Static Cold Storage Research Articles

Normothermic Machine Perfusion Reconstitutes Porcine Kidney Tissue Metabolism But Induces an Inflammatory Response, Which Is Reduced by Complement C5 Inhibition

Normothermic machine perfusion (NMP) is a clinical strategy to reduce renal ischemia-reperfusion injury (IRI). Optimal NMP should restore metabolism and minimize IRI induced inflammatory responses. Microdialysis was used to evaluate renal metabolism. This study aimed to assess the effect of complement inhibition on NMP induced inflammatory responses. Twenty-two pig kidneys underwent 18 h of static cold storage (SCS) followed by 4 h of NMP using a closed-circuit system. Kidneys were randomized to receive a C5-inhibitor or placebo during SCS and NMP. Perfusion resulted in rapidly stabilized renal flow, low renal resistance, and urine production. During SCS, tissue microdialysate levels of glucose and pyruvate decreased significantly, whereas glycerol increased (p < 0.001). In the first hour of NMP, glucose and pyruvate increased while glycerol decreased (p < 0.001). After 4 h, all metabolites had returned to baseline. Inflammatory markers C3a, soluble C5b-9, TNF, IL-6, IL-1β, IL-8, and IL-10 increased significantly during NMP in perfusate and kidney tissue. C5-inhibition significantly decreased perfusate and urine soluble C5b-9 (p < 0.001; p = 0.002, respectively), and tissue IL-1β (p = 0.049), but did not alter other inflammatory markers. Microdialysis can accurately monitor the effect of NMP on renal metabolism. Closed-circuit NMP induces inflammation, which appeared partly complement-mediated. Targeting additional immune inhibitors should be the next step.

Liver Transplant Using Normothermic Machine Perfusion in Patients With High-Acuity Illness

This case-control study compares outcomes of normothermic machine perfusion vs static cold storage used in liver transplant for complex patients.

Machine Perfusion or Straight to Transplant? Predictive Value of Flavin Mononucleotide Levels in Flush Solution of Human Liver Allograft.

This study examined the predictive value of Flavin Mononucleotide (FMN) levels in the flush solution used during cold storage of donor livers on outcomes post-transplantation. Static cold storage for liver grafts induces hypoxia with subsequent impaired mitochondrial function and Flavin Mononucleotide (FMN) release upon reperfusion. This study enrolled 62 recipients who received whole liver grafts from donation after brain death (n=50) and circulatory death donors (n=12) between June 2022 and July 2023. FMN concentrations were measured in flush solutions on the back-table. ROC-curve analysis identified an FMN level cut-off for graft survival. Post-transplant outcomes were examined according to FMN levels. FMN level was significantly associated with graft survival, with an area-under-the-curve (AUC) of 0.858 (95%CI: 0.754-0.963, P<0.001), outperforming the donor risk index (AUC 0.571, 95%CI: 0.227-0.915, P=0.686). The study cohort was divided into low-FMN (<37.5ng/mL, n=40) and high-FMN groups (≥37.5ng/mL, n=22). The low-FMN group had superior one-year graft survival compared with the high-FMN group (100% vs. 77%, P=0.003). Levels of transaminases within 7 days post-transplant were significantly higher in the high-FMN group (P=0.003). The high-FMN group developed acute rejections (41% vs. 15%, P=0.023) and early allograft dysfunction (50% vs. 20%, P=0.014) more frequently. Median comprehensive complication index in the high-FMN group was significantly higher (54 [interquartile range, 40-78] vs. 42 [interquartile range, 28-52], P=0.017). The FMN level measured in donor livers' cold storage flush solution is a valid biomarker to predict post-transplant outcomes. Liver grafts with high FMN levels may benefit from machine perfusion to improve outcomes.

Dual hypothermic oxygenated machine perfusion of the liver reduces post transplant biliary complications - a retrospective cohort study.

Corroborating evidence for use of hypothermic oxygenated machine perfusion (HOPE) prior to orthotopic liver transplantation (OLT) suggests a beneficial effect in regards to biliary complications. Here, we aim to evaluate whether perfusion via portal vein alone (sHOPE) or via additional perfusion of the hepatic artery (dHOPE) have diverging impact on outcomes after OLT when compared to use of static cold storage (SCS). Consecutive patients undergoing OLT at Medical University of Vienna (2018 to 2023) were retrospectively analyzed. Donor organs were procured using SCS, or subjected to end-ischemic sHOPE or dHOPE. Severity of biliary complications was classified according to degree of therapeutic intervention (endoscopic retrograde cholangiopancreatography or surgical revision). 247 patients were included (69 SCS, 76 sHOPE, 102 dHOPE). Hospitalization was shorter for patients after HOPE (median in days: SCS=25 vs HOPE=20, P=0.019). Biliary complications were less frequent in patients after HOPE (SCS=37.7% vs HOPE=22.5%, P=0.015). A significantly lower incidence of surgical revisions for biliary complications was observed in the HOPE cohort (24.6% vs 11.8%, P=0.012). When evaluating outcome according to HOPE-modality, a significant reduction in biliary complications (P=0.006) and surgical revisions (P=0.002) was only observed in dHOPE patients in comparison to SCS. Further, only dHOPE was significantly associated with reduced need for surgical revision for biliary complications upon uni- and multivariable logistic regression (odds ratio=0.336, P=0.011). HOPE leads to a reduction of biliary complications and associated surgical revisions. This effect seems to be primarily associated with use of dHOPE, while both methods appear as feasible options for preconditioning of donor grafts prior to OLT.

Outcomes of Donation After Circulatory Death Heart Transplantation Using Normothermic Regional Perfusion

BackgroundDonation after circulatory death (DCD) with cardiopulmonary bypass for thoracoabdominal normothermic regional perfusion (TA-NRP) has led to increased use of donor hearts. Rejection rates and long-term survival outcomes are not known. MethodsA single-center retrospective cohort review of patients who underwent DCD heart transplantation from January 2020 to December 2023 was performed. Donor and recipient characteristics, operative characteristics, and posttransplantation outcomes were analyzed. Subgroup analysis comparing co-localized vs distant donors and recipients was performed. The primary end point was 1-year survival. Secondary end points included incidences of primary graft dysfunction (PGD), cardiac allograft vasculopathy (CAV), rejection rate, and overall mortality. Our TA-NRP protocol has remained the same, consisting of sternotomy, ligation of aortic arch vessels, establishment of cardiopulmonary bypass, reintubation, resuscitation of the heart, and cold static storage during transport. ResultsIn total, 32 recipients underwent DCD heart transplantation, including 26 isolated hearts, 3 heart-lungs, and 3 heart-kidneys. The median age was 56 years for recipients and 39 years for donors; 21 donors and recipients were co-localized, whereas 11 were distant. One-year survival was 100%. Two patients required mechanical circulatory support for PGD. Four patients experienced grade 2R acute cellular rejection. Five patients had grade 1 CAV at 1 year. On subgroup analysis, distant donors and recipients had longer warm (47 vs 30 minutes; P < .005) and cold (213 vs 76 minutes; P < .005) ischemia times, without any other differences. ConclusionsOutcomes after DCD heart transplantation using TA-NRP remain encouraging with acceptable rates of rejection, PGD, CAV, and survival at 1 year.

Preservation of coagulation function by normothermic machine perfusion in liver transplant as evidenced by thromboelastography parameters

The use of normothermic machine perfusion over static cold storage in liver transplantation has been shown to reduce post-transplant risks of early allograft dysfunction, primary nonfunction, and ischemic cholangiopathy, and its increasing use has played a role in the expanded utilization of marginal livers. While studies have demonstrated improved clinical outcomes utilizing normothermic machine perfusion over static cold storage preservation, real-time intraoperative data reflecting the quality and viability of normothermic machine perfusion livers is limited. This retrospective, single-center study compared normothermic machine perfusion vs static cold storage livers in first-time liver transplant recipients through the evaluation of synthetic coagulation function as measured by thromboelastography and conventional coagulation testing. Secondarily, transfusion utilization between the two cohorts were reviewed. 186 liver transplant recipients receiving allografts from donors after circulatory death were included in the study, of which 99 (53%) allografts were preserved in static cold storage, and 87 (47%) allografts were placed on the TransMedics Organ Care System. Study findings showed normothermic machine perfusion livers supported with the TransMedics Organ Care System were associated with increased synthetic coagulation function and less excess fibrinolysis in the post-reperfusion period compared to static cold storage livers, and that these findings were better reflected in real-time with thromboelastography monitoring vs conventional coagulation testing. Following reperfusion, there was a significant decrease in the transfusion of blood products in the normothermic machine perfusion group compared with that in the static cold storage group. Overall, we determined that the use of intraoperative thromboelastography can provide real-time data to assess one aspect of reperfusion liver quality and viability.

Hyperspectral imaging of human liver allografts for prediction of initial graft function

PurposeIschemia reperfusion injury represents a significant yet difficult to assess risk factor for short- and long-term graft impairment in human liver transplantation (LT). As a non-invasive, non-ionizing tool, hyperspectral imaging (HSI) is capable of correlating optical properties with organ microperfusion. Hence, we here performed a study of human liver allografts assessed by HSI for microperfusion and prediction of initial graft function.MethodsImages of liver parenchyma of 37 human liver allografts were acquired at bench preparation, during normothermic machine perfusion (NMP), if applicable, and after reperfusion in the recipient. A specialized HSI acquisition software computed oxygen saturation (StO2), tissue hemoglobin indices (THI), near infrared perfusion indices (NIR), and tissue water indices (TWI). HSI parameters were analyzed for differences with regard to preservation technique, reperfusion sequence and presence of early allograft dysfunction (EAD).ResultsOrgan preservation was performed by means of NMP (n = 31) or static cold storage (SCS; n = 6). Patients’ demographics, donor characteristics, presence of EAD (NMP 36.7% vs. SCS 50%, p = 0.6582), and HSI parameters were comparable between both groups of preservation method. In organs developing EAD, NIR at 1, 2, and 4 h NMP and after reperfusion in the recipient was significantly lower (1 h NMP: 18.6 [8.6–27.6] vs. 28.3 [22.5–39.4], p = 0.0468; 2 h NMP: 19.4 [8.7–30.4] vs. 37.1 [27.5–44.6], p = 0.0011; 4 h NMP: 26.0 [6.8–37.1] vs. 40.3 [32.3–49.9], p = 0.0080; reperfusion: 13.0 [11.5–34.3] vs. 30.6 [19.3–44.0], p = 0.0212).ConclusionHSI assessment of human liver allografts is feasible during organ preservation and in the recipient. NIR during NMP and after reperfusion might predict the onset of EAD. Larger trials are warranted for assessment of this novel technique in human LT.

Cost-effectiveness of Dual Hypothermic Oxygenated Machine Perfusion Versus Static Cold Storage in DCD Liver Transplantation.

Ex situ machine perfusion of the donor liver, such as dual hypothermic oxygenated machine perfusion (DHOPE), is increasingly used in liver transplantation. Although DHOPE reduces ischemia/reperfusion-related complications after liver transplantation, data on cost-effectiveness are lacking. Our objective was to evaluate the cost-effectiveness of DHOPE in donation after circulatory death (DCD) liver transplantation. We performed an economic evaluation of DHOPE versus static cold storage (SCS) based on a multicenter randomized controlled trial in DCD liver transplantation (DHOPE-DCD trial; ClinicalTrials.gov number, NCT02584283). All patients enrolled in the 3 participating centers in the Netherlands were included. Costs related to the transplant procedure, hospital stay, readmissions, and outpatients treatments up to 1 y posttransplant were calculated. The cost for machine perfusion was calculated using 3 scenarios: (1) costs for machine perfusion, (2) machine perfusion costs plus costs for personnel, and (3) scenario 2 plus depreciation expenses for a dedicated organ perfusion room. Of 119 patients, 60 received a liver after DHOPE and 59 received a liver after SCS alone. The mean total cost per patient up to 1 y posttransplant was €126 221 for the SCS group and €110 794 for the DHOPE group. The most significant reduction occurred in intensive care costs (28.4%), followed by nonsurgical interventions (24.3%). In cost scenario 1, DHOPE was cost-effective after 1 procedure. In scenarios 2 and 3, cost-effectiveness was achieved after 25 and 30 procedures per year, respectively. Compared with conventional SCS, machine perfusion using DHOPE is cost-effective in DCD liver transplantation, reducing the total medical costs up to 1 y posttransplant.

Using an Isolated Working Rat Heart Model to Test Donor Heart Preservation Strategies.

Optimization of donor heart preservation solutions has played a key role in reducing ischemia-reperfusion injury in donor hearts during organ retrieval, transportation, and transplantation. Previous work from our laboratory showed that the addition of glyceryl trinitrate and erythropoietin to donor heart preservation solutions could significantly improve cardiac functional recovery after prolonged cold storage and in donation after circulatory death hearts. This supplementation protocol has been implemented in clinical use in transplant units around Australia, Belgium, and the United Kingdom. Here, we outline a protocol for testing supplementation strategies using an ex vivo isolated working rat heart (IWRH) perfusion circuit. Using this methodology, supplementation strategies can be tested in the context of prolonged cold static storage, donation after brain death, and donation after circulatory death donor heart preservation. Cardiac functional recovery, measured by aortic flow, coronary flow, cardiac output, pulse pressure, and heart rate, can be used to determine whether a particular preservation strategy can minimize ischemia-reperfusion injury of the donor heart.

Enhanced VCA Storage: A Pilot Study Demonstrating Supercooling in Orthotopic Rodent Hindlimb Transplantation

The field of vascularized composite allograft (VCA) transplantation has seen steady, rapid growth, with new innovations driving the evolution from experimental procedures to more standardized therapies. With this expansion comes challenges with graft allocation, preservation, and postoperative graft rejection. Here, we outline the first example of subzero nonfreezing (SZNF), supercooled storage of a whole rat hindlimb with orthotopic transplantation. Rat hindlimbs were procured, loaded, and supercooled for 48 hours at -4°C (n = 4), after which, they were recovered. The loading and recovery phase were performed using subnormothermic machine perfusion (SNMP) during which viability markers (glucose and oxygen consumption, lactate, and resistance) were tracked. Control limbs underwent static cold storage (SCS). After ex vivo validation, the model was piloted in a transplant model, comparing 48 hours of SZNF (n = 1), 48 hours of SCS (n = 1), and 72 hours of SCS (n = 1), which demonstrated no survival beyond postoperative day 4 in the SCS models, and survival until the end of study (postoperative day [POD] 28) in the SZNF model. This study demonstrates the promise of this model in future studies on long-term VCA preservation.

Static magnetic field increases the antioxidant stress ability of static cold storage livers and improves post-storage quality

Static magnetic field increases the antioxidant stress ability of static cold storage livers and improves post-storage quality

Perfusate hemoglobin during normothermic liver machine perfusion as biomarker of early allograft dysfunction: Apilot study.

Normothermic machine perfusion (NMP) aims to reduce ischemia-reperfusion injury in donor livers and its clinical manifestation, early allograft dysfunction (EAD) by maintaining perfusion and oxygenation. However, there is limited data on which NMP perfusate biomarkers might be associated with such EAD and the role of perfusate hemoglobin has not been assessed. We performed a pilot retrospective analysis of adult donor livers undergoing NMP between 2020 and 2022 at our center. NMP was commenced at the recipient hospital after initial static cold storage. All NMP circuits were primed in the same manner according to the manufacturer's instructions. Livers were stratified by initial perfusate hemoglobin below (≤5.2 mmol/L) or above (>5.2 mmol/L) the median. The association between hemoglobin levels and EAD or recipient peak transaminase levels was assessed. Among 23 livers, eight were considered unsuitable for transplantation, leaving 15 livers for assessment. Higher initial hemoglobin was associated with a lower risk of EAD (0% vs. 55.6%, p = 0.04). Perfusate hemoglobin decreased after NMP initiation (p = 0.003) and negatively correlated with recipient peak transaminase levels (ALT: ρ = -0.72, p = 0.002; AST: ρ = -0.79, p < 0.001). Consistently, higher hemoglobin livers also demonstrated lower perfusate liver enzymes. Perfusate hemoglobin levels decreased during NMP, and lower perfusate hemoglobin levels were associated with a higher incidence of EAD and higher levels of liver injury markers. Maintaining higher hemoglobin levels during NMP may help reduce ischemia-reperfusion injury and prevent or attenuate EAD. Larger prospective studies are needed to validate the findings of this pilot study.

Matched pair analysis of the effect of longer hypothermic machine perfusion time on kidney transplant outcomes.

Hypothermic machine perfusion (HMP) has demonstrated benefits in terms of early kidney transplant function compared to static cold storage. While longer preservation times have shown detrimental effects, a previous paired study indicated that longer pump times (the second kidney in a pair) might lead to improved outcomes. To revisit the prior paired study's somewhat unexpected results by reviewing our program's experience. A total of 61 pairs of transplant recipients who received kidneys from the same donor (2012-2021) were analyzed. Patients were divided into two groups depending on whether they were transplanted first (K1) or second (K2). Therefore, the patients in each pair had identical donor characteristics, except for time on the pump. Statistical analyses included Kaplan-Meyer analysis and paired tests, including McNemar's test, student's paired t-test, or Wilcoxon's test, as appropriate. The two groups of recipients had similar demographics (age, body mass index, diabetes, time on dialysis, sensitization and retransplants). Cold ischemic times for K1 and K2 were 8.9 (95%CI: 7.9, 9.8) and 14.7 hours (13.7, 15.8) (P < 0.0001), respectively. Overall, K2 had a higher rate of freedom from biopsy-proven acute rejection at 1 year (P = 0.015). Delayed graft function was less common in K2, 12/61 (20%) than in K1, 20/61 (33%) (P = 0.046). Finally, K2 showed a higher graft survival than K1 (P = 0.023). Our results agree with a previous study that suggested possible advantages to longer pump times. Both studies should encourage further research into HMP's potential anti-inflammatory effect.

Normothermic ex vivo kidney perfusion preserves mitochondrial and graft function after warm ischemia and is further enhanced by AP39

We previously reported that normothermic ex vivo kidney perfusion (NEVKP) is superior in terms of organ protection compared to static cold storage (SCS), which is still the standard method of organ preservation, but the mechanisms are incompletely understood. We used a large animal kidney autotransplant model to evaluate mitochondrial function during organ preservation and after kidney transplantation, utilizing live cells extracted from fresh kidney tissue. Male porcine kidneys stored under normothermic perfusion showed preserved mitochondrial function and higher ATP levels compared to kidneys stored at 4 °C (SCS). Mitochondrial respiration and ATP levels were further enhanced when AP39, a mitochondria-targeted hydrogen sulfide donor, was administered during warm perfusion. Correspondingly, the combination of NEVKP and AP39 was associated with decreased oxidative stress and inflammation, and with improved graft function after transplantation. In conclusion, our findings suggest that the organ-protective effects of normothermic perfusion are mediated by maintenance of mitochondrial function and enhanced by AP39 administration. Activation of mitochondrial function through the combination of AP39 and normothermic perfusion could represent a new therapeutic strategy for long-term renal preservation.

Innovations in Liver Preservation Techniques for Transplants from Donors after Circulatory Death: A Special Focus on Transplant Oncology.

Liver transplantation is the preferred treatment for end-stage liver disease. Emerging evidence suggests a potential role for liver transplantation in treating liver tumors such as colorectal liver metastases and cholangiocarcinoma. However, due to a limited donor pool, the use of marginal grafts from donation after circulatory death (DCD) donors is increasing to meet demand. Machine perfusion is crucial in this context for improving graft acceptance rates and reducing ischemia-reperfusion injury. Few studies have evaluated the role of machine perfusion in the context of transplant oncology. Perfusion machines can be utilized in situ (normothermic regional perfusion-NRP) or ex situ (hypothermic and normothermic machine perfusion), either in combination or as a complement to conventional in situ cold flush and static cold storage. The objective of this analysis is to provide an up-to-date overview of perfusion machines and their function in donation after circulatory death with particular attention to their current and likely potential effects on transplant oncology. A literature review comparing standard cold storage to machine perfusion methods showed that, so far, there is no evidence that these devices can reduce the tumor recurrence rate. However, some evidence suggests that these innovative perfusion techniques can improve graft function, reduce ischemia-reperfusion injury, and, based on this mechanism, may lead to future improvements in cancer recurrence.

Low-Volume Ex Situ Lung Perfusion System for Single Lung Application in a Small Animal Model Enables Optimal Compliance With "Reduction" in 3R Principles of Animal Research.

Ex situ lung perfusion (ESLP) is used for organ reconditioning, repair, and re-evaluation prior to transplantation. Since valid preclinical animal models are required for translationally relevant studies, we developed a 17mL low-volume ESLP for double- and single-lung application that enables cost-effective optimal compliance "reduction" of the 3R principles of animal research. In single-lung mode, ten Fischer344 and Lewis rat lungs were subjected to ESLP and static cold storage using STEEN or PerfadexPlus. Key perfusion parameters, thermal lung imaging, blood gas analysis (BGA), colloid oncotic pressure (COP), lung weight gain, histological work-up, and cytokine analysis were performed. Significant differences between perfusion solutions but not between the rat strains were detected. Most relevant perfusion parameters confirmed valid ESLP with homogeneous lung perfusion, evidenced by uniform lung surface temperature. BGA showed temperature-dependent metabolic activities with differences depending on perfusion solution composition. COP is not decisive for pulmonary oedema and associated weight gain, but possibly rather observed chemokine profile and dextran sensitivity of rats. Histological examination confirmed intact lung architecture without infarcts or hemorrhages due to optimal organ procurement and single-lung application protocol using our in-house-designed ESLP system.

P.331: Static cold storage using a novel kidney envelope for preservation of donor kidney.

P.331: Static cold storage using a novel kidney envelope for preservation of donor kidney.

Transplantation Outcomes in Hepatitis C Virus-Positive Donor Hearts After Circulatory Death

Although the use of hepatitis C virus (HCV)-positive hearts has been shown to be safe and effective among donors with donation after brain death (DBD), it remains unknown whether such organs recovered after circulatory death (DCD) have similar outcomes. In contradistinction to recovery from DBD using cold static organ storage, DCD procurement processes typically use normothermic-perfusion transport strategies that necessitate the use of a large volume of donor blood and involve exposure to temperatures oscillating between cold to dominantly normothermic conditions. We performed a retrospective analysis of United Network for Organ Sharing (UNOS) registry data in the United States and found that clinical outcomes do not differ with respect to rates of treated allograft rejection, early and 1-year survival. Ideally, the organ-recovery source should not result in a bias in organ-offer acceptance from HCV-positive donors, although long-term outcome data are yet unavailable.

The current landscape of in situ and ex situ machine perfusion utilization for liver grafts from cardiac donation after circulatory death donors in the US

Donation after circulatory death (DCD) is driving the increase in deceased organ donors in the United States. Normothermic regional perfusion (NRP) and ex situ machine perfusion (es-MP) have been instrumental in improving liver transplant outcomes and graft utilization. This study examines the current landscape of liver utilization from cardiac DCD donors in the United States. Using the United Network for Organ Sharing Standard Transplant Analysis and Research file, all adult (≥18 years old) DCD donors in the United States from which the heart was used for transplantation from October 1, 2020, to September 30, 2023, were compared by procurement technique (NRP versus super rapid recovery [SRR]) and storage strategy (es-MP versus static cold storage). One hundred eighty-eight livers were transplanted from 309 thoracoabdominal NRP donors (61% utilization) versus 305 (56%) liver transplants from 544 SRR donors. es-MP was used in 20% (n = 38) of NRP cases versus 32% (98) of SRR cases. Of the liver grafts, 281 (59%) were exposed to NRP, es-MP, or both. While there is widespread utilization of machine perfusion, more research is needed to determine optimal graft management strategies, particularly concerning the use of multiple technologies in complementary ways. More complete data collection is necessary at a national level to address these important research questions.

261.10: Prolonged static cold storage results in significant pelvic hematomas during normothermic machine perfusion of porcine kidney grafts.

261.10: Prolonged static cold storage results in significant pelvic hematomas during normothermic machine perfusion of porcine kidney grafts.