Machine Perfusion Research Articles

Use of Machine Perfusion in the United States Increases Organ Utilization and Improves DCD Graft Survival in Liver Transplantation.

Adoption of machine perfusion (MP) technology has rapidly expanded in liver transplantation without real-world data on utilization and outcomes, which are critical to understand the appropriate application of MP technology. The Organ Procurement and Transplant Network/Standard Transplant Analysis and Research database was used to identify all deceased donor livers procured with intent for transplant between October 27, 2015 (date of first recorded MP) and June 30, 2023 (n = 67 795). Liver allografts were cohorted by donation after brain death (DBD; n = 59 957) or circulatory death (DCD; n = 7873) and analyzed by static cold storage (SCS) or MP preservation method. Donor demographics, organ utilization, and graft survival were evaluated. By 2023, 12.5% of all livers and 37.2% of DCD livers underwent MP preservation (82.6% normothermic, 6.7% hypothermic, and 10.8% other/unknown). Compared with SCS, MP liver donors were older (DBD: 48 versus 40 y [P < 0.001]; DCD: 43 versus 38 y [P < 0.001]) with higher body mass index (DBD: 28.8 versus 26.9 kg/m2 [P < 0.001]; DCD: 27.7 versus 26.9 kg/m2 [P = 0.004]). Donor livers had similar levels of macrosteatosis (median 5%). Graft utilization was higher for MP than SCS after DBD (96.4% versus 93.0%, P < 0.001) and DCD (91.4% versus 70.3%, P < 0.001) donation. Graft survival was similar between MP and SCS livers from DBD donors (P = 0.516), whereas MP-preserved grafts had superior survival from DCD donors at 1 and 3 y posttransplant (P = 0.013 and 0.037). Patient survival was similar across all groups at 3 y (P = 0.322). The use of MP in liver transplantation increased rates of liver utilization and improved graft survival after DCD. Further monitoring of MP outcomes is required to understand long-term benefits.

A betaine-contained solution reduced cold ischemia damage through inhibiting vacuolar degeneration in livers

A new osmoprotectant-containing multiple saccharide (MS) solution was formulated for this study. The primary objectives were to compare the effects of the MS solution with those of the University of Wisconsin (UW) solution and hypertonic citrate adenine (HCA) solution on liver cold preservation, as well as to investigate the mechanisms underlying osmolarity-induced injury. Rat livers were cold-stored for 18 h at 4 °C using the different solutions and subsequently subjected to 2 h of normothermic machine perfusion (NMP) for functional assessment. The livers were categorized into four groups: HCA, UW, MS, and a control group. Liver function and histological changes were evaluated using biochemical markers such as lactate dehydrogenase (LDH), alongside histopathological analysis. Additionally, the expression of aquaporin 9 (AQP9) and hydrogen peroxide (H2O2) in hepatocytes was examined. Liver damage was significantly reduced in the UW and MS groups (p < 0.05). Histopathological analysis revealed a decrease in hepatic apoptosis and injury scores in the MS group compared to the HCA group (p < 0.05). No significant differences in liver function changes were observed between the MS and UW groups. Furthermore, examination of liver tissue showed increased H2O2 fluorescence intensity and decreased AQP9 protein levels in livers exhibiting vacuolar degeneration. In conclusion, the MS solution demonstrated superior effectiveness in preserving the liver during cold storage by inhibiting vacuolar degeneration caused by intracellular H2O2 accumulation.

Dynamics of Ischemia/Reperfusion Injury Markers During Normothermic Liver Machine Perfusion

Background. A comprehensive mechanistic assessment of normothermic machine perfusion (NMP) is an essential step toward identifying biomarkers to assess liver viability. Although some studies have evaluated the effect of NMP on inflammation markers, there are other key pathological mechanisms involved in ischemia/reperfusion injury (IRI) that have not yet been evaluated. Methods. Eight human donor livers preserved by NMP were included to analyze IRI during preservation. Concentrations of several biomarkers involved in different biological processes of IRI were measured in the perfusate. Results. Perfusate levels of intercellular adhesion molecule 1, P-selectin, vascular cell adhesion molecule 1, metalloproteinase with thrombospondin motif type 1, member 13, phospholipase A2 group VII, and syndecan-1 progressively increased during NMP. Noteworthy, perfusate lactate levels showed a strong correlation with C-X-C motif chemokine ligand 10 (P = 0.001), intercellular adhesion molecule 1 (P = 0.01), and urokinase plasminogen activator (P = 0.001). Conclusions. Perfusate lactate correlates with the main underlying biological mechanisms occurring in the NMP environment. Moreover, several IRI biomarkers accumulate during NMP, which may limit the extent of the benefits of this technology.

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

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

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 &amp;lt; 0.001). In the first hour of NMP, glucose and pyruvate increased while glycerol decreased (p &amp;lt; 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 &amp;lt; 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.

Long-term machine perfusion of human split livers: a new model for regenerative and translational research.

Recent advances in machine perfusion have revolutionised the field of transplantation by prolonging preservation, permitting evaluation of viability prior to implant and rescue of discarded organs. Long-term perfusion for days-to-weeks provides time to modify these organs prior to transplantation. By using long-term normothermic machine perfusion to facilitate liver splitting and subsequent perfusion of both partial organs, possibilities even outside the clinical arena become possible. This model remains in its infancy but in the future, could allow for detailed study of liver injury and regeneration, and ex-situ treatment strategies such as defatting, genetic modulation and stem-cell therapies. Here we provide insight into this new model for research and highlight its great potential and current limitations.

Unlocking the Promise of Liver Perfusion Technologies for Pediatric Transplantation: A State-of-the-Art Review.

Outcomes after pediatric liver transplantation are generally excellent, but the limited avavailability of suitable, size-matched liver allografts remains a significant barrier. Machine perfusion technology has emerged as a promising approach to expand the donor pool, enabling the use of less ideal whole liver grafts, such as livers donated after circulatory death, and enhancing the execution of split liver transplantation. This review examines the application of machine perfusion in pediatric liver transplantation, focusing on two primary techniques: hypothermic oxygentaed perfusion and normothermic machine perfusion. These methods optimize storage, resuscitation, and assessment of liver grafts before transplantation, potentially expanding the range of usable donor organs. The use of machine perfusion allows for the consideration of suboptimal donor livers and facilitates split liver transplantation, both of which could increase organ availability for pediatric patients. Implementation of machine perfusion could also help reduce waiting list mortality by enabling the safe use of a broader spectrum of donor organs. Adoption of machine perfusion in pediatric liver transplantation will require collaborative, multidisciplinary efforts across transplant centers. By fostering cooperative learning and sharing resources. the integration of machine perfusion into clinical practice has the potential to reduce mortality among children awaiting liver transplantation.

A Guide to the Implementation and Design of Ex Vivo Perfusion Machines for Vascularized Composite Allotransplantation.

Ex vivo machine perfusion (EVMP) is a versatile platform utilized in vascularized composite allotransplantation (VCA) to prolong preservation, salvage tissue, and evaluate graft viability. However, there is no consensus on best practices for VCA. This article discusses the common components, modifications, and considerations necessary for a successful VCA perfusion. A systematic literature review was performed in several databases (PubMed, Scopus, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov) to identify articles published on VCA EVMP (face, limb, abdominal wall, uterus, penis, and free flaps) before August 2022. Graft type and animal model, general perfusion parameters, core components of the circuit, and optional components for enhanced monitoring were extracted from the articles. A total of 1370 articles were screened, and 46 articles met inclusion criteria. Most articles (84.8%) were published in the last 10 years. Pigs were the main model used, but 10 protocols used human grafts. Free flaps were the most common graft type (41.3%), then upper extremities/forelimbs (28.3%), uteruses (17.4%), and hindlimbs (13.0%). Postperfusion replantation occurred in 15.2% of studies. Normothermic perfusion predominated (54.1%), followed by hypothermic (24.3%), and subnormothermic (21.6%). The majority of studies (87.0%) oxygenated their systems, most commonly with carbogen. EVMP is a rapidly growing area of research. Leveraging EVMP in VCA can optimize VCA procedures and allow for expansion into replantation, flap salvage, and other areas of plastic surgery. Currently, VCA EVMP is achieved through a variety of approaches, but standardization is necessary to advance this technology and attain clinical translation.

Perfusate Biomarkers of DCD Cardiac Graft Quality Identified With Proteomics: Studies in an Isolated Rat Heart Model.

Heart transplantation with donation after circulatory death (DCD) enhances cardiac graft availability, but exposes hearts to potentially damaging conditions, such as warm ischemia. Normothermic machine perfusion (NMP), used for graft transportation, allows biomarker determination in perfusate. Using our isolated, rat heart model of DCD, we evaluated potent. Isolated, perfused adult male Wistar rat hearts (n = 5/group) underwent different warm ischemic durations to simulate DCD, followed by reperfusion to simulate NMP. Perfusate samples were collected after 10 min reperfusion, and proteins were analyzed using mass spectrometry. Cardiac recovery was evaluated after 60 min reperfusion. The relationship between perfusate proteins and cardiac recovery was investigated. Cardiac recovery decreased with increasing ischemic duration. Principal component analysis of perfusate proteins demonstrated segregation by ischemic group. Several proteins demonstrated an On-Off pattern, and correlated with key outcome measurements. Other proteins were released by all hearts and were confirmed as predictors of cardiac recovery, for example, heat shock protein 70 and valosin-containing protein (area under the curve [AUC] = 0.962-0.968, respectively; P < 0.05 for all). Additionally, proteins such as glycogen phosphorylase, muscle associated (AUC = 0.9632; P < 0.05) showed potential as novel biomarkers for evaluating cardiac graft quality, unlike lactate release after 10 min of reperfusion (AUC = 0.60). Multiple perfusate proteins, such as heat shock protein 70, valosin-containing protein, or glycogen phosphorylase, muscle associated, released during early reperfusion are promising as biomarkers for assessing graft quality during NMP. Perfusate proteins, as biomarkers, offer the possibility of both rapid immune detection and out-of-hospital implementation, and may provide valuable information about graft quality, especially when profiled with serial sampling during NMP.

Comment on “Impact of Back-to-Base Normothermic Machine Perfusion on Complications and Costs: A Multi-Center, Real-World Risk-Matched Analysis”

Comment on “Impact of Back-to-Base Normothermic Machine Perfusion on Complications and Costs: A Multi-Center, Real-World Risk-Matched Analysis”

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.

Current basic research in normothermic machine perfusion.

Background Normothermic machine perfusion (NMP) is gradually being introduced into clinical transplantation to improve the quality of organs and increase utilisation. This review details current understanding of the underlying mechanistic effects of NMP in the heart, lung, liver and kidney. It also considers recent advancements to extend the perfusion interval in these organs and the use of NMP to introduce novel therapeutic interventions, with a focus on organ modulation. Summary The re-establishment of circulation during NMP leads to the upregulation of inflammatory and immune mediators, similar to an ischaemia reperfusion injury (IRI) response. The level of injury is determined by the condition of the organ, but inflammation may also be exacerbated by the passenger leucocytes that emerge from the organ during perfusion. There is evidence that damaged organs can recover and that prolonged NMP may be advantageous. In the liver, successful 7 day NMP has been achieved. The delivery of therapeutic agents to an organ can aid repair and be used to modify the organ to reduce immunogenicity or change the structure of the blood group antigens to create a universal donor blood group organ. Key messages The application of NMP in organ transplantation is a growing area of research and is increasingly being used in the clinic. In the future NMP may offer the opportunity to change practice. If organs can be preserved for days on an NMP system, transplantation may become an elective rather than an emergency procedure. The ability to introduce therapies during NMP is an effective way to treat an organ and avoid the complexity of treating the recipient.

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.

A reproducible extended ex-vivo normothermic machine liver perfusion protocol utilising improved nutrition and targeted vascular flows

BackgroundNormothermic machine perfusion of donor livers has become standard practice in the field of transplantation, allowing the assessment of organs and safe extension of preservation times. Alongside its clinical uses, there has been expanding interest in extended normothermic machine perfusion (eNMP) of livers as a potential vehicle for medical research. Reproducible extended normothermic machine perfusion has remained elusive due to its increased complexity and monitoring requirements. We set out to develop a reproducible protocol for the extended normothermic machine perfusion of whole human livers.MethodsHuman livers declined for transplantation were perfused using a blood-based perfusate at 36 °C using the Liver Assist device (XVIVO, Sweden), with continuous veno-venous haemofiltration in-parallel. We developed the protocol in a stepwise fashion.ResultsPerfusion techniques utilised included: targeted physiological vascular flows, phosphate replacement (to prevent hypophosphataemia), N-acetylcysteine (to prevent methaemoglobin accumulation), and the utilisation of sodium lactate as both a nutritional source and real-time measure of hepatocyte function. All five human livers perfused with the developed protocol showed preserved function with a median perfusion time of 168 h (range 120–184 h), with preserved viability throughout.ConclusionsLivers can be reproducibly perfused in excess of 120 (range 121–184) hours with evidence of preserved hepatocyte and cholangiocyte function.

Normothermic Ex Vivo Perfusion Before Transplantation of the Kidney (NEXT-Kidney): A Single-center, Nonrandomized Feasibility Study.

There is conflicting evidence regarding the efficacy of normothermic machine perfusion (NMP) in suboptimal deceased donor kidneys. We aimed to assess the feasibility and short-term efficacy of brief preimplantation NMP in circulatory death (DCD) kidneys. In this nonrandomized, single-center, prospective clinical trial, DCD kidneys underwent 1 to 3 h of NMP before implantation, aiming to achieve short ischemic times off NMP. The primary outcomes included feasibility and safety. Secondary outcomes included efficacy outcomes (delayed graft function and estimated glomerular filtration rate (eGFR) at 1, 6, and 12 mo), which were compared with the contralateral kidney that did not receive NMP. Eighteen DCD kidneys underwent NMP between 2020 and 2022, with at least 1 h completed in 16 (88.9%) of these kidneys (median 1 h); one kidney was removed after 5 min because of cannula failure and another at 54 min because of a sudden drop in blood flows. There was no episode of graft loss on the machine or postoperative vascular thromboses. All 18 kidneys were transplanted, with no cases of PNF or graft loss at 12 mo. Seventeen of the contralateral CS kidneys were transplanted. Compared with the contralateral kidneys, a lower incidence of delayed graft function (23.5% versus 64.7%; P = 0.046) was observed. There were no differences in the eGFR slopes between the two groups over time (P = 0.254). NMP is safe, feasible and efficacious in the Australian setting, with this relatively small cohort demonstrating good early outcomes compared to CS alone in our study of DCD kidneys.

Expression of sPD-L1 levels in an ex vivo liver perfusion model.

The programmed cell death protein 1 (PD-1) acts as a central inhibitory immune checkpoint receptor. The soluble form of its primary ligand, sPD-L1, was found to be elevated in serum of patients with cancer, infectious diseases and chronic inflammation. So far, the hepatic origin of sPD-L1 has received relatively little attention and is therefore subject of this study in the context of normothermic machine perfusion (NMP) of liver grafts. sPD-L1 concentrations as well as several well-established clinically relevant laboratory parameters were determined in the perfusate of 16 donor liver grafts undergoing normothermic machine perfusion (NMP) up to 30 hours (h). sPD-L1 levels continuously increased during NMP and significantly correlated with markers of hepatic synthesis (cholinesterase), acute-phase proteins (von Willebrand factor, procalcitonin, antithrombin, interleukin-6, fibrinogen) and liver decay markers (gamma-glutamyltransferase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase). Perfusate leukocytes were in the lower reference range, and decreased after 12h. Mean sPD-L1 levels in the perfusate correlated with donor levels of gamma-glutamyltransferase, alanine aminotransferase, creatinine and blood urea nitrogen. Our study reveals a significant increase of concentration of sPD-L1 following ischemia-reperfusion injury in a hepatic ex vivo model. sPD-L1 concentrations during NMP correlate with established acute-phase proteins and liver cell decay markers suggesting that hepatic sPD-L1 synthesis or shedding increases during the acute phase and cell decay. Furthermore, sPD-L1 correlates with established liver function and synthesis parameters as well as with donor laboratory values and might therefore be a potential biomarker for hepatic function of liver grafts.

The Interconnection Between the Liver and Other Organs: Insights for Hepatic Long–Term Normothermic Machine Perfusion

ABSTRACTNormothermic machine perfusion (NMP) is emerging as a promising technique for organ preservation, evaluation, and scientific research, offering the potential to enhance the viability and function of donor organs. To fully harness the benefits of NMP, sustained long–term NMP (LNMP) at 36°C for periods exceeding 24 h is required. However, the development of stable LNMP devices is hindered by our limited understanding of ex vivo liver physiology. This review synthesizes insights from clinical and experimental studies to highlight the knowledge gaps associated with the impact of the absence of various organs or systems on isolated livers during ex vivo perfusion. Additionally, it discusses liver injuries and adverse events documented in published liver LNMP studies, elucidating their underlying mechanisms. By analyzing these findings, the paper proposes a series of recommendations to establish a more stable LNMP platform, aiming to optimize the outcomes of liver preservation and expand the applications of NMP in clinical practice and research.

Incremental impact of organ allocation changes and machine perfusion technology on liver transplant waitlist and volumes

Incremental impact of organ allocation changes and machine perfusion technology on liver transplant waitlist and volumes

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.

Validation of mitochondrial FMN as a predictor for early allograft dysfunction and patient survival measured during hypothermic oxygenated perfusion

Hypothermic oxygenated machine perfusion (HOPE) preconditions liver grafts before transplantation. While beneficial effects on patient outcomes were demonstrated, biomarkers for viability assessment during HOPE are scarce and lack validation. This study aims to validate the predictive potential of perfusate flavin mononucleotide (FMN) during HOPE to enable the implementation of FMN-based assessment into clinical routine and to identify safe organ acceptance thresholds. FMN was measured in perfusate samples of 50 liver grafts at multiple time points. After transplantation, patients were followed up for development of early allograft dysfunction (EAD), transplantation, and 1-year survival. FMN concentrations were significantly higher for grafts that developed EAD at 5 and 60 minutes into HOPE (p = 0.008, p = 0.026). The strongest predictive potential of FMN for EAD was observed at 5 minutes of HOPE with an AUC of 0.744. Similarly, 5-minute FMN was predictive for 1-year mortality (p &lt; 0.001), reaching a remarkable AUC of 0.890. Cutoffs for prediction of EAD (10.6 ng/mL) and early mortality (23.5 ng/mL) were determined and allowed risk stratification of grafts. Particularly, patients receiving low-risk grafts developed EAD in 9% of cases, while all patients survived the first postoperative year. In contrast, high-risk organs developed an incidence of EAD at 62%, accompanied by the necessity of retransplantation in 38% of cases. One-year mortality in the high-risk cohort was 62%. Evaluation of FMN as early as 5 minutes during HOPE allows for risk stratification of liver grafts. Low-risk grafts, according to FMN, display a negligible risk for patients. Yet, high-risk grafts are associated with increased risk for EAD, transplantation, and early mortality and should not be used for transplantation without further assessment.