Kidney Normothermic Machine Perfusion Can Be Used as a Preservation Technique and a Model of Reperfusion to Deliver Novel Therapies and Assess Inflammation and Immune Activation

Assessing Biomarkers of Porcine Kidneys under Normothermic Machine Perfusion-Can We Gain Insight into a Marginal Organ?

To identify potentially transplantable organs in a pool of marginal kidneys, 33 porcine slaughterhouse kidneys were perfused for 4 h with whole blood. During the normothermic perfusion, plasma, urine, and tissue samples were taken. Several biomarkers for tubule injury, endothelial activation, and inflammatory response were evaluated for a potential correlation with macroscopic appearance, histology, and filtration activity. Generally, biomarker levels increased during perfusion. TLR-4, EDN-1, and NGAL were not associated with any classification. In contrast, a steeper increase in NAG and IL-6 in plasma correlated with a poor macroscopic appearance at 4 h, indicating a higher inflammatory response in the kidneys with worse macroscopy early on, potentially due to more damage at the tubules. Although long-term effects on the graft could not be assessed in this setting, early observation under machine perfusion with whole blood was feasible. It allowed the assessment of kidneys under conditions comparable to reperfusion. This setting could give surgeons further insight into the quality of marginal kidneys and an opportunity to pre-treat them.

Impact of a Single Dose of Alpha-1-Antitrypsin in a Rat Model of Bilateral Kidney Ischemia Reperfusion Injury

INTRODUCTION

Renal ischemia reperfusion injury is a major cause of perioperative acute kidney injury. Alpha-1-antitrypsin (AAT), a protease inhibitor, might improve outcomes by reducing inflammation and apoptosis. We investigated the effects of a single intravenous dose of AAT immediately before ischemia in a rat bilateral renal clamping model.

METHODS

Both renal pedicles of male Sprague-Dawley rats were clamped (45 min). Plasma and renal tissue were collected at 3 h, 24 h, and 7 d. Intravenous AAT (60 mg/kg) was administered 5 min before clamping. Controls received saline. Shams underwent surgery without clamping or injection. Kidney function was assessed by plasma creatinine; injury by aspartate aminotransferase, heart-type-fatty-acid-binding-protein, and histopathology. Renal gene expression of tumor necrosis factor α, interleukin (IL)-6, heat shock protein 70, Chemokine (C-X-C motif) ligand 2, cyclo-oxygenase 2, endothelin-1, IL-10, heme oxygenase 1, B-cell lymphoma 2, and bcl-2-like protein 4 were determined by quantitative reverse transcriptase polymerase chain reaction.

RESULTS

None of the 3 h and 24 h end points were different between Control and AAT. In Sham, survival was 100% (6/6), 33% in Control (2/6), and 83% (5/6) in AAT (overall log-rank 0.03). At 7 d, plasma creatinine was lower with higher glomerular filtration rate in surviving AAT treated animals compared to Control (P < 0.001, P 0.03, respectively). These also had lower tumor necrosis factor α and IL-6 gene expression (P 0.001, P < 0.001, respectively).

CONCLUSIONS

These data suggest that a single intravenous dose of AAT immediately before ischemia might affect proinflammatory gene expression, glomerular filtration rate and animal survival at 1 wk after reperfusion despite an absence of improvement in early renal function and injury. These findings deserve further investigating in sufficiently powered studies including both sexes.

Ex vivo normothermic preservation of a kidney graft from uncontrolled donation after circulatory death over 73 hours

The transplant community is focused on prolonging the ex vivo preservation time of kidney grafts to allow for long-distance kidney graft transportation, assess the viability of marginal grafts, and optimize a platform for the translation of innovative therapeutics to clinical practice, especially those focused on cell and vector delivery to organ conditioning and reprogramming. We describe the first case of feasible preservation of a kidney from a donor after uncontrolled circulatory death over a 73-h period using normothermic perfusion and analyze hemodynamic, biochemical, histological, and transcriptomic parameters for inflammation and kidney injury. The mean pressure and flow values were 71.24 ± 9.62 mmHg and 99.65 ± 18.54 mL/min, respectively. The temperature range was 36.7°C-37.2°C. The renal resistance index was 0.75 ± 0.15 mmHg/mL/min. The mean pH was 7.29 ± 0.15. The lactate concentration peak increased until 213 mg/dL at 6 h, reaching normal values after 34 h of perfusion (8.92 mg/dL). The total urine output at the end of perfusion was 1.185 mL. Histological analysis revealed no significant increase in acute tubular necrosis (ATN) severity as perfusion progressed. The expression of KIM-1, VEGF, and TGFβ decreased after 6-18 h of perfusion until 60 h in which the expression of these genes increased again together with the expression of β-catenin, Ki67, and TIMP1. We show that normothermic perfusion can maintain a kidney graft viable ex vivo for 3 days, thus allowing a rapid translation of pre-clinical therapeutics to clinical practice.

Normothermic ex vivo perfusion of deceased donor kidneys and its clinical potential in kidney transplantation outcomes

In recent years, normothermic machine perfusion (NMP) has emerged in conversation surrounding organ preservation and transplantation techniques with the goal of improving patient and clinical outcomes. This is in great attempt to address the rate of non-utilization and the shortage of available organs in kidney transplantation. This focus in mind, normothermic perfusion presents itself as a potential tool to mimic physiological conditions and improve current preservation methods, such as static cold storage. This review serves to improve understanding of the observed connection between the consequences of ischemia and reperfusion injury and traditional preservation techniques as well as how renal NMP may mitigate these issues. Previous studies suggest that reducing time in static cold storage methods by promoting the normothermic perfusion model results in decreased delayed graft function and post-transplant complications. This review also aims to present the immense clinical potential NMP has on future kidney transplantation success and what this means for the fields of nephrology and transplantation. While great strides have been made to evaluate normothermic perfusion's impact on kidney graft viability and transplant success, future research into unified protocol, clinically relevant biomarkers, cost-utility analysis, and use with associated therapeutic and imaging modalities is paramount.

CC-4066 therapy delivered to kidneys during cold storage and assessed with normothermic reperfusion is feasible and safe

Introduction

Currently there is an urgent need to translate interventions that may be beneficial to marginal donor kidneys prior to transplant, to improve their quality from bench to bedside. This project investigated the effects of CC-4066, a potent dual inhibitor of cyclophilin proteins A and D, treatment during static cold storage (SCS) in a porcine model of renal ischemia-reperfusion injury (IRI) using Normothermic Reperfusion (NR).

Materials and methods

Porcine kidneys and autologous blood were retrieved in pairs from a local abattoir (n = 7). One kidney from each pair was randomly allocated to treatment and one allocated to control and flushed with preservation solution containing CC-4066 or vehicle. After 7 h of SCS kidneys underwent 3 h Normothermic Reperfusion (NR) with autologous whole blood while perfusion characteristics and samples were collected.

Results

Perfusion and metabolic parameters showed similar trends and no statistical differences were observed between the groups. IL-6 showed a significant increase over time but no significant difference between groups (p-value 0.009 and 0.14 respectively, two-way ANOVA). Oxygen consumption and lactate levels were similar between groups but there was increased vacuolation on histology in the control group.

Conclusions

The addition of CC-4066 during SCS of kidneys is safe and feasible and has no adverse or detrimental effects on perfusion during assessment on NR. There was no difference in cytokine levels although there was a trend towards less vacuolation on histology in the treatment group.

Differential Cytokine Levels during Normothermic Kidney Perfusion with Whole Blood- or Red Blood Cell-Based Perfusates-Results of a Scoping Review and Experimental Study

The ideal composition of the perfusate for normothermic kidney perfusion is unknown, though the perfusate commonly used to perfuse human kidneys contains leukocyte-depleted packed red blood cells (RBC), as this is believed to prevent excessive inflammation. We performed a systematic search identifying 19 articles reporting on cytokine levels during normothermic pig or human kidney perfusion. Cytokine levels varied widely across the reported studies. No direct comparisons of perfusate cytokines during perfusion with RBC or whole blood were performed, and no data on how these levels are influenced by ischemia are available. Therefore, we compared perfusate IL-6, IL-1β, TNF-α, TGF-β, IL-10, IL-8, and CCL2 levels during 4 h normothermic pig kidney perfusion with a whole blood- or RBC-based perfusate. Kidneys were exposed to either 1 h of warm or 22 h of cold ischemia. We found no evidence of different perfusate cytokine or gene expression levels in whole blood or RBC perfusions. There was no clear evidence to suggest that cytokine concentrations differ between ischemically injured kidneys and controls. In conclusion, pro-inflammatory and anti-inflammatory cytokines and chemokines are detectable in the perfusate and urine of kidneys undergoing normothermic perfusion. It is unclear how cytokine levels change in different ischemic conditions and whether the use of a leukocyte filter plays a role.