The impact of normothermic and hypothermic preservation methods on kidney lipidome-comparative study using chemical biopsy with microextraction probes.

Introduction: Normothermic ex vivo kidney perfusion (NEVKP) is designed to replicate physiological conditions to improve graft outcomes. A comparison of the impact of hypothermic and normothermic preservation techniques on graft quality was performed by lipidomic profiling using solid-phase microextraction (SPME) chemical biopsy as a minimally invasive sampling approach. Methods: Direct kidney sampling was conducted using SPME probes coated with a mixed-mode extraction phase in a porcine autotransplantation model of the renal donor after cardiac death, comparing three preservation methods: static cold storage (SCS), NEVKP, and hypothermic machine perfusion (HMP). The lipidomic analysis was done using ultra-high-performance liquid chromatography coupled with a Q-Exactive Focus Orbitrap mass spectrometer. Results: Chemometric analysis showed that the NEVLP group was separated from SCS and HMP groups. Further in-depth analyses indicated significantly (p < 0.05, VIP > 1) higher levels of acylcarnitines, phosphocholines, ether-linked and longer-chain phosphoethanolamines, triacylglycerols and most lysophosphocholines and lysophosphoethanolamines in the hypothermic preservation group. The results showed that the preservation temperature has a more significant impact on the lipidomic profile of the kidney than the preservation method's mechanical characteristics. Conclusion: Higher levels of lipids detected in the hypothermic preservation group may be related to ischemia-reperfusion injury, mitochondrial dysfunction, pro-inflammatory effect, and oxidative stress. Obtained results suggest the NEVKP method's beneficial effect on graft function and confirm that SPME chemical biopsy enables low-invasive and repeated sampling of the same tissue, allowing tracking alterations in the graft throughout the entire transplantation procedure.

Combining Oxygenated Cold Perfusion With Normothermic Ex Vivo Perfusion Improves the Outcome of Donation After Circulatory Death Porcine Kidney Transplantation.

BACKGROUND: Ex vivo machine perfusion is a novel preservation technique for storing and assessing marginal kidney grafts. All ex vivo perfusion techniques have advantages and shortcomings. The current study analyzed whether a combination of oxygenated hypothermic machine perfusion (oxHMP) followed by a short period of normothermic ex vivo kidney perfusion (NEVKP) could combine the advantages of both techniques. METHODS: Porcine kidneys were exposed to 30 min of warm ischemia followed by perfusion. Kidneys underwent either 16-h NEVKP or 16-h oxHMP. The third group was exposed to 16-h oxHMP followed by 3-h NEVKP (oxHMP + NEVKP group). After contralateral nephrectomy, grafts were autotransplanted and animals were followed up for 8 d. RESULTS: All animals survived the follow-up period. Grafts preserved by continuous NEVKP showed improved function with lower peak serum creatinine and more rapid recovery compared with the other 2 groups. Urine neutrophil gelatinase-associated lipocalin, a marker of kidney injury, was found to be significantly lowered on postoperative day 3 in the oxHMP + NEVKP group compared with the other 2 groups. CONCLUSIONS: A short period of NEVKP after oxHMP provides comparable short-term outcomes to prolonged NEVKP and is superior to oxHMP alone. A combination of oxHMP with end-ischemic NEVKP could be an attractive, practical strategy to combine the advantages of both preservation techniques.

Metabolomic and lipidomic landscape of porcine kidney associated with kidney perfusion in heart beating donors and donors after cardiac death.

Transplant centers are currently facing a lack of tools to ensure adequate evaluation of the quality of the available organs, as well as a significant shortage of kidney donors. Therefore, efforts are being made to facilitate the effective use of available organs and expand the donor pool, particularly with expanded criteria donors. Fulfilling a need, we aim to present an innovative analytical method based on solid-phase microextraction (SPME) - chemical biopsy. In order to track changes affecting the organ throughout the entire transplant procedure, porcine kidneys were subjected to multiple samplings at various time points. The application of small-diameter SPME probes assured the minimal invasiveness of the procedure. Porcine model kidney autotransplantation was executed for the purpose of simulating two types of donor scenarios: donors with a beating heart (HBD) and donors after cardiac death (DCD). All renal grafts were exposed to continuous normothermic ex vivo perfusion. Following metabolomic and lipidomic profiling using high-performance liquid chromatography coupled to a mass spectrometer, we observed differences in the profiles of HBD and DCD kidneys. The alterations were predominantly related to energy and glucose metabolism, and differences in the levels of essential amino acids, purine nucleosides, lysophosphocholines, phosphoethanolamines, and triacylglycerols were noticed. Our results indicate the potential of implementing chemical biopsy in the evaluation of graft quality and monitoring of renal function during perfusion.

Decellularization of porcine kidney with submicellar concentrations of SDS results in the retention of ECM proteins required for the adhesion and maintenance of human adult renal epithelial cells.

When decellularizing kidneys, it is important to maintain the integrity of the acellular extracellular matrix (ECM), including associated adhesion proteins and growth factors that allow recellularized cells to adhere and migrate according to ECM specificity. Kidney decellularization requires the ionic detergent sodium dodecyl sulfate (SDS); however, this results in a loss of ECM proteins important for cell adherence, migration, and growth, particularly glycosaminoglycan (GAG)-associated proteins. Here, we demonstrate that using submicellar concentrations of SDS results in a greater retention of structural proteins, GAGs, growth factors, and cytokines. When porcine kidney ECM scaffolds were recellularized using human adult primary renal epithelial cells (RECs), the ECM promoted cell survival and the uniform distribution of cells throughout the ECM. Cells maintained the expression of mature renal epithelial markers but did not organize on the ECM, indicating that mature cells are unable to migrate to specific locations on ECM scaffolds.

Normothermic Ex Vivo Kidney Perfusion for Human Kidney Transplantation: First North American Results.

BACKGROUND: Normothermic ex vivo kidney perfusion (NEVKP) has shown promising results for preservation, assessment, and reconditioning of kidney allografts in preclinical studies. Here, we report the first North American safety and feasibility study of deceased donor kidneys grafts transplanted following preservation with NEVKP. METHODS: Outcomes of 13 human kidney grafts that received 1 to 3 h of NEVKP after being transported in an anoxic hypothermic machine perfusion device were compared with a matched control group of 26 grafts that were preserved with anoxic hypothermic machine perfusion alone. RESULTS: Grafts were perfused for a median of 171 min (range, 44-275 min). The delayed graft function rate in NEVKP versus control patients was 30.8% versus 46.2% ( P = 0.51). During the 1-y follow-up, no differences in postoperative graft function, measured by serum creatinine, necessity for dialysis, and urine production, were found between the study group and the control group. There were no differences in 1 y posttransplantation graft or patient survival between the 2 groups. CONCLUSIONS: Our study demonstrates the safety and feasibility of NEVKP for human deceased donor kidney transplantation. Further studies are warranted to explore how this technology can minimize cold ischemia, improve posttransplant graft function, and assess and repair expanded criteria kidney grafts.

Prolonged warm ischemia time leads to severe renal dysfunction of donation-after-cardiac death kidney grafts.

Kidney transplantation with grafts procured after donation-after-cardiac death (DCD) has led to an increase in incidence of delayed graft function (DGF). It is thought that the warm ischemic (WI) insult encountered during DCD procurement is the cause of this finding, although few studies have been designed to definitely demonstrate this causation in a transplantation setting. Here, we use a large animal renal transplantation model to study the effects of prolonged WI during procurement on post-transplantation renal function. Kidneys from 30 kg-Yorkshire pigs were procured following increasing WI times of 0 min (Heart-Beating Donor), 30 min, 60 min, 90 min, and 120 min (n = 3-6 per group) to mimic DCD. Following 8 h of static cold storage and autotransplantation, animals were followed for 7-days. Significant renal dysfunction (SRD), resembling clinical DGF, was defined as the development of oliguria < 500 mL in 24 h from POD3-4 along with POD4 serum potassium > 6.0 mmol/L. Increasing WI times resulted in incremental elevation of post-operative serum creatinine that peaked later. DCD120min grafts had the highest and latest elevation of serum creatinine compared to all groups (POD5: 19.0 ± 1.1 mg/dL, p < 0.05). All surviving animals in this group had POD4 24 h urine output < 500 cc (mean 235 ± 172 mL) and elevated serum potassium (7.2 ± 1.1 mmol/L). Only animals in the DCD120min group fulfilled our criteria of SRD (p = 0.003), and their renal function improved by POD7 with 24 h urine output > 500 mL and POD7 serum potassium < 6.0 mmol/L distinguishing this state from primary non-function. In a transplantation survival model, this work demonstrates that prolonging WI time similar to that which occurs in DCD conditions contributes to the development of SRD that resembles clinical DGF.

Prolonged Normothermic Ex Vivo Kidney Perfusion Is Superior to Cold Nonoxygenated and Oxygenated Machine Perfusion for the Preservation of DCD Porcine Kidney Grafts.

The increased usage of marginal grafts has triggered interest in perfused kidney preservation to minimize graft injury. We used a donation after circulatory death (DCD) porcine kidney autotransplantation model to compare 3 of the most frequently used ex vivo kidney perfusion techniques: nonoxygenated hypothermic machine perfusion (non-oxHMP), oxygenated hypothermic machine perfusion (oxHMP), and normothermic ex vivo kidney perfusion (NEVKP). METHODS: Following 30 min of warm ischemia, grafts were retrieved and preserved with either 16 h of non-oxHMP, oxHMP, or NEVKP (n = 5 per group). After contralateral nephrectomy, grafts were autotransplanted and animals were followed for 8 d. Kidney function and injury markers were compared between groups. RESULTS: NEVKP demonstrated a significant reduction in preservation injury compared with either cold preservation method. Grafts preserved by NEVKP showed superior function with lower peak serum creatinine (NEVKP versus non-oxHMP versus oxHMP: 3.66 ± 1.33 mg/dL, 8.82 ± 3.17 mg/dL, and 9.02 ± 5.5 mg/dL) and more rapid recovery. The NEVKP group demonstrated significantly increased creatinine clearance on postoperative day 3 compared with the cold perfused groups. Tubular injury scores on postoperative day 8 were similar in all groups. CONCLUSIONS: Addition of oxygen during HMP did not reduce preservation injury of DCD kidney grafts. Grafts preserved with prolonged NEVKP demonstrated superior initial graft function compared with grafts preserved with non-oxHMP or oxHMP in a model of pig DCD kidney transplantation.

Transcriptome Analysis of Kidney Grafts Subjected to Normothermic Ex Vivo Perfusion Demonstrates an Enrichment of Mitochondrial Metabolism Genes.

Normothermic ex vivo kidney perfusion (NEVKP) has demonstrated superior outcomes for donation-after-cardiovascular death grafts compared with static cold storage (SCS). To determine the mechanisms responsible for this, we performed an unbiased genome-wide microarray analysis. METHODS: Kidneys from 30-kg Yorkshire pigs were subjected to 30 min of warm ischemia followed by 8 h of NEVKP or SCS, or no storage, before autotransplantation. mRNA expression was analyzed on renal biopsies on postoperative day 3. Gene set enrichment analysis was performed using hallmark gene sets, Gene Ontology, and pathway analysis. RESULTS: The gene expression profile of NEVKP-stored grafts closely resembled no storage kidneys. Gene set enrichment analysis demonstrated enrichment of fatty acid metabolism and oxidative phosphorylation following NEVKP, whereas SCS-enriched gene sets were related to mitosis, cell cycle checkpoint, and reactive oxygen species (q < 0.05). Pathway analysis demonstrated enrichment of lipid oxidation/metabolism, the Krebs cycle, and pyruvate metabolism in NEVKP compared with SCS (q < 0.05). Comparison of our findings with external data sets of renal ischemia-reperfusion injury revealed that SCS-stored grafts demonstrated similar gene expression profiles to ischemia-reperfusion injury, whereas the profile of NEVKP-stored grafts resembled recovered kidneys. CONCLUSIONS: Increased transcripts of key mitochondrial metabolic pathways following NEVKP storage may account for improved donation-after-cardiovascular death graft function, compared with SCS, which promoted expression of genes typically perturbed during IRI.

Normothermic Ex-vivo Kidney Perfusion in a Porcine Auto-Transplantation Model Preserves the Expression of Key Mitochondrial Proteins: An Unbiased Proteomics Analysis.

Normothermic ex-vivo kidney perfusion (NEVKP) results in significantly improved graft function in porcine auto-transplant models of donation after circulatory death injury compared with static cold storage (SCS); however, the molecular mechanisms underlying these beneficial effects remain unclear. We performed an unbiased proteomics analysis of 28 kidney biopsies obtained at three time points from pig kidneys subjected to 30 min of warm ischemia, followed by 8 h of NEVKP or SCS, and auto-transplantation. 70/6593 proteins quantified were differentially expressed between NEVKP and SCS groups (false discovery rate < 0.05). Proteins increased in NEVKP mediated key metabolic processes including fatty acid ß-oxidation, the tricarboxylic acid cycle, and oxidative phosphorylation. Comparison of our findings with external datasets of ischemia-reperfusion and other models of kidney injury confirmed that 47 of our proteins represent a common signature of kidney injury reversed or attenuated by NEVKP. We validated key metabolic proteins (electron transfer flavoprotein subunit beta and carnitine O-palmitoyltransferase 2, mitochondrial) by immunoblotting. Transcription factor databases identified members of the peroxisome proliferator-activated receptors (PPAR) family of transcription factors as the upstream regulators of our dataset, and we confirmed increased expression of PPARA, PPARD, and RXRA in NEVKP with reverse transcription polymerase chain reaction. The proteome-level changes observed in NEVKP mediate critical metabolic pathways. These effects may be coordinated by PPAR-family transcription factors and may represent novel therapeutic targets in ischemia-reperfusion injury.

Normothermic Ex Situ Liver Perfusion Enhances Mitochondrial Function of DCD Grafts as Evidenced by High-throughput Metabolomics.

BACKGROUND: Normothermic ex situ liver perfusion (NEsLP) reduces reperfusion injury of donation after circulatory death (DCD) grafts and optimizes graft function. The goal of our study was to elucidate how NEsLP impacts global metabolism in DCD grafts using high-throughput metabolomics. METHODS: Pig livers were preserved by 2 different techniques: static cold storage and NEsLP. Grafts obtained from heart-beating donors were compared with donation after circulatory death (DCD) grafts with either 30 minutes (DCD30) or 60 minutes (DCD60) ischemia time. Liver tissues were collected at the end of preservation period (T0) with either cold storage or NEsLP (n = 5 per group). Grafts were transplanted into recipient pigs and a second liver biopsy was collected 2 hours following liver transplantation (T1). Snap-frozen tissue was processed and analyzed by Sciex 6600 Q-TOF high-resolution mass spectrometer. Data analysis was performed using MetaboAnalyst 4.0 software. RESULTS: Prolonged ischemia resulted in 38 out of 81 metabolites being differentially abundant over time. Mitochondrial metabolism was significantly affected, with disruption in oxidative phosphorylation capacity i.e the Warburg effect (P = 3.62E-03) and urea cycle (P = 7.95E-0.4). NEsLP resulted in improved mitochondrial metabolism and glycolysis (4.20E-02) oxidation of branched chain fatty acids (P = 4.07E-02). CONCLUSIONS: This unbiased, high-throughput metabolomics study reveals that mitochondrial function is globally rescued with NEsLP, associated with improvement in DCD graft function. NEsLP is able to rescue DCD grafts, improving their metabolic function to that of livers not exposed to DCD procurement.

Significant Dysfunction of Kidney Grafts Exposed to Prolonged Warm Ischemia Is Minimized Through Normothermic Ex Vivo Kidney Perfusion.

Normothermic ex vivo kidney perfusion (NEVKP) is an emerging technique for renal graft preservation. We investigated whether NEVKP could improve early function of severely injured grafts and reduce the incidence of significant renal dysfunction (SRD) similar to delayed graft function in a model of donation after circulatory death. METHODS: Kidneys from 30-kg Yorkshire pigs were removed following 120 minutes of warm ischemia (WI). These grafts were then preserved in static cold storage (SCS, n = 6) or subjected to NEVKP (n = 5) for 8 hours before heterotopic autotransplantation. SRD was defined as postoperative day (POD) 4 oliguria <500 mL/24 h with serum K +> 6.0 mmol/L. RESULTS: All 4 surviving animals with 120 minutes WI grafts stored with SCS developed SRD, compared with 1/5 in the NEVKP group (P = 0.02). The NEVKP group, when compared with SCS, also demonstrated significantly decreased serum creatinine peak values (1118.51 ± 206.90 µmol/L versus 1675.56 ± 98.15 µmol/L; P = 0.002) and higher creatinine clearance (POD4: 9.05 ± 6.97 mL/min versus 0.89 ± 0.56 mL/min; P = 0.05). By POD7, serum creatinine was not significantly different than baseline in the NEVKP (431.49 ± 492.50 µmol/L versus 90.19 ± 14.15 µmol/L, respectively; P = 0.20) but remained elevated following SCS (1189.25 ± 309.47 µmol/L versus 97.26 ± 29.18 µmol/L, respectively; P < 0.01). Histology demonstrated significantly decreased tubular injury scores compared with SCS grafts (P = 0.03). CONCLUSIONS: Kidney grafts subjected to 120 minutes WI before retrieval showed significant improvement in function, prevention of SRD, and decreased injury following 8 hours of NEVKP.

Using a Chemical Biopsy for Graft Quality Assessment.

Kidney transplantation is a life-saving treatment for a large number of people with end-stage renal dysfunction worldwide. The procedure is associated with an increased survival rate and greater quality of patient's life when compared to conventional dialysis. Regrettably, transplantology suffers from a lack of reliable methods for organ quality assessment. Standard diagnostic techniques are limited to macroscopic appearance inspection or invasive tissue biopsy, which do not provide comprehensive information about the graft. The proposed protocol aims to introduce solid phase microextraction (SPME) as an ideal analytical method for comprehensive metabolomics and lipidomic analysis of all low molecular compounds present in kidneys allocated for transplantation. The small size of the SPME probe enables performance of a chemical biopsy, which enables extraction of metabolites directly from the organ without any tissue collection. The minimum invasiveness of the method permits execution of multiple analyses over time: directly after organ harvesting, during its preservation, and immediately after revascularization at the recipient's body. It is hypothesized that the combination of this novel sampling method with a high-resolution mass spectrometer will allow for discrimination of a set of characteristic compounds that could serve as biological markers of graft quality and indicators of possible development of organ dysfunction.

Normothermic Ex Vivo Liver Perfusion Prevents Intrahepatic Platelet Sequestration After Liver Transplantation.

BACKGROUND: The detrimental role of platelets in sinusoidal endothelial cell (SEC) injury during liver transplantation (LT) has been previously addressed after static cold storage (SCS), however, it is currently unknown after normothermic ex vivo liver perfusion (NEVLP). METHODS: Pig LT was performed with livers from heart-beating donors or donation after circulatory death (DCD) donors subjected to SCS or NEVLP (n = 5/group). RESULTS: All pigs except for 1 (DCD-SCS-group) survived 4 days. The heart-beating donor- and DCD-NEVLP-groups showed significantly lower aspartate transaminase-levels compared with the SCS-groups 3 hours post-LT (P = 0.006), on postoperative day (POD) 2 (P = 0.005), POD3 (P = 0.007), and on POD4 (P = 0.012). Post-LT total platelet count recovered faster in the NEVLP than in the SCS-groups at 12 hours (P = 0.023) and 24 hours (P = 0.0038). Intrahepatic sequestration of platelets was significantly higher in the SCS-groups 3 hours postreperfusion and correlated with severity of SEC injury. In both SCS-groups, levels of tumor growth factor-ß were higher 3 hours post-LT, on POD1 and on POD3. Moreover, platelet factor 4 levels and platelet-derived extracellular vesicles were increased in the SCS-groups. Hyaluronic acid levels were significantly higher in the SCS-groups, indicating a higher grade of endothelial cell dysfunction. Platelet inhibition achieved by pretreatment with clopidogrel (n = 3) partly reversed the detrimental effects on SEC injury and therefore provided further evidence of the important role of platelets in ischemia/reperfusion injury and SEC injury. CONCLUSIONS: Normothermic perfusion of liver grafts before transplantation effectively reduced platelet aggregation and SEC injury, which translated into an improved posttransplant organ function.

Normothermic Ex Vivo Kidney Perfusion Improves Early DCD Graft Function Compared With Hypothermic Machine Perfusion and Static Cold Storage.

BACKGROUND: Better preservation strategies for the storage of donation after circulatory death grafts are essential to improve graft function and to increase the kidney donor pool. We compared continuous normothermic ex vivo kidney perfusion (NEVKP) with hypothermic anoxic machine perfusion (HAMP) and static cold storage (SCS) in a porcine kidney autotransplantation model. METHODS: Porcine kidneys were exposed to 30 minutes of warm ischemia and then reimplanted following either 16 hours of either SCS, HAMP (LifePort 1.0), or NEVKP before autotransplantation (n = 5 per group). The contralateral kidney was removed. Animals were followed for 8 days. RESULTS: Grafts preserved by NEVKP demonstrated improved function with more rapid recovery compared with HAMP and SCS (mean peak serum creatinine: 3.66 ± 1.33 mg/dL [postoperative d 1 [(POD1)], 8.82 ± 3.17 mg/dL [POD2], and 12.90 ± 2.19 mg/dL [POD3], respectively). The NEVKP group demonstrated significantly increased creatinine clearance calculated on POD3 (63.6 ± 19.0 mL/min) compared with HAMP (13.5 ± 10.3 mL/min, P = 0.001) and SCS (4.0 ± 2.6 mL/min, P = 0.001). Histopathologic injury scores on POD8 were lower in both perfused groups (NEVKP and HAMP, score: 1-1.5) compared with SCS (score: 1-3, P = 0.3), without reaching statistical significance. CONCLUSIONS: NEVKP storage significantly improved early kidney function compared with both cold preservation strategies, although HAMP also demonstrates improvement over SCS. NEVKP may represent a novel, superior preservation option for donation after circulatory death renal grafts compared with conventional hypothermic methods.

Impact of Different Clinical Perfusates During Normothermic Ex Situ Liver Perfusion on Pig Liver Transplant Outcomes in a DCD Model.

BACKGROUND: Human albumin/dextran (HA-D), bovine-gelatin (BG), and packed red blood cells plus plasma have been used in European and North-American clinical trials of normothermic ex situ liver perfusion (NEsLP). We compared the effects of these perfusates in a porcine model during NEsLP and after transplantation. METHODS: Porcine livers were retrieved 30 minutes after circulatory death. After 5 hours of NEsLP, grafts were transplanted. Three groups (n = 6) were assessed (HA-D vs BG vs whole blood [WB]). One group of static cold storage (SCS) was evaluated for comparison with the perfusion groups. Hemodynamic variables, liver and endothelial injury, and function were assessed during NEsLP and posttransplantation. RESULTS: Hepatic artery flow was higher since the beginning of NEsLP in the HA-D group (HA-D, 238 ± 90 mL/min vs BG, 97 ± 33 mL/min vs WB, 148 ± 49 mL/min; P = 0.01). Hyaluronic acid was lower in the HA-D at the end of perfusion (HA-D, 16.28 ± 7.59 ng/µL vs BG, 76.05 ± 15.30 ng/µL vs WB, 114 ± 46 ng/µL; P < 0.001). After transplant, aspartate aminotransferase was decreased in the HA-D group when compared with the rest of the groups (HA-D, 444 ± 226 IU/L vs BG, 1033 ± 694 IU/L vs WB, 616 ± 444 IU/L vs SCS, 2235 ± 1878 IU/L). At 5 hours after transplant, lactate was lower in the HA-D group (HA-D, 3.88 ± 1.49 mmol/L vs BG, 7.79 ± 2.68 mmol/L vs WB, 8.16 ± 3.86 mmol/L vs SCS, 9.06 ± 3.54 mmol/L; P = 0.04). International Normalized Ratio was improved in HA-D group compared to the rest of the groups (HA-D, 1.23 ± 0.30 vs BG, 1.63 ± 0.20 vs WB, 1.50 ± 0.31 vs SCS, 1.97 ± 1.55; P = 0.03) after transplantation. In contrast, BG displayed lower aspartate aminotransferase levels during NEsLP (HA-D, 183 ± 53 IU/L vs BG, 142 ± 52 IU/L vs WB, 285 ± 74 IU/L; P = 0.01) and less cleaved-caspase-3 staining (HA-D, 2.05 ± 0.73% vs BG, 0.95 ± 1.14% vs WB, 1.74 ± 0.54% vs SCS, 7.95 ± 2.38%) compared with the other groups. On the other hand, the bile from the WB showed higher pH (HA-D, 7.54 ± 0.11 vs BG, 7.34 ± 0.37 vs WB, 7.59 ± 0.18) and lower glucose levels (HA-D, 0.38 ± 0.75 mmol/L vs BG, 1.42 ± 1.75 mmol/L vs WB, 0 ± 0 mmol/L) by the end of perfusion. CONCLUSIONS: Overall HA-D displayed more physiologic conditions during NEsLP that were reflected in less graft injury and improved liver function and survival after transplantation. Optimization of the perfusates based on the beneficial effects found with these different solutions would potentially improve further the outcomes through the use of NEsLP in marginal grafts.

Predictor parameters of liver viability during porcine normothermic ex situ liver perfusion in a model of liver transplantation with marginal grafts.

Normothermic ex situ liver perfusion (NEsLP) offers the opportunity to assess biomarkers of graft function and injury. We investigated NEsLP parameters (biomarkers and markers) for the assessment of liver viability in a porcine transplantation model. Grafts from heart-beating donors (HBD), and from donors with 30 minutes (donation after cardiac death [DCD]30'), 70 minutes (DCD70'), and 120 minutes (DCD120') of warm ischemia were studied. The HBD, DCD30', and DCD70'-groups had 100% survival. In contrast, 70% developed primary nonfunction (PNF) and died in the DCD120'-group. Hepatocellular function during NEsLP showed low lactate (≤1.1 mmol/L) in all the groups except the DCD120'-group (>2 mmol/L) at 4 hours of perfusion (P = .04). The fold-urea increase was significantly lower in the DCD120'-group (≤0.4) compared to the other groups (≥0.65) (P = .01). As for cholangiocyte function, bile/perfusate glucose ratio was significantly lower (<0.6) in all the groups except the DCD120'-group (≥0.9) after 3 hours of perfusion (<0.01). Bile/perfusate Na+ ratio was significantly higher (≥1.2) after 3 hours of perfusion in all the groups except for the DCD120'-group (≤1) (P < .01). Three hours after transplantation, the DCD120'-group had a significantly higher international normalized ratio (>5) compared to the rest of the groups (≤1.9) (P = .02). Rocuronium levels were higher at all the time-points in the animals that developed PNF during NEsLP and after transplantation. This study demonstrates that biomarkers and markers of hepatocellular and cholangiocyte function during NEsLP correlate with the degree of ischemic injury and posttransplant function.

PPAR-gamma activation is associated with reduced liver ischemia-reperfusion injury and altered tissue-resident macrophages polarization in a mouse model.

BACKGROUND: PPAR-gamma (γ) is highly expressed in macrophages and its activation affects their polarization. The effect of PPAR-γ activation on Kupffer cells (KCs) and liver ischemia-reperfusion injury (IRI) has not yet been evaluated. We investigated the effect of PPAR-γ activation on KC-polarization and IRI. MATERIALS AND METHODS: Seventy percent (70%) liver ischemia was induced for 60mins. PPAR-γ-agonist or vehicle was administrated before reperfusion. PPAR-γ-antagonist was used to block PPAR-γ activation. Liver injury, necrosis, and apoptosis were assessed post-reperfusion. Flow-cytometry determined KC-phenotypes (pro-inflammatory Nitric Oxide +, anti-inflammatory CD206+ and anti-inflammatory IL-10+). RESULTS: Liver injury assessed by serum AST was significantly decreased in PPAR-γ-agonist versus control group at all time points post reperfusion (1hr: 3092±105 vs 4469±551; p = 0.042; 6hr: 7041±1160 vs 12193±1143; p = 0.015; 12hr: 5746±328 vs 8608±1259; p = 0.049). Furthermore, liver apoptosis measured by TUNEL-staining was significantly reduced in PPAR-γ-agonist versus control group post reperfusion (1hr:2.46±0.49 vs 6.90±0.85%;p = 0.001; 6hr:26.40±2.93 vs 50.13±8.29%; p = 0.048). H&E staining demonstrated less necrosis in PPAR-γ-agonist versus control group (24hr:26.66±4.78 vs 45.62±4.57%; p = 0.032). The percentage of pro-inflammatory NO+ KCs was significantly lower at all post reperfusion time points in the PPAR-γ-agonist versus control group (1hr:28.49±4.99 vs 53.54±9.15%; p = 0.040; 6hr:5.51±0.54 vs 31.12±9.58%; p = 0.009; 24hr:4.15±1.50 vs 17.10±4.77%; p = 0.043). In contrast, percentage of anti-inflammatory CD206+ KCs was significantly higher in PPAR-γ-agonist versus control group prior to IRI (8.62±0.96 vs 4.88 ±0.50%; p = 0.04). Administration of PPAR-γ-antagonist reversed the beneficial effects on AST, apoptosis, and pro-inflammatory NO+ KCs. CONCLUSION: PPAR-γ activation reduces IRI and decreases the pro-inflammatory NO+ Kupffer cells. PPAR-γ activation can become an important tool to improve outcomes in liver surgery through decreasing the pro-inflammatory phenotype of KCs and IRI.

Normothermic Ex Vivo Kidney Perfusion Reduces Warm Ischemic Injury of Porcine Kidney Grafts Retrieved After Circulatory Death.

BACKGROUND: Cold storage is poorly tolerated by kidney grafts retrieved after donation after circulatory death. It has been determined that normothermic ex vivo kidney perfusion (NEVKP) preservation decreases injury by minimizing cold ischemic storage. The impact of NEVKP on warm ischemic injury is unknown. METHODS: We compared pig kidneys retrieved after 30 minutes warm ischemia and immediate transplantation (no-preservation) with grafts that were exposed to 30 minutes of warm ischemia plus 8-hour NEVKP or plus 8-hour static cold storage (SCS). RESULTS: After transplantation, the NEVKP group demonstrated lower daily serum creatinine levels indicating better early graft function compared with no-preservation (P = 0.02) or SCS group (P < 0.001). In addition, NEVKP preserved grafts had a significantly lower grade of tubular injury and interstitial inflammation 30 minutes after reperfusion compared to grafts without any storage (injury score, NEVKP 1-2 vs no-preservation, 2-2, P = 0.029; inflammation score, NEVKP, 0-0.5 vs no-preservation, 1-2; P = 0.002), although it did not reach significance level when compared to the SCS group (injury score, 1-2, P = 0.071; inflammation score, 1-1; P = 0.071). Regeneration was assessed 30 minutes after reperfusion by Ki-67 staining. The NEVKP group demonstrated significantly higher number of Ki-67-positive cells: 9.2 ± 3.7 when compared with SCS group (3.9 ± 1.0, P = 0.015) and no-preservation group (4.2 ± 0.7, P = 0.04). CONCLUSIONS: In this porcine model of donation after circulatory death kidney transplantation NEVKP reduced kidney injury and improved graft function when compared with no-preservation. The results suggest that NEVKP does not cause additional damage to grafts during the preservation period, but may reverse the negative effects of warm ischemic insult itself and promotes regeneration.

Normothermic ex vivo kidney perfusion for graft quality assessment prior to transplantation.

Normothermic ex vivo kidney perfusion (NEVKP) represents a novel approach for graft preservation and functional improvement in kidney transplantation. We investigated whether NEVKP also allows graft quality assessment before transplantation. Kidneys from 30-kg pigs were recovered in a model of heart-beating donation (group A) after 30 minutes (group B) or 60 minutes (group C) (n = 5/group) of warm ischemia. After 8 hours of NEVKP, contralateral kidneys were resected, grafts were autotransplanted, and the pigs were followed for 3 days. After transplantation, renal function measured based on peak serum creatinine differed significantly among groups (P < .05). Throughout NEVKP, intrarenal resistance was lowest in group A and highest in group C (P < .05). intrarenal resistance at the initiation of NEVKP correlated with postoperative renal function (P < .001 at NEVKP hour 1). Markers of acid-base homeostasis (pH, HCO3- , base excess) differed among groups (P < .05) and correlated with posttransplantation renal function (P < .001 for pH at NEVKP hour 1). Similarly, lactate and aspartate aminotransferase were lowest in noninjured grafts versus donation after circulatory death kidneys (P < .05) and correlated with posttransplantation kidney function (P < .001 for lactate at NEVKP hour 1). In conclusion, assessment of perfusion characteristics and clinically available perfusate biomarkers during NEVKP allows the prediction of posttransplantation graft function. Thus, NEVKP might allow decision-making regarding whether grafts are suitable for transplantation.

Comparison of BQ123, Epoprostenol, and Verapamil as Vasodilators During Normothermic Ex Vivo Liver Machine Perfusion.

BACKGROUND: The optimal vasodilator to avoid hepatic artery vasospasm during normothermic ex vivo liver perfusion (NEVLP) is yet to be determined. We compared safety and efficacy of BQ123 (endothelin1 antagonist), epoprostenol (prostacyclin analogue), and verapamil (calcium channel antagonist). METHODS: Livers from porcine heart beating donors were perfused for 3 hours and transplanted into recipient pigs. Four groups were compared: group 1, livers perfused with a dose of 1.25 mg of BQ123 at baseline and at 2 hours of perfusion; group 2, epoprostenol at a continuous infusion of 4 mg/h; group 3, verapamil 2.5 mg at baseline and at 2 hours of perfusion; group 4, no vasodilator used during ex vivo perfusion. Liver injury and function were assessed during perfusion, and daily posttransplantation until postoperative day (POD) 3. All groups were compared with a cold storage group for postoperative graft function. RESULTS: Hepatic artery flow during NEVLP was significantly higher in BQ123 compared with verapamil, epoprostenol, and no vasodilator-treated livers. Aspartate aminotransferase levels were significantly lower with BQ123 and verapamil compared with epoprostenol and control group during perfusion. Peak aspartate aminotransferase levels were lower in pigs receiving BQ123 and verapamil perfused grafts compared with epoprostenol and control group. International Normalized Ratio, alkaline phosphatase, and total bilirubin levels were lower in the BQ123 and verapamil groups compared to epoprostenol group. Cold storage group had increased markers of ischemia reperfusion injury and slower graft function recovery compared to machine perfused grafts. CONCLUSION: The use of BQ123, epoprostenol, and verapamil during NEVLP is safe. Livers perfused with BQ123 and verapamil have higher hepatic artery flow and reduced hepatocyte injury during perfusion compared with epoprostenol. Hepatic artery flow is significantly reduced in the absence of vasodilators during NEVLP.