Technical optimization of spatially resolved single-cell transcriptomic datasets to study clinical liver disease.

Single cell and spatially resolved 'omic' techniques have enabled deep characterization of clinical pathologies that remain poorly understood, providing unprecedented insights into molecular mechanisms of disease. However, transcriptomic platforms are costly, limiting sample size, which increases the possibility of pre-analytical variables such as tissue processing and storage procedures impacting RNA quality and downstream analyses. Furthermore, spatial transcriptomics have not yet reached single cell resolution, leading to the development of multiple deconvolution methods to predict individual cell types within each transcriptome 'spot' on tissue sections. In this study, we performed spatial transcriptomics and single nucleus RNA sequencing (snRNAseq) on matched specimens from patients with either histologically normal or advanced fibrosis to establish important aspects of tissue handling, data processing, and downstream analyses of biobanked liver samples. We observed that tissue preservation technique impacts transcriptomic data, especially in fibrotic liver. Single cell mapping of the spatial transcriptome using paired snRNAseq data generated a spatially resolved, single cell dataset with 24 unique liver cell phenotypes. We determined that cell-cell interactions predicted using ligand-receptor analysis of snRNAseq data poorly correlated with cellular relationships identified using spatial transcriptomics. Our study provides a framework for generating spatially resolved, single cell datasets to study gene expression and cell-cell interactions in biobanked clinical samples with advanced liver disease.

Living Donor Liver Transplantation for Hepatocellular Carcinoma Within and Outside Traditional Selection Criteria: A Multicentric North American Experience.

OBJECTIVE: To evaluate long-term oncologic outcomes of patients post-living donor liver transplantation (LDLT) within and outside standard transplantation selection criteria and the added value of the incorporation of the New York-California (NYCA) score. BACKGROUND: LDLT offers an opportunity to decrease the liver transplantation waitlist, reduce waitlist mortality, and expand selection criteria for patients with hepatocellular carcinoma (HCC). METHODS: Primary adult LDLT recipients between October 1999 and August 2019 were identified from a multicenter cohort of 12 North American centers. Posttransplantation and recurrence-free survival were evaluated using the Kaplan-Meier method. RESULTS: Three hundred sixty LDLTs were identified. Patients within Milan criteria (MC) at transplantation had a 1, 5, and 10-year posttransplantation survival of 90.9%, 78.5%, and 64.1% versus outside MC 90.4%, 68.6%, and 57.7% ( P = 0.20), respectively. For patients within the University of California San Francisco (UCSF) criteria, respective posttransplantation survival was 90.6%, 77.8%, and 65.0%, versus outside UCSF 92.1%, 63.8%, and 45.8% ( P = 0.08). Fifty-three (83%) patients classified as outside MC at transplantation would have been classified as either low or acceptable risk with the NYCA score. These patients had a 5-year overall survival of 72.2%. Similarly, 28(80%) patients classified as outside UCSF at transplantation would have been classified as a low or acceptable risk with a 5-year overall survival of 65.3%. CONCLUSIONS: Long-term survival is excellent for patients with HCC undergoing LDLT within and outside selection criteria, exceeding the minimum recommended 5-year rate of 60% proposed by consensus guidelines. The NYCA categorization offers insight into identifying a substantial proportion of patients with HCC outside the MC and the UCSF criteria who still achieve similar post-LDLT outcomes as patients within the criteria.

Review of pediatric combined heart-liver transplantation: A roadmap to success.

BACKGROUND: Combined heart-liver transplantation (CHLT) is a promising technique to address end stage organ failure in patients with concomitant heart failure and chronic liver disease. While most experience with CHLT has involved adult patients, the expanding population of children born with univentricular congenital heart disease who underwent the Fontan procedure and develop Fontan-associated liver disease (FALD) has emerged as a growing indication for pediatric CHLT. METHODS: Currently, CHLT is performed at a select subset of experienced transplant centers, especially in the pediatric population. RESULTS: While technically demanding, CHLT may offer survival benefit when compared to heart transplant alone with decreased rejection of both synchronous allografts and equivalent outcomes with respect to waitlist time and post-operative complications. Limitations in the technique can be attributed to need for an appropriate multidisciplinary care center, challenges with donor organ availability and allocation, and the complexity associated with patient selection and peri-operative management. CONCLUSION: In this review, we summarize the history of CHLT, discuss patient selection, and highlight key facets of peri-operative care in the pediatric population.

Technical optimization of spatially resolved single-cell transcriptomic datasets to study clinical liver disease.

Single cell and spatially resolved 'omic' techniques have enabled deep characterization of clinical pathologies that remain poorly understood, providing unprecedented insights into molecular mechanisms of disease. However, transcriptomic platforms are costly, limiting sample size, which increases the possibility of pre-analytical variables such as tissue processing and storage procedures impacting RNA quality and downstream analyses. Furthermore, spatial transcriptomics have not yet reached single cell resolution, leading to the development of multiple deconvolution methods to predict individual cell types within each transcriptome 'spot' on tissue sections. In this study, we performed spatial transcriptomics and single nucleus RNA sequencing (snRNASeq) on matched specimens from patients with either histologically normal or advanced fibrosis to establish important aspects of tissue handling, data processing, and downstream analyses of biobanked liver samples. We observed that tissue preservation technique impacts transcriptomic data, especially in fibrotic liver. Deconvolution of the spatial transcriptome using paired snRNASeq data generated a spatially resolved, single cell dataset with 24 unique liver cell phenotypes. We determined that cell-cell interactions predicted using ligand-receptor analysis of snRNASeq data poorly correlated with celullar relationships identified using spatial transcriptomics. Our study provides a framework for generating spatially resolved, single cell datasets to study gene expression and cell-cell interactions in biobanked clinical samples with advanced liver disease.

Impact of gut microbiota on liver transplantation.

The gut microbiota has been gaining attention due to its interactions with the human body and its role in pathophysiological processes. One of the main interactions is the "gut-liver axis," in which disruption of the gut mucosal barrier seen in portal hypertension and liver disease can influence liver allograft function over time. For example, in patients who are undergoing liver transplantation, preexisting dysbiosis, perioperative antibiotic use, surgical stress, and immunosuppressive use have each been associated with alterations in gut microbiota, potentially impacting overall morbidity and mortality. In this review, studies exploring gut microbiota changes in patients undergoing liver transplantation are reviewed, including both human and experimental animal studies. Common themes include an increase in Enterobacteriaceae and Enterococcaceae species and a decrease in Faecalibacterium prausnitzii and Bacteriodes, while a decrease in the overall diversity of gut microbiota after liver transplantation.

Potential association between public medical insurance, waitlist mortality, and utilization of living donor liver transplantation: An analysis of the Scientific Registry of Transplant Recipients.

BACKGROUND: The Affordable Care Act (ACA) and subsequent Medicaid expansion has increased utilization of public health insurance. Living donor liver transplantation (LDLT) increases access to transplant and is associated with improved survival but consistently represents < 5% of LT in the United States. STUDY DESIGN: National registry data were analyzed to evaluate the impact of insurance payor on waitlist mortality and LDLT rates at LDLT centers since implementation of the ACA. RESULTS: Public insurance [Medicare RR 1.18 (1.13-1.22) P < .001, Medicaid RR 1.22 (1.18-1.27) P < .001], Latino ethnicity (P < .001), and lower education level (P = .02) were associated with increased waitlist mortality at LDLT centers. LDLT recipients were more likely to have private insurance (70.4% vs. 59.4% DDLT, P < .001), be Caucasian (92.1% vs. 83% DDLT, P < .001), and have post-secondary education (66.8% vs. 54.1% DDLT, P < .001). Despite 78% of LDLT centers being located in states with Medicaid expansion, there was no change in LDLT utilization among recipients with Medicaid (P = .196) or Medicare (P = .273). CONCLUSION: Despite Medicaid expansion, registry data suggests that patients with public medical insurance may experience higher waitlist mortality and underutilize LDLT at centers offering LDLT. It is possible that Medicaid expansion has not increased access to LDLT.

HCV Eradication with Direct-Acting Antivirals Does Not Impact HCC Progression on the Waiting List or HCC Recurrence after Liver Transplantation.

Background: The introduction of direct-acting antivirals (DAA) for HCV has led to high rates of HCV eradication. Treatment of patients awaiting liver transplantation (LT) has been controversial. Recent data suggests that DAA treatment may accelerate recurrent HCC. The impact of DAA on delisting for HCC progression or recurrent HCC post-LT has not been well characterized. Methods: A retrospective review of both waitlist patients and LT recipients at a single institution was performed. Patient demographics, HCV treatment, HCC features and treatments, biopsy results, and graft and patient survival were evaluated. Patients on the LT waitlist or who were transplanted between January 2014 and December 2015 were included. Data was collected through December 2017 to have a minimum of two years of follow-up. Results: In the study period, 128 adult LT were performed. 44 patients were HCV+, and 68.2% (N=30) also had HCC. 38.6% (N=17) of HCV+ patients received DAA pre-LT, and 94.1% (N=16/17) achieved sustained virologic response (SVR) pre-LT. Among untreated HCV+ patients who underwent LT, 81.5% (N=22/27) received DAA post-LT, with 82.6% achieving SVR post-LT (N=18/22). 82.1% (N=23/28) of untreated post-LT patients underwent liver biopsy prior to therapy, and 52.2% had at least F1 METAVIR fibrosis. 87.5% (N=14/16) of active waitlist patients received DAA and achieved SVR. HCV eradication did not result in higher rates of delisting for HCC progression. Due to local HCC listing criteria of total tumor volume and AFP, 60% (N=18/30) of HCV+/HCC patients were beyond Milan criteria at the time of LT. Despite this, there was no difference in HCC recurrence rates post-LT, whether patients achieved SVR pre- or post-LT. Conclusions: These data suggest that HCV eradication pre-LT does not significantly impact waitlist time for HCV+ patients with HCC. HCV eradication does not impact rates of delisting for HCC progression or rates of HCC recurrence post-LT.

Case series and systematic review of acquired diaphragmatic hernia after liver transplantation.

BACKGROUND: ADH is a rare and potentially fatal complication following LT. In this study, a systematic review was completed to identify risk factors which may contribute to ADH. METHODS: Transplant databases at three LT programs were reviewed. Four pediatric and zero adult cases were identified. Next, a systematic review was completed. Fourteen studies describing 41 patients with ADH were identified. Patient demographics, transplant characteristics, and features of ADH diagnosis were examined. RESULTS: The majority (90.2%) of ADH were in children. In pediatric LT, 95.1% received a segmental allograft. ADH occurred in the right P diaphragm 92.7% of the time, and 87.8% were repaired primarily. Patient demographics, post-transplant complications, and immunosuppression regimens were broad and failed to predict ADH. Most patients presented with either respiratory or gastrointestinal symptoms. There were two pediatric deaths related to undiagnosed ADH. The combined worldwide incidence of ADH in pediatric LT is 1.5% (34/2319 patients). CONCLUSION: ADH is a rare complication post-LT that primarily occurs in pediatric recipients. When diagnosed early, ADH can be repaired primarily with good outcomes.

Hepatic Epithelioid Hemangioendothelioma Presenting as an Enlarging Vascular Lesion within the Spleen.

Epithelioid hemangioendothelioma (EHE) is a rare vascular neoplasm with variable malignant potential that most often presents within the liver. Many patients present with bilobar or extrahepatic disease, and the current treatment paradigm involves liver transplantation, with favorable long term results. Up to 25% of patients are diagnosed incidentally following imaging for other indications, and confirmation of diagnosis requires histologic analysis, as there are no classical imaging features to distinguish hepatic EHE (HEHE) from other solid hepatic lesions. Here we describe a case of microscopic HEHE that was diagnosed following splenectomy for an enlarging vascular tumor within the spleen. Due to the unexpected diagnosis of EHE within the spleen and coexisting but stable appearing liver hemangiomata, a left hepatic lobectomy was performed. Explant histology revealed benign hemangiomata and diffuse, microscopic HEHE. The patient ultimately underwent liver transplantation. HEHE can be a challenging diagnosis, and this case emphasizes that any enlarging vascular lesion, even within the spleen, should prompt a high index of suspicion for HEHE in the setting of known hemangiomata.

AEB071 (sotrastaurin) does not exhibit toxic effects on human islets in vitro, nor after transplantation into immunodeficient mice.

AEB071 (AEB, sotrastaurin), a specific inhibitor of protein kinase C, reduces T-lymphocyte activation and cytokine release. AEB delays islet allograft rejection in rats and prevents rejection when combined with cyclosporine. Since many immunosuppressive agents have toxic effects on the function of transplanted islets, we investigated whether this was also the case with AEB. Human islets were transplanted into Rag-knockout mice randomly assigned to vehicle control, AEB or sirolimus treatment groups. Non-fasting blood glucose levels, body weight and glucose tolerance was measured in recipients. In a separate experiment, human islets were cultured in the presence of AEB and assayed for glucose dependent insulin secretion and level of ß-cell apoptosis. Eighty-six percent of the AEB-treated recipients achieved normoglycemia following transplant (compared with none in sirolimus-treated group, p < 0.05). AEB-treated recipients exhibited similar glucose homeostasis as vehicle-treated controls, which was better than in sirolimus-treated recipients. Human islets cultured with AEB showed similar rates of ß-cell apoptosis (p = 0.98 by one-way ANOVA) and glucose stimulated insulin secretion (p = 0.15) as those cultured with vehicle. These results suggest that AEB is not associated with toxic effects on islet engraftment or function. AEB appears to be an appropriate immunosuppressive candidate for clinical trials in islet transplantation.

Caspase inhibitor therapy synergizes with costimulation blockade to promote indefinite islet allograft survival.

OBJECTIVE: Costimulation blockade has emerged as a selective nontoxic maintenance therapy in transplantation. However, these drugs must be combined with other immunomodulatory agents to ensure long-term graft survival. RESEARCH DESIGN AND METHODS: Recent work has demonstrated that caspase inhibitor therapy (EP1013) prevents engraftment phase islet loss and markedly reduces the islet mass required to reverse diabetes. The "danger" hypothesis suggests that reduction in graft apoptosis should reduce the threshold for immunosuppression and increase the possibility for tolerance induction. Thus, the impact of combination of EP1013 treatment with costimulation blockade (CTLA4-Ig) was investigated in this study. RESULTS: Islet allografts were completed in fully major histocompatibility complex (MHC)-mismatched mice (Balb/C to B6). When animals received vehicle or EP1013, there was no difference in graft survival. CTLA4-Ig resulted in prolonged graft survival in 40% of the animals, whereas EP1013+CLTA4-Ig resulted in a significant increase in graft survival (91% >180 days; P = 0.01). Ex vivo analysis revealed that animals receiving EP1013 or EP1013+CTLA4-Ig had a reduced frequency of alloreactive interferon (IFN)-gamma-secreting T-cells and an increased frequency of intragraft Foxp3(+) Treg cells. Alloantibody assays indicated that treatment with EP1013 or CTLA4-Ig prevented allosensitization. CONCLUSIONS: This study suggests that addition of caspase inhibitor therapy to costimulation blockade will improve clinical transplantation by minimizing immune stimulation and thus reduce the requirement for long-term immunosuppressive therapy. The approach also prevents allosensitization, which may be an important component of chronic graft loss in clinical transplantation.

Vascular endothelial growth factor expression in hepatic epithelioid hemangioendothelioma: Implications for treatment and surgical management.

Epithelioid hemangioendothelioma (EHE) is a low-grade, malignant vascular tumor that most commonly presents within the liver. Patients with hepatic EHE are often candidates for liver transplantation as the disease is usually multifocal at diagnosis. Although these patients achieve excellent early outcomes post-transplant, there are very few data regarding tumor markers that can further direct chemotherapy in hepatic EHE to prevent recurrent disease. The purpose of this study was to analyze the expression of the angiogenic factor vascular endothelial growth factor (VEGF) and its receptors in hepatic EHE. Six patients with hepatic EHE were assessed for liver transplantation at our center. Pathology specimens of primary and recurrent EHE were analyzed by hematoxylin and eosin staining and by immunofluorescence for VEGF, fetal liver kinase 1 (Flk-1), and fms-related tyrosine kinase 1 (Flt-1) expression. Five patients underwent liver transplantation, and 1 patient underwent liver resection. Biopsy-proven recurrent EHE occurred in 3 patients. VEGF expression was present in 100% of the EHE specimens examined, whereas Flt-1 expression was present in only 1 sample, and Flk-1 was not observed in any of the specimens. In 1 patient with recurrent hepatic EHE post-liver transplantation, a progressive increase in the VEGF fluorescence intensity and distribution was observed. In conclusion, in this series, VEGF expression was observed in all hepatic EHE specimens analyzed. These data suggest that anti-VEGF chemotherapeutic agents will be of use in patients with hepatic EHE, particularly as a means of reducing the tumor volume prior to resection, as a means of treating unresectable or metastatic disease, or as an adjuvant therapy in the setting of liver transplantation.

Inhibition of Th17 cells regulates autoimmune diabetes in NOD mice.

OBJECTIVE: The T helper 17 (Th17) population, a subset of CD4-positive T-cells that secrete interleukin (IL)-17, has been implicated in autoimmune diseases, including multiple sclerosis and lupus. Therapeutic agents that target the Th17 effector molecule IL-17 or directly inhibit the Th17 population (IL-25) have shown promise in animal models of autoimmunity. The role of Th17 cells in type 1 diabetes has been less clear. The effect of neutralizing anti-IL-17 and recombinant IL-25 on the development of diabetes in NOD mice, a model of spontaneous autoimmune diabetes, was investigated in this study. RESEARCH DESIGN AND METHODS AND RESULTS: Although treatment with either anti-IL-17 or IL-25 had no effect on diabetes development in young (<5 weeks) NOD mice, either intervention prevented diabetes when treatment was started at 10 weeks of age (P < 0.001). Insulitis scoring and immunofluorescence staining revealed that both anti-IL-17 and IL-25 significantly reduced peri-islet T-cell infiltrates. Both treatments also decreased GAD65 autoantibody levels. Analysis of pancreatic lymph nodes revealed that both treatments increased the frequency of regulatory T-cells. Further investigation demonstrated that IL-25 therapy was superior to anti-IL-17 during mature diabetes because it promoted a period of remission from new-onset diabetes in 90% of treated animals. Similarly, IL-25 delayed recurrent autoimmunity after syngeneic islet transplantation, whereas anti-IL-17 was of no benefit. GAD65-specific ELISpot and CD4-positive adoptive transfer studies showed that IL-25 treatment resulted in a T-cell-mediated dominant protective effect against autoimmunity. CONCLUSIONS: These studies suggest that Th17 cells are involved in the pathogenesis of autoimmune diabetes. Further development of Th17-targeted therapeutic agents may be of benefit in this disease.

Porcine marginal mass islet autografts resist metabolic failure over time and are enhanced by early treatment with liraglutide.

Although insulin independence is maintained in most islet recipients at 1 yr after transplant, extended follow-up has revealed that many patients will eventually require insulin therapy. Previous studies have shown that islet autografts are prone to chronic failure in large animals and humans, suggesting that nonimmunological events contribute to islet graft functional decay. Early intervention with therapies that promote graft stability should provide a measurable benefit over time. In this study, the efficacy of the long-acting glucagon-like peptide-1 analog liraglutide was explored in a porcine marginal mass islet autograft transplant model. Incubation with liraglutide enhanced porcine islet survival and function after prolonged culture. Most vehicle-treated (83%) and liraglutide-treated (80%) animals became insulin independent after islet autotransplantation. Although liraglutide therapy did not improve insulin independence rates or blood glucose levels after transplant, a significant increase in insulin secretion and acute-phase insulin response was observed in treated animals. Surprisingly, no evidence for deterioration of graft function was observed in any of the transplanted animals over more than 18 months of follow-up despite significant weight gain; in fact, an enhanced response to glucose developed over time even in control animals. Histological analysis showed that intraportally transplanted islets remained highly insulin positive, retained alpha-cells, and did not form amyloid deposits. This study demonstrates that marginal mass porcine islet autografts have stable long-term function, even in the presence of an increasing metabolic demand. These results are discrepant with previous large animal studies and suggest that porcine islets may be resistant to metabolic failure.

The caspase selective inhibitor EP1013 augments human islet graft function and longevity in marginal mass islet transplantation in mice.

OBJECTIVE: Clinical islet transplantation can provide insulin independence in patients with type 1 diabetes, but chronic graft failure has been observed. This has been attributed in part to loss of >or=60% of the transplanted islets in the peritransplant period, resulting in a marginal implant mass. Strategies designed to maximize survival of the initial islet mass are likely to have major impact in enhancing long-term clinical outcomes. EP1013 (N-benzyloxycabonyl-Val Asp-fluoromethyl ketone [zVD-FMK]), is a broad-spectrum caspase selective inhibitor with no observed toxicity in rodents. RESEARCH DESIGN AND METHODS: The therapeutic benefit of EP1013 was examined in a syngeneic rodent islet transplant model using deceased donor human islets to determine whether the amount of tissue required to restore euglycemia in diabetic animals could be reduced. RESULTS: EP1013 (combined pretransplant islet culture for 2 h and in vivo treatment for days 0-5 posttransplant) significantly improved marginal islet mass function following syngeneic islet transplantation in mice, even at lower doses, compared with previous studies using the pan-caspase inhibitor N-benzyloxycabonyl-Val Ala-Asp-fluoromethyl ketone (zVAD-FMK). EP1013 supplementation in vitro improved human islet yields following prolonged culture and reversed diabetes following implantation of a marginal human islet mass (80-90% reduction) into mice. CONCLUSIONS: Our data suggest that EP1013 therapy will markedly reduce the islet mass required in clinical islet transplantation, improving insulin independence rates following single-donor infusion.