008, 75/154 kidneys were transplanted into 74 recipients. We classified the recipients into two groups: group 1 (n=61) without DGF and group 2 (n=13) with DGF.

RESULTS

On univariate analysis, recipient age (P=.048) cause of brain death (traumatic brain injury vs disease, P=.016), blood urea nitrogen (P=.002), serum creatinine (P=.001), arterial pH (P=.019), and serum sodium level (P=.012) just before organ procurement showed significant differences. On multivariate analysis, the cause of brain death (P=.015, hazard ratio [HR]: 7.086), the terminal serum creatinine>or=1.5 mg/dL before organ procurement (P=.007, HR: 10.132), and recipient age over >or=50 years (P=.021, HR: 7.767) were independent risk factors for the development of DGF. Graft failures occurred among 5/74 recipients with 5-year graft survivals between group 1 and group 2 of 91.7% and 84.6%, respectively. Patient death occurred in five cases, most by due to infection. The 5-year patient survival between groups 1 and 2 were 93.9% and 84.6%, respectively (P = .106).

CONCLUSION

The independent risk factors for DGF were the cause of brain death, the terminal creatinine level, and the recipient age. In deceased donor kidney transplantation, DGF may have less effect on long-term patient and graft survivals.

Machine perfusion preservation for kidney grafts with a high creatinine from uncontrolled donation after cardiac death

BACKGROUND

This study evaluated the usefulness of machine perfusion preservation parameters as selection criteria for donation after cardiac arrest (DCD) with high creatinine level. The aim of this study is to evaluate to whether DCD donor >50 years old and with high creatinine are acceptable.

METHODS

We examined 17 kidneys from uncontrolled DCD who showed creatinine levels >3.0 mg/dL before procurement. The study included the following two groups: group 1 (n = 9), donor age <50 years old versus group 2 (n = 8), donor age >50 years old.

RESULTS

There were no significant differences in donors or preservation conditions among the 2 groups, including age, terminal creatinine, warm ischemic time, cold perfusion time, and total ischemic time. A greater resistance of 47.9 mmHg/mL per min/g was observed among group 2, compared with 42.5 mmHg/mL per min/g in group 1. A shorter ATN period (8.2 days) was noted in group 1, compared with 21.2 days for group 2. The flow rate (mL/g/min) was not significantly different between the two groups. The best-Cr level was 1.22 mg/dL in group 1 and 1.94 mg/dL in group 2.

CONCLUSION

Machine perfusion flow was a reliable indicator of graft viability in uncontrolled DCD, particularly kidneys with high creatinine level. Even older donors were acceptable if the machine perfusion preservation parameters such as flow rate and pressure were acceptable; however, they may show severe delayed graft function.

Machine perfusion or cold storage in organ transplantation: indication, mechanisms, and future perspectives

Most organs are currently preserved by cold storage (CS) prior to transplantation. However, as more so called marginal donor organs are utilized, machine perfusion has regained clinical interest. Recent studies have demonstrated advantages of pulsatile perfusion over CS preservation for kidney transplantation. However, it remains unclear whether there is a significant benefit of one preservation method over the other in general, or, whether the utilization of particular preservation approaches needs to be linked to organ characteristics. Proposed protective mechanisms of pulsatile perfusion remain largely obscure. It can be speculated that pulsatile perfusion may not only provide nutrition and facilitate the elimination of toxins but also trigger protective mechanisms leading to the amelioration of innate immune responses. Those aspects may be of particular relevance when utilizing grafts with suboptimal quality which may have an increased vulnerability to ischemia/reperfusion injury and compromised repair mechanisms. This review aims to enunciate the principles of organ perfusion and preservation as they relate to indication, aspects of organ protection and to highlight future developments.

An in vivo autotransplant model of renal preservation: cold storage versus machine perfusion in the prevention of ischemia/reperfusion injury

There is increasing proof that organ preservation by machine perfusion is able to limit ischemia/reperfusion injury in kidney transplantation. This study was designed to compare the efficiency in hypothermic organ preservation by machine perfusion or cold storage in an animal model of kidney autotransplantation. Twelve pigs underwent left nephrectomy after warm ischemic time; the organs were preserved in machine perfusion (n = 6) or cold storage (n = 6) and then autotransplanted with immediate contralateral nephrectomy. The following parameters were compared between the two groups of animals: hematological and urine indexes of renal function, blood/gas analysis values, histological features, tissue adenosine-5'-triphosphate (ATP) content, perforin gene expression in kidney biopsies, and organ weight changes were compared before and after preservation. The amount of cellular ATP was significantly higher in organs preserved by machine perfusion; moreover, the study of apoptosis induction revealed an enhanced perforin expression in the kidneys, which underwent simple hypothermic preservation compared to the machine-preserved ones. Organ weight was significantly decreased after cold storage, but it remained quite stable for machine-perfused kidneys. The present model seems to suggest that organ preservation by hypothermic machine perfusion is able to better control cellular impairment in comparison with cold storage.

Association between delayed graft function and allograft and patient survival: a systematic review and meta-analysis

BACKGROUND

Delayed graft function (DGF) is a common complication of renal transplantation. The short-term consequences of DGF are well known, but the long-term relationship between DGF and patient and graft survival is controversial in the published literature. We conducted a systematic review and meta-analysis to precisely estimate these relationships.

METHODS

We performed a literature search for original studies published through March 2007 pertaining to long-term (>6 months) outcomes of DGF. The primary outcome was graft survival. Secondary outcomes were patient survival, acute rejection and kidney function.

RESULTS

When compared to patients without DGF, patients with DGF had a 41% increased risk of graft loss (RR 1.41, 95% CI 1.27-1.56) at 3.2 years of follow-up. There was no significant relationship between DGF and patient survival at 5 years (RR 1.14, 95% CI 0.94-1.39). The mean creatinine in the non-DGF group was 1.6 mg/dl. Patients with DGF had a higher mean serum creatinine (0.66 mg/dl, 95% CI 0.57-0.74) compared to patients without DGF at 3.5 years of follow-up. DGF was associated with a 38% relative increase in the risk of acute rejection (RR 1.38, 95% CI 1.29-1.47).

CONCLUSION

The results of this meta-analysis emphasize and quantify the long-term detrimental association between DGF and important graft outcomes like graft survival, acute rejection and renal function. Efforts to prevent and treat DGF should be aggressively investigated in order to improve graft survival given the deficit in the number of kidney donors.

Association of lower costs of pulsatile machine perfusion in renal transplantation from expanded criteria donors

Pulsatile machine perfusion (PMP) has been shown to reduce delayed graft function (DGF) in expanded criteria donor (ECD) kidneys. Here, we investigate whether there is a cost benefit associated with PMP utilization in ECD kidney transplants. We analyzed United States Renal Data System (USRDS) data describing Medicare-insured ECD kidney transplant recipients in 1995-2004 (N = 5840). We examined total Medicare payments for transplant hospitalization and annually for 3 years posttransplant according to PMP utilization. After adjusting for other recipient, donor and transplant factors, PMP utilization was associated with a $2130 reduction (p = 0.007) in hospitalization costs. PMP utilization was also associated with lower DGF risk (p < 0.0001). PMP utilization did not predict differences in rejection, graft survival, patient survival, or costs at 1, 2 and 3 years posttransplant. PMP utilization is correlated with lower costs for the transplant hospitalization, which is likely due to the associated reduction in DGF among recipients of PMP kidneys. However, there is no difference in long-term Medicare costs for ECD recipients by PMP utilization. A prospective trial is necessary as it will help determine if the associations seen here are due to PMP utilization and not differences in the population studied.

Improved preservation of warm ischemic livers by hypothermic machine perfusion with supplemented University of Wisconsin solution

Hypothermic machine perfusion (HMP) has the potential to improve recovery and preservation of Donation after Cardiac Death (DCD) livers, including uncontrolled DCD livers. However, current perfusion solutions lack the needed substrates to improve energy recovery and minimize hepatic injury, if warm ischemic time (WIT) is extended. This proof-of-concept study tested the hypothesis that the University of Wisconsin (UW) solution supplemented with anaplerotic substrates, calcium chloride, thromboxane A2 inhibitor, and antioxidants could improve HMP preservation and minimize reperfusion injury of warm ischemic livers. Preflushed rat livers subjected to 60 min WIT were preserved for 5 h with standard UW or supplemented UW (SUW) solution. Post preservation hepatic functions and viability were assessed during isolated perfusion with Krebs-Henseleit solution. Livers preserved with SUW showed significantly (p < .001) improved recovery of tissue ATP levels (micromol/g liver), 2.06 +/- 0.10 (mean +/- SE), as compared to the UW group, 0.70 +/- 0.10, and the level was 80% of that of fresh control livers (2.60 +/- 0.13). At the end of 1 h of rewarming, lactate dehydrogenase (U/L) in the perfusate was significantly (p < .05) lower in the SUW group (429 +/- 58) as compared to ischemia-reperfusion (IR) (781 +/- 12) and the UW group (1151 +/- 83). Bile production (microg/min/g liver) was significantly (p < .05) higher in the SUW group (280 +/- 13) as compared to the IR (224 +/- 24) and the UW group (114 +/- 14). The tissue edema formation assessed by tissue wet-dry ratio was significantly (p < .05) higher in UW group. Histology showed well-preserved hepatic structure in the SUW group. In conclusion, this study suggests that HMP with SUW solution has the potential to restore and preserve livers with extended WIT.

[Ischemia-reperfusion syndrome and role of preservation graft technique after laparoscopic versus open nephrectomy in a experimental model of living donor kidney transplant]

INTRODUCTION

Delayed graft function alter living donor transplantation is a subject of debate. Delayed graft function can be partially explained by renal ischemia-reperfusion injury, when severe is associated with decreased graft survival. In this experimental living donor model study, we analyze the hemodynamic, histological and biochemical effects of laparoscopic nephrectomy. We also, analyze the effect of a pulsatile machine perfusion for kidney preservation during cold ischemia time.

MATERIAL AND METHODS

Twenty large-white pigs (average weight 40-45 kgrs) were divided in 4 experimental groups: Group A: Laparoscopic nephrectomy+ immediate graft perfusion in pulsatile vacuum pump+autotransplant Group B: Laparoscopic nephrectomy+ immediate graft perfusion by gravity+autotransplant Group C: Open nephrectomy+immediate graft perfusion in pulsatile vacuum pump+autotransplant Group D: Open nephrectomy+ immediate graft perfusion by gravity+autotransplant Both laparoscopic and open nephrectomy were completed transperitoneally according to standardized technique. Hypothermic perfusion was done in a system designed in our lab.

RESULTS

We observed a decreased renal artery flow in kidneys procured laparoscopically compared to open nephrectomy. We found an artery flow recovery during the first 60 minutes after revascularization. Renal machine perfusion during cold ischemia time seems to have no beneficial effect, but shows a deleterious effect on hemodynamic event for renal transplantation. Lower plasma nitric oxide level is observed in kidneys obtained by laparoscopy compared with open surgical technique. And finally, we also found higher histological damage in proximal tubular and endothelial cell, in kidneys obtained by laparoscopy compared with open surgery.

CONCLUSIONS

In our experience: Laparoscopic nephrectomy versus open nephrectomy produces, in a model of living donor transplant, a lower value or renal blood flow and a higher value of renal vascular resistanse. These hemodynamic findings tend to normalize by 60 min after the reperfusion. A lower blood concentration of nitric oxide after the transplant was detected in laparoscopic group Vs open surgery group.

Marked variation in the definition and diagnosis of delayed graft function: a systematic review

BACKGROUND

The term delayed graft function (DGF) is commonly used to describe the need for dialysis after receiving a kidney transplant. DGF increases morbidity after transplantation, prolongs hospitalization and may lead to premature graft failure. Various definitions of DGF are used in the literature without a uniformly accepted technique to identify DGF.

METHODS

We performed a systematic review of the literature to identify all of the different definitions and diagnostic techniques to identify DGF.

RESULTS

We identified 18 unique definitions for DGF and 10 diagnostic techniques to identify DGF.

CONCLUSIONS

The utilization of heterogeneous clinical criteria to define DGF has certain limitations. It will lead to delayed and sometimes inaccurate diagnosis of DGF. Hence a diagnostic test that identifies DGF reliably and early is necessary. Heterogeneity, in the definitions used for DGF, hinders the evolution of a diagnostic technique to identify DGF, which requires a gold standard definition. We are in need of a new definition that is uniformly accepted across the kidney transplant community. The new definition will be helpful in promoting better communication among transplant professionals and aids in comparing clinical studies of diagnostic techniques to identify DGF and thus may facilitate clinical trials of interventions for the treatment of DGF.

Determinants of discard of expanded criteria donor kidneys: impact of biopsy and machine perfusion

We examined factors associated with expanded criteria donor (ECD) kidney discard. Scientific Registry of Transplant Recipients (SRTR)/Organ Procurement and Transplantation Network (OPTN) data were examined for donor factors using logistic regression to determine the adjusted odds ratio (AOR) of discard of kidneys recovered between October 1999 and June 2005. Logistic and Cox regression models were used to determine associations with delayed graft function (DGF) and graft failure. Of the 12,536 recovered ECD kidneys, 5139 (41%) were discarded. Both the performance of a biopsy (AOR = 1.21, p = 0.02) and the degree of glomerulosclerosis (GS) on biopsy were significantly associated with increased odds of discard. GS was not consistently associated with DGF or graft failure. The discard rate of pumped ECD kidneys was 29.7% versus 43.6% for unpumped (AOR = 0.52, p < 0.0001). Among pumped kidneys, those with resistances of 0.26-0.38 and >0.38 mmHg/mL/min were discarded more than those with resistances of 0.18-0.25 mmHg/mL/min (AOR = 2.5 and 7.9, respectively). Among ECD kidneys, pumped kidneys were less likely to have DGF (AOR = 0.59, p < 0.0001) but not graft failure (RR = 0.9, p = 0.27). Biopsy findings and machine perfusion are important correlates of ECD kidney discard; corresponding associations with graft failure require further study.

The Influence of Pulsatile Preservation in Kidney Transplantation From Non–Heart-Beating Donors

Continuous hypothermic pulsatile perfusion (CHPP) may offer improved early function compared with cold static perfusion (CSP) for heart-beating cadaveric donors. With an expanding pool of donors, ie, non-heart-beating donors (NHBD), we present our preliminary results with the use of CHPP compared with CSP to preserve kidney grafts retrieved from NHBD. Eighteen consecutive locally procured cadaveric kidneys from NHBD were preserved using CHPP using UW machine perfusion solution in the Life Port kidney transporter. Perfusion parameters were measured serially during pulsatile perfusion. This group was compared with 18 NHBD cadaveric kidneys preserved with CSP. No organs were lost due to faulty technique of preparation or preparation of pulsatile perfusion. Immediate renal function was observed in 13 cases (72.2%). In CSP in NHBD, we had 16 cases with delayed graft function (88.8%). These early results show that the use of pulsatile perfusion to preserve kidneys from NHBD may be associated with improved early outcomes. Longer follow-up is required to answer the more important question as to whether it offers long-term improvements that justify the extra cost and complexity.

Should we discard the graft? Analysis of the renal grafts with a total ischemia time of more than 24 hours donated after cardiac death

The objective is to investigate the outcome of transplantation using kidney grafts from donors after cardiac death (DCDs) with a total ischemia time (TIT) longer than 24 h. All 373 kidneys were procured from DCDs. They were procured using the in-situ regional cooling technique. Grafts were classified into two groups according to TIT. Fifty-three grafts had a TIT longer than 24 h (group 1), and the other 320 grafts (group 2) were less than 24 h. The numbers of never functioning grafts (PGF) were 3 in group 1 (5.7%) and 17 in group 2 (5.3%), a nonsignificant difference. Graft survival rates at 3, 5 and 10 years posttransplant were 84.9%, 73.0% and 64.1% in group 1, and 76.3%, 69.9% and 57.1% in group 2, which demonstrate no significant difference. The significant risk factors for graft failure were donor age, serum creatinine level on hospitalization and WIT. However, TIT longer than 24 h was not employed. Multivariate logistic regression indicated that only WIT was associated with an increase in the risk of PGF. Our results demonstrate that kidneys from DCDs, even if their TIT is more than 24 h, should be considered a worthwhile source of renal grafts.

Influence of Pulsatile Perfusion Preservation on Outcomes in Kidney Transplantation from Expanded Criteria Donors

BACKGROUND

Expanded criteria donors (ECDs) increase the donor organ pool, but the value of transplanting these kidneys has been questioned because of concerns about diminished survival, poorer renal function, and higher rates of delayed graft function.

STUDY DESIGN

Retrospective analysis of intermediate-term outcomes in ECD kidney transplantations according to method of preservation at a single center using a standardized approach.

RESULTS

Over a 5-year period, we performed 141 donations-after-brain-death ECD kidney transplantations into adult recipients. A total of 114 kidneys (81%) were managed with combined cold-storage and pulsatile perfusion preservation (PPP), and the remaining 27 (19%) were preserved with cold storage (CS). The PPP group had a higher proportion of kidneys preserved for longer than 30 hours (28% versus 0, p < 0.001) and a longer mean cold ischemia time (24.5 hours PPP versus 19 hours CS, p < 0.01). Other donor and recipient characteristics were similar between groups. Incidence of delayed graft function was 11% in PPP-stored kidneys versus 37% in CS kidneys (p = 0.002). With a mean followup of 27 months, patient (91% PPP versus 96% CS) and kidney graft survival (81% PPP versus 81.5% CS) rates were comparable. Mean 12-month serum creatinine (1.9 mg/dL) and calculated Modification of Diet in Renal Disease glomerular filtration rate (41 mL/min) values were similar between groups.

CONCLUSIONS

Despite longer cold ischemia times, recipients of ECD kidneys managed with PPP had similar survival and functional outcomes, but experienced a marked reduction in the rate of delayed graft function.

Application of machine perfusion preservation as a viability test for marginal kidney graft

BACKGROUND

This study evaluated the usefulness of machine perfusion preservation parameters as indicators of kidney graft viability.

METHODS

Eighty-eight cadaveric kidneys were analyzed in this study. Of these, 74 kidneys (84.1%) were procured from nonheartbeating donors. The criteria for an acceptable kidney for transplantation were a perfusion flow of more than 0.4 mL/min/g with a concurrent decreasing perfusion pressure. The average perfusion pressure was 30-50 mmHg. We divided the kidneys into three groups: group 1 (n=35), 0.45-0.65 mL/min/g machine perfusion flow (MPF); group 2 (n=30), 0.65-0.90 mL/min/g MPF; and group 3 (n=23), more than 0.9 mL/min/g MPF.

RESULTS

A higher rate of primary nonfunction (PNF; 25.7%) was found in group 1, compared with 6.7% in group 2 and 0% in group 3. A higher rate of 30.4% immediate function was found in group 3, compared with 16.7% in group and 8.6% in group 1. However, a longer period of acute tubular necrosis (ATN; 12.0 days) was found in group 1 compared with 8.6 days in group 2 and 8.7 days in group 3. PNF was detected in 7 (77.8%) cases with more than 16 hr of total ischemic time (TIT) in group 1. In contrast, all of nine cases with more than 16 hr of TIT in group 3 were functional.

CONCLUSIONS

MPF is a reliable indicator of graft viability based on the rate of PNF and immediate renal allograft function, especially in marginal donors.

Pulsatile perfusion reduces the incidence of delayed graft function in expanded criteria donor kidney transplantation

The use of expanded criteria donors (ECD) has been proposed to help combat the discrepancy between organ availability and need. ECD kidneys are associated with delayed graft function (DGF) and worse long-term survival. The aim of this study is to evaluate the impact of pulsatile perfusion (PP) on DGF and graft survival in transplanted ECD kidneys. From January 2000 to December 2003, 4618 ECD kidney-alone transplants were reported to the United Network for Organ Sharing. PP was performed on 912 renal allografts. The prognostic factors of DGF were analyzed using multivariate logistic regression analysis. Risk factors for reduced allograft viability were greater in donors and recipients of PP kidneys. Three-year graft survival of ECD kidneys preserved with PP was similar to cold storage (CS) kidneys. The incidence of DGF in PP kidneys was significantly lower than CS kidneys (26% vs. 36%, p < 0.001). Despite having a greater number of risk factors for reduced graft viability, the ECD-PP kidneys had similar graft survival compared to ECD-CS kidneys. The use of PP, by decreasing the incidence of DGF, may possibly lead to lower overall costs and increased utilization of donor kidneys.

Hypothermic machine perfusion of liver grafts for transplantation: technical development in human discard and miniature swine models

INTRODUCTION

Cold storage (CS) is the standard preservation technique for liver transplantation (LTx). Hypothermic machine perfusion (HMP) is an alternative preservation technique that provides a continuous supply of substrates and removes waste products. HMP improves early graft function in kidney transplantation, especially for marginal organs: To our knowledge there have been no reports HMP in human LTx. The aim of this study was to develop a reproducible technique for liver HMP prior to initiating a clinical trial.

METHODS

For the discard protocol, between May 2001 and March 2002, 10 nontransplantable human livers were obtained. We designed a model of atraumatic, centrifugal HMP of the portal vein (PV) and hepatic artery (HA) via donor vascular conduit. Livers were perfused at 3 degrees C to 5 degrees C with Vasosol solution for 5 to 10 hours using a modified Medtronic Portable Bypass System. Perfusion variables (temp, flow, pressure) where recorded every 30 minutes. During the study, we also validated our techniques in an animal model. For the animal protocol; six swine were used as liver donors and randomized to 12 hours of CS in UW (n = 3) or 12 hours of HMP using Vasosol solution (n = 3). LTx was performed in six swine. Animals survived until postoperative day 5.

RESULTS

For the discard protocol, mean HMP time was 6.7 +/- 1.8 hours. Target flow was 0.7 mL/g liver/min. PV and HA pressure ranged from 3 to 5 and 12 to 18 mm Hg, respectively. All grafts were maintained at 3 degrees C to 5 degrees C during HMP. For the animal protocol, all recipients had good liver function and survived to postoperative day 5. AST and TBili were similar between CS and HMP.

CONCLUSIONS

Our method of liver HMP appears to be a safe and reliable method to preserve livers. A clinical trial is now underway to evaluate this technique in human LTx.

Beyond Operational Tolerance: Effect of Ischemic Injury on Development of Chronic Damage in Renal Grafts

BACKGROUND

The induction of operational tolerance is the holy grail of clinical transplantation. However, in animal models with operational tolerance, long- term grafts still develop chronic damage. The elucidation of the impact of allogenic versus nonallogeneic factors in such a model is important. This study examined the effect of a clinically relevant combination of warm ischemia and cold preservation in the absence of allogeneic response (isografts) and in the context of operational tolerance.

METHODS

Dark Agouti (DA) rat kidneys were transplanted into DA recipients (isografts) or Albino Surgery recipients (allografts) tolerized by two transfusions of DA blood, under cover of cyclosporin A. Grafts were subjected to minimal cold preservation or to 30 mins warm ischemia followed by 24 hrs cold preservation.

RESULTS

After an initial peak of renal dysfunction, serum creatinine concentration returned to normal in isografts and nonischemic allografts, but remained significantly elevated in ischemic allografts (P<0.0002) throughout 6 months follow-up. Both allograft groups developed proteinuria. At 6 months, ischemic isografts and nonischemic allografts demonstrated very mild tubular atrophy and interstitial fibrosis. Tubulointerstitial injury was significantly more severe in ischemic allografts (P<0.01 vs. nonischemic allografts) and was associated with increased infiltrating monocyte/macrophages and NK cells (P<0.05). Moderate glomerulosclerosis was a feature of both allograft groups (P<0.05).

CONCLUSIONS

The modified allogeneic response in operationally tolerant recipients acts in synergy with ischemia/reperfusion injury in the development of chronic damage. Strategies to limit or modify the initial ischemia/reperfusion injury may ameliorate chronic tubulointerstitial damage. Progressive glomerular damage and proteinuria in allografts may require other pharmacological intervention.

Are we frozen in time? Analysis of the utilization and efficacy of pulsatile perfusion in renal transplantation

Preservation techniques are crucial to deceased donor kidney transplantation (DDTx), but the efficacy of pulsatile perfusion (PP) versus cold storage (CS) remains uncertain. We describe patterns of PP use and explore four fundamental questions. What kidneys are selected for PP? How does PP affect utilization of donated kidneys? What effect does PP have on outcomes? When does PP appear to be most efficacious? We examined rates of PP in DDTx in the United States from 1994 to 2003. We generated models for organ utilization, delayed graft function (DGF) and for the use of PP. We analyzed the long-term effect of PP with multivariate Cox models. The utilization rates for non-expanded criteria donors (ECDs) were similar by storage type, but for ECDs there was a significantly higher utilization rate with PP (70% with PP vs. 59% with CS, p < 0.001). Use of PP was widely variable across transplant centers. DGF rates were significantly lower with PP (27.6% vs. 19.6%). PP was associated with a mild benefit on death censored graft survival (adjusted hazard ratio = 0.88, 95% CI 0.85-0.91). Reduced DGF and significantly lower discard rates of ECDs associated with PP suggest an important utility of PP in renal transplantation. Additional evidence of improvement in graft survival, particularly in more recent years, provides further encouraging evidence for the use of PP.

Pushing the envelope in renal preservation

INTRODUCTION

Novel preservation techniques may diminish ischemia/reperfusion (I/R) injury. Our preservation laboratory has modified Belzer MPS for machine perfusion (MP) with prostaglandin E1 (PGE 1), nitroglycerin (NTG), and polyethylene glycol-superoxide dismutase (PEG-SOD) to attenuate I/R injury. We reviewed our recent experience using this novel formulation (NF) compared with standard perfusates.

RESULTS

Between January 1998 and March 2000, 1060 consecutive kidneys were preserved in our laboratory. One hundred forty-eight kidneys (14%) were discarded. Fifty-eight percent of kidneys during this time period underwent MP (n = 532). En bloc kidney pairs were randomly assigned to pulsatile MP using Waters RM3 or MOX-100 perfusion systems using 1 of 3 perfusates; NF (NF; n = 119), Belzer MPS (MPS; n = 201), or Belzer II albumin gluconate (ALB; n = 212) Significant improvements in delayed graft function (DGF) rate were seen with NF versus other perfusates (8% vs 14% vs 19%, respectively; P =.03). At 6 months, graft survival was significantly improved with NF compared with MPS and ALB (96% vs 90% vs 87%, respectively; P =.03). NF also produced a significantly higher percentage of recipients with a serum creatinine level < or = 1.5 mg/dL.

CONCLUSIONS

Novel modifications of standard MP perfusate improved outcomes after renal transplantation. Preservation-based interventions targeted to ameliorate I/R injury can improve outcomes and may allow expansion of the donor pool.

PULSATILE MACHINE PERFUSION WITH VASOSOL SOLUTION IMPROVES EARLY GRAFT FUNCTION AFTER CADAVERIC RENAL TRANSPLANTATION

BACKGROUND

Cold storage is the most common method of preservation in renal transplantation, but pulsatile machine perfusion (MP) is increasingly used for purposes of ex vivo assessment and resuscitation of high risk allografts. Vasosol (VSL) MP solution (MPS) (Pike Laboratories Inc, Eagle, PA) is a novel perfusate with enhanced vasodilatory and antioxidant capacity. We report our experience with VSL in machine preservation of renal allografts.

METHODS

Locally procured cadaver kidney pairs undergoing MP were randomized to VSL or control solution (Belzer MPS; Trans-Med, Elk River, MN). En bloc perfusion was performed according to standard MP procedures. Transplantation was performed at 1 of 12 local transplant centers. Donor and recipient data were collected prospectively.

RESULTS

Data from 162 transplanted kidneys were analyzed. A total of 82 renal grafts were perfused with VSL, and 80 were perfused with control solution. No organs were lost secondary to the technique of MP. There was no difference in donor or recipient age between groups. Kidneys perfused with VSL exhibited significantly higher rates of immediate function and significantly less delayed graft function (12.2% vs. 21.2%). Discharge creatinine and length of stay were also significantly improved in the VSL group. One-year graft and patient survivals were equivalent (95%) in both groups.

CONCLUSIONS

VSL improved early graft function and shortened the length of stay compared with Belzer MPS. Further improvement in preservation solutions in conjunction with pulsatile perfusion shows promise in improving early outcomes after renal transplantation, especially for extended criteria donor kidneys.

Pulsatile machine perfusion vs. cold storage of kidneys for transplantation: a rapid and systematic review

OBJECTIVE

To identify and prioritize key areas for further research in kidney preservation systems.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis of the effectiveness of machine perfusion and cold storage techniques in reducing delayed graft function (DGF) and improving graft survival in recipients of kidneys from beating and non-heart-beating donors. Literature quantifying the link between DGF and graft survival was used to evaluate the potential long-term impact of machine perfusion and cold storage systems. Cox proportional hazards modelling was used to predict graft survival and graft years gained over 10 yr. Monte Carlo sensitivity analysis was conducted to evaluate stochastic uncertainties within the model.

RESULTS

Machine perfusion leads to a relative risk of DGF of approximately 80% (67%, 96%) compared with cold storage, although the evidence base is limited in quality and study size. Direct evidence on graft survival at 1 yr demonstrates no statistically significant difference between machine perfusion and cold storage. Predictions based upon quantifying the link between DGF and graft survival suggest potential improvements of between 0 and 6% at 10 yr.

DISCUSSION

Studies of high methodological quality and sufficient size are required to determine whether machine preservation leads to reduce rates of DGF. Predicted impact on graft survival implies that direct evidence would require a large population followed up over a long period of time. Registry database analysis supported by validation of the link between DGF and graft survival may be preferable and more feasible than randomized controlled trials.