Static Cold Storage Research Articles

Ex vivo kidney machine perfusion: meta-analysis of randomized clinical trials.

Machine perfusion is an organ preservation strategy used to improve function over simple storage in a cold environment. This article presents an updated systematic review and meta-analysis of machine perfusion in deceased donor kidneys. RCTs from November 2018 to July 2023 comparing machine perfusion versus static cold storage in kidney transplantation were evaluated for systematic review. The primary outcome in meta-analysis was delayed graft function. A total 19 studies were included, and 16 comparing hypothermic machine perfusion with static cold storage were analysed. The risk of delayed graft function was lower with hypothermic machine perfusion (risk ratio (RR) 0.77, 95% c.i. 0.69 to 0.86), even in kidneys after circulatory death (RR 0.78, 0.68 to 0.90) or brain death (RR 0.73, 0.63 to 0.84). Full hypothermic machine perfusion decreased the risk of delayed graft function (RR 0.69, 0.60 to 0.79), whereas partial hypothermic machine perfusion did not (RR 0.92, 0.69 to 1.22). Normothermic machine perfusion or short-term oxygenated hypothermic machine perfusion preservation after static cold storage was equivalent to static cold storage in terms of delayed graft function and 1-year graft survival. Hypothermic machine perfusion reduces delayed graft function risks and normothermic approaches show promise.

Novel portable hypothermic machine perfusion preservation device enhances cardiac viability of donated human hearts.

Heart transplant remains the gold standard treatment for patients with advanced heart failure. However, the list of patients waiting for a heart transplant continues to increase. We have developed a portable hypothermic oxygenated machine perfusion device, the VP.S ENCORE®, to extend the allowable preservation time. The purpose of this study was to test the efficacy of the VP.S. ENCORE® using deceased donors derived hearts. Hearts from brain-dead donors not utilized for transplant (n = 11) were offered for research from the Texas Organ Sharing Alliance (TOSA), South and Central Texas' Organ Procurement Organization (OPO) and were preserved in the VP.S ENCORE® for 4 (n = 2), 6 (n = 3), and 8 (n = 3) hours or were kept in static cold storage (SCS) (n = 3). After preservation, the hearts were placed in an isolated heart Langendorff model for reperfusion and evaluated for cardiac function. The mean donor age was 37.82 ± 12.67 with the youngest donor being 19 and the oldest donor being 58 years old. SCS hearts mean weight gain (%) was -1.4 ± 2.77, while perfused at 4 h was 5.6 ± 6.04, perfused at 6 h 2.1 ± 6.04, and 8 h was 7.2 ± 10.76. Venous and arterial lactate concentrations were less than 2.0 mmol/L across all perfused hearts. Left ventricular contractility (+dPdT, mmHg/s) for 4 h (1,214 ± 1,064), 6 (1,565 ± 141.3), and 8 h (1,331 ± 403.6) were within the range of healthy human heart function. Thus, not significant as compared to the SCS group (1,597 ± 342.2). However, the left ventricular relaxation (mmHg/s) was significant in 6-hour perfused heart (p < 0.05) as compared to SCS. Gene expression analysis of inflammation markers (IL-6, IL-1β) showed no significant differences between SCS and perfused hearts, but a 6-hour perfusion led to a downregulated expression of these markers. The results demonstrate that the VP.S ENCORE® device enhances cardiac viability and exhibits comparable cardiac function to a healthy heart. The implications of these findings suggest that the VP.S ENCORE® could introduce a new paradigm in the field of organ preservation, especially for marginal hearts.

(43) - A Newly Produced Polymerized Bovine Hemoglobin and Hemoglobin-Based Heart Preservation Solution Prolonged Preservation Duration of Donor Heart in Cold Static Storage and Reduced Myocardial Injury After Allograft Transplantation

(43) - A Newly Produced Polymerized Bovine Hemoglobin and Hemoglobin-Based Heart Preservation Solution Prolonged Preservation Duration of Donor Heart in Cold Static Storage and Reduced Myocardial Injury After Allograft Transplantation

(708) - Preservation of Ventricular Contractility of Old Donor Hearts During Static Cold Storage by the Senomorphic Agent Ruxolitinib is More Effective in Hearts from Female Donors

(708) - Preservation of Ventricular Contractility of Old Donor Hearts During Static Cold Storage by the Senomorphic Agent Ruxolitinib is More Effective in Hearts from Female Donors

(1253) - Cold Static Storage Combined with Intraoperative Cardioplegia Protection Strategy Yields Low Primary Graft Dysfunction

(1253) - Cold Static Storage Combined with Intraoperative Cardioplegia Protection Strategy Yields Low Primary Graft Dysfunction

Impact of Back-to-Base Normothermic Machine Perfusion on Complications and Costs: A Multicenter, Real-World Risk-Matched Analysis.

Assess cost and complication outcomes after liver transplantation (LT) using normothermic machine perfusion (NMP). End-ischemic NMP is often used to aid logistics, yet its impact on outcomes after LT remains unclear, as does its true impact on costs associated with transplantation. Deceased donor liver recipients at 2 centers (January 1, 2019, to June 30, 2023) were included. Retransplants, splits, and combined grafts were excluded. End-ischemic NMP (OrganOx-Metra) was implemented in October 2022 for extended-criteria donation after brain death (DBDs), all donations after circulatory deaths (DCDs), and logistics. NMP cases were matched 1:2 with static cold storage controls (SCS) using the Balance-of-Risk [donation after brain death (DBD)-grafts] and UK-DCD Score (DCD-grafts). Overall, 803 transplantations were included, 174 (21.7%) receiving NMP. Matching was achieved between 118 NMP-DBDs with 236 SCS; and 37 NMP-DCD with 74 corresponding SCS. For both graft types, median inpatient comprehensive complications index values were comparable between groups. DCD-NMP grafts experienced reduced cumulative 90-day comprehensive complications index (27.6 vs 41.9, P =0.028). NMP also reduced the need for early relaparotomy and renal replacement therapy, with subsequently less frequent major complications (Clavien-Dindo ≥IVa). This effect was more pronounced in DCD transplants. NMP had no protective effect on early biliary complications. Organ acquisition/preservation costs were higher with NMP, yet NMP-treated grafts had lower 90-day pretransplant costs in the context of shorter waiting list times. Overall costs were comparable for both cohorts. This is the first risk-adjusted outcome and cost analysis comparing NMP and SCS. In addition to logistical benefits, NMP was associated with a reduction in relaparotomy and bleeding in DBD grafts, and overall complications and post-LT renal replacement for DCDs. While organ acquisition/preservation was more costly with NMP, overall 90-day health care costs-per-transplantation were comparable.

Real-time monitoring of mitochondrial oxygenation during machine perfusion using resonance Raman spectroscopy predicts organ function

Organ transplantation is a life-saving procedure affecting over 100,000 people on the transplant waitlist. Ischemia reperfusion injury (IRI) is a major challenge in the field as it can cause post-transplantation complications and limit the use of organs from extended criteria donors. Machine perfusion technology has the potential to mitigate IRI; however, it currently fails to achieve its full potential due to a lack of highly sensitive and specific assays to assess organ quality during perfusion. We developed a real-time and non-invasive method of assessing organs during perfusion based on mitochondrial function and injury using resonance Raman spectroscopy. It uses a 441 nm laser and a high-resolution spectrometer to quantify the oxidation state of mitochondrial cytochromes during perfusion. This index of mitochondrial oxidation, or 3RMR, was used to understand differences in mitochondrial recovery of cold ischemic rodent livers during machine perfusion at normothermic temperatures with an acellular versus cellular perfusate. Measurement of the mitochondrial oxidation revealed that there was no difference in 3RMR of fresh livers as a function of normothermic perfusion when comparing acellular versus cellular-based perfusates. However, following 24 h of static cold storage, 3RMR returned to baseline faster with a cellular-based perfusate, yet 3RMR progressively increased during perfusion, indicating injury may develop over time. Thus, this study emphasizes the need for further refinement of a reoxygenation strategy during normothermic machine perfusion that considers cold ischemia durations, gradual recovery/rewarming, and risk of hemolysis.

Design of a Multiparametric Perfusion Bioreactor System for Evaluating Sub-Normothermic Preservation of Rat Abdominal Wall Vascularized Composite Allografts.

Static cold storage (SCS), the current clinical gold standard for organ preservation, provides surgeons with a limited window of time between procurement and transplantation. In vascularized composite allotransplantation (VCA), this time limitation prevents many viable allografts from being designated to the best-matched recipients. Machine perfusion (MP) systems hold significant promise for extending and improving organ preservation. Most of the prior MP systems for VCA have been built and tested for large animal models. However, small animal models are beneficial for high-throughput biomolecular investigations. This study describes the design and development of a multiparametric bioreactor with a circuit customized to perfuse rat abdominal wall VCAs. To demonstrate its concept and functionality, this bioreactor system was employed in a small-scale demonstrative study in which biomolecular metrics pertaining to graft viability were evaluated non-invasively and in real time. We additionally report a low incidence of cell death from ischemic necrosis as well as minimal interstitial edema in machine perfused grafts. After up to 12 h of continuous perfusion, grafts were shown to survive transplantation and reperfusion, successfully integrating with recipient tissues and vasculature. Our multiparametric bioreactor system for rat abdominal wall VCA provides an advanced framework to test novel techniques to enhance normothermic and sub-normothermic VCA preservations in small animal models.

Should advanced perfusion be the standard of care for donation after circulatory death liver transplant?

As an alternative to static cold storage (SCS), advanced perfusion techniques such as normothermic regional perfusion and ex-situ perfusion (normothermic or hypothermic) have emerged as a way to improve the ischemic injury suffered by donation after circulatory death (DCD) livers. Multiple studies have been published that have demonstrated superior post-DCD liver transplant outcomes when using advanced perfusion compared with SCS. In particular, these studies have shown lower rates of ischemic cholangiopathy with advanced perfusion. In addition to the improved post-liver transplant outcomes, studies have also demonstrated higher rates of liver utilization from DCD donors when advanced perfusion is used compared with SCS. Given the high rates of graft loss in patients who develop ischemic cholangiopathy, the significant reduction seen in DCD donor livers that have undergone advanced perfusion represents a key step in more broad utilization of these livers. With such compelling evidence from multiple trials, it seems reasonable to ask the question: should advanced perfusion be the standard of care for DCD liver transplant?

O92: Machine perfusion in liver transplantation; Cochrane review and meta-analysis

Abstract Introduction Several novel machine perfusion technologies have been developed which attempt to improve outcomes compared with ice-box static cold storage (SCS). We aimed to evaluate the effects of different methods of machine perfusion liver transplantation. Methods We used standard, extensive Cochrane search methods to identify randomised machine perfusion trials. Data extraction was performed independently by two authors. Pairwise random-effects meta-analysis was performed. We assessed bias using Risk of Bias 2 and used GRADE to assess certainty of evidence. Results We included seven randomised trials (1024 transplant recipients from 1301 randomised/included livers); four compared end-ischaemic hypothermic oxygenated perfusion (HOPE) with SCS, and three compared normothermic machine perfusion (NMP) with SCS. When compared with SCS, HOPE was associated with improvement in the following clinically relevant outcomes: graft survival (HR=0.45, 95% CI=0.23-0.87; P=0.02; high-certainty evidence), serious adverse events (OR=0.45, 0.22-0.91; P=0.03; moderate-certainty evidence) and clinically significant ischaemic cholangiopathy (OR=0.31, 0.11-0.92; P=0.03; high-certainty evidence). NMP was not associated with improvement in any of these clinically relevant outcomes, although evidence for these outcomes was low certainty. NMP was associated with improved utilisation compared with SCS (one trial found a 50% lower rate of organ discard; P = 0.008). Conclusions Where the decision has been made to transplant a DCD or marginal DBD liver, HOPE will provide superior clinically relevant outcomes compared with SCS alone (graft survival, adverse events, cholangiopathy). NMP appears to improve utilisation of grafts that would otherwise be discarded, but well-powered trials specifically designed to assess utilisation are required.

O72: Machine perfusion in deceased-donor kidney transplantation: Cochrane review and meta-analysis

Abstract Background Several novel machine perfusion technologies have been developed which aim to improve kidney transplant outcomes compared with ice-box static cold storage (SCS). These machine perfusion technologies can be applied “continuous” from donor centre, or only at the recipient centre (“end-ischaemic”). We aimed to compare machine perfusion technologies with each other and with SCS. Methods We searched the Cochrane Kidney and Transplant Register of Studies to 20 June 2023. Two independent authors screened articles and extracted data. Pairwise random-effects meta-analysis was performed, with additional indirect comparisons performed. Main results 22 studies (4007 participants) were included. “Continuous” non-oxygenated hypothermic machine perfusion (HMP) versus SCS improves graft-survival (follow-up=1-10 years, HR=0.55, 95% confidence interval=0.40-0.77, P=0.0005, GRADE: high-certainty evidence), reduces delayed graft function (RR 0.78, 0.64-0.96, P=0.02; high-certainty evidence) and is cost-saving. Beneficial effects persist when cold ischaemic times were short, but were only seen when HMP was “continuous”; End-ischaemic oxygenated HMP (median 4.6hours) does not improve outcomes. Addition of oxygen to continuous HMP further improves graft-survival in DCD donors. End-ischaemic normothermic machine perfusion (NMP) does not improve outcomes versus SCS; indirect comparison revealed that continuous non-oxygenated HMP was associated with improved graft survival compared with end-ischaemic NMP (HR=0.31, 0.11-0.92, P=0.03). Conclusions Continuous HMP (initiated in donor hospital) is superior to SCS in deceased-donor kidney transplantation. Timing of HMP is important, and benefits have not been demonstrated with end-ischaemic HMP. Whilst end-ischaemic NMP is inferior to continuous HMP on indirect comparisons, further studies assessing NMP for viability assessment and therapeutic delivery are in progress.

O225: Oxygenated hypothermic machine perfusion (HMPO2) of the pancreas; a porcine circulatory death model to compare a ‘continuous’ and an ‘end-ischaemic’ approach

Abstract Pancreas and islet cell transplantation are used in the treatment of patients with diabetes complications. During static cold storage (SCS) ATP is depleted, and by-products of anaerobic respiration accumulate. Ischaemia-reperfusion injury (IRI) affects quantity and viability of islets and it is characterised by acinar necrosis, oedema, and endothelial disruption (graft pancreatitis). The introduction of HMPO2 in liver &amp; kidney preservation has demonstrated a significant reduction in the consequences of IRI. Pancreas HMPO2 was shown to be feasible in pre-clinical studies. We aimed to compare a ‘continuous’ to an ‘end-ischaemic’ approach of HMPO2 in pancreases using a porcine circulatory death model. Porcine pancreases were either started on HMPO2 for the totality of the cold storage time (‘Continuous’ group, n=6) or for the last two hours of the cold storage time (‘End’ group, n=6). All pancreases then underwent normothermic reperfusion (NR) to mimic transplantation. Glucose stimulated insulin secretion (GSIS) was measured using Mercodia human insulin ELISA (n=3 in each group). Both groups had no significant change of wet-to-dry ratio during the experiment, despite an increase in gross weight. Flows were higher during NR in the Continuous group. Amylase, Lipase and LDH increased throughout the study for all pancreases and showed no statistically significant difference between both groups. The Continuous group had a significantly greater insulin secretion in response to glucose stimulation and followed a biphasic pattern. Continuous HMPO2 preserved islet function and was a superior mode of preservation, showing no statistically significant difference in oedema or markers of damage, with improved perfusion parameters.

O242: Prolonged subnormothermic acellular machine perfusion of human kidneys

Abstract Introduction Prolonged periods of ex vivo perfusion are required to effectively deliver regenerative therapies directly to a kidney before transplantation. This provides time to start repair processes and reduce the likelihood of early graft dysfunction. The aim of this study was to assess the capability of extending the preservation interval using subnormothermic acelllular machine perfusion (SNAP). Methods After a period of static cold storage, 12 human kidneys declined for transplantation were perfused with an oxygenated human serum albumin-based solution at 32°C for 6, 12 or 24h (n=4 per group). After preservation all kidneys were reperfused with a red blood cell-based solution at 37°C for 4h for assessment. Results Functional parameters remained stable during SNAP in all kidneys. However, the perfusate flow rate was significantly lower in the 24h group (24h 166±45, 12h 266±45, 6h 214±36 mL/min/100g; P=0.008). After reperfusion, levels of urinary neutrophil gelatinase-associated lipocalin (uNGAL), insulin-like growth factor binding protein 7 (IGFBP7) and liver-type fatty acid-binding protein (L-FABP) were similar between groups (P&amp;gt;0.05). Levels of oxygen consumption were significantly lower in 24h kidneys compared to 12h (24h 1.45±0.86, 12h 4.3±1.78 mL/min/100g; P=0.0294). Histological evaluation showed a preserved renal morphology in all kidneys, except for the 24h group which showed a mild increase in tubular and endothelial damage. Conclusion This study demonstrated that human kidneys can be successfully preserved with SNAP for up to 12h. There was some evidence of additional ischaemic injury in the 24h SNAP kidneys which warrants further investigation.

A Novel Hypobaric Perfusion Method to Remove Microthrombi in Kidney Grafts with Prolonged Circulatory Arrest: A Pilot Study on a Porcine Model.

Intragraft microthrombi prevent complete organ perfusion, thereby compromising the viability maintained by preservation solutions or machine perfusion. Herein, we developed and evaluated a hypobaric perfusion method for flushing microthrombi from kidney grafts with prolonged circulatory arrest in a porcine model. Porcine renal grafts with 1-h warm ischemia were flushed with heparin-containing perfusate in a normobaric environment (control group) or a hypobaric environment of -20 to -30 mm Hg (hypobaric perfusion group) for 10 min using a gravity drip from a 1-m height. Perfusion parameters, histological findings in ex vivo blood perfusion experiments (2 control and 4 hypobaric perfusion kidneys), and safety in allogeneic porcine transplantation experiments (1 donor to 2 recipients) were evaluated. The -20 mm Hg hypobaric perfusion group exhibited greater maximal flow than the control group (20.4 versus 6.9 mL/min; P = 0.028). Histological evaluation following 3 h of static cold storage and 10 min ex vivo porcine whole-blood perfusion revealed statistically significant reductions in congestion and edema (1.5 versus 3, and 0.5 versus 4 on a 5-point scale, from 0 to 4; P = 0.014 and 0.006, respectively) in the medulla along with improved ischemia-reperfusion injury scores (4.0 versus 4.7 on a 6-point scale, from 0 to 5; P = 0.004) in the -20 mm Hg hypobaric perfusion group. Kidney grafts perfused under -30 mm Hg hypobaric environment followed by 3 h of static cold storage could be used for porcine allogeneic transplantation without any macroscopic damage to the graft, effect on intraoperative handling, or perioperative adverse events. Thus, the hypobaric perfusion method was considered safe. Perfusion in a hypobaric environment may prevent graft congestion, edema, and further reperfusion injury by flushing out erythrocytes occluding the medullary capillaries, improving marginal renal graft quality, and reducing the number of discarded grafts.

Thyroid hormone protects human lung epithelial cells from cold preservation and warm reperfusion-induced injury

BackgroundCellular stress associated with static-cold storage (SCS) and warm reperfusion of donor lungs can contribute to ischemia–reperfusion (IR) injury during transplantation. Adding cytoprotective agents to the preservation solution may be conducive to reducing graft deterioration and improving post-transplant outcomes.MethodsSCS and warm reperfusion were simulated in human lung epithelial cells (BEAS-2B) by exposing cells to low potassium dextran glucose solution at 4 °C for different periods and then switching back to serum-containing culture medium at 37 °C. Transcriptomic analysis was used to explore potential cytoprotective agents. Based on its results, cell viability, caspase activity, cell morphology, mitochondrial function, and inflammatory gene expression were examined under simulated IR conditions with or without thyroid hormones (THs).ResultsAfter 18 h SCS followed by 2 h warm reperfusion, genes related to inflammation and cell death were upregulated, and genes related to protein synthesis and metabolism were downregulated in BEAS-2B cells, which closely mirrored gene profiles found in thyroid glands of mice with congenital hypothyroidism. The addition of THs (T3 or T4) to the preservation solution increases cell viability, inhibits activation of caspase 3, 8 and 9, preserves cell morphology, enhances mitochondrial membrane potential, reduces mitochondrial superoxide production, and suppresses inflammatory gene expression.ConclusionAdding THs to lung preservation solutions may protect lung cells during SCS by promoting mitochondrial function, reducing apoptosis, and inhibiting pro-inflammatory pathways. Further in vivo testing is warranted to determine the potential clinical application of adding THs as therapeutics in lung preservation solutions.

3-O-Methyl-D-Glucose Blunts Cold Ischemia Damage in Kidney via Inhibiting Ferroptosis

BackgroundThe glucose derivative 3-O-methyl-D-glucose (OMG) is used as a cryoprotectant in freezing cells. However, its protective role and the related mechanism in static cold storage (CS) of organs are unknown. The present study aimed to investigate the effect of OMG on cod ischemia damage in cold preservation of donor kidney. MethodsPretreatment of OMG on kidney was performed in an isolated renal cold storage model in rats. LDH activity in renal efflux was used to evaluate the cellular damage. Indicators including iron levels, mitochondrial damage, MDA level, and cellular apoptosis were measured. Kidney quality was assessed via a kidney transplantation (KTx) model in rats. The grafted animals were followed up for 7 days. Ischemia reperfusion (I/R) injury and inflammatory response were assessed by biochemical and histological analyses. ResultsOMG pretreatment alleviated prolonged CS-induced renal damage as evidenced by reduced LDH activities and tubular apoptosis. Kidney with pCS has significantly increased iron, MDA, and TUNEL+ cells, implying the increased ferroptosis, which has been partly inhibited by OMG. OMG pretreatment has improved the renal function (p <0.05) and prolonged the 7-day survival of the grafting recipients after KTx, as compared to the control group. OMG has significantly decreased inflammation and tubular damage after KTx, as evidenced by CD3-positive cells and TUNEL-positive cells. ConclusionOur study demonstrated that OMG protected kidney against the prolonged cold ischemia-caused injuries through inhibiting ferroptosis. Our results suggested that OMG might have potential clinical application in cold preservation of donor kidney.

The Predictive Value of Graft Viability and Bioenergetics Testing Towards the Outcome in Liver Transplantation.

Donor organ biomarkers with sufficient predictive value in liver transplantation (LT) are lacking. We herein evaluate liver viability and mitochondrial bioenergetics for their predictive capacity towards the outcome in LT. We enrolled 43 consecutive patients undergoing LT. Liver biopsy samples taken upon arrival after static cold storage were assessed by histology, real-time confocal imaging analysis (RTCA), and high-resolution respirometry (HRR) for mitochondrial respiration of tissue homogenates. Early allograft dysfunction (EAD) served as primary endpoint. HRR data were analysed with a focus on the efficacy of ATP production or P-L control efficiency, calculated as 1-L/P from the capacity of oxidative phosphorylation P and non-phosphorylating respiration L. Twenty-two recipients experienced EAD. Pre-transplant histology was not predictive of EAD. The mean RTCA score was significantly lower in the EAD cohort (-0.75 ± 2.27) compared to the IF cohort (0.70 ± 2.08; p = 0.01), indicating decreased cell viability. P-L control efficiency was predictive of EAD (0.76 ± 0.06 in IF vs. 0.70 ± 0.08 in EAD-livers; p = 0.02) and correlated with the RTCA score. Both RTCA and P-L control efficiency in biopsy samples taken during cold storage have predictive capacity towards the outcome in LT. Therefore, RTCA and HRR should be considered for risk stratification, viability assessment, and bioenergetic testing in liver transplantation.

Evaluating the Effects of Kidney Preservation at 10 °C with Hemopure and Sodium Thiosulfate in a Rat Model of Syngeneic Orthotopic Kidney Transplantation.

Kidney transplantation is preferred for end-stage renal disease. The current gold standard for kidney preservation is static cold storage (SCS) at 4 °C. However, SCS contributes to renal graft damage through ischemia-reperfusion injury (IRI). We previously reported renal graft protection after SCS with a hydrogen sulfide donor, sodium thiosulfate (STS), at 4 °C. Therefore, this study aims to investigate whether SCS at 10 °C with STS and Hemopure (blood substitute), will provide similar protection. Using in vitro model of IRI, we subjected rat renal proximal tubular epithelial cells to hypoxia-reoxygenation for 24 h at 10 °C with or without STS and measured cell viability. In vivo, we preserved 36 donor kidneys of Lewis rats for 24 h in a preservation solution at 10 °C supplemented with STS, Hemopure, or both followed by transplantation. Tissue damage and recipient graft function parameters, including serum creatinine, blood urea nitrogen, urine osmolality, and glomerular filtration rate (GFR), were evaluated. STS-treated proximal tubular epithelial cells exhibited enhanced viability at 10 °C compared with untreated control cells (p < 0.05). Also, STS and Hemopure improved renal graft function compared with control grafts (p < 0.05) in the early time period after the transplant, but long-term function did not reach significance. Overall, renal graft preservation at 10 °C with STS and Hemopure supplementation has the potential to enhance graft function and reduce kidney damage, suggesting a novel approach to reducing IRI and post-transplant complications.

Two-day Static Cold Preservation of α1,3-Galactosyltransferase Knockout Kidney Grafts Before Simulated Xenotransplantation.

Transplantation remains the preferred treatment for end-stage kidney disease but is critically limited by the number of available organs. Xenografts from genetically modified pigs have become a promising solution to the loss of life while waiting for transplantation. However, the current clinical model for xenotransplantation will require off-site procurement, leading to a period of ischemia during transportation. As of today, there is limited understanding regarding the preservation of these organs, including the duration of viability, and the associated molecular changes. Thus, our aim was to evaluate the effects of static cold storage (SCS) on α1,3-galactosyltransferase knockout (GGTA1 KO) kidney. After SCS, viability was further assessed using acellular sub-normothermic ex vivo perfusion and simulated transplantation with human blood. Compared to baseline, tubular and glomerular interstitium was preserved after 2 days of SCS in both WT and GGTA1 KO kidneys. Bulk RNA-sequencing demonstrated that only eight genes were differentially expressed after SCS in GGTA1 KO kidneys. During sub-normothermic perfusion, kidney function, reflected by oxygen consumption, urine output, and lactate production was adequate in GGTA1 KO grafts. During a simulated transplant with human blood, macroscopic and histological assessment revealed minimal kidney injury. However, GGTA1 KO kidneys exhibited higher arterial resistance, increased lactate production, and reduced oxygen consumption during the simulated transplant. In summary, our study suggests that SCS is feasible for the preservation of porcine GGTA1 KO kidneys. However, alternative preservation methods should be evaluated for extended preservation of porcine grafts.

Comprehensive bile acid pool analysis during ex-vivo liver perfusion in a porcine model of ischemia-reperfusion injury

Bile acids (BA) are key for liver regeneration and injury. This study aims at analyzing the changes in the BA pool induced by ischemia-reperfusion (IRI) and investigates the impact of hypothermic oxygenated perfusion (HOPE) on the BA pool compared to static cold storage (SCS). In a porcine model of IRI, liver grafts underwent 30 min of asystolic warm ischemia followed by 6 h of SCS (n = 6) ± 2 h of HOPE (n = 6) and 2 h of ex-situ warm reperfusion. The BA pool in bile samples was analyzed with liquid chromatography coupled with tandem mass spectrometry. We identified 16 BA and observed significant changes in response to ischemia-reperfusion, which were associated with both protective and injury mechanisms. Second, HOPE-treated liver grafts exhibited a more protective BA phenotype, characterized by a more hydrophilic BA pool compared to SCS. Key BA, such as GlycoCholic Acid, were identified and were associated with a decreased transaminase release and improved lactate clearance during reperfusion. Partial Least Square-Discriminant Analysis revealed a distinct injury profile for the HOPE group. In conclusion, the BA pool changes with liver graft IRI, and preservation with HOPE results in a protective BA phenotype compared to SCS.