Normothermic Ex Vivo Liver Perfusion Using Steen Solution as Perfusate for Human Liver Transplantation: First North American Results

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1 ORIGINAL ARTICLE SELZNER ET AL. Normothermic Ex Vivo Liver Perfusion Using Steen Solution as Perfusate for Human Liver Transplantation: First North American Results Markus Selzner, 1 Nicolas Goldaracena, 1 Juan Echeverri, 1 Johan M. Kaths, 1 Ivan Linares, 1 Nazia Selzner, 2 Cyril Serrick, 3 Max Marquez, 1 Gonzalo Sapisochin, 1 Eberhard L. Renner, 2 Mamatha Bhat, 2 Ian D. McGilvray, 1 Leslie Lilly, 2 Paul D. Greig, 1 Cynthia Tsien, 2 Mark S. Cattral, 1 Anand Ghanekar, 1 and David R. Grant 1 Departments of Surgery; 2 Medicine, and 3 Perfusion Services, Multi-Organ Transplant Program, Toronto General Hospital, Toronto, Ontario, Canada The European trial investigating normothermic ex vivo liver perfusion (NEVLP) as a preservation technique for liver transplantation (LT) uses gelofusine, a non US Food and Drug Administration approved, bovine-derived, gelatin-based perfusion solution. We report a safety and feasibility clinical NEVLP trial with human albumin based Steen solution. Transplant outcomes of 10 human liver grafts that were perfused on the Metra device at 37 8C with Steen solution, plus 3 units of erythrocytes were compared with a matched historical control group of 30 grafts using cold storage (CS) as the preservation technique. Ten liver grafts were perfused for 480 minutes ( minutes). All livers cleared lactate (final lactate 1.46 mmol/l; mmol/l) and produced bile (61 ml; ml) during perfusion. No technical problems occurred during perfusion, and all NEVLP-preserved grafts functioned well after LT. NEVLP versus CS had lower aspartate aminotransferase and alanine aminotransferase values on postoperative days 1-3 without reaching significance. No difference in postoperative graft function between NEVLP and CS grafts was detected as measured by day 7 international normalized ratio (1.1 [1-1.56] versus 1.1 [1-1.3]; P 5 0.5) and bilirubin (1.5; mg/dl versus 2.78; mg/dl; P 5 0.5). No difference was found in the duration of intensive care unit stay (median, 1 versus 2 days; range, 0-8 versus 0-23 days; P 5 0.5) and posttransplant hospital stay (median, 11 versus 13 days; range, 8-17 versus 7-89 days; P ). Major complications (Dindo-Clavien 3b) occurred in 1 patient in the NEVLP group (10%) compared with 7 (23%) patients in the CS group (P 5 0.5). No graft loss or patient death was observed in either group. Liver preservation with normothermic ex vivo perfusion with the Metra device using Steen solution is safe and results in comparable outcomes to CS after LT. Using US Food and Drug Administration approved Steen solution will avoid a potential regulatory barrier in North America. Liver Transplantation , 2016 AASLD. Received March 19, 2016; accepted May 23, Abbreviations: ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; CIT, cold ischemia time; CNI, calcineurin inhibitor; CS, cold storage; DCD, donation after circulatory death; EtOH, ethanol; HBD, heart-beating donation; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; HTK, histidine tryptophan ketoglutarate; ICU, intensive care unit; INR, international normalized ratio; LOH, length of hospital stay; LT, liver transplantation; MELD, Model for End- Stage Liver Disease; NASH, nonalcoholic steatohepatitis; NEVLP, normothermic ex vivo liver perfusion; WIT, warm ischemia time. The success of liver transplantation (LT) has increased its demand, resulting in an ongoing severe organ shortage. As a result, 20%-30% of patients on the liver transplant waiting list either die or are delisted for disease progression without receiving an organ offer. (1) One strategy to address this gap is to offer marginal grafts, such as livers retrieved by donation after circulatory death (DCD), (2) livers with severe steatosis, (3) or grafts obtained from older donors. (4) Unfortunately, we are currently unable to predict which grafts will work well and which will fail. As a result, many marginal grafts are declined and the full potential of the marginal donor pool has not been used. ORIGINAL ARTICLE 1501

2 SELZNER ET AL. LIVER TRANSPLANTATION, November 2016 Inability to predict graft function is partly due to cold storage (CS), which blocks liver cell function. To overcome this shortcoming, normothermic ex vivo liver perfusion (NEVLP) has been developed as a novel preservation technique. (5) Porcine transplant studies have shown that NEVLP reduces cold ischemic injury and offers the opportunity for graft assessment and repair. (6) In a recent European pilot trial of NEVLP in 20 patients, Ravikumar and colleagues reported favorable outcomes with a portable liver perfusion device (Metra device) using gelofusine mixed with packed red blood cells as the perfusate. (7) Gelofusine is not currently approved for use in North America. It is a 4% wt/vol solution of succinylated gelatin, which is widely used in Europe as a plasma expander. This solution contains bovine-derived products, which have the potential to transmit an infectious agent causing spongiform encephalopathy. Approval to use this product in North America will therefore require regulatory confirmation of the safe sourcing and processing of the bovinederived components. In contrast, in our porcine studies of NEVLP, we used the Steen solution to perfuse the liver with excellent results. (8-10) Steen solution contains human albumin and dextran and does not have any bovine-derived components. In addition, it is approved by the US Food and Drug Administration as a preservation solution for human lung transplantation. (11) Herein, we report our initial experience using the Metra device and Steen solution plus red cells as a perfusate to preserve and assess human livers for transplantation. The goal of this pilot study was to determine the safety and Address reprint requests to David R. Grant, M.D., Multi-Organ Transplant Program, Division of General Surgery, Toronto General Hospital, 585 University Avenue, Toronto, ON M5G 2N2, Canada. Telephone: ; FAX: ; david.grant@uhn.ca This work is part of the Canadian National Transplant Research Program. We thank Uwe Mummenhoff and the Birmingham family for their generous support. We thank XVIVO Perfusion Inc. (Goteborg, Sweden) for providing us with Steen solution. Copyright VC 2016 by the American Association for the Study of Liver Diseases. View this article online at wileyonlinelibrary.com. DOI /lt Potential conflict of interest: Nothing to report. feasibility of portable NEVLP with Steen solution plus packed red blood cells as perfusate. Patients and Methods STUDY DESIGN The study was designed as a single-arm, nonblinded pilot study to assess the safety and feasibility of NEVLP with Steen solution for LT. All transplants were performed at the Multi-Organ Transplant Program, Toronto General Hospital. Between June 2015 and December 2015, all deceased donor full-size grafts (from heart-beating donation [HBD] or DCD) that were within a 2-hour automobile drive to our institution were eligible for inclusion in this study. Recipients participating in the study had to be 18 years of age or older and had provided written informed consent prior to the organ offer. Recipient candidates waiting for multiple organ transplants, patients with fulminant liver failure, or retransplantation were excluded from the study. The research ethics board of the Toronto General Hospital approved this study. The costs of the trial were covered by philanthropic donations. A control group preserved with static CS using histidine tryptophan ketoglutarate (HTK) or University of Wisconsin solution was retrospectively matched 3:1 based on stepwise matching for 30-day survival, donor age, recipient medical Model for End-Stage Liver Disease (MELD) score (calculated MELD without taking exception points into account), and donor type (DCD versus HBD). The 30-day survival was used as matching criteria to exclude several patients with early graft loss from the control group, which might have biased the results in favor of the perfusion group. To achieve a well-matched control group of adequate sample size, we included transplants performed between 2005 and Similar to the NEVLP recipient, recipients with retransplantation, multiorgan transplants, or fulminant hepatic failure were excluded. SETUP AND PRIMING OF THE DEVICE The Metra device was transported to the donor hospital using a purpose-modified vehicle with an electronic liftgate, 3-point restraints for the perfusion device, and an alternating power source, purchased by the Trillium Gift of Life organ procurement agency for the specific purposes of this study. The Metra device was set up by trained cardiovascular perfusionists working at the 1502 ORIGINAL ARTICLE

3 LIVER TRANSPLANTATION, Vol. 22, No. 11, 2016 SELZNER ET AL. Toronto General Hospital. The machine was primed with 3 units of packed red blood cells and 500 ml of Steen solution. Bolus injections of cefuroxime, heparin, and calcium gluconate, as well as continuous infusions of taurocholic acid, heparin, insulin, and prostacyclin were added to the perfusate according to the manufacturer s recommendations. The perfusion temperature was maintained at 37 8C during the entire perfusion. Following 15 minutes of machine priming, ml of bicarbonate was added to adjust the perfusate ph to The donor liver was procured in the usual technique and flushed in situ with cold HTK solution. The back-table preparation of the graft was performed at the donor hospital, carefully suturing openings in the vena cava, portal vein, and hepatic artery branches. After vessel preparation, the portal vein, hepatic artery, vena cava, and bile duct were cannulated. The liver was flushed with an additional 500 ml of Steen solution to remove the cold preservation solution (HTK) before connecting the organ to the perfusion device. At this time, the perfusate ph was again adjusted to a ph of by adding additional bicarbonate if needed. The liver was observed for at least 20 minutes at the donor hospital to confirm stable perfusion conditions and no leakage of the perfusate. The organ was then transported to the Toronto General Hospital in the organ procurement agency s vehicle. PERFUSION CHARACTERISTICS Perfusion characteristics were not measured during organ transport. After arriving at the Toronto General Hospital, the Metra device was taken to the organ repair laboratory in the operating room. Hepatic artery and portal flow and pressure, blood gases, and lactate were assessed every 30 minutes. In addition, perfusate levels of lactate, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and bilirubin, as well as bile flow were measured hourly. A culture swab was taken at the end of the perfusion from the perfusate. DONOR, PREOPERATIVE RECIPIENT, AND PERIOPERATIVE CHARACTERISTICS Donor age, sex, and body mass index (BMI) were documented at the time of donation. For the recipients, the following preoperative data were collected: age, sex, preoperative biochemical profile, calculated medical MELD score, and underlying etiology of liver disease. Organ procurement for deceased donation was performed as previously described. (12) Cold ischemia time (CIT), warm ischemia time (WIT), and type of biliary anastomosis were documented as perioperative variables. A duct-to-duct biliary reconstruction was the preferred choice whenever possible. RECIPIENT OUTCOME DATA Recipient variables after transplantation were prospectively collected from our database and retrospectively analyzed for short-term and longterm outcomes. Outcome was measured by 90-day patient and graft survival, biochemical markers of graft reperfusion injury (AST, ALT), and function (international normalized ratio [INR], bilirubin). Renal function was assessed by serum creatinine and requirement for dialysis in the first week after transplantation. Length of intensive care unit (ICU) and hospital stay were evaluated. All complications within the same hospitalization were recorded and graded according to the Dindo-Clavien score. (13) IMMUNOSUPPRESSION PROTOCOL LT was performed using the standard techniques as previously described. (14) The immunosuppressive regimen consisted of a calcineurin inhibitor (CNI; cyclosporine or tacrolimus) and steroids for the first 3 months. Antimetabolite drugs were used in a CNIsparing regimen when there was concern for CNIinduced neurotoxicity or nephrotoxicity, as well as in candidates who were considered high-risk for rejection (eg, due to underlying autoimmune liver disease). In our protocol, steroids were tapered over the first 3 months following transplantation and then stopped. STATISTICAL ANALYSIS Statistical analysis was performed using SPSS, version 20 (SPSS Inc., Chicago, IL). Fisher s exact test and analysis of variance were used to compare categorical and continuous variables, respectively. All data were expressed as median and range. The Mann-Whitney U test was performed for nonparametric continuous endpoints. Graft and patient survival were determined by the Kaplan-Meier method, and survival curves were compared with the log-rank test. A P value of < 0.05 was considered statistically significant. ORIGINAL ARTICLE 1503

4 SELZNER ET AL. LIVER TRANSPLANTATION, November 2016 TABLE 1. Donor, Recipient, and Perioperative Characteristics NEVLP (n 5 10) CS (n 5 30) P Value Donor age, years 48 (17-75) 46 (22-68) 0.56 Donor BMI, kg/m 2 27 (17-36) 25 (20-29) 0.14 Recipient age, years 56 (45-71) 54 (42-63) 0.32 Recipient medical MELD 21 (8-40) 23 (7-37) 0.85 Recipient BMI, kg/m 2 26 (18-42) 28 (24-41) 0.14 DCD graft 2 (20) 6 (20) 1 HCV cirrhosis 3 (30) 14 (47) 1 EtOH cirrhosis 4 (40) 18 (60) 0.74 NASH cirrhosis 3 (30) 5 (17) 0.34 HCC 4 (40) 20 (67) 0.72 Blood loss, ml 3000 ( ,500) 2500 ( ,000) 0.84 Preservation time, mintues 586 ( ) 634 ( ) 0.11 WIT, minutes 49 (21-76) 46 (39-67) 0.86 NOTE: Data are given as median (range) or n (%). Results Twelve organs were procured, and 10 underwent transplantation. In 1 liver from a DCD, a replaced right hepatic artery was divided during organ retrieval. The artery was reconstructed at the donor hospital, and the graft was perfused. The recipient surgeon declined the graft because of concerns regarding the arterial reconstruction. Another liver, procured from a marginal donor on high-dose vasopressors, was not implanted because the lactate in the perfusion solution remained persistently elevated with low graft bile production. The final 10 patients who received a liver transplant with NEVLP as the preservation method were then 1:3 matched with 30 patients treated with CS as the graft preservation. Matching variables (donor age, recipient medical MELD, and graft type) were identical in both groups. Follow-up was limited to 3 months in both groups. DONOR AND PERIOPERATIVE CHARACTERISTICS Donor age and BMI were similar between both groups. All livers were full-size deceased donor grafts. Two grafts in the NEVLP group and 6 livers in the CS group were retrieved from DCD donors with a withdrawal time of 28 and 30 minutes. Steatosis was not present in either DCD graft. Total preservation and WITs were comparable in NEVLP and CS patients (Table 1). No difference was observed regarding blood loss or transfusion requirements. Similarly, duration of the operation and requirements of intraoperative vasopressors were identical in NEVLP versus CS patients. Duct-to-duct biliary reconstruction was the preferred bile duct reconstruction in the NEVLP (80%) and CS (97%) groups (P 5 0.8). Cava replacement technique was used in the majority of cases in NEVLP (90%) and CS (85%) patients. Postoperatively, the preferred immunosuppression regimen was tacrolimun-based in the NEVLP (100%) and CS (83%) groups (P 5 0.9). In the presence of renal dysfunction, the start of CNI administration was delayed with basiliximab induction after transplantation in the NEVLP (40%) and CS (43%) groups (P 5 0.9). PERFUSION CHARACTERISTICS Median perfusion time was 480 minutes ( minutes). No problems occurred during machine perfusion and transport. During the first 2 hours of perfusion, corresponding to the organ transport phase, hepatic artery flow (median, 370 cc; range, cc/minute) and portal vein flow (median, 1070; range, cc/minute) remained stable. PO 2 (median, 14.4 mm Hg; range, mm Hg) and PCO 2 (median, 4.8 mm Hg; range, mm Hg) were in the target range with mild acidosis (median, ph 7.26, range, ph ). All transplanted livers demonstrated good organ function during normothermic ex vivo machine perfusion with a total bile production of 61 ml ( ml) and perfusate lactate reduction with a final lactate during perfusion of 1.46 mmol/l ( mmol/l). AST and ALT levels were stable during the perfusion and tended to be higher in DCD grafts. All transplanted livers had a stable hepatic artery flow (median, 300 ml/minute; range, ml/minute) and portal venous flow (median, 1250 ml/minute; range, ml/minute) during the perfusion in a pressure-controlled system (Table 2) ORIGINAL ARTICLE

5 LIVER TRANSPLANTATION, Vol. 22, No. 11, 2016 SELZNER ET AL. TABLE 2. Normothermic Ex Vivo Perfusion Characteristics NEVLP (n 5 10) Perfusion time, minutes 480 ( ) Peak AST, U/L 1647 ( ) Peak ALT, U/L 444 ( ) Bile production, ml 61 (14-146) Final lactate, mmol/l 1.46 ( ) ph 7.26 ( ) Hepatic artery flow, ml/minutes 300 ( ) Portal venous flow, ml/minutes 1250 ( ) NOTE: Data are provided as median and range. RECIPIENT DEMOGRAPHICS AND PREOPERATIVE STATUS The etiology of liver disease, recipient age, BMI, and preoperative MELD score were similar between both groups (Table 1). LIVER INJURY AND FUNCTION FOLLOWING LT Reperfusion injury was determined by AST and ALT serum levels after transplantation. The NEVLP group versus the CS group had decreased AST levels on day 1 (1182 U/L [ U/L] versus 1474 U/L [ U/L]), day 2 (216 U/L [ U/L] versus 475 U/L [ U/L]), and day 3 (102 U/L [ U/L] versus 262 U/L [ U/L]) without reaching significance (Fig. 1). ALT levels demonstrated a similar profile with decreased ALT values in the NEVLP versus CS group in the first 3 days without reaching significance (Fig. 1). No differences were observed in ALP levels 1 week and 3 months after TABLE 3. Graft Function and Injury After Transplantation NEVLP (n 5 10) CS (n 5 30) transplantation. Posttransplant liver function was assessed by postoperative bilirubin levels and INR. INR values and bilirubin levels after 1 week and 3 months showed no difference between the groups (Table 3). SHORT-TERM CLINICAL OUTCOME AFTER LT P Value ALT peak 48 hours, U/L 619 ( ) 949 ( ) 0.55 INR peak 2.6 (2-4.4) 2.7 ( ) 0.61 INR 1 week 1.1 (1-1.56) 1.1 (1-1.3) 0.47 INR 3 month 1 (1-2) 1 (1-2) 0.91 Bilirubin 1 week, mg/dl 1.5 ( ) 2.78 (0.4-15) 0.49 Bilirubin 3 month, mg/dl 0.4 ( ) 0.6 (0.2-18) 0.21 ALP 1 week, U/L 202 (96-452) 147 (87-456) 0.21 ALP 3 month, U/L 111 ( ) 132 (54-657) 0.33 Creatinine 1 week, mg/dl 1.0 ( ) 0.9 ( ) 0.76 Creatinine 3 month, mg/dl 1.1 ( ) 1.1 ( ) 0.53 NOTE: Data are provided as median and range. Length of ICU stay, intermediate care stay, and posttransplant overall hospital stay was similar in both groups (Table 4). Notably, 3 patients in the NEVLP group and 5 patients in the CS group were fast-tracked with immediate posttransplant extubation and avoidance of ICU stay. Minor complications (Dindo-Clavien < 3b) occurred in 6 (60%) NEVLP patients compared with 16 (53%) patients of the CS group (P 5 0.8). Only 1 (10%) patient in the NEVLP group experienced a major complication (Dindo-Clavien 3b). This patient developed a severe pneumonia posttransplant requiring reintubation and ventilation for 3 days. Following FIG. 1. ALT and AST following transplantation with NEVLP or CS as the preservation technique. NEVLP-perfused grafts had lower ALT and AST values in the first 3 postoperative days without reaching significance. ORIGINAL ARTICLE 1505

6 SELZNER ET AL. LIVER TRANSPLANTATION, November 2016 extubation the patient recovered without further problems. No biliary complications were observed in the NEVLP patients. Seven (23%) patients in the CS group experienced a major complication including gastrointestinal bleeding, intra-abdominal abscess, bile duct stricture, and intra-abdominal bleeding. No graft loss or patient death occurred during the follow-up in either group. Discussion TABLE 4. Clinical Outcome NEVLP (n 5 10) CS (n 5 30) P Value ICU stay, days 1 (0-8) 2 (0-23) 0.54 Stepdown unit stay, days 3 (1-8) 3 (1-32) 0.3 LOH after LT, days 11 (8-17) 13 (7-89) 0.23 Fast-tracked patients 3 (30) 5 (17) 0.5 (no ICU after LT) Minor complications 6 (60) 16 (53) 0.8 (Dindo-Clavien < 3b) Major complications 1 (10) 7 (23) 0.5 (Dindo-Clavien 3b) Graft loss at 3 months 0 0 Patient death at 3 months 0 0 NOTE: Data are provided as median and range or n (%). This is the first study demonstrating that NEVLP with Steen solution as perfusate is safe for LT. With careful planning and preparation, no grafts were lost to technical issues or machine failure during this pilot study. All liver grafts had excellent function following transplantation. There is ample experimental evidence suggesting that NEVLP has the potential to provide better liver preservation than cold static storage. Brockmann et al. (5) reported decreased markers of preservation injury and improved survival with NEVLP when compared with CS in a pig model of LT. Fondevila et al. (15) found that porcine DCD liver grafts exposed to 120 minutes of warm ischemia had 100% animal survival with NEVLP, whereas all pigs died when CS was used as the preservation technique. Similarly, Boehnert et al. (9) as well as Knaak et al. (8) found that NEVLP significantly reduces bile duct injury when compared with CS in a porcine model of DCD LT. Reddy et al. (16) noted that the protective effects of NEVLP are attenuated when prolonged CS is added prior to the start of warm perfusion. These findings were also observed by our own group in a pig model of LT (data not shown). Therefore, innovators in this field are now focused on developing transportable perfusion equipment that will allow NEVLP to start at the donor hospital, in order to minimize the CIT before the liver is placed on normothermic perfusion. Different machine types have been recently developed (Metra-Organox, OCSLiver-Transmedic, and Liver Assist-Organ Assist) and have entered, or are about to enter, assessment by clinical trials. Machine reliability will be a key focus of these studies because warm perfused grafts are likely to be lost if normothermic perfusion is interrupted during transport. In our series, the Metra device perfusion characteristics remained stable during the entire perfusion period and no machine failure was observed. The optimal perfusion solution for portable NEVLP devices is still under investigation. Most of the animal studies of NEVLP used fresh whole blood or diluted blood as perfusate. (17) Fresh whole human blood is rarely available in the clinical setting, and in addition, contains unwanted mediators of reperfusion injury. In the European trial of the Metra device, Ravikumar et al. used gelofusine plus packed red blood cells as the perfusate with good outcomes. (7) Because gelofusine is not currently approved for use in North America, we chose to use the Steen solution instead, which is approved for lung preservation in Canada and the United States. The Steen solution contains human serum albumin with the aim to provide an optimal colloid osmotic pressure for organ storage. In addition, it also contains dextran 40 to coat and reduce leukocyte interactions with the vascular endothelium. Before undertaking this clinical trial, we performed extensive animal studies using the Steen solution to confirm its effectiveness for NEVLP. (8-10,18) A direct comparison of Steen solution and gelofusine has not been performed to date. The luxury of having additional time to review graft anatomy and assess graft function with NEVLP before transplantation proved beneficial, allowing us to decline 2 grafts that we believe would have had a high risk of graft failure. One graft placed on the Metra device had been obtained from a HBD on high-dose vasopressors with rising liver enzymes before procurement. This liver graft was not used because of patchy perfusion on the machine and a persistently elevated lactate level suggesting poor liver function. A second graft from a non HBD was not used by the receiving surgeon because of a hepatic artery retrieval injury that occurred during the DCD retrieval when liver and pancreas were both procured for transplantation. Ten grafts underwent transplantation with excellent graft function that was comparable with the case ORIGINAL ARTICLE

7 LIVER TRANSPLANTATION, Vol. 22, No. 11, 2016 SELZNER ET AL. matched historical controls at our center (Tables 3 and 4; Fig. 1). Although not measureable, our transplant teams perceived less pressure to complete the recipient hepatectomy quickly and less instability upon reperfusion when Metra-perfused livers were implanted. The present study was not designed to evaluate the efficacy of NEVLP to reduce preservation injury in marginal grafts. All grafts used in this trial fulfilled our criteria for transplantation and were expected to provide satisfactory graft function with standard CS. Although not yet confirmed in human studies, many animal studies suggest that marginal grafts supported by NEVLP will have better outcomes than grafts preserved with standard CS. (8,15,17,19,20) If this is confirmed in human studies, it will allow us to expand the donor pool and increase the number of available liver grafts for our patients on the transplant waiting list. The increased complexity and costs of organ procurement with NEVLP, demonstrated in this feasibility study, will be warranted if this technology allows us to perform more liver transplants with increased safety. For centers contemplating NEVLP, it is worth noting that this study required several months of planning, new resources, and significant training time. Our organ procurement agency bought a purpose-equipped motor vehicle to transport the Metra device, which is large (45-inch depth by 23-inch width by 42-inch height) and heavy (weight, 187 lbs) when compared with CS containers. This vehicle was equipped with 3-point restraints for safe transportation, a power source to provide an alternating current to run the machine during ground travel, and a power liftgate to facilitate moving the device in and out of the vehicle. Portable biochemistry measurement devices were also purchased to provide timely donor sample analysis. Cardiovascular perfusionists were recruited to oversee the setup, priming, and calibration of the perfusion device. Three mock perfusion runs were performed before the first clinical case was undertaken. It is also worth noting that in addition to the startup costs, the ongoing costs of NEVLP were greater than the costs of CS. The perfusion kits and supplies for the Metra device were much more expensive than CS supplies. Each case was performed by 2 fully trained procurement surgeons and a cardiovascular perfusionist to set up, monitor device performance, and be available for troubleshooting if necessary. Performing the back table at the donor hospital, connecting the liver to the perfusion device, and waiting an additional 20 minutes at the donor site to ensure the perfusion was stable prolonged the organ retrieval time by at least 2 hours. Two motor vehicles were required for team travel: 1 for the device and a perfusionist to monitor its performance during travel, and another for the rest of the team and the other equipment. The present study has several limitations and strengths. The study group has a small sample size, and the control group was selected from a historic transplant population. In addition, the costeffectiveness of the NEVLP technology was not evaluated. The study data were collected prospectively with a planned analysis using a matched-pair cohort to minimize confounding factors. The same surgical and medical teams and protocols were used to care for all recipients. In summary, this pilot study suggests that NEVLP with Steen solution as perfusate is safe and feasible as a preservation technique for human LT. 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