Evaluation of outcomes in renal transplantation with hypothermic machine perfusion for the preservation of kidneys from expanded criteria donors

A proof-of-principle for decontamination of transplantation kidney through UV-C exposition of the perfusate solution

Kidney transplantation is a common yet highly demanding medical procedure worldwide, enhancing the quality of life for patients with chronic kidney disease. Despite its prevalence, the procedure faces a shortage of available organs, partly due to contamination by microorganisms, leading to significant organ disposal. This study proposes utilizing photonic techniques associated with organ support machines to prevent patient contamination during kidney transplantation. We implemented a decontamination system using ultraviolet-C (UV-C) irradiation on the preservation solution circulating through pigs' kidneys between harvest and implant. UV-C irradiation, alone or combined with ultrasound (US) and Ps80 detergent during ex-vivo swine organ perfusion in a Lifeport® Kidney Transporter machine, aimed to reduce microbiological load in both fluid and organ. Results show rapid fluid decontamination compared to microorganism release from the organ, with notable retention. By including Ps80 detergent at 0.5% during UV-C irradiation 3 log10 (CFU mL-1) of Staphylococcus aureus bacteria previously retained in the organ were successfully removed, indicating the technique's feasibility and effectiveness.

Prompt Thrombo-Inflammatory Response to Ischemia-Reperfusion Injury and Kidney Transplant Outcomes

Introduction

In kidney transplantation (KT), the role of the intravascular innate immune system (IIIS) in response to ischemia-reperfusion injury (IRI) is not well-understood. Here, we studied parallel changes in the generation of key activation products of the proteolytic cascade systems of the IIIS following living donor (LD) and deceased donor (DD) transplantation and evaluated potential associations with clinical outcomes.

Methods

In a cohort study, 63 patients undergoing LD (n = 26) and DD (n = 37) transplantation were prospectively included. Fifteen DD kidneys were preserved with hypothermic machine perfusion (HMP), and the remaining were cold stored. Activation products of the kallikrein-kinin, coagulation, and complement systems were measured in blood samples obtained systemically at baseline and locally from the transplant renal vein at 1, 10, and 30 minutes after reperfusion.

Results

DD kidneys exhibited a prompt and interlinked activation of all 3 cascade systems of IIIS postreperfusion, indicating a robust and local thrombo-inflammatory response to IRI. In this initial response, the complement activation product sC5b-9 exhibited a robust correlation with other IIIS activation markers and displayed a strong association with short-term and mid-term (24-month) graft dysfunction. In contrast, LD kidneys did not exhibit this thrombo-inflammatory response. The use of HMP was associated with reduced thromboinflammation and preserved mid-term kidney function.

Conclusion

Kidneys from DD are vulnerable to a prompt thrombo-inflammatory response to IRI, which adversely affects both short-term and long-term allograft function. Strategies aimed at minimizing graft immunogenicity prior to reperfusion are crucial to mitigate the intricate inflammatory response to IRI.

ERRATUM: Kidney decontamination during perfusion for transplantation procedure: In vitro and ex vivo viability analysis

Organ transplantations have an increasing medical relevance. It is becoming a regular procedure with an increase in individuals waiting for organs. The increase in the number of discarded organs is mostly due to the donor's bacterial and/or viral infection. In this article, we are demonstrating the feasibility of reduction of the bacterial load in the kidney model by using Ultraviolet-C (UV-C) as a germicidal agent in circulating liquids. Using Staphylococcus aureus as a bacteria model, we were able to demonstrate that in less than 30 min of liquid circulation and associated to irradiation, the bacterial load of the perfusate Custodiol® HTK, histidine-tryptophan-ketoglutarate (solution with 5 log CFU ml^-1 ), was fully eliminated. A modeling approach was created to verify the possibility of bacterial load decrease, when an organ (here, a renal experimental model) is present in the circuit, releasing a varied rate of microorganisms over time, while the solution is irradiated. Finally, we use an ex vivo model with a swine kidney, circulating in the preservation solution with a Lifeport® Kidney Transporter machine, to demonstrate that we can contaminate the organ and then promote the elimination of the microbiological load. The results show the feasibility of the technique.

Paving the Way for Personalized Medicine in First Kidney Transplantation: Interest of a Creatininemia Latent Class Analysis in Early Post-transplantation

Plasma creatinine is a marker of interest in renal transplantation but data on its kinetics in the first days following transplantation are scarce. The aim of this study was to identify clinically relevant subgroups of creatinine trajectories following renal transplantation and to test their association with graft outcome. Among 496 patients with a first kidney transplant included in the French ASTRE cohort at the Poitiers University hospital, 435 patients from donation after brain death were considered in a latent class modeling. Four distinct classes of creatinine trajectories were identified: "poor recovery" (6% of patients), "intermediate recovery" (47%), "good recovery" (10%) and "optimal recovery" (37%). Cold ischemia time was significantly lower in the "optimal recovery" class. Delayed graft function was more frequent and the number of hemodialysis sessions was higher in the "poor recovery" class. Incidence of graft loss was significantly lower in "optimal recovery" patients with an adjusted risk of graft loss 2.42 and 4.06 times higher in "intermediate recovery" and "poor recovery" patients, respectively. Our study highlights substantial heterogeneity in creatinine trajectories following renal transplantation that may help to identify patients who are more likely to experience a graft loss.

The new French kidney allocation system for donations after brain death: Rationale, implementation, and evaluation

In recent decades, the allocation policies of many countries have moved from center-based to patient-based approaches. The new French kidney allocation system (KAS) of donations after brain death for adult recipients, implemented in 2015, was principally designed to introduce a unified allocation score (UAS) to be applied locally for one kidney and nationally for the other and to replace regional borders by a new geographical model. The new KAS balances dialysis duration and waiting time to compensate for listing delays and provides more effective longevity matching between donors and recipients with better HLA and age matching. We report these changes, with their rationale and main results. Results show improved HLA matching for young recipients and more rapid access to transplant for older recipients. Young recipients also had better access to transplantation. Transplant access decreased for recipients aged 60-69 and required tuning of KAS parameters. In conclusion, our results strongly indicate that national or adequately broad geographic allocation areas, combined with multiplicative interactions between allocation criteria, permit multivariate optimization of organ allocation and thus improve national kidney sharing and balance HLA matching and age matching, at the price of longer cold ischemic times and more logistical constraints than with local allocation.

Kidney decontamination during perfusion for transplantation procedure: In vitro and ex vivo viability analysis

Organ transplantations have an increasing medical relevance. It is becoming a regular procedure with an increase in individuals waiting for organs. The increase in the number of discarded organs is mostly due to the donor bacterial and/or viral infection. In this article, we are demonstrating the feasibility of reduction of the bacterial load in kidney model by using ultraviolet-C as a germicidal agent in circulating liquids. Using Staphylococcus aureus as a bacteria model, we were able to demonstrate that in less than 30 min of liquid circulation and associated to irradiation, the bacterial load of the perfusate Custodiol HTK, histidine-tryptophan-ketoglutarate (solution with 5 log CFU mL^-1 ), was fully eliminated. A modeling approach was created to verify the possibility of bacterial load decrease, when an organ (here, a renal experimental model) is present in the circuit, releasing a varied rate of microorganisms over time, while the solution is irradiated. Finally, we use an ex vivo model with swine kidney, circulating in the preservation solution with a Lifeport Kidney Transporter machine, to demonstrate that we can contaminate the organ and then promote the elimination of the microbiological load. The results show the feasibility of the technique.

Advances in Hypothermic and Normothermic Perfusion in Kidney Transplantation

Hypothermic and normothermic machine perfusion in kidney transplantation are purported to exert a beneficial effect on post-transplant outcomes compared to the traditionally used method of static cold storage. Kidney perfusion techniques provide a window for organ reconditioning and quality assessment. However, how best to deliver these preservation methods or improve organ quality has not yet been conclusively defined. This review summarises the promising advances in machine perfusion science in recent years, which have the potential to further improve early graft function and prolong graft survival.

Advances in Kidney Preservation Techniques and Their Application in Clinical Practice

The use of cold preservation solutions to rapidly flush and cool the kidney followed by static cold storage in ice has been the standard kidney preservation technique for the last 50 y. Nonetheless, changing donor demographics that include organs from extended criteria donors and donation after circulatory death donors have led to the adoption of more diverse techniques of preservation. Comparison of hypothermic machine perfusion and static cold storage techniques for deceased donor kidneys has long been debated and is still contested by some. The recent modification of hypothermic machine perfusion techniques with the addition of oxygen or perfusion at subnormothermic or near-normothermic temperatures are promising strategies that are emerging in clinical practice. In addition, the use of normothermic regional perfusion to resuscitate abdominal organs of donation after circulatory death donors in situ before cold flushing is also increasingly being utilized. This review provides a synopsis of the different types of preservation techniques including their mechanistic effects and the outcome of their application in clinical practice for different types of donor kidney.

Optimal donation of kidney transplants after controlled circulatory death

Controlled donation after circulatory death (cDCD) is used for "extended criteria" donors with poorer kidney transplant outcomes. The French cDCD program started in 2015 and is characterized by normothermic regional perfusion, hypothermic machine perfusion, and short cold ischemia time. We compared the outcomes of kidney transplantation from cDCD and brain-dead (DBD) donors, matching cDCD and DBD kidney transplants by propensity scoring for donor and recipient characteristics. The matching process retained 442 of 499 cDCD and 809 of 6185 DBD transplantations. The DGF rate was 20% in cDCD recipients compared with 28% in DBD recipients (adjusted relative risk [aRR], 1.43; 95% confidence interval [CI] 1.12-1.82). When DBD transplants were ranked by cold ischemia time and machine perfusion use and compared with cDCD transplants, the aRR of DGF was higher for DBD transplants without machine perfusion, regardless of the cold ischemia time (aRR with cold ischemia time <18 h, 1.57; 95% CI 1.20-2.03, vs aRR with cold ischemia time ≥18 h, 1.79; 95% CI 1.31-2.44). The 1-year graft survival rate was similar in both groups. Early outcome was better for kidney transplants from cDCD than from matched DBD transplants with this French protocol.

Ex Vivo Mesenchymal Stem Cell Therapy to Regenerate Machine Perfused Organs

Transplantation represents the treatment of choice for many end-stage diseases but is limited by the shortage of healthy donor organs. Ex situ normothermic machine perfusion (NMP) has the potential to extend the donor pool by facilitating the use of marginal quality organs such as those from donors after cardiac death (DCD) and extended criteria donors (ECD). NMP provides a platform for organ quality assessment but also offers the opportunity to treat and eventually regenerate organs during the perfusion process prior to transplantation. Due to their anti-inflammatory, immunomodulatory and regenerative capacity, mesenchymal stem cells (MSCs) are considered as an interesting tool in this model system. Only a limited number of studies have reported on the use of MSCs during ex situ machine perfusion so far with a focus on feasibility and safety aspects. At this point, no clinical benefits have been conclusively demonstrated, and studies with controlled transplantation set-ups are urgently warranted to elucidate favorable effects of MSCs in order to improve organs during ex situ machine perfusion.

Hypothermic Machine Perfusion of Kidneys Compensates for Extended Storage Time: A Single Intervention With a Significant Impact

INTRODUCTION

Delayed graft function (DGF) adversely affects graft survival and function. Machine perfusion (MP) improves DGF rate and may compensate for extended storage time.

MATERIAL AND METHODS

In this single-center cohort study, we included 193 consecutive kidney transplantations. MP was used in 78 kidneys (36%) and static cold storage (CS) in 115 kidneys (64%). CS kidneys were transplanted first followed by MP kidneys if stored differently. Pairs of kidneys from the same donor were subjected for subgroup analysis and included 58 pairs. The primary endpoints were the rate of DGF and 1- and 5-year graft survival. The secondary endpoints were the rate of the primary nonfunction, mortality, acute rejection, duration of DGF, and 5-year estimated glomerular filtration rate.

RESULTS

Median cold ischemia time (CIT) was significantly different between the MP and CS groups (24 vs 20 hours, P < .05). MP significantly reduced the rate of DGF (MP vs CS: 21.8% vs 42.6%, P < .05, odds ratio 0.34, 95% confidence interval 0.17-0.67) with no impact on overall 1- and 5-year survival rates. Storage method did not affect the duration of DGF, mortality rate, acute rejection, or the 5-year estimated glomerular filtration rate.

CONCLUSIONS

Hypothermic pulsatile MP significantly reduced the rate of DGF in kidneys transplanted with CIT equal to or longer than 12 hours. It is safe and may compensate for longer storage time.

[Acute renal failure of the donor in encephalic death: A real contraindication to kidney transplantation?]

INTRODUCTION

The shortage of kidney transplants encourages the expansion of the limits of eligibility criteria for donation. Many donors who are brain dead display acute renal failure at the time of death; is this a real contraindication to harvesting? The aim of this study was to assess kidney graft survival from donors after brain death with confirmed acute renal failure, with or without anuria previous donation.

MATERIALS AND METHODS

All of the transplants performed in two university hospitals between 2010 and 2017 were analyzed retrospectively. All patients who underwent single kidney transplant from a brain-dead donor with acute renal failure (ARF) were included in this study. ARI was defined here by a decrease over 50 % of glomerular filtration rate (GFR) to a threshold below 45mL/min/1.73 m² at the time of kidney procurement. Kidney graft survival, incidence of delayed graft function (DGF) and the GFR at 12 months were analyzed. Analysis of kidney transplant survival based on pre-implantation biopsies was additionally done.

RESULTS

One hundred and sixty four patients were transplanted with a kidney from donor with ARF during the selected period. At the admission in ICU the average GFR was 67,7±19mL/min/1,73m². At the time of donation, the average age of donors was 56.4±17.7 years, the GFR was 33.7±8.0mL/min/1.73 m² 16 % of donors were anuric. Cold ischemia time (CIT) was 16.8±5.0hours. The average age of recipients was 55.6±14.1 years. 81 % of the cases were primary transplants. Graft function took place within 7.8±9.4 days after transplantation. There were two non-primary functions (PNF). One hundred and fifty two patients (93 %) had a functional graft at 12 months. The mean GFR at 12 months was 46.8±20.1mL/min/1.73 m² and 122 patients (73 %) had a GFR greater than 30mL/min/1.73 m². Seventy-one percent of preimplantation biopsies revealed acute tubular necrosis (ATU); no cortical necrosis was observed. Survival of theses grafts was 85 %, comparable to the total population of study (P=0,21) CONCLUSION: The acute renal failure of the brain-dead donor should not alone be systematically a contraindication to harvesting and kidney transplantation.

Effect of preservation solutions for static cold storage on kidney transplantation outcomes: A National Registry Study

This study aimed to evaluate how 5 preservation solutions for static cold storage affected kidney transplant outcomes. It included all first single kidney transplants during 2010-2014 from donations after brain death in the French national transplant registry, excluding preemptive transplants and transplants of kidneys preserved with a hypothermic perfusion machine. The effects of each preservation solution on delayed graft function (DGF) and 1-year transplant failure were evaluated with hierarchical multivariable logistic regression models. The study finally included 7640 transplanted kidneys: 3473 (45.5%) preserved with Institut Georges Lopez-1 solution (IGL-1), 773 (10.1%) with University of Wisconsin solution, 731 (9.6%) with Solution de Conservation des Organes et Tissus (SCOT, organ and tissue preservation solution), 2215 (29.0%) with Celsior, and 448 (5.9%) with histidine-tryptophan-ketoglutarate. Primary nonfunction rates did not differ by solution. After adjustment for donor, recipient, and transplant characteristics, the DGF risk was significantly lower with IGL-1 than with all other solutions (odds ratio [OR] 0.55, 95% confidence interval [CI] 0.48-0.64). Conversely, SCOT was associated with a DGF risk significantly higher than the other solutions (OR 2.69, 95% CI 2.21-3.27) and triple that of IGL-1 (OR 3.37, 95% CI 2.72-4.16). One year after transplantation, the transplant failure rate did not differ significantly by preservation solution. The difference between the groups for 1-year mean creatinine clearance was not clinically relevant.

Donor pretreatment and machine perfusion: current views

PURPOSE OF REVIEW

To summarise recently published studies of donor pretreatment and machine perfusion strategies in kidney transplantation.

RECENT FINDINGS

The sparsity of donor pretreatment trials has resulted in the re-analysis of already existing data, and RCTs are urgently needed to reinvigorate this aspect of donor research. Uncontrolled donation after circulatory death kidney transplantation has the highest risk of delayed graft function and graft failure, and recent studies have reported that normothermic regional perfusion improves graft function and survival in this setting. Hypothermic machine perfusion reduces delayed graft function following deceased donor kidney transplantation across donor types but unanswered questions still remain regarding its use. The use of oxygenated hypothermic machine perfusion appears to improve graft function in controlled donation after circulatory death mediated by a reduction in acute rejection. Ex-situ normothermic perfusion is emerging and while technically challenging it may facilitate the delivery of pretreatments.

SUMMARY

RCTs are urgently needed to reinvigorate research into donor pretreatment and to establish the place of specific preservation techniques in deceased donor kidney transplantation.

[Postoperative complications and long-term outcomes of transplantation with expended criteria donors transplants]

OBJECTIVE

The objective of this study was to analyze early, late complications and outcomes following expended criteria donors (ECD) kidney transplantation compared to standard donors.

MATERIALS AND METHODS

We performed a retrospective study including 470 patients who received a kidney transplant between 2005 and 2016. Expended criteria donors were defined following the United Network of Organ Sharing criteria. In each group, length of stay, delayed graft function, surgical site infection, acute rejection, surgical complications by type and according to Clavien and Dindo classification were analyzed in univariate and multivariate analysis. The impact of ECD transplant on transplant and patient survival was assessed using a Cox proportional regression model.

RESULTS

One hundred and ninety seven (41.9%) patients received ECD kidney. The mean follow-up was 61,4 months (22.4-93.89). Patients with ECD transplant presented more delayed graft function (HR=2.1 (1.1-3.68), P=0.008) but the rate of complications including surgical complications was not different. Patients and transplant survival were decreased in ECD transplant group (P=0.005 et 0.001 respectively). In multivariate analysis ECD kidney was an independent factor only associated with decreased transplant survival (HR=1.81 (1.1-2.98), P=0.029) but not with patient survival.

CONCLUSION

ECD kidney transplantation was not associated with increased postoperative complications but a higher rate of delayed graft function. Nevertheless, it was associated with a decreased transplant survival. The use of pulsatile perfusion machine for explanted criteria transplant should be evaluated to improve these results.

A Retrospective Propensity Score Matched Analysis Reveals Superiority of Hypothermic Machine Perfusion over Static Cold Storage in Deceased Donor Kidney Transplantation

Hypothermic machine perfusion (HMP) has been introduced as an alternative to static cold storage (SCS) in kidney transplantation, but its true benefit in the clinical routine remains incompletely understood. The aim of this study was to assess the effect of HMP vs. SCS in kidney transplantation. All kidney transplants performed between 08/2015 and 12/2019 (n = 347) were propensity score (PS) matched for cold ischemia time (CIT), extended criteria donor (ECD), gender mismatch, cytomegalovirus (CMV) mismatch, re-transplantation and Eurotransplant (ET) senior program. A total of 103 HMP and 103 SCS instances fitted the matching criteria. Prior to PS matching, the CIT was longer in the HMP group (17.5 h vs. 13.3 h; p < 0.001), while the delayed graft function (DGF) rates were 29.8% and 32.3% in HMP and SCS, respectively. In the PS matched groups, the DGF rate was 64.1% in SCS vs. 31.1% following HMP: equivalent to a 51.5% reduction of the DGF rate (OR 0.485, 95% CI 0.318–0.740). DGF was associated with decreased 1- and 3-year graft survival (100% and 96.3% vs. 90.8% and 86.7%, p = 0.001 and p = 0.008) or a 4.1-fold increased risk of graft failure (HR = 4.108; 95% CI: 1.336–12.631; p = 0.014). HMP significantly reduces DGF in kidney transplantation. DGF remains a strong predictor of graft survival.

Expanded criteria donors in deceased donor kidney transplantation - An Asian perspective

There is an increasing gulf between demand and supply for kidneys in end-stage renal failure patients worldwide, especially Asia. Renal transplantation is often the treatment of choice for long-suffering patients who have to undergo dialysis on a regular basis. The utilization of expanded criteria donors (ECDs) to address the donor pool shortage has been proven to be a legitimate solution. Metzger first described the classification of standard criteria donor and ECD in 2002. Since then, the criterion has undergone various modifications, with the key aims of optimizing organ procurement rate while minimizing discard and rejection rates. We review the methods to improve selection, characterization of risks, and surgical techniques. Although the ECD kidneys have a higher risk of impaired donor and recipient outcome than the "standard criteria" transplants, it may be justified by the improved overall survival of these patients compared to those who remained on dialysis. It is, therefore, crucial that we perform meticulous selection, along with state of the art surgical techniques to maximize the use of this scarce resource. In this article, we review the pre-procurement and post-procurement processes implemented to preserve outcomes.

Machine Perfusion of Extended Criteria Donor Organs: Immunological Aspects

Due to higher vulnerability and immunogenicity of extended criteria donor (ECD) organs used for organ transplantation (Tx), the discovery of new treatment strategies, involving tissue allorecognition pathways, is important. The implementation of machine perfusion (MP) led to improved estimation of the organ quality and introduced the possibility to achieve graft reconditioning prior to Tx. A significant number of experimental and clinical trials demonstrated increasing support for MP as a promising method of ECD organ preservation compared to classical static cold storage. MP reduced ischemia-reperfusion injury resulting in the protection from inadequate activation of innate immunity. However, there are no general agreements on MP protocols, and clinical application is limited. The objective of this comprehensive review is to summarize literature on immunological effects of MP of ECD organs based on experimental studies and clinical trials.