Portable hypothermic oxygenated machine perfusion for organ preservation in liver transplantation: A randomized, open-label, clinical trial.

BACKGROUND AND AIMS: In liver transplantation, cold preservation induces ischemia, resulting in significant reperfusion injury. Hypothermic oxygenated machine perfusion (HMP-O 2 ) has shown benefits compared to static cold storage (SCS) by limiting ischemia-reperfusion injury. This study reports outcomes using a novel portable HMP-O 2 device in the first US randomized control trial. APPROACH AND RESULTS: The PILOT trial (NCT03484455) was a multicenter, randomized, open-label, noninferiority trial, with participants randomized to HMP-O 2 or SCS. HMP-O 2 livers were preserved using the Lifeport Liver Transporter and Vasosol perfusion solution. The primary outcome was early allograft dysfunction. Noninferiority margin was 7.5%. From April 3, 2019, to July 12, 2022, 179 patients were randomized to HMP-O 2 (n=90) or SCS (n=89). The per-protocol cohort included 63 HMP-O 2 and 73 SCS. Early allograft dysfunction occurred in 11.1% HMP-O 2 (N=7) and 16.4% SCS (N=12). The risk difference between HMP-O 2 and SCS was -5.33% (one-sided 95% upper confidence limit of 5.81%), establishing noninferiority. The risk of graft failure as predicted by Liver Graft Assessment Following Transplant score at seven days (L-GrAFT 7 ) was lower with HMP-O 2 [median (IQR) 3.4% (2.4-6.5) vs. 4.5% (2.9-9.4), p =0.024]. Primary nonfunction occurred in 2.2% of all SCS (n=3, p =0.10). Biliary strictures occurred in 16.4% SCS (n=12) and 6.3% (n=4) HMP-O 2 ( p =0.18). Nonanastomotic biliary strictures occurred only in SCS (n=4). CONCLUSIONS: HMP-O 2 demonstrates safety and noninferior efficacy for liver graft preservation in comparison to SCS. Early allograft failure by L-GrAFT 7 was lower in HMP-O 2 , suggesting improved early clinical function. Recipients of HMP-O 2 livers also demonstrated a lower incidence of primary nonfunction and biliary strictures, although this difference did not reach significance.

The decedent model: A new paradigm for de-risking high stakes clinical trials like xenotransplantation.

The first 2 living recipients of pig hearts died unexpectedly within 2 months, despite both recipients receiving what over 30 years of nonhuman primate (NHP) research would suggest were the optimal gene edits and immunosuppression to ensure success. These results prompt us to question how faithfully data from the NHP model translate into human outcomes. Before attempting any further heart xenotransplants in living humans, it is highly advisable to gain a more comprehensive understanding of why the promising preclinical NHP data did not accurately predict outcomes in humans. It is also unlikely that additional NHP data will provide more information that would de-risk a xenoheart clinical trial because these cases were based on the best practices from the most successful NHP results to date. Although imperfect, the decedent model offers a complementary avenue to determine appropriate treatment regimens to control the human immune response to xenografts and better understand the biologic differences between humans and NHP that could lead to such starkly contrasting outcomes. Herein, we explore the potential benefits and drawbacks of the decedent model and contrast it to the advantages and disadvantages of the extensive body of data generated in the NHP xenoheart transplantation model.

Center use of technical variant grafts varies widely and impacts pediatric liver transplant waitlist and recipient outcomes in the United States.

To assess the impact of technical variant grafts (TVGs) [including living donor (LD) and deceased donor split/partial grafts] on waitlist (WL) and transplant outcomes for pediatric liver transplant (LT) candidates, we performed a retrospective analysis of Organ Procurement and Transplantation Network (OPTN) data on first-time LT or liver-kidney pediatric candidates listed at centers that performed >10 LTs during the study period, 2004-2020. Center variance was plotted for LT volume, TVG usage, and survival. A composite center metric of TVG usage and WL mortality was developed to demonstrate the existing variation and potential for improvement. Sixty-four centers performed 7842 LTs; 657 children died on the WL. Proportions of WL mortality by center ranged from 0% to 31% and those of TVG usage from 0% to 76%. Higher TVG usage, from deceased donor or LD, independently or in combination, significantly correlated with lower WL mortality. In multivariable analyses, death from listing was significantly lower with increased center TVG usage (HR = 0.611, CI: 0.40-0.92) and LT volume (HR = 0.995, CI: 0.99-1.0). Recipients of LD transplants (HR = 0.637, CI: 0.51-0.79) had significantly increased survival from transplant compared with other graft types, and recipients of deceased donor TVGs (HR = 1.066, CI: 0.93-1.22) had statistically similar outcomes compared with whole graft recipients. Increased TVG utilization may decrease WL mortality in the US. Hence, policy and training to increase TVG usage, availability, and expertise are critical.

Physiologic considerations of pig-to-human kidney xenotransplantation.

PURPOSE OF REVIEW: The greatest challenge facing end-stage kidney disease (ESKD) patients is the scarcity of transplantable organs. Advances in genetic engineering that mitigate xenogeneic immune responses have made transplantation across species a potentially viable solution to this unmet need. Preclinical studies and recent reports of pig-to-human decedent renal xenotransplantation signify that clinical trials are on the horizon. Here, we review the physiologic differences between porcine and human kidneys that could impede xenograft survival. Topics addressed include porcine renin and sodium handling, xenograft water handling, calcium, phosphate and acid-base balance, responses to porcine erythropoietin and xenograft growth. RECENT FINDINGS: Studies in nonhuman primates (NHPs) have demonstrated that genetically modified pig kidneys can survive for an extended period when transplanted into baboons. In recent studies conducted by our group and others, hyperacute rejection did not occur in pig kidneys lacking the α1,3Gal epitope transplanted into brain-dead human recipients. These experimental trials did not study potential clinical abnormalities arising from idiosyncratic xenograft responses to human physiologic stimuli due to the brief duration of observation this model entails. SUMMARY: Progress in biotechnology is heralding an era of xenotransplantation. We highlight the physiologic considerations for xenogeneic grafts to succeed.

Living donor liver transplant candidate and donor selection and engagement: Meeting report from the living donor liver transplant consensus conference.

INTRODUCTION: Living donor liver transplantation (LDLT) is a promising option for mitigating the deceased donor organ shortage and reducing waitlist mortality. Despite excellent outcomes and data supporting expanding candidate indications for LDLT, broader uptake throughout the United States has yet to occur. METHODS: In response to this, the American Society of Transplantation hosted a virtual consensus conference (October 18-19, 2021), bringing together relevant experts with the aim of identifying barriers to broader implementation and making recommendations regarding strategies to address these barriers. In this report, we summarize the findings relevant to the selection and engagement of both the LDLT candidate and living donor. Utilizing a modified Delphi approach, barrier and strategy statements were developed, refined, and voted on for overall barrier importance and potential impact and feasibility of the strategy to address said barrier. RESULTS: Barriers identified fell into three general categories: 1) awareness, acceptance, and engagement across patients (potential candidates and donors), providers, and institutions, 2) data gaps and lack of standardization in candidate and donor selection, and 3) data gaps regarding post-living liver donation outcomes and resource needs. CONCLUSIONS: Strategies to address barriers included efforts toward education and engagement across populations, rigorous and collaborative research, and institutional commitment and resources.

Stable liver graft post anti-PD1 therapy as a bridge to transplantation in an adolescent with hepatocellular carcinoma.

BACKGROUND: Immunotherapy, specifically immune checkpoint inhibitors (ICIs), including anti-programmed cell death 1 (anti-PD1), has recently received clinical approval for the treatment of adult hepatocellular carcinoma (HCC). However, the safety and efficacy of ICIs prior to solid organ transplant are unknown, especially in pediatrics. Safety reports are variable in adults, with some series describing subsequent allograft rejection and loss while others report successful transplants without allograft rejection.As ICIs stimulate the immune system by blocking the interaction between PD1 and the ligand-receptor pair programmed cell death-ligand 1 (PDL1), the downstream effects of T-cell activation increase the risk of graft rejection. METHODS: Here, we present a case of an adolescent with moderately differentiated non-fibrolamellar HCC treated with pembrolizumab, an anti-PD1 therapy, who subsequently underwent successful orthotopic liver transplantation (OLT). RESULTS: Our patient received an OLT 138 days from the last pembrolizumab dose with graft preservation. The patient has no evidence of recurrent disease or any episode of allograft rejection 48 months post OLT. Staining of tumor and normal tissues from longitudinal specimens finds PDL1 positive Kupffer cells present in normal liver and peritumoral areas with no changes post anti-PD1 therapy. In contrast, tumor cells were negative for PDL1. CONCLUSION: This case represents a basis for optimism in potential use of anti-PD1 therapy in liver transplant candidates and supports further investigation of immune checkpoint inhibitors use in this unique patient population.

Living Donor Liver Transplantation: Overview, Imaging Technique, and Diagnostic Considerations.

OBJECTIVE. The purpose of this article is to discuss the process of becoming a liver donor, describe the surgical methods used for transplantation, and critically review preoperative and intraoperative imaging techniques. CONCLUSION. Radiologists play a vital role in ensuring the safety of living liver donors; however, consensus guidelines do not exist for imaging protocol or reporting. Standardization would provide more consistent image quality across centers, improve communication with the transplant team, and facilitate data mining for quality assurance and research.

Living Donor Liver Transplantation: Preoperative Planning and Postoperative Complications.

OBJECTIVE. The purposes of this article are to highlight the similarities and differences in workup and work flow across multiple institutions in the preoperative imaging assessment of liver donors; to lay the foundation for developing consensus guidelines; to illustrate clinically relevant anatomic variants; to introduce a standardized reporting template; and to review postprocessing work flow and postoperative donor complications. CONCLUSION. Further investigation and consensus are needed to determine protocols, time intervals, and duration of follow-up of liver donors that are cost-effective and clinically relevant.

Evaluation of a three-session biliary dilation protocol following transplant-related biliary stricture in pediatric patients.

To evaluate whether a serial biliary dilation protocol improves outcomes and decreases total biliary drainage time for biliary strictures following pediatric liver transplantation. From 2006 to 2016, 213 orthotopic deceased and living related liver transplants were performed in 199 patients with a median patient age of 3.1 years at a single pediatric hospital. Patients with biliary strictures were managed by IR or surgically by the transplant team. Patients managed by IR were divided into two groups. The first group was managed with a standardized three-session protocol consisting of dilation every two weeks for three dilations. The second group was managed clinically with varying number and interval of dilations as determined by a multidisciplinary team. The location of biliary stricture, duration of drainage, number of balloon dilations, balloon diameter, time interval between dilations, and success of percutaneous treatment were recorded. Thirty-four patients developed biliary strictures. Thirty-one patients were managed with percutaneous intervention. Three strictures could not be crossed and were converted to operative management. Ten patients were managed in the three-session protocol, and 18 patients were managed in the clinically treated group. There was no significant difference in clinical success rates between groups, 80% and 61%, respectively. The three-session protocol group trended toward a lower total biliary drain indwell time (median 49 days) compared with the clinically treated group (median 89 days), P = .089. Our study suggests that a three-session dilation protocol following transplant-related biliary stricture may decrease total biliary drainage time for some patients.

Liver atrophy and regeneration in noncirrhotic portal vein thrombosis: Effect of surgical shunts.

The goal of the study is to characterize the relationship between portal vein thrombosis (PVT) and hepatic atrophy in patients without cirrhosis and the effect of various types of surgical shunts on liver regeneration and splenomegaly. Patients without cirrhosis with PVT suffer from presinusoidal portal hypertension, and often hepatic atrophy is a topic that has received little attention. We hypothesized that patients with PVT have decreased liver volumes, and shunts that preserve intrahepatic portal flow enhance liver regeneration. Sixty-four adult and pediatric patients with PVT who underwent surgical shunt placement between 1998 and 2011 were included in a retrospective study. Baseline liver volumes from adult patients were compared with standard liver volume (SLV) as well as a group of healthy controls undergoing evaluation for liver donation. Clinical assessment, liver function tests, and liver and spleen volumes from cross-sectional imaging were compared before and after surgery. A total of 40 patients received portal flow-preserving shunts (32 mesoportal and 8 selective splenorenal), whereas 24 received portal flow-diverting shunts (16 nonselective splenorenal and 8 mesocaval). Baseline adult liver volumes were 26% smaller than SLV (1248 versus 1624 cm3 ; P = 0.02) and 20% smaller than the control volumes (1248 versus 1552 cm3 ; P = 0.02). Baseline adult spleen volumes were larger compared with controls (1258 versus 229 cm3 ; P < 0.001). Preserving shunts were associated with significant increase in liver volumes (886 versus 1131 cm3 ; P = 0.01), whereas diverting shunts were not. Diverting shunts significantly improved splenomegaly. In conclusion, we have demonstrated that patients without cirrhosis with PVT have significant liver atrophy and splenomegaly. Significant liver regeneration was achieved after portal flow-preserving shunts. Liver Transplantation 24 881-887 2018 AASLD.

Roux-en-Y enterolith leading to obstruction and ischemic necrosis after pediatric orthotopic liver transplantation.

Biliary complications are a common cause of morbidity after liver transplantation, with biliary stone formation being a known occurrence generally upstream of a stricture. A 12-year-old boy, who underwent an orthotopic liver transplantation at 11 months of age for biliary atresia, presented acutely with fever and abdominal pain. Cross-sectional imaging revealed Roux-en-Y limb dilatation and thickening. He was explored and was found to have an ischemic Roux limb secondary to an obstructing enterolith. A segmental bowel resection and revision of his hepaticojejunostomy was performed. While rare, biliary enteroliths may present as either a bowel obstruction or cholangitis and should be considered in the differential diagnosis of a patient following biliary reconstruction. Additionally, anatomic etiologies should be considered and potentially surgically corrected.

Recurrence After Liver Transplantation for Hepatocellular Carcinoma: A New MORAL to the Story.

OBJECTIVE: We sought to develop a "Model Of Recurrence After Liver transplant" (MORAL) for hepatocellular carcinoma (HCC). BACKGROUND: The Milan criteria are used to allocate livers to patients with HCC requiring liver transplantation (LT) but do not include objective measures of tumor biology. Biological markers including the neutrophil-lymphocyte ratio (NLR) and alpha-fetoprotein (AFP) have been associated with recurrence risk. METHODS: Prospective cohort study of adults undergoing LT for HCC between January 2001 and December 2012. RESULTS: A total of 339 patients were included. On multivariable Cox regression analysis, 3 preoperatively available factors were independent predictors of worse recurrence-free survival (RFS), namely, an NLR ≥ 5 (P < 0.0001, hazard ratio, HR: 6.2), AFP > 200 (P < 0.0001, HR: 3.8), and Size >3 cm (P < 0.001, HR: 3.2). The Pre-MORAL score was constructed from the hazard ratios and assigning patients points in an additive fashion, with a minimum of 0 points (no factors) and a maximum of 13 points (all 3 factors). The highest risk patients in the Pre-MORAL had a 5-year RFS of 17.9% compared with 98.6% for the low risk group (P < 0.0001). The post-MORAL was constructed similarly using the 4 postoperatively available independent predictors of worse RFS, grade 4 HCC's (P < 0.0001, HR: 5.6), vascular invasion (P = 0.019, HR: 2.0), size >3 cm (P < 0.0001, HR: 3.2) and number >3 (P = 0.048, HR: 1.8). The pre- and post-MORAL were superior to Milan at predicting recurrence with c-statistics of 0.82 and 0.87, compared with 0.63, respectively. We then combined the scores to produce a combo-MORAL, with a c-statistic of 0.91 for predicting recurrence. CONCLUSIONS: The MORAL score provides a simple, highly accurate tool for predicting recurrence and risk-stratification pre- and postoperatively.

Expanding the Margins: High Volume Utilization of Marginal Liver Grafts Among >2000 Liver Transplants at a Single Institution.

OBJECTIVE: Marginal livers (ML) have been used to expand the donor pool. National utilization of MLs is variable, and in some centers, they are never used. We examined the outcomes of MLs in the largest single center series of MLs used to date and compared outcomes to standard (SL) and living donor (LD) livers. METHODS: Analysis of a prospectively maintained database of all liver transplants performed at our institution from 1998 to 2016. ML grafts were defined as livers from donors >70, livers discarded regionally and shared nationally, livers with cold ischemic time >12 hours, livers from hepatitis C virus positive donors, livers from donation after cardiac death donors, livers with >30% steatosis, and livers split between 2 recipients. RESULTS: A total of 2050 liver transplant recipients were studied, of these 960 (46.8%) received ML grafts. ML recipients were more likely to have lower MELDs and have hepatocellular carcinoma. Most MLs used were from organs turned down regionally and shared nationally (69%) or donors >70 (22%). Survival of patients receiving MLs did not significantly differ from patients receiving SL grafts (P = 0.08). ML and SL recipients had worse survival than LDs (P < 0.01). Despite nearly half of our recipients receiving MLs, overall survival was significantly better than national survival over the same time period (P = 0.04). Waitlist mortality was significantly lower in our series compared with national results (19% vs 24.0%, P < 0.0001). CONCLUSIONS: Outcomes of recipients of ML grafts are comparable to SL transplants. Despite liberal use of these grafts, we have been able to successfully reduce waitlist mortality while exceeding national post-transplant survival metrics.

Leaning to the Left: Increasing the Donor Pool by Using the Left Lobe, Outcomes of the Largest Single-center North American Experience of Left Lobe Adult-to-adult Living Donor Liver Transplantation.

OBJECTIVE: Centers offering adult living donor liver transplantation (LDLT) mostly use right lobe grafts due to fears of providing recipients with insufficient hepatic volume, and the technical challenges presented by using left lobe grafts (LLGs). LLGs therefore represent approximately 5% of adult LDLTs performed in the United States. Here we present the largest North American experience with the use of LLG for adult LDLT. METHODS: Analysis of a prospectively maintained database of LDLTs performed from 1998 to 2015 at our institution. RESULTS: A total of 214 adult LDLTs were studied. Fifty-six patients (26%) received LLG. LLG recipients were more likely to be women, had significantly lower BMI, graft weight, and graft-weight-recipient-weight ratios (P < 0.05 for all). There were no significant differences in vascular or biliary complication between the groups. No significant differences existed in patient or graft survival at 1, 3, and 5 years (P = 0.747 and P = 0.398 respectively). Despite significantly increased risk of small-for-size syndrome in LLG, there was no increased risk of retransplant within 90-days or perioperative mortality in LLG recipients (P = 0.308 and P = 0.932 respectively). Graft type did not predict patient or graft outcomes on regression analysis (P = 0.857 and 0.399 respectively). CONCLUSIONS: Despite smaller graft sizes, outcomes of adult LDLT using LLG are comparable to right lobe grafts transplants. Left lobes can provide an important resource in an era of severe organ shortages, and these data should serve to allay the concerns of the transplant community in the United States.

Standing the test of time: outcomes of a decade of prioritizing patients with hepatocellular carcinoma, results of the UNOS natural geographic experiment.

UNLABELLED: Priority is given to patients with hepatocellular carcinoma (HCC) to receive liver transplants, potentially causing significant regional disparities in organ access and possibly outcomes in this population. Our aim was to assess these disparities by comparing outcomes in long waiting time regions (LWTR, regions 5 and 9) and short waiting time regions (SWTR regions 3 and 10) by analyzing the United Network for Organ Sharing (UNOS) database. We analyzed 6,160 HCC patients who received exception points in regions 3, 5, 9, and 10 from 2002 to 2012. Data from regions 5 and 9 were combined and compared to data from regions 3 and 10. Survival was studied in three patient cohorts: an intent-to-treat cohort, a posttransplant cohort, and a cohort examining overall survival in transplanted patients only (survival from listing to last posttransplant follow-up). Multivariate analysis and log-rank testing were used to analyze the data. Median time on the list in the LWTR was 7.6 months compared to 1.6 months for SWTR, with a significantly higher incidence of death on the waiting list in LWTR than in SWTR (8.4% versus 1.6%, P < 0.0001). Patients in the LWTR were more likely to receive loco-regional therapy, to have T3 tumors at listing, and to receive expanded-criteria donor (ECD) or donation after cardiac death (DCD) grafts than patients in the SWTR (P < 0.0001 for all). Survival was significantly better in the LWTR compared to the SWTR in all three cohorts (P < 0.0001 for all three survival points). Being listed/transplanted in an SWTR was an independent predictor of poor patient survival on multivariate analysis (P < 0.0001, hazard ratio = 1.545, 95% confidence interval 1.375-1.736). CONCLUSION: This study provides evidence that expediting patients with HCC to transplant at too fast a rate may adversely affect patient outcomes.

Risk Factors for 30-Day Unplanned Readmission After Hepatectomy: Analysis of 438 Pediatric Patients from the ACS-NSQIP-P Database.

BACKGROUND: Hepatic resections are uncommon in children. Most studies reporting complications of these procedures and risk factors associated with unplanned readmissions are limited to retrospective data from single centers. We investigated risk factors for 30-day unplanned readmission after hepatectomy in children using the American College of Surgeons National Surgical Quality Improvement-Pediatric database. METHODS: The database was queried for patients aged 0-18 years who underwent hepatectomy for the treatment of liver lesions from 2012 to 2018. Chi-squared tests were performed to evaluate for potential risk factors for unplanned readmissions. A multivariate regression analysis was performed to identify independent predictors for unplanned 30-day readmissions. RESULTS: Among 438 children undergoing hepatectomy, 64 (14.6%) had unplanned readmissions. The median age of the hepatectomy cohort was 1 year (0-17); 55.5% were male. Patients readmitted had significantly higher rates of esophageal/gastric/intestinal disease (26.56% vs. 14.97%; p=0.022), current cancer (85.94% vs. 75.67%; p=0.012), and enteral and parenteral nutritional support (31.25% vs. 17.65%; p=0.011). Readmitted patients had significantly higher rates of perioperative blood transfusion (67.19% vs. 52.41%; p=0.028), organ/space surgical site infection (10.94% vs. 1.07%; p<.001), sepsis (15.63% vs. 3.74%; p<.001), and total parenteral nutrition at discharge (9.09% vs. 2.66%; p=0.041). Organ/space surgical site infection was an independent risk factor for unplanned readmission (OR=9.598, CI [2.070-44.513], p=0.004) by multivariable analysis. CONCLUSION: Unplanned readmissions after liver resection are frequent in pediatric patients. Organ/space surgical site infections may identify patients at increased risk for unplanned readmission. Strategies to reduce these complications may decrease morbidity and costs associated with unplanned readmissions.