Impact of Temperature on Porcine Liver Machine Perfusion From Donors After Cardiac Death

Normothermic machine perfusion (NMP) has been introduced as a promising technology to preserve and possibly repair marginal liver grafts. The aim of this study was to compare the effect of temperature on the preservation of donation after cardiac death (DCD) liver grafts in an ex vivo perfusion model after NMP (38.5°C) and subnormothermic machine perfusion (SNMP, 21°C) with a control group preserved by cold storage (CS, 4°C). Fifteen porcine livers with 60 min of warm ischemia were preserved for 10 h by NMP, SNMP or CS (n = 5/group). After the preservation phase all livers were reperfused for 24 h in an isolated perfusion system with whole blood at 38.5°C to simulate transplantation. At the end of transplant simulation, the NMP group showed significantly lower hepatocellular enzyme level (AST: 277 ± 69 U/L; ALT: 22 ± 2 U/L; P < 0.03) compared to both SNMP (AST: 3243 ± 1048 U/L; ALT: 127 ± 70 U/L) and CS (AST: 3150 ± 1546 U/L; ALT: 185 ± 97 U/L). There was no significant difference between SNMP and CS. Bile production was significantly higher in the NMP group (219 ± 43 mL; P < 0.01) compared to both SNMP (49 ± 84 mL) and CS (12 ± 16 mL) with no significant difference between the latter two groups. Histologically, the NMP livers showed preserved cellular architecture compared to the SNMP and CS groups. NMP was able to recover DCD livers showing superior hepatocellular integrity, biliary function, and microcirculation compared to SNMP and CS. SNMP showed some significant benefit over CS, yet has not shown any advantage over NMP.     

Inducing Hepatitis C Virus Resistance After Pig Liver Transplantation—A Proof of Concept of Liver Graft Modification Using Warm Ex Vivo Perfusion

Normothermic ex vivo liver perfusion (NEVLP) offers the potential to optimize graft function prior to liver transplantation (LT). Hepatitis C virus (HCV) is dependent on the presence of miRNA(microRNA)‐122. Miravirsen, a locked‐nucleic acid oligonucleotide, sequesters miR‐122 and inhibits HCV replication. The aim of this study was to assess the efficacy of delivering miravirsen during NEVLP to inhibit miR‐122 function in a pig LT model. Pig livers were treated with miravirsen during NEVLP or cold storage (CS). Miravirsen absorption, miR‐122 sequestration, and miR‐122 target gene derepression were determined before and after LT. The effect of miravirsen treatment on HCV infection of hepatoma cells was also assessed. NEVLP improved miravirsen uptake versus CS. Significant miR‐122 sequestration and miR‐122 target gene derepression were seen with NEVLP but not with CS. In vitro data confirmed miravirsen suppression of HCV replication after established infection and prevented HCV infection with pretreatment of cells, analogous to the pretreatment of grafts in the transplant setting. In conclusion, miravirsen delivery during NEVLP is a potential strategy to prevent HCV reinfection after LT. This is the first large‐animal study to provide “proof of concept” for using NEVLP to modify and optimize liver grafts for transplantation.     

Hypothermic Machine Preservation in Human Liver Transplantation: The First Clinical Series

Hypothermic machine perfusion (HMP) is widely used to preserve kidneys for transplantation with improved results over cold storage (CS). To date, successful transplantation of livers preserved with HMP has been reported only in animal models. In this, the first prospective liver HMP study, 20 adults received HMP‐preserved livers and were compared to a matched group transplanted with CS livers. HMP was performed for 3–7 h using centrifugal perfusion with Vasosol^® solution at 4–6°C. There were no cases of primary nonfunction in either group. Early allograft dysfunction rates were 5% in the HMP group versus 25% in controls (p = 0.08). At 12 months, there were two deaths in each group, all unrelated to preservation or graft function. There were no vascular complications in HMP livers. Two biliary complications were observed in HMP livers compared with four in the CS group. Serum injury markers were significantly lower in the HMP group. Mean hospital stay was shorter in the HMP group (10.9 ± 4.7 days vs. 15.3 ± 4.9 days in the CS group, p = 0.006). HMP of donor livers provided safe and reliable preservation in this pilot case‐controlled series. Further multicenter HMP trials are now warranted.     

Continuous Normothermic Ex Vivo Kidney Perfusion Is Superior to Brief Normothermic Perfusion Following Static Cold Storage in Donation After Circulatory Death Pig Kidney Transplantation

Hypothermic preservation is known to cause renal graft injury, especially in donation after circulatory death (DCD) kidney transplantation. We investigated the impact of cold storage (SCS) versus short periods of normothermic ex vivo kidney perfusion (NEVKP) after SCS versus prolonged, continuous NEVKP with near avoidance of SCS on kidney function after transplantation. Following 30 min of warm ischemia, kidneys were removed from 30‐kg Yorkshire pigs and preserved for 16 h with (A) 16 h SCS, (B) 15 h SCS + 1 h NEVKP, (C) 8 h SCS + 8 h NEVKP, and (D) 16 h NEVKP. After contralateral kidney resection, grafts were autotransplanted and pigs followed up for 8 days. Perfusate injury markers such as aspartate aminotransferase and lactate dehydrogenase remained low; lactate decreased significantly until end of perfusion in groups C and D (p < 0.001 and p = 0.002). Grafts in group D demonstrated significantly lower serum creatinine peak when compared to all other groups (p < 0.001) and 24‐h creatinine clearance at day 3 after surgery was significantly higher (63.4 ± 19.0 mL/min) versus all other groups (p < 0.001). Histological assessment on day 8 demonstrated fewer apoptotic cells in group D (p = 0.008). In conclusion, prolonged, continuous NEVKP provides superior short‐term outcomes following DCD kidney transplantation versus SCS or short additional NEVKP following SCS.     

Impact of Machine Perfusion Preservation of Liver Grafts From Donation After Cardiac Death

Because of the critical shortage of deceased donor grafts, using a donation after cardiac death (DCD) donor is an important resource. However, the ischemic damage of those DCD grafts jeopardizes organ viability during cold storage. Maintaining organ viability after donation until transplantation is important for optimal graft function and survival. This review describes the effective preservation in transplantation for DCD livers. Concepts and development of machine perfusion for DCD liver grafts to reduce ischemia/reperfusion injury are discussed. Despite the fact that hypothermic machine perfusion might be superior to static cold preservation, DCD livers are exposed to hypothermia-induced damage. Recently, some groups introduced the beneficial effects of normothermic or subnormothermic machine perfusion in DCD liver preservation and transplantation.     

Liver Transplantation After Ex Vivo Normothermic Machine Preservation: A Phase 1 (First‐in‐Man) Clinical Trial

The number of donor organs suitable for liver transplantation is restricted by cold preservation and ischemia–reperfusion injury. We present the first patients transplanted using a normothermic machine perfusion (NMP) device that transports and stores an organ in a fully functioning state at 37°C. In this Phase 1 trial, organs were retrieved using standard techniques, attached to the perfusion device at the donor hospital, and transported to the implanting center in a functioning state. NMP livers were matched 1:2 to cold‐stored livers. Twenty patients underwent liver transplantation after NMP. Median NMP time was 9.3 (3.5–18.5) h versus median cold ischaemia time of 8.9 (4.2–11.4) h. Thirty‐day graft survival was similar (100% NMP vs. 97.5% control, p = 1.00). Median peak aspartate aminotransferase in the first 7 days was significantly lower in the NMP group (417 IU [84–4681]) versus (902 IU [218–8786], p = 0.03). This first report of liver transplantation using NMP‐preserved livers demonstrates the safety and feasibility of using this technology from retrieval to transplantation, including transportation. NMP may be valuable in increasing the number of donor livers and improving the function of transplantable organs.     

Cytoprotective Effects of Mesenchymal Stem Cells During Liver Transplantation from Donors After Cardiac Death in Rats

Background

Liver transplantation from donors after cardiac death (DCD) might increase the pool of available organs. Recently, some investigators reported the potential use of mesenchymal stem cells (MSCs) to improve the outcome of liver transplantation from DCD. The aim of this study was to evaluate the cytoprotective effects and safety of MSC transplantation on liver grafts from DCD.

Preservation of pig liver allografts after warm ischemia: normothermic perfusion versus cold storage

Warm ischemia is known to induce substantial damage to the liver parenchyma. With respect to clinical liver transplantation, the tolerance of the liver to warm ischemia and the preservation of these organs have not been studied in detail. In isolated reperfused pig livers we proceeded according to the following concept: Livers were subjected to 1 or 3 h of warm ischemia. Subsequently, these organs were preserved by either normothermic perfusion or cold storage (histidine-tryptophan-α-ketoglutarate, HTK) for 3 h each. After storage, liver function was assessed in a reperfusion circuit for another 3 h. Parameters under evaluation were bile flow, perfusion flow, oxygen consumption, enzyme release into the perfusate (creatine kinase, glutamic oxaloacetic transaminase (GOT), lactic dehydrogenase, and glutamic pyruvic transaminase), and histomorphology. Damage to the liver was lowest after warm ischemia of 1 h. The results after cold storage were superior to those after normothermic perfusion (GOT: 3.2±0.3 and 2.6±0.2 U/g liver; cumulative bile production: 14.7±2.1 and 9.4±1 ml, respectively;P<0.05). In contrast, we found substantial damage at the end of reperfusion in livers undergoing 3 h of warm ischemia under both preservation techniques with severe hepatocellular pyknoses and essentially altered nonparenchymal cells. The results suggest that pig livers undergoing 1 h of warm ischemia and cold storage for 3 h with HTK solution may lead to functioning after transplantation.     

Ex vivo Normothermic Machine Perfusion and Viability Testing of Discarded Human Donor Livers

In contrast to traditional static cold preservation of donor livers, normothermic machine perfusion may reduce preservation injury, improve graft viability and potentially allows ex vivo assessment of graft viability before transplantation. We have studied the feasibility of normothermic machine perfusion in four discarded human donor livers. Normothermic machine perfusion consisted of pressure and temperature controlled pulsatile perfusion of the hepatic artery and continuous portal perfusion for 6 h. Two hollow fiber membrane oxygenators provided oxygenation of the perfusion fluid. Biochemical markers in the perfusion fluid reflected minimal hepatic injury and improving function. Lactate levels decreased to normal values, reflecting active metabolism by the liver (mean lactate 10.0 ± 2.3 mmol/L at 30 min to 2.3 ± 1.2 mmol/L at 6 h). Bile production was observed throughout the 6 h perfusion period (mean rate 8.16 ± 0.65 g/h after the first hour). Histological examination before and after 6 h of perfusion showed well‐preserved liver morphology without signs of additional hepatocellular ischemia, biliary injury or sinusoidal damage. In conclusion, this study shows that normothermic machine perfusion of human donor livers is technically feasible. It allows assessment of graft viability before transplantation, which opens new avenues for organ selection, therapeutic interventions and preconditioning.     

A Novel Oxygenated Machine Perfusion System for Preservation of the Liver

Machine perfusion (MP) is a potential method to increase the donor pool for organ transplantation. However, MP systems for liver grafts remain difficult to use because of organ‐specific demands. Our aim was to test a novel, portable MP system for hypothermic preservation of the liver. A portable, pressure‐regulated, oxygenated MP system designed for kidney preservation was adapted to perfuse liver grafts via the portal vein (PV). Three porcine livers underwent 20 h of hypothermic perfusion using Belzer MP solution. The MP system was assessed for perfusate flow, temperature, venous pressure, and pO₂/pCO₂ during the preservation period. Biochemical and histological parameters were analyzed to determine postpreservation organ damage. Perfusate flow through the PV increased over time from 157 ± 25 mL/min at start to 177 ± 25 mL/min after 20 h. PV pressure remained stable at 13 ± 1 mm Hg. Perfusate temperature increased from 9.7 ± 0.6°C at the start to 11.0 ± 0.0°C after 20 h. Aspartate aminotransferase and lactate dehydrogenase increased from 281 ± 158 and 308 ± 171 U/L after 1 h to 524 ± 163 and 537 ± 168 U/L after 20 h, respectively. Blood gas analysis showed a stable pO₂ of 338 ± 20 mm Hg before perfusion of the liver and 125 ± 14 mm Hg after 1 h perfusion. The pCO₂ increased from 15 ± 5 mm Hg after 1 h to 53 ± 4 mm Hg after 20 h. No histological changes were found after 20 h of MP. This study demonstrated the feasibility of a portable MP system for preservation of the liver and showed that continuous perfusion via the PV can be maintained with an oxygen‐driven pump system without notable preservation damage of the organ.     

Controlled Oxygenated Rewarming of Cold Stored Liver Grafts by Thermally Graduated Machine Perfusion Prior to Reperfusion

The quality of cold‐stored livers declines with the extension of ischemic time, increasing the risk of primary dys or nonfunction. A new concept to rescue preserved marginal liver grafts by gentle oxygenated warming‐up prior to blood reperfusion was investigated. Porcine livers were preserved by cold storage (CS) in modified HTK‐solution for 18 h. Some grafts were subsequently subjected to 90 min of controlled oxygenated rewarming (COR) by machine perfusion with gradual increase of perfusate temperature up to 20°C or simple oxygenated machine perfusion in hypothermia (HMP) or subnormothermia (SNP). Graft viability was assessed thereafter by 4 h of normothermic blood reperfusion ex vivo. Endischemic tissue energetics were significantly improved by COR or SNP and to a notably lesser extent by HMP. COR significantly reduced cellular enzyme loss, gene expression and perfusate activities of TNF‐alpha, radical mediated lipid peroxidation (LPO) and increase of portal vascular perfusion resistance upon reperfusion, while HMP or SNP were less protective. Only COR resulted in significantly more bile production than after CS. Histological injury score and caspase 3‐activation were significantly lower after COR than after CS. Oxygenated rewarming prior to reperfusion seems to be a promising technique to improve subsequent organ recovery upon reperfusion of long preserved liver grafts.     

Improved Preservation of Warm Ischemic Livers by Hypothermic Machine Perfusion with Supplemented University of Wisconsin Solution

Hypothermic machine perfusion (HMP) has the potential to improve recovery and preservation of Donation after Cardiac Death (DCD) livers, including uncontrolled DCD livers. However, current perfusion solutions lack the needed substrates to improve energy recovery and minimize hepatic injury, if warm ischemic time (WIT) is extended. This proof-of-concept study tested the hypothesis that the University of Wisconsin (UW) solution supplemented with anaplerotic substrates, calcium chloride, thromboxane A₂ inhibitor, and antioxidants could improve HMP preservation and minimize reperfusion injury of warm ischemic livers. Preflushed rat livers subjected to 60 min WIT were preserved for 5 h with standard UW or supplemented UW (SUW) solution. Post preservation hepatic functions and viability were assessed during isolated perfusion with Krebs–Henseleit solution. Livers preserved with SUW showed significantly (p <. 001) improved recovery of tissue ATP levels (μ mol/g liver), 2.06 ± 0.10 (mean ± SE), as compared to the UW group, 0.70 ± 0.10, and the level was 80% of that of fresh control livers (2.60 ± 0.13). At the end of 1 h of rewarming, lactate dehydrogenase (U/L) in the perfusate was significantly (p <. 05) lower in the SUW group (429 ± 58) as compared to ischemia–reperfusion (IR) (781 ± 12) and the UW group (1151 ± 83). Bile production (μ g/min/g liver) was significantly (p <. 05) higher in the SUW group (280 ± 13) as compared to the IR (224 ± 24) and the UW group (114 ± 14). The tissue edema formation assessed by tissue wet–dry ratio was significantly (p <. 05) higher in UW group. Histology showed well-preserved hepatic structure in the SUW group. In conclusion, this study suggests that HMP with SUW solution has the potential to restore and preserve livers with extended WIT.     

Ultrasound-Targeted Microbubble Cavitation During Machine Perfusion Reduces Microvascular Thrombi and Graft Injury in a Rat Liver Model of Donation After Circulatory Death

BackgroundIschemic cholangiopathy is a process of bile duct injury that might result from peribiliary vascular plexus (PBP) thrombosis and remains a dreaded complication in liver transplantation from donors after circulatory death (DCD). The aim of this study was to propose a mechanical method of clot destruction to clear microvascular thrombi in DCD livers before transplantation.MethodsSonothrombolysis (STL) is a process by which inertial cavitation of circulating microbubbles entering an ultrasound field create a high-energy shockwave at a microbubble-thrombus interface, causing mechanical clot destruction. The effectiveness of STL in DCD liver treatment remains unclear. We carried out STL treatment during normothermic, oxygenated, ex vivo machine perfusion (NMP), introducing microbubbles into the perfusate with the liver enveloped in an ultrasound field.ResultsThe STL livers showed reduction in hepatic arterial and PBP thrombus and decreases in hepatic arterial and portal venous flow resistance, reduced parenchymal injury as measured by aspartate transaminase release and oxygen consumption, and improved cholangiocyte function. Light and electron microscopy showed reduction of hepatic arterial and PBP thrombus in STL livers compared with controls and preserved hepatocyte structure, sinusoid endothelial morphology, and biliary epithelial microvilli.ConclusionIn this model, STL improved flow and functional measures in DCD livers undergoing NMP. These data suggest a novel therapeutic approach to treat PBP injury in DCD livers, which may ultimately increase the pool of grafts available to patients awaiting liver transplantation.     

Warm flush at 37 °C following cold storage attenuates reperfusion injury in preserved rat livers

Abstract Pretransplant rinse solutions have been shown to reduce reperfusion injury in cold-stored liver grafts, especially at the nonparenchymal level in sinusoidal endothelial cells (SEC). In this study, different rinse temperatures were tested in a rat liver preservation model. Livers were washed out in situ via the portal vein with cold (4°C) University of Wisconsin (UW) solution, and after hepatectomy (t0), were stored for 8,16, or 24 h of cold ischemia time (CIT). After storage, livers were flushed with UW solution at either 4 °C, 20 °C, or 37 °C and reperfused for 90 min (37 °C). Control livers were reperfused at t0 without preflush. Levels of hyaluronic acid (HA), purine nucleoside phosphorylase (PNP), AST, and LDH were measured in the reperfusion medium. Bile production was monitored during reperfusion. At the end of reperfusion, liver biopsies were taken for enzyme histochemistry (5′-nucleotidase and LDH). After 8-h CIT and a flush at 4°C, a release of endogenous HA (-7 %) was observed, whereas uptake of exogenous HA occurred after the 20°C flush (2 %, P = NS) and after the 37°C flush (24 %, p < 0.001). HA release occurred at all three preflush temperatures after the 16-h CIT but was significantly lower when flushed at 37 °C (-10 %) that at 4 °C and 20 °C (-64 % and -17 %, respectively, p =0.05). After the 24-h CIT, the release of endogenous HA increased in the 4 °C and 20 °C preflush groups, but not in the 37 °C group. Levels of PNP and AST increased until the 24-h CIT in all groups but were significantly lower after preflush at 37 °C. Release of LDH did not increase with increasing periods of cold storage in any of the flush series. Compared to control livers, mean bile production during reperfusion was significantly decreased following preflush at 4°C or 37 °C after all periods of CIT. No differences in mean bile production could be demonstrated in the three preflush groups after any period of CIT. LDH activity in liver tissue was best preserved after the 8 and 16-h CIT in combination with the 37 °C preflush, indicating less hepatocellular damage. In conclusion, in cold stored rat livers flushed at 37 °C before reperfusion, SEC and hepatocellular damage is attenuated.     

Liver Transplantation Using Grafts From Donors After Circulatory Death: A Propensity Score–Matched Study From a Single Center

The use of livers from donation after circulatory death (DCD) is increasing, but concerns exist regarding outcomes following use of grafts from “marginal” donors. To compare outcomes in transplants using DCD and donation after brain death (DBD), propensity score matching was performed for 973 patients with chronic liver disease and/or malignancy who underwent primary whole‐liver transplant between 2004 and 2014 at University Hospitals Birmingham NHS Foundation Trust. Primary end points were overall graft and patient survival. Secondary end points included postoperative, biliary and vascular complications. Over 10 years, 234 transplants were carried out using DCD grafts. Of the 187 matched DCDs, 82.9% were classified as marginal per British Transplantation Society guidelines. Kaplan–Meier analysis of graft and patient survival found no significant differences for either outcome between the paired DCD and DBD patients (p = 0.162 and p = 0.519, respectively). Aspartate aminotransferase was significantly higher in DCD recipients until 48 h after transplant (p < 0.001). The incidences of acute kidney injury and ischemic cholangiopathy were greater in DCD recipients (32.6% vs. 15% [p < 0.001] and 9.1% vs. 1.1% [p < 0.001], respectively). With appropriate recipient selection, the use of DCDs, including those deemed marginal, can be safe and can produce outcomes comparable to those seen using DBD grafts in similar recipients.     

Novel short-term hypothermic oxygenated perfusion (HOPE) system prevents injury in rat liver graft from non-heart beating donor

OBJECTIVE: To assess a machine perfusion system in rescuing liver grafts from non-heart-beating donors (NHBD). SUMMARY BACKGROUND DATA: The introduction of extracorporeal liver perfusion systems in the clinical routine depends on feasibility. Conceivably, perfusion could be performed during recipient preparation. We investigated whether a novel rat liver machine perfusion applied after in situ ischemia and cold storage can rescue NHBD liver grafts. METHODS: We induced cardiac arrest in male Brown Norway rats by phrenotomy and ligation of the subcardial aorta. We studied 2 experimental groups: 45 minutes of warm in situ ischemia + 5 hours cold storage versus 45 minutes of warm in situ ischemia + 5 hours cold storage followed by 1 hour hypothermic oxygenated extracorporeal perfusion (HOPE). In both groups, livers were reperfused in a closed sanguineous isolated liver perfusion device for 3 hours at 37 degrees C. To test the benefit of HOPE on survival, we performed orthotopic liver transplantation in both experimental groups. RESULTS: After cold storage and reperfusion, NHBD livers showed necrosis of hepatocytes, increased release of AST, and decreased bile flow. HOPE improved NHBD livers significantly with a reduction of necrosis, less AST release, and increased bile flow. ATP was severely depleted in cold-stored NHBD livers but restored in livers treated by HOPE. After orthotopic liver transplantation, grafts treated by HOPE demonstrated a significant extension on animal survival. CONCLUSIONS: We demonstrate a beneficial effect of HOPE by preventing reperfusion injury in a clinically relevant NHBD model.     

The calcium channel blocker nisoldipine minimizes the release of tumor necrosis factor and interleukin-6 following rat liver transplantation

Kupffer cells, when activated, release toxic cytokines such as tumor necrosis factor (TNF), which can cause tissue injury. Takei et al. have reported that nisoldipine, a calcium channel blocker which decreases phagocytotic activity by Kupffer cells, also diminishes liver and lung injury and dramatically improves survival following liver transplantation [27]. Therefore, we studied the effect of nisoldipine on the time course of TNF and interleukin-6 (IL-6) release following cold storage and liver transplantation in the rat. Livers were stored under survival and non-survival conditions in cold Euro-Collins solution in the presence or absence of nisoldipine (1.4 µM). After storage, the effluent was collected for determination of cytokines. The liver was then transplanted orthotopically and serum was collected at various time intervals for up to 5 h. In the effluent, TNF levels were very low in both the control and nisoldipine-treated groups and IL-6 was not measurable. Furthermore, when livers were stored under survival conditions and transplanted (liver stored in the cold for 4 h), serum TNF (2 U/ml) and IL-6 (350 U/ml) values were minimal in both the control and nisoldipine-treated groups. In contrast, when livers were stored under non-survival conditions and transplanted (liver stored in the cold for 10 h), TNF levels increased to 15 ± 2 U/ml, 150 min after graft reperfusion, an increase which was prevented by nisoldipine (6.5 U/ml). Serum IL-6 levels were also elevated 300 min after transplantation in livers stored for 10 h. Nisoldipine also reduced the release of this cytokine. Serum transaminases (SGOT) were elevated to values around 2000 U/l 5 h following transplantation. In the nisoldipine-treated group, values were lower between 60 and 300 min. In the lung, interstitial and alveolar edema and cellular infiltration were detectable 5 h post-operatively and were diminished by nisoldipine. These data confirmed that TNF and IL-6 release were minimal following cold storage and transplantation of livers stored under survival conditions, but were elevated transiently after transplantation under non-survival conditions. Nisoldipine prevented cytokine release, most likely by blocking the activation of Kupffer cells, which may explain how it decreases liver and lung injury very early following liver transplantation.     

Influence of different preservation solutions and intentional hemodilution of recipient on viability of preserved and transplanted rat kidneys

A total of 81 rat kidney grafts, flushed out and cold stored in either Sacks' or University of Wisconsin (UW) solution, were transplantated into hemodiluted (Hct=30%±4%) or untreated (Hct=43%±3%) recipients. The cold ischemia times (CIT) used were 24 and 36 h. One week after transplantation, the surviving recipients (n=67) were contralaterally nephrectomized. The experiment was terminated after a total period of 4 weeks, and the percentage of surviving animals were determined for each treatment. Data was pooled and the results show that grafts cold stored in UW solution were viable to a significantly greater extent and after longer CIT than grafts cold stored in Sacks' solution (47% vs 23%;P<0.05). Recipient hemodilution did not improve graft viability (39% vs 32%; NS). Kidneys cold stored for 24 h were viable to a greater extent than kidneys with a CIT of 36 h (50% vs 15%;P<0.01).     

Preliminary Single‐Center Canadian Experience of Human Normothermic Ex Vivo Liver Perfusion: Results of a Clinical Trial

After extensive experimentation, outcomes of a first clinical normothermic machine perfusion (NMP) liver trial in the United Kingdom demonstrated feasibility and clear safety, with improved liver function compared with standard static cold storage (SCS). We present a preliminary single‐center North American experience using identical NMP technology. Ten donor liver grafts were procured, four (40%) from donation after circulatory death (DCD), of which nine were transplanted. One liver did not proceed because of a technical failure with portal cannulation and was discarded. Transplanted NMP grafts were matched 1:3 with transplanted SCS livers. Median NMP was 11.5 h (range 3.3–22.5 h) with one DCD liver perfused for 22.5 h. All transplanted livers functioned, and serum transaminases, bilirubin, international normalized ratio, and lactate levels corrected in NMP recipients similarly to controls. Graft survival at 30 days (primary outcome) was not statistically different between groups on an intent‐to‐treat basis (p = 0.25). Intensive care and hospital stays were significantly more prolonged in the NMP group. This preliminary experience demonstrates feasibility as well as potential technical risks of NMP in a North American setting and highlights a need for larger, randomized studies.     

Comparison of HTK- and UW-solution for liver preservation tested in an orthotopic liver transplantation model in the pig

The aim of this experimental study was to compare the preservation potency of University of Wisconsin (UW) and HTK (Bretschneider) solutions in an orthotopic liver transplantation (OLT) model in pigs. Livers were harvested using an in situ perfusion technique, where organs were flushed with the solution being tested, stored on ice — cold storage (CS) — for 2 or 24 h and then transplanted. Parameters monitored were liver enzymes in serum, hepatic water content, high energy phosphates, nuclear magnetic resonance (NMR) relaxation time T2, light microscopy and bile production. CS for 24 h is an extreme in pig liver preservation and is not compatible with animal survival. Biopsies showed drastic morphological changes and grafts did not produce bile in either group. (Bile production 2 h CS: HTK, 5.6 ± 1.8 ml/h; UW, 4.7 ± 2.3 ml/h) Enzyme release after reperfusion (ASGOT, ?LDH) was higher in long-term preservation. Hepatic tissue water content significantly decreased during CS in UW preserved livers. Edema alter reperfusion (?H₂0: HTK 24 h = + 5.6%, UW 24 h= + 4.8%) and regeneration capacity after reperfusion (UW 2 h = 63%, HTK 2 h = 55%, UW 24 h = 30%, HTK 24 h = 30%) were not significantly different. However, we did not observe major differences in preservation potency between the solutions tested. Differences were correlated, rather, with length 9 time of CS, than with the solution used. Therefore, HTK solution seemed to be a low potassium containing alternative to UW solution.