Oral (pre-recorded)
OT01 Transplantation: Liver 
Selection of Presentations from Abstract Submissions
OT01-02 An in vitro 3D Model of Functional Human Liver Organoids
Aiste Gulla, United States

A. Gulla1,2,3, J. Denkovskij3, J. Novikova4, A. Misiunas5, D. Vitkus6, R. Rackauskas7, V. Sokolovas7, K. Strupas7, A. Ziogas8,9
1Department of Surgery, Georgetown University Hospital, United States, 2Department of Surgery, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Lithuania, 3Center for Innovative Medicine, Lithuania, 4Vilnius Gediminas Technical Institute, Lithuania, 5Center for Physical Sciences and Technology, Lithuania, 6Faculty of Medicine, Institute of Clinical Medicine, Vilnius University, Lithuania, 7Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Lithuania, 8Centre for Innovative Medicine, Lithuania, 9Vilnius Gediminas Technical University, Lithuania

Introduction: The development of adequate model systems to investigate human liver function and metabolism in health and disease has proved challenging. Three-dimensional (3D) liver tissues reconstituted from liver cells, termed liver organoids, have enormous potential for investigating aspects of liver disorders and drug toxicity. The aim of our study is by integration of multiple novel surgical techniques, engineering of growth factors and morphogens bound to extracellular matrix, direct cell reprogramming to produce functional 3D liver organoids.
Methods: Tissue from 20 liver resections were used for hepatocyte isolations. Tissue underwent a two-step EDTA/collagenase digestion. Cell viability was determined by ATP luminescence and 7AAD. qPCR, FACS, Western blot, imunofluorescence analysis and biochemical assays were undertaken to ascertain cellular phenotype and function in 3D cultures. Additionally, liver development-associated signaling pathways were tested.
Results: We demonstrate that there is direct correlation between liver status, the number and viability of isolated hepatocytes and their functional properties in 2D and 3D environment. FACS analysis indicated that prolonged cultivation in 2D leads to changes in cell populations. We also generated functional liver 3D organoids that maintained viability up to three weeks, produced albumin and expressed liver specific genes HNF4, CK19, AAT, CYP3A4.
Conclusions: We have successfully established a method for the culture of human liver organoids in novel engineered 3D environments that can be used for biomarker discovery, drug toxicity studies and liver transplantation.
OT01-04 Preoperative Splenomegaly Is a Risk Factor for Prolonged Splenomegaly after Liver Transplantation and Can Result in Hypersplenism and Graft Fibrosis
Kojiro Taura, Japan

K. Taura1, H.N. Nguyen1, S. Yao1, T. Kaido2, Y. Uemoto1, Y. Kimura1, S. Yagi1, K. Hata1, S. Uemoto1
1Surgery, Kyoto University, Japan, 2Surgery, St Luke's International Hospital, Japan

Background: Splenomegaly (SM) often persists after liver transplantation (LT), however, its predictors and clinical significance are unknown.
Methods: We analyzed 415 LT recipients in our institution to clarify this issue. First, predictors and clinical consequences of persistent SM three years after LT were analyzed among spleen-preserved recipients. Second, the clinical data of surviving recipients three years after LT were compared between splenectomized and spleen-preserved recipients using propensity score matching (PSM). Third, survival outcomes were compared between splenectomized and spleen-preserved recipients after PSM. SM was determined as a splenic volume (SV)/body surface area (BSA) > 152 ml/m2 based on the CT splenic volumetry data of 140 donors.
Results: In the first analysis, among 119 recipients with preoperative SM, 86 (73.6%) recipients had persistent SM 3 years after LT. Preoperative SV/BSA was the only independent predictor for the persistent SM and it was associated with lower platelet (PLT) and white blood cell (WBC) counts and significant graft fibrosis (≥ Metavir F2) (21.4% vs. 2.8%, p = 0.01). In the second analysis, spleen preservation was related to lower PLT and WBC counts and a higher proportion of significant graft fibrosis (26.7% vs. 7.1%, p = 0.022) three years after LT. In the third analysis, spleen-preserved recipients showed worse survival than splenectomized recipients (73.3% vs. 84.5% at 3 years after LT, p = 0.04).
Conclusions: Preoperative SM frequently persists more than three years after LT and is associated with subclinical hypersplenism, graft fibrosis and even death.
OT01-05 Usefulness of Mac-2 Binding Protein Glycosylation Isomer (M2BPGi) for Evaluating Graft Status after Liver Transplantation
Yusuke Kimura, Japan

Y. Kimura1, K. Taura1, H.N. Nguyen1, Y. Uemoto1, S. Seo1, K. Iwaisako2, T. Imai3, S. Uemoto1
1Surgery, Kyoto University, Japan, 2Medical Life Systems, Doshisha University, Japan, 3Medical Statistics, Kyoto University, Japan

Introduction: Mac-2 binding protein glycosylation isomer (M2BPGi) is a novel serum biomarker for liver fibrosis, but studies have suggested that its values can be influenced by some other factors. Studies on M2BPGi in liver transplant (LT) patients are scarce. This study aimed to evaluate the usefulness of M2BPGi measurement in LT recipients.
Methods: We collected clinicopathological data of 233 LT recipients who underwent liver biopsy in Kyoto University Hospital between August 2015 and June 2019.
Results: The median value of M2BPGi in patients with Metavir F0, F1, F2 and ≧F3 were 0.61, 0.76, 1.16, and 1.47, respectively. The median value of M2BPGi in patients with Metavir A0, A1, and ≧A2 were 0.53, 1.145, and 2.24, respectively. Spearman correlation analysis indicated a significant positive correlation between F factor and M2BPGi value (r=0.25 p< 0.001) and between A factor and M2BPGi value (r=0.46 p< 0.001). The difference calculated by subtracting Spearman's rank correlation coefficient between A factor and M2BPGi value from that between F factor and M2BPGi value was 0.21 (95% confidence interval was 0.095-0.39), indicating necroinflammatory activity had a stronger impact on M2BPGi value than fibrosis stage. The area under the receiver operating characteristic curve of M2BPGi for predicting ≧A1 were 0.75, which was significantly higher than other liver fibrosis and inflammation markers.
Conclusion: M2BPGi values are more strongly influenced by necroinflammatory activity than by fibrosis stage. M2BPGi may be useful to detect early stage of liver inflammation that cannot be detected by the routine blood examination in LT recipients.
OT01-06 The Development of a Tissue Methylation-Specific Cell Free DNA Biomarker for Organ Rejection Following Liver Transplantation
Daniel R A Cox, Australia

D.R.A. Cox1,2, N. Low1,2, S.K. Goh2, C. Christophi1,2, A. Testro3, A. Dobrovic1, V. Muralidharan1,2
1Department of Surgery, University of Melbourne, Australia, 2HPB Surgery & Transplant Unit, Austin Health, Australia, 3Liver Transplant Unit, Department of Gastroenterology & Hepatology, Austin Health, Australia

Introduction: Graft-derived cell-free DNA (gdcfDNA) quantification is an emerging, minimally-invasive tool for monitoring organ health and detecting acute cellular rejection following liver transplantation (LT). Issues with the scalability of laboratory workflows, which usually require genotyping of the donor/recipient, have slowed its translation into clinical use. Recent work has illustrated that patterns of DNA methylation are unique to the tissue of origin. We describe the development of a hepatocyte methylation-specific cfDNA (MS-cfDNA) biomarker to quantify gdcfDNA without the requirement for donor/recipient genotyping. We report a pilot study of the biomarker in two cohorts of LT patients.
Methods: Cohort 1: blood was collected from 10 patients post-LT, at 8 time-points. cfDNA was extracted from plasma and underwent bisulfite modification. Droplet-digital PCR was used to quantify gdcfDNA using the MS-cfDNA biomarker. A gdcfDNA assay employing donor/recipient genotyping was used to cross-validate results. Cohort 2: blood was collected from 50 patients undergoing liver biopsy for suspected rejection. The MS-cfDNA biomarker was used to quantify gdcfDNA at the time of biopsy.
Results: The MS-cfDNA biomarker was successful in quantifying gdcfDNA post-LT and mapping trends of organ injury. The MS-cfDNA biomarker produced significant linear correlation in values to a gdcfDNA assay utilising genotyping. gdcfDNA quantification at the time of biopsy was used with the aim of establishing diagnostic thresholds for rejection.
Conclusions: A MS-cfDNA biomarker is effective for monitoring gdcfDNA following LT. It has a major advantage over previous gdcfDNA quantification techniques; it does not require genotyping, giving it greater feasibility for translation into transplantation care.
OT01-08 Is MELD Score the Best Method of Predicting Waiting List Mortality in the Australian and New Zealand Liver Transplant Population?
Eunice Lee, Australia

E. Lee1,2, M. Perini1,2, G. Oniscu3, R. Jones4, G. Starkey4, B. Wang4, E. Makalic5, M. Fink1,2
1Austin Hospital, Australia, 2University of Melbourne, Australia, 3Edinburgh Transplant Centre, United Kingdom, 4Austin Health, Australia, 5Melbourne School of Population and Global Health, University of Melbourne, Australia

Introduction: Model for end-stage liver disease (MELD) score is a reproducible, validated and widely accepted method for prioritisation of patients for liver transplantation, although there are some limitations. The aim was to create an Australian and New Zealand (ANZ) population-derived waiting list mortality score, and to compare the discriminative ability of this score to MELD and MELD-Na scores.
Method: All transplants from January 1998 to May 2019 were included, using data from the ANZ Liver Transplant Registry. The outcome considered was patient death prior to transplantation. The ANZ-derived waiting list mortality score was created by randomly splitting the data into training and test datasets (70:30). Elastic net regularisation was used to select variables to create the multivariable Cox model. Discrimination of MELD, MELD-Na and the ANZ scores was compared using the c-statistic.
Results: 4886 listings were included, with a total of 534 waiting list deaths. 30 of 39 variables were selected for the ANZ score Cox model, with the highest hazard ratios for patients who were ventilated at time of listing (HR 4.4, 95% CI 2.22-8.68) and patients listed from 2006 to 2011 (HR 2.54, CI 1.69-3.82). The c-statistic for MELD and MELD-Na score was 0.76 and 0.77 respectively. The c-statistic for the ANZ score was 0.8.
Conclusion: The discriminative ability of all 3 scores was similar, despite a large number of variables included in the ANZ score. Both MELD and MELD-Na are simple to calculate and performed well in predicting waiting list mortality in the ANZ transplant population.
OT01-09 Long Term Outcomes of Hepatic Resection Following Orthotopic Liver Transplant
Skyle Murphy, Australia

S. Murphy, P. Hodgkinson, T. O-Rourke, K. Slater, S. Yeung, J. Fawcett
Department of Surgery, Princess Alexandra Hospital, Australia

Liver resection is sometimes used as a graft saving procedure following orthotopic liver transplantation. In this single centre retrospective cohort study, 12 adult patients underwent resection over a 20 year period, including recipients of split livers and second grafts. Indications for resection were ischemic cholangiopathy, hepatic artery thrombus, chronic biliary obstruction, biliary-vascular fistula, bile leak, recurrent PSC and recurrent HCC. There was no perioperative mortality. Median follow up was 89 months. At the completion of the study 40% of patients had functioning grafts. One third required retransplantation with a median 1 year 6 months post resection. 3 patients were deceased (recurrent HCC n=1, PSC n=1 and unspecified causes n=1). Total graft survival was 91.7% at 1 year, 73.3% at 5 years and 64.2% at 10 years. Liver resection following liver transplant in select patients may salvage the graft or delay the need for retransplantation.
OT01-10 Liver Transplantation in the Elderly: An Updated Review of 55,267 Patients in the United States
Krishnaraj Mahendraraj, United States

K. Mahendraraj, N. Nissen, K. Kosari, G. Voidonikolas, T. Todo, T. Brennan, A. Klein, I. Kim
Surgery, Cedars-Sinai Medical Center, United States

Introduction: Liver transplantation in the elderly is regarded with caution due to increased morbidity. This study assesses the postoperative outcomes of orthotopic liver transplantation (OLT) in elderly patients.
Method: Data on 55,267 OLT recipients from the Scientific Registry of Transplant Recipients over a 10 year period (2007-2017) was analyzed. Three age-based subgroups were created: elderly (age 70 and over), middle-age (age 50-69), and young (age 18-49).
Results: There were 1,622 elderly OLT patients, 40,271 middle-age patients and 13,374 young patients. Median MELD-Na score of elderly patients was significantly lower, with 63.8% elderly patients having MELD< 20. Most elderly patients received OLT for hepatocellular carcinoma. Elderly patients spend a longer time on the waitlist, and received more marginal organs (older age, DCD, ECD, history of malignancy, more macrosteatosis). Elderly patients had lower post-transplant survival (66.15% vs. 71.4% and 71.7%) and lower graft survival (68.4% vs. 73.9% and 75.7%), p< 0.01. They had more graft complications (hepatic artery thrombosis, infection, primary non-function), p>0.05, but lower 6-month and 1-year rejection rates. Kaplan-Meier 5-year graft survival was 3.98 years in the elderly vs. 4.03 years and 4.76 years in other groups, p< 0.001.
Conclusions: Elderly recipients tended to be relatively healthy at the time of transplant, but tended to wait longer for donor organs with more marginal characteristics. Despite having a lower overall and graft survival rate, this difference (less than 5%) was not clinically significant. These results suggest that OLT is safe and viable in the elderly, even using marginal donor organs.
[Clinical Outcomes for 55,267 Orthotopic Liver Transplantation Recipients from the SRTR (2007-2017)]
OT01-11 Development of an Ex-vivo Normothermic Perfusion Machine in Latin America, Implementation and Results in a Porcine Animal Liver Transplant Experiment
Sergio Andrés Riveros, Chile

S.A. Riveros1, G. Ochoa2, P. Achurra2, C. Marino2, E. Morales2, M.J. Zenteno3, L. Alegria4, D. Soto4, R. Rebolledo5
1Digestive Surgery, Pontificia Universidad Católica de Chile, Chile, 2Digestive Surgery, Pontificia Universidad Catolica de Chile, Chile, 3Veterinary Medicine Anesthesiology, Universidad de Chile, Chile, 4Intensive Medicine, Pontificia Universidad Catolica de Chile, Chile, 5Experimental Surgery UC, Pontificia Universidad Catolica de Chile, Chile

Introduction: Donation in Chile and Latin America has been historically low. In order to increase the graft pool and recuperate low quality grafts, our design a normothermic perfusion machine developed in Chile.
Methods: Experimental study of porcine liver transplant (N=20) comparing cold static preservation (CSP) and normothermic perfusion (NTP), in two types of grafts; shock liver (SL) and control liver (CL), creating 4 experimental groups: CSP-CL (N=5), CSP-SL (N=5), NTP-CL (N=6) and NTP-SL (N=4). Each experiment have three phases: procurement, preservation and transplantation. We compare variables on NTP phase for 3 hours and 5-hours follow-up after portal reperfusion between 4 groups. Statistical analysis with ANOVA test.
Results: During the preservation of the NTP-SL group were no differences related to the NTP-CL group in portal flow, arterial flow, portal pH, lactate, bile production, AST, ALT, PA and LDH (pNS). During the transplant the average time was 174 min, 31 min anhepatic time, survived surgery 90% and survived at 5 hours of follow-up 80%, without differences between the four groups (pNS). When comparing NTP-SL with PEF-SL results a significant decrease in AST, ALT and PA in favor of NTP (p< 0.05).
Conclusion: Our local NTP machine model shows safety when compared to CSP and a decrease in markers of post-reperfusion injury in short-term follow-up.
[ALT results in hourly monitoring from portal reperfusion.]
OT01-12 Incorporation of von Willebrand Factor Improves MELD-Na Based Prediction of Early Mortality on the Waiting List for Liver Transplantation
David Pereyra, Austria

D. Pereyra, G. Györi, B. Rumpf, C. Köditz, G. Ortmayr, J. Santol, G. Berlakovic, P. Starlinger
Department of Surgery, Medical University of Vienna, General Hospital Vienna, Austria

Introduction: Today, Model of End-Stage Liver Disease (MELD) is commonly used for decision making and organ allocation in orthotopic liver transplantation (OLT). Still, recent reports suggest that MELD may underestimate complications arising from portal hypertension or infection. In this context, von Willebrand factor antigen (vWF-Ag) - previously introduced as a robust surrogate parameter for portal venous pressure - was shown to be associated to adverse outcome in patients with cirrhosis while being independent from portal hypertension. Accordingly, this study aimed to evaluate the value of vWF-Ag as an auxiliary marker for risk stratification on the waitlist for OLT.
Methods: MELD and vWF-Ag at time of listing were assessed in 269 patients. Patients were followed up for mortality on the waitlist and overall survival.
Results: Patients dying within three months on the waitlist displayed elevated levels of vWF-Ag (p< 0.001). Interestingly, MELD and vWF-Ag showed a similar predictive potential for three-month mortality (AUC:vWF-Ag=0.739;MELD=0.770). Yet, a cut-off for vWF-Ag at 413% was found to harbor a higher risk for patients when compared to the previously used cut-off for MELD at 15 points (vWF-Ag:OR=10.873,95%-confidence interval:3.160-36.084, p< 0.001; MELD:OR=6.527,95%-confidence interval:2.216-19.227, p=0.001). Ultimately, combination of vWF-Ag and MELD significantly improved prediction of three-month waitlist mortality (AUC: vWF-Ag+MELD=0.836).
Conclusion: A single measurement of vWF-Ag at listing for OLT was found to increase the predictive potential for early mortality on the waitlist. Thus, introduction of vWF-Ag evaluation into the allocation process for patients listed for OLT might lead to a decrease in waitlist mortality.
OT01-13 Hypoxia-induced Angiogenesis Rescues Survival from Small for Size Syndrome (SFSS)
Alexandra Dili, Belgium

A. Dili1,2, M. De Rudder1, B. Pirlot1, C. Bertrand2, L. Dewachter3, C. Bouzin4, I. Leclercq1
1Institut de Recherche Expérimentale et Clinique-pôle Gastroenterology, Université Catholique de Louvain (UCL), Belgium, 2Surgery, CHU-UCL Namur, Site Godinne, Belgium, 3Laboratoire de Physiologie et Pharmacologie, Université Libre de Bruxelles, Belgium, 4Institut de Recherche Expérimentale et Clinique-imaging Platform, Université Catholique de Louvain (UCL), Belgium

After extended hepatectomy, hepatocyte proliferation proceeds sinusoidal endothelial cell (SEC) remodeling causing a transient perturbation of the lobular architecture with proliferating hepatocytes forming avascular, hypoxic, clusters. Hypoxia is, thus, considered at the origin of liver dysfunction in SFSS-hepatectomy. Recently, we showed that activation of hypoxia sensors in an upfront SFSS-hepatectomy surged an early angiogenic switch and preserved the sinusoidal architecture with a favorable impact on survival.
Aim: to decipher the role hypoxia-induced angiogenesis in SFSS-setting hepatectomy.
Methods: we developed a mouse model of SFSS-hepatectomy (PHx-80%) and used PHx-70% as controls. SFSS‐hepatectomy mice were submitted to normoxia (inspired oxygen fraction-FiO2: 21%), local hypoxia (hepatic artery ligation (PHx-HAL)), and systemic hypoxia by placing the animals in hypoxic chambers (FiO2: 11%, PHx-HC). We assessed mortality, hepatocyte and liver SEC proliferation.
Results: Compared to PHx-70%, PHx-80% showed high mortality rates (68% on postoperative day (POD) 7 (p=0,002)). Hepatocyte proliferation on POD 3 was higher in PHx-80% (p=0,03), while SEC proliferation did not differ, suggesting an amplified disorganization of the regenerating lobule in SFSS-hepatectomy. Compared to normoxic PHx-80%, PHx-HAL tended to have a favorable impact on survival (75% on POD3), while animals subjected to SFSS- hepatectomy and placed into hypoxic chambers showed improved survival (p=0,0007). Hepatocyte proliferation was similar between the hypoxic and normoxic SFSS-liver remnants. However, local and systemic hypoxia significantly triggered early angiogenesis.
Conclusions: The current data suggest that hypoxia rescues survival from SFSS. By balancing angiogenesis with hepatocyte proliferation, hypoxia restores the lobular liver architecture allowing an efficient regeneration after major hepatectomy.
OT01-14 Radioembolization Does Not Appear to Result in Superior Results Compared with TACE for HCC
Ola Ahmed, United States

W. Chapman1, W. Johnston2, S.-H. Chang3, N. Vachharajani1, A. Khan1, M.M. Doyle1, O. Ahmed4
1Department of Surgery, Washington University School of Medicine, United States, 2University of Pennsylvania, United States, 3Washington University School of Medicine, United States, 4Department of Surgery, Washington University School of Medicine, United States

Introduction:TACE and Radioembolization with Y-90 are used as alternative treatment strategies for patients with HCC. We assessed whether Y-90 resulted in superior results, performing statistical adjustment to control for HCC disease status.
Methods: All patients receiving neo-adjuvant loco-regional therapy (LRT) for HCC after January 2010 to January, 2018 were assessed using a prospective database. Patients were stratified by LRT: transarterial chemoembolization (TACE) and radioembolization of yttrium-90 (Y90), while patients receiving both were excluded. Survival analyses assessed patient overall survival (OS) and progression-free survival (PFS). All analyses were conducted using inverse probability of treatment weighting (IPTW), where propensity scores were used to generate weights with covariates including patients' demographics and tumor characteristics, to balance the distributions across the treatment groups. All tests were two-sided; statistical significance was determined using α=0.05.
Results: A total of 787 HCC patients receiving TACE (n=681, 87%) or Y90 (n=106, 13%) from 2010-2018. The two groups were statistically significant different in size (4.5 + 3.1 cm vs 8.3 + 4.8, p< 0.001), > 3 tumors (12.5% vs 36.7%, p< 0.001) and bilobar disease 17.3% vs 44.6%). Patient IPTW-adjusted OS and PFS (Figure 1) were statistically significantly different between the two groups (log-rank test p-value < 0.0001 for both). Patients receiving Y90 were less likely to receive LT (odds ratio: 0.49, 95% confidence interval, CI: 0.38-0.63).
Conclusion:Using IPTW to control for differences in HCC status, we were unable to demonstrate superiority of Y-90 over standard TACE treatment. These results have lead us to re-assess selection of regional therapy strategies.
[TACE versus Radioembolization]
OT01-15 Impact of Biliary Complications on Outcomes after Pediatric Liver Transplant
Adeel Khan, United States

A. Khan1, S. Kulkarni2, M. Mendiola-Pla2, N. Vachharajani2, M. Nadler2, J. Stoll2, J. Lowell2, W. Chapman2, M.M. Doyle2
1Department of Surgery, Washington University School of Medicine, United States, 2Washington University School of Medicine, United States

Introduction: Biliary complications (BCs) are seen in up to 50% of pediatric liver transplant (PLT) recipients and contribute to considerable post-procedural morbidity.
Methods: Retrospective review of all patients developing BC's after PLT at tertiary care hospital from 2002-2019. Outcomes of BC patients were compared with PLT recipients who did not develop BCs (control) and risk factors were identified.
Results: BC's were seen in 39 (18%) of the 221 PLT's performed during the study-period: 8 leaks, 26 strictures, 5 leaks+strictures. There was no difference between BC and control groups in recipient age, gender, weight, etiology, type of biliary reconstruction, and cold and warm ischemia times. Univariate and multivariate analysis identified Caucasian race, use of living donor and/or partial grafts, use of T-tubes and/or internal stents, operative time>7hrs, acute cellular rejection (ACR), PLT before 2010 and donor age>10 kg as independent risk factors of BC's(P< 0.05), while use of T-tubes/internal stents was independently associated with decreased survival. The 39 BC patients required 10 surgeries, 23 ERCPs and 223 PTC procedures for definitive repair, and demonstrated higher rates of 30- and 90- day readmission (p< 0.05). There was no difference in overall patient and graft survival between the two groups.
Conclusions: T-tubes/internal stents, partial grafts, prolonged operative-time and ACR in post-transplant period are risk factors for BC's and add considerable morbidity and cost through frequent readmissions and need for multiple procedures. Timely and effective intervention strategies based on multidisciplinary approach can help successfully treat BC's without impacting patient and graft survival.