Aging reduces proliferative capacities of liver by switching pathways of C/EBPalpha growth arrest

Comprehensive Review of Future Liver Remnant (FLR) Assessment and Hypertrophy Techniques Before Major Hepatectomy: How to Assess and Manage the FLR

BACKGROUND

The regenerative capacities of the liver and improvements in surgical techniques have expanded the possibilities of resectability. Liver resection is often the only curative treatment for primary and secondary malignancies, despite the risk of post-hepatectomy liver failure (PHLF). This serious complication (with a 50% mortality rate) can be avoided by better assessment of liver volume and function of the future liver remnant (FLR).

OBJECTIVE

The aim of this review was to understand and assess clinical, biological, and imaging predictors of PHLF risk, as well as the various hypertrophy techniques, to achieve an adequate FLR before hepatectomy.

METHOD

We reviewed the state of the art in liver regeneration and FLR hypertrophy techniques.

RESULTS

The use of new biological scores (such as the aspartate aminotransferase/platelet ratio index + albumin-bilirubin [APRI+ALBI] score), concurrent utilization of 99mTc-mebrofenin scintigraphy (HBS), or dynamic hepatocyte contrast-enhanced MRI (DHCE-MRI) for liver volumetry helps predict the risk of PHLF. Besides portal vein embolization, there are other FLR optimization techniques that have their indications in case of risk of failure (e.g., associating liver partition and portal vein ligation for staged hepatectomy, liver venous deprivation) or in specific situations (transarterial radioembolization).

CONCLUSION

There is a need to standardize volumetry and function measurement techniques, as well as FLR hypertrophy techniques, to limit the risk of PHLF.

Aging insights from heterochronic parabiosis models

Heterochronic parabiosis consists of surgically connecting the circulatory systems of a young and an old animal. This technique serves as a model to study circulating factors that accelerate aging in young organisms exposed to old blood or induce rejuvenation in old organisms exposed to young blood. Despite the promising results, the exact cellular and molecular mechanisms remain unclear, so this study aims to explore and elucidate them in more detail.

Systematic review and meta-analysis of the effect of N-acetylcysteine on outcomes after liver resection

BACKGROUND

N-Acetylcysteine (NAC) is a recognized antioxidative agent that facilitates the conjugation of toxic metabolites. In recent years, NAC has been routinely used to limit ischaemia-reperfusion injury in liver transplantation. There remains, however, contradictory evidence on its effectiveness in liver resection. This meta-analysis examines the effectiveness of NAC in improving outcomes following hepatectomy.

METHODS

A comprehensive search of the MEDLINE, EMBASE, and Cochrane databases was performed to identify relevant randomized controlled trials (RCTs) published since database inception until November 2023. The outcomes of Day 1 biochemical markers (lactate, ALT, bilirubin, and INR), length of stay, transfusion rates, and morbidity were extracted. Quantitative pooling of data was based on a random-effects model. The study protocol was registered on PROSPERO (Registration no: CRD42023442429).

RESULTS

Five RCTs reporting on 388 patients undergoing hepatectomy were included in the analysis. There were no significant differences in patient demographics between groups. Post-operative lactate was lower in patients receiving NAC (WMD -0.61, 95% CI -1.19 to -0.04, I2 = 67%). There were, however, no differences in the post-operative INR (WMD -0.04, 95% CI -0.19 to 0.12, I2 = 96%) and ALT (WMD -94.94, 95% CI -228.46 to 40.38; I2 = 67%). More importantly, there were no statistically significant differences in length of stay, transfusion rates, and morbidity between the two groups.

CONCLUSION

The administration of NAC in liver resection did not alter important biochemical parameters suggesting any real effectiveness in reducing hepatic dysfunction. There were no improvements in the clinical outcomes of length of stay, transfusion rates, and overall morbidity.

Perihilar cholangiocarcinoma resection: Is it beneficial for survival in elderly patients?

INTRODUCTION

As the population ages, surgeons are growing frequently faced with hard choices among a vast array of treatment options for the elderly. This study was to investigate safety and efficacy of resection in elderly patients with perihilar cholangiocarcinoma (PHCC).

PATIENTS AND METHODS

Literature reading and meta-analysis unveiled that elderly PHCC patients held a higher risk of death within 90 days after hepatectomy relative to younger patients, but their 5-year overall survival and disease-free survival were comparable. Among PHCC patients who underwent hepatectomy, the proportion of elderly patients with tumor classification Bismuth I-II and tumor stage pStage 1-3 was significantly higher than that of younger patients.

RESULTS

Curative resection R0 was more common in elderly patients than younger patients, but the difference was not statistically significant. Because of more comorbidities and less physiological reserve of elderly patients, they seemed to suffer more postoperative complications.

CONCLUSION

Considering improved life expectancy, it is crucial to treat elderly PHCC patients appropriately and attempts should be made to radical surgery based on comorbidities and functional status.

Multi-parametric atlas of the pre-metastatic liver for prediction of metastatic outcome in early-stage pancreatic cancer

Metastasis occurs frequently after resection of pancreatic cancer (PaC). In this study, we hypothesized that multi-parametric analysis of pre-metastatic liver biopsies would classify patients according to their metastatic risk, timing and organ site. Liver biopsies obtained during pancreatectomy from 49 patients with localized PaC and 19 control patients with non-cancerous pancreatic lesions were analyzed, combining metabolomic, tissue and single-cell transcriptomics and multiplex imaging approaches. Patients were followed prospectively (median 3 years) and classified into four recurrence groups; early (<6 months after resection) or late (>6 months after resection) liver metastasis (LiM); extrahepatic metastasis (EHM); and disease-free survivors (no evidence of disease (NED)). Overall, PaC livers exhibited signs of augmented inflammation compared to controls. Enrichment of neutrophil extracellular traps (NETs), Ki-67 upregulation and decreased liver creatine significantly distinguished those with future metastasis from NED. Patients with future LiM were characterized by scant T cell lobular infiltration, less steatosis and higher levels of citrullinated H3 compared to patients who developed EHM, who had overexpression of interferon target genes (MX1 and NR1D1) and an increase of CD11B+ natural killer (NK) cells. Upregulation of sortilin-1 and prominent NETs, together with the lack of T cells and a reduction in CD11B+ NK cells, differentiated patients with early-onset LiM from those with late-onset LiM. Liver profiles of NED closely resembled those of controls. Using the above parameters, a machine-learning-based model was developed that successfully predicted the metastatic outcome at the time of surgery with 78% accuracy. Therefore, multi-parametric profiling of liver biopsies at the time of PaC diagnosis may determine metastatic risk and organotropism and guide clinical stratification for optimal treatment selection.

Cold ischemia time in liver transplantation: An overview

The standard approach to organ preservation in liver transplantation is by static cold storage and the time between the cross-clamping of a graft in a donor and its reperfusion in the recipient is defined as cold ischemia time (CIT). This simple definition reveals a multifactorial time frame that depends on donor hepatectomy time, transit time, and recipient surgery time, and is one of the most important donor-related risk factors which may influence the graft and recipient's survival. Recently, the growing demand for the use of marginal liver grafts has prompted scientific exploration to analyze ischemia time factors and develop different organ preservation strategies. This review details the CIT definition and analyzes its different factors. It also explores the most recent strategies developed to implement each timestamp of CIT and to protect the graft from ischemic injury.

Right portal vein ligation is still relevant for left hemi-liver hypertrophy: results of a comparative study using a propensity score between right portal vein ligation and embolization

BACKGROUND

In two-stage hepatectomy for bilobar liver metastases from colorectal cancer, future liver remnant (FLR) growth can be achieved using several techniques, such as right portal vein ligation (RPVL) or right portal vein embolization (RPVE). A few heterogeneous studies have compared these two techniques with contradictory results concerning FLR growth. The objective of this study was to compare FLR hypertrophy of the left hemi-liver after RPVL and RPVE.

STUDY DESIGN

This was a retrospective comparative study using a propensity score of patients who underwent RPVL or RPVE prior to major hepatectomy between January 2010 and December 2020. The endpoints were FLR growth (%) after weighting using the propensity score, which included FLR prior to surgery and the number of chemotherapy cycles. Secondary endpoints were the percentage of patients undergoing simultaneous procedures, the morbidity and mortality, the recourse to other liver hypertrophy procedures, and the number of invasive procedures for the entire oncologic program in intention-to-treat analysis.

RESULTS

Fifty-four consecutive patients were retrospectively included and analyzed, 18 in the RPVL group, and 36 in the RPVE group. The demographic characteristics were similar between the groups. After weighting, there was no significant difference between the RPVL and RPVE groups for FLR growth (%), respectively 32.5% [19.3-56.0%] and 34.5% [20.5-47.3%] (p = 0.221). There was no significant difference regarding the secondary outcomes except for the lower number of invasive procedures in RPVL group (median of 2 [2.0, 3.0] in RPVL group and 3 [3.0, 3.0] in RPVE group, p = 0.001)).

CONCLUSION

RPVL and RPVE are both effective to provide required left hemi-liver hypertrophy before right hepatectomy. RPVL should be considered for the simultaneous treatment of liver metastases and the primary tumor.

C/ebpα represses the oncogenic Runx3-Myc axis in p53-deficient osteosarcoma development

Osteosarcoma (OS) is characterized by TP53 mutations in humans. In mice, loss of p53 triggers OS development, and osteoprogenitor-specific p53-deleted mice are widely used to study the process of osteosarcomagenesis. However, the molecular mechanisms underlying the initiation or progression of OS following or parallel to p53 inactivation remain largely unknown. Here, we examined the role of transcription factors involved in adipogenesis (adipo-TFs) in p53-deficient OS and identified a novel tumor suppressive molecular mechanism mediated by C/ebpα. C/ebpα specifically interacts with Runx3, a p53 deficiency-dependent oncogene, and, in the same manner as p53, decreases the activity of the oncogenic axis of OS, Runx3-Myc, by inhibiting Runx3 DNA binding. The identification of a novel molecular role for C/ebpα in p53-deficient osteosarcomagenesis underscores the importance of the Runx-Myc oncogenic axis as a therapeutic target for OS.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

2022 KLCA-NCC Korea practice guidelines for the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the fourth most common cancer among men in South Korea, where the prevalence of chronic hepatitis B infection is high in middle and old age. The current practice guidelines will provide useful and sensible advice for the clinical management of patients with HCC. A total of 49 experts in the fields of hepatology, oncology, surgery, radiology, and radiation oncology from the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2018 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions. These guidelines provide useful information and direction for all clinicians, trainees, and researchers in the diagnosis and treatment of HCC.

Epigenome-wide analysis of aging effects on liver regeneration

BACKGROUND

Aging is known to exert an effect on liver regeneration, with the ability of liver to regenerate displaying a significant decline over time. Liver physiological parameters such as liver volume, blood flow, and metabolism, as well as the ability to regenerate after injury have all been shown to decrease at old age in humans and model systems, with a number of molecular mechanisms proposed to be involved, including DNA methylation-dependent genome remodeling. To address how changes in DNA methylation mediate the adverse aging effect on liver regeneration, we searched for differentially methylated genomic regions (DMRs) in mouse livers co-regulated by aging and regeneration and determined their associated genes and enriched pathways.

RESULTS

DMRs were identified using whole-genome bisulfite sequencing (WGBS). Pathway analysis of aging DMR-mapped genes revealed two distinct phases of aging, 2-to-8 and 8-to-16 months old (m/o). Regenerative DMR-mapped differentially expressed genes (DEGs) were enriched in pathways controlling cell proliferation and differentiation. Most DMRs shared by both aging and regeneration changed in the same methylation direction between 2 and 8 m/o but in the opposite direction between 8 and 16 m/o. Regenerative DMRs inversely affected by aging during 8-to-16 m/o were found in the promoter/gene regions of 12 genes. Four regenerative DEGs were synchronously regulated by early aging and inversely regulated by mid-to-late aging DMRs. Lead DMR-mapped genes were validated by their expression profiles in liver aging and regeneration.

CONCLUSIONS

Our study has uncovered new DMRs and gene targets inversely affected by liver aging and regeneration to explain the adverse aging effect on liver regeneration. These findings will be of fundamental importance to understand the epigenomic changes underlying the biology of aging on liver regeneration.

Emerging role of aging in the progression of NAFLD to HCC

With the aging of global population, the incidence of nonalcoholic fatty liver disease (NAFLD) has surged in recent decades. NAFLD is a multifactorial disease that follows a progressive course, ranging from simple fatty liver, nonalcoholic steatohepatitis (NASH) to liver cirrhosis and hepatocellular carcinoma (HCC). It is well established that aging induces pathological changes in liver and potentiates the occurrence and progression of NAFLD, HCC and other age-related liver diseases. Studies of senescent cells also indicate a pivotal engagement in the development of NAFLD via diverse mechanisms. Moreover, nicotinamide adenine dinucleotide (NAD⁺), silence information regulator protein family (sirtuins), and mechanistic target of rapamycin (mTOR) are three vital and broadly studied targets involved in aging process and NAFLD. Nevertheless, the crucial role of these aging-associated factors in aging-related NAFLD remains underestimated. Here, we reviewed the current research on the roles of aging, cellular senescence and three aging-related factors in the evolution of NAFLD to HCC, aiming at inspiring promising therapeutic targets for aging-related NAFLD and its progression.

Lean body mass predicts postoperative liver failure in patients with hepatocellular carcinoma

BACKGROUND

Post-hepatectomy liver failure (PHLF) is a severe complication of liver surgery in hepatocellular carcinoma (HCC) patients. Reduced lean body mass (LBM) decreases the immune activity and increases adverse clinical outcomes among cancer patients.

OBJECTIVE

We aimed to assess the association between LBM and PHLF in HCC patients.

METHODS

PHLF was defined and graded based on the International Study Group of Liver Surgery (ISGLS) criteria. Patients with Grade B or Grade C were included in PHLF ⩾ Grade B group, while others in PHLF < Grade B group. LBM was measured via preoperative computed tomography images. Binary logistic regression was applied for investigating the association between LBM and PHLF. The receiver operating characteristic curve was used to identify potential cut-off values and assess the predictive ability of the measured variables.

RESULTS

The PHLF ⩾ Grade B group had significantly lower LBM levels (means ± standard deviation: 57.0 ± 14.1) than PHLF < Grade B group (67.2 ± 15.7) (p< 0.001). After controlling other variables, LBM was an independent protective factor for PHLF ⩾ Grade B (Odds Ratio: 0.406, 95% confidence interval: 0.172-0.957, p= 0.039). The prevalence of PHLF ⩾ Grade B in each quartile of LBM was 29.4% (15/51), 25.5% (13/51), 19.2% (10/52) and 4.0% (2/50), respectively (ptrend< 0.001).

CONCLUSIONS

LBM might be a protective factor for PHLF in HCC patients. Our findings might help to develop a novel strategy to reduce the occurrence of hepatic dysfunction following major liver resection. Multicentric prospective studies and further molecular biologic investigation are needed.

2022 KLCA-NCC Korea Practice Guidelines for the Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the fourth most common cancer among men in South Korea, where the prevalence of chronic hepatitis B infection is high in middle and old age. The current practice guidelines will provide useful and sensible advice for the clinical management of patients with HCC. A total of 49 experts in the fields of hepatology, oncology, surgery, radiology, and radiation oncology from the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2018 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions. These guidelines provide useful information and direction for all clinicians, trainees, and researchers in the diagnosis and treatment of HCC.

2022 KLCA-NCC Korea practice guidelines for the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the fourth most common cancer among men in South Korea, where the prevalence of chronic hepatitis B infection is high in middle and old age. The current practice guidelines will provide useful and sensible advice for the clinical management of patients with HCC. A total of 49 experts in the fields of hepatology, oncology, surgery, radiology, and radiation oncology from the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2018 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions. These guidelines provide useful information and direction for all clinicians, trainees, and researchers in the diagnosis and treatment of HCC.

Liver Regeneration: Changes in Oxidative Stress, Immune System, Cytokines, and Epigenetic Modifications Associated with Aging

The regenerative capacity of the liver decreases with increase in age. In recent years, studies in mice have found that the regenerative capacity of the liver is associated with changes in the immune system of the liver, cytokines in the body, aging-related epigenetic modifications in the cell, and intracellular signaling pathways. In the immune system of the aging liver, monocytes and macrophages play an important role in tissue repair. During tissue repair, monocytes and macrophages undergo a series of functional and phenotypic changes to initiate and maintain tissue repair. Studies have discovered that knocking out macrophages in the liver during the repair phase results in significant impairment of liver regeneration. Furthermore, as the body ages, the secretion and function of cytokines undergo a series of changes. For example, the levels of interleukin-6, transforming growth factor-alpha, hepatocyte growth factor, and vascular endothelial growth factor undergo changes that alter hepatocyte regulation, thereby affecting its proliferation. In addition, body aging is accompanied by cellular aging, which leads to changes in gene expression and epigenetic modifications. Additionally, this in turn causes alterations in cell function, morphology, and division and affects the regenerative capacity of the liver. As the body ages, the activity of associated functional proteins, such as CCAAT-enhancer-binding proteins, p53, and switch/sucrose nonfermentable complex, changes in the liver, leading to alterations in several signaling pathways, such as the Hippo, PI3K-Akt, mTOR, and STAT3 pathways. Therefore, in recent years, research on aging and liver regeneration has primarily focused on the immune system, signaling pathways, epigenetic changes of senescent cells, and cytokine secretion in the liver. Hence, this review details the roles of these influencing factors in liver regeneration and impact of aging-related factors.

Aging Activates the Immune System and Alters the Regenerative Capacity in the Zebrafish Heart

Age-associated organ failure and degenerative diseases have a major impact on human health. Cardiovascular dysfunction has an increasing prevalence with age and is one of the leading causes of death. In contrast to humans, zebrafish have extraordinary regeneration capacities of complex organs including the heart. In addition, zebrafish has recently become a model organism in research on aging. Here, we have compared the ventricular transcriptome as well as the regenerative capacity after cryoinjury of old and young zebrafish hearts. We identified the immune system as activated in old ventricles and found muscle organization to deteriorate upon aging. Our data show an accumulation of immune cells, mostly macrophages, in the old zebrafish ventricle. Those immune cells not only increased in numbers but also showed morphological and behavioral changes with age. Our data further suggest that the regenerative response to cardiac injury is generally impaired and much more variable in old fish. Collagen in the wound area was already significantly enriched in old fish at 7 days post injury. Taken together, these data indicate an ‘inflammaging’-like process in the zebrafish heart and suggest a change in regenerative response in the old.

Liver regeneration biology: Implications for liver tumour therapies

The liver has remarkable regenerative potential, with the capacity to regenerate after 75% hepatectomy in humans and up to 90% hepatectomy in some rodent models, enabling it to meet the challenge of diverse injury types, including physical trauma, infection, inflammatory processes, direct toxicity, and immunological insults. Current understanding of liver regeneration is based largely on animal research, historically in large animals, and more recently in rodents and zebrafish, which provide powerful genetic manipulation experimental tools. Whilst immensely valuable, these models have limitations in extrapolation to the human situation. In vitro models have evolved from 2-dimensional culture to complex 3 dimensional organoids, but also have shortcomings in replicating the complex hepatic micro-anatomical and physiological milieu. The process of liver regeneration is only partially understood and characterized by layers of complexity. Liver regeneration is triggered and controlled by a multitude of mitogens acting in autocrine, paracrine, and endocrine ways, with much redundancy and cross-talk between biochemical pathways. The regenerative response is variable, involving both hypertrophy and true proliferative hyperplasia, which is itself variable, including both cellular phenotypic fidelity and cellular trans-differentiation, according to the type of injury. Complex interactions occur between parenchymal and non-parenchymal cells, and regeneration is affected by the status of the liver parenchyma, with differences between healthy and diseased liver. Finally, the process of termination of liver regeneration is even less well understood than its triggers. The complexity of liver regeneration biology combined with limited understanding has restricted specific clinical interventions to enhance liver regeneration. Moreover, manipulating the fundamental biochemical pathways involved would require cautious assessment, for fear of unintended consequences. Nevertheless, current knowledge provides guiding principles for strategies to optimise liver regeneration potential.

Dysfunction of aged liver of male albino rats and the effect of intermitted fasting; Biochemical, histological, and immunohistochemical study

Intermittent fasting exerts beneficial effects on most age-related degenerative changes throughout the body. This study aimed to investigate the possible protective effects and mechanism of intermittent fasting on aged liver in male albino rats. Forty male albino rats were used in this study and were divided into four equal groups; Group I served as control ; rats aged 1 month sacrfied when they reached age of 4 month. Group II; rats aged 1 month with intermittent fasting for 3 months. The rats sacrfied when they reached age of 4 mounth Group III; rats aged 15-month fed an ad-libitum diet. The rats sacrified when they reached age of 18 month. Group IV; 15 month rats with intermittent fasting for 3 months. The rats sacrified when they reached age of 18 month. Liver specimens were excised and processed for biochemical, histological, and immunohistochemical study. Blood samples were collected for biochemical study. The result showed a significant increase in liver injury, oxidative stress, and inflammatory markers with a marked decrease in the autophagy marker in group III if compared with both group I and II. Additionally, group III showed hepatic vacuolations, cellular filtration, and congestion in both central and portal veins. A highly significant increase in the mean color intensity of positive immunochemical reaction for anti caspase 3 and anti-TNFα as well as a highly significant increase in the surface area fraction of collagen fibers were noticed in group III if compared with group I and II. Interestingly, intermittent fasting (group IV) remarkably reduced the previous alternation that that occurred in group III. It could be concluded that various biochemical, histological, and immunohistochemical alterations were observed in liver rat in group III. Beneficial effects of fasting on these changes were recorded in group IV through its anti-inflammatory, anti-apoptotic effect as well as its effect in modulating autophagy in aged liver cells. This might open the gate for further research and provide a new line for therapeutic intervention in aged liver. These data lead to speculate that sporadic fasting might represent a simple, safe, and inexpensive means to fight the changes occurred in the aged liver.

Risk Factors for Development of Biliary Stricture After Liver Transplant in Adult Patients: A Single-Center Retrospective Study

Identification of risk factors for biliary stricture after liver transplant and its potential prevention is crucial to improve the outcomes and reduce the complications. We retrospectively analyzed donor and recipient characteristics with intraoperative and postoperative parameters to identify the risk factors for development of post-transplant anastomotic and nonanastomotic biliary strictures with additional analysis of the time onset of those strictures. A total of 412 patients were included in this study. Mean (SD) follow-up time was 79 (35) months (range, 1-152 months). Biliary stricture was diagnosed in 84 patients (20.4%). Multivariate analysis indicated that postoperative biliary leakage (odd ratio [OR], 3.94; P = .001), acute cellular rejection (OR, 3.05; P < .001), donor age older than 47.5 years (OR, 2.05; P = .032), preoperative recipient platelet value < 77.5 × 10³/mL (OR, 1.91; P = .023), University of Wisconsin solution (OR, 1.73; P = .041)), recipient male sex (OR, 1.78; P = .072), portal/arterial flow ratio > 4 (OR, 1.76; P = .083), and intraoperative bleeding > 2850 mL (OR, 1.70; P = .053) were independent risk factors for biliary stricture regardless of the time of their appearance. Multiple risk factors for biliary stricture were determined in this study. Some of these risk factors are preventable, and implementation of strategies to eliminate some of those factors should reduce the development of post-transplant biliary stricture.

The Aging Liver: Redox Biology and Liver Regeneration

Significance: During aging, excessive production of reactive species in the liver leads to redox imbalance with consequent oxidative damage and impaired organ homeostasis. Nevertheless, slight amounts of reactive species may modulate several transcription factors, acting as second messengers and regulating specific signaling pathways. These redox-dependent alterations may impact the age-associated decline in liver regeneration. Recent Advances: In the last few decades, relevant findings related to redox alterations in the aging liver were investigated. Consistently, recent research broadened understanding of redox modifications and signaling related to liver regeneration. Other than reporting the effect of oxidative stress, epigenetic and post-translational modifications, as well as modulation of specific redox-sensitive cellular signaling, were described. Among them, the present review focuses on Wnt/β-catenin, the nuclear factor (erythroid-derived 2)-like 2 (NRF2), members of the Forkhead box O (FoxO) family, and the p53 tumor suppressor. Critical Issues: Even though alteration in redox homeostasis occurs both in aging and in impaired liver regeneration, the associative mechanisms are not clearly defined. Of note, antioxidants are not effective in slowing hepatic senescence, and do not clearly improve liver repopulation after hepatectomy or transplant in humans. Future Directions: Further investigations are needed to define mutual redox-dependent molecular pathways involved both in aging and in the decline of liver regeneration. Preclinical studies aimed at the characterization of these pathways would define possible therapeutic targets for human trials. Antioxid. Redox Signal. 35, 832-847.

Aged-related Function Disorder of Liver is Reversed after Exposing to Young Milieu via Conversion of Hepatocyte Ploidy

Previous study showed that senescent hepatocytes from aged liver could be rejuvenated after repopulated in the young recipient liver. The proliferative capacity of hepatocytes was restored with the senescence reversal. However, it is unknown whether metabolic and homeostatic function of aged liver, as well as age-dependent liver steatosis could be rejuvenated or alleviated. Here, we found that senescent hepatocytes from aged liver were rejuvenated after exposing to young blood. An autonomous proliferation of senescent hepatocytes which resulting in ploidy reversal might be the underlying mechanism of senescent reversal. After performing 2/3 partial hepatectomy (2/3PHx) in young blood exposed old liver, delayed DNA synthesis of senescent hepatocytes was rescued and the number of BrdU positive hepatocytes was restored from 4.39±2.30% to 17.85±3.21%, similarly to that in the young mice at 36 hours post 2/3PHx. Moreover, Cyclin A2 and Cyclin E1 overexpression of hepatocytes in aged liver facilitating the G1/S phase transition was contributed to enhance liver regeneration. Furthermore, lipid droplet spread widely in the elderly human liver and old mouse liver, but this aged-associated liver steatosis was alleviated as senescence reversal. Collectively, our study provides new thoughts for effectively preventing age-related liver diseases.

Aging Liver: Can Exercise be a Better Way to Delay the Process than Nutritional and Pharmacological Intervention? Focus on Lipid Metabolism

BACKGROUND & AIMS

Nowadays, the world is facing a common problem that the population aging process is accelerating. How to delay metabolic disorders in middle-aged and elderly people, has become a hot scientific and social issue worthy of attention. The liver plays an important role in lipid metabolism, and abnormal lipid metabolism may lead to liver diseases. Exercise is an easily controlled and implemented intervention, which has attracted extensive attention in improving the health of liver lipid metabolism in the elderly. This article reviewed the body aging process, changes of lipid metabolism in the aging liver, and the mechanism and effects of different interventions on lipid metabolism in the aging liver, especially focusing on exercise intervention.

METHODS

A literature search was performed using PubMed-NCBI, EBSCO Host and Web of Science, and also a report from WHO. In total, 143 studies were included from 1986 to 15 February 2020.

CONCLUSION

Nutritional and pharmacological interventions can improve liver disorders, and nutritional interventions are less risky relatively. Exercise intervention can prevent and improve age-related liver disease, especially the best high-intensity interval training intensity and duration is expected to be one of the research directions in the future.

IL-1R1 deficiency impairs liver regeneration after 2/3 partial hepatectomy in aged mice

Inflammation has a dual effect: it can protect the body and destroy tissue and cell as well. The purpose of this experiment was to determine the role of IL-1R1 in liver regeneration (LR) after partial hepatectomy (PH) in aged mice. The wild-type (WT, n = 36) and the IL-1R1 knockout (KO, n = 36) 24-month-old C57BL/6J mice underwent two-thirds PH; 33 WT mice underwent sham operation. Liver coefficient was calculated by liver/body weight. The mRNA and protein expressions of genes were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting methods, respectively. Compared with WT mice, liver coefficient was lower in the IL-1R1 KO aged mice at 168 and 192 h (p = 0.039 and p = 0.027). The mRNA transcription of inflammation-related genes and cell cycle-associated genes decreased or delayed. The protein expressions of proliferation-related marker PCNA and proliferation-associated signaling pathway components JNK1, NF-κB and STAT3 reduced or retarded. There was stronger activation of proapoptotic proteins caspase-3, caspase-8 and BAX in the IL-1R1 KO mice at different time points (p < 0.05 or p < 0.01). IL-1R1 KO reduced inflammation and caused impaired liver regeneration after 2/3 partial hepatectomy in aged mice. Maintaining proper inflammation may contribute to regeneration after liver partly surgical resection in the elderly.

Src homolog and collagen homolog1 isoforms in acute and chronic liver injuries

Src homolog and collagen homolog (SHC) proteins are adaptor proteins bound to cell surface receptors that play an important role in signal transduction and related diseases. As an important member of the SHC protein family, SHC1 regulates cell proliferation and apoptosis, reactive oxygen species (ROS) production, and oxidative stress. Three isomeric proteins namely, p46shc, p52shc, and p66shc, are produced from the same SHC1 gene locus. All the three proteins are found in the liver, and are widely expressed in various hepatic cells. SHC1 has been proven to be associated with acute and chronic liver injuries of different etiologies, and plays important roles in liver fibrosis and hepatocellular carcinoma (HCC). Therefore, this review summarizes recent studies that discuss and explore the role of SHC1 in the occurrence and progression of liver diseases. We also provide a theoretical basis for future studies.

Liver Regeneration after Hepatectomy and Partial Liver Transplantation

The liver is a unique organ with an abundant regenerative capacity. Therefore, partial hepatectomy (PHx) or partial liver transplantation (PLTx) can be safely performed. Liver regeneration involves a complex network of numerous hepatotropic factors, cytokines, pathways, and transcriptional factors. Compared with liver regeneration after a viral- or drug-induced liver injury, that of post-PHx or -PLTx has several distinct features, such as hemodynamic changes in portal venous flow or pressure, tissue ischemia/hypoxia, and hemostasis/platelet activation. Although some of these changes also occur during liver regeneration after a viral- or drug-induced liver injury, they are more abrupt and drastic following PHx or PLTx, and can thus be the main trigger and driving force of liver regeneration. In this review, we first provide an overview of the molecular biology of liver regeneration post-PHx and -PLTx. Subsequently, we summarize some clinical conditions that negatively, or sometimes positively, interfere with liver regeneration after PHx or PLTx, such as marginal livers including aged or fatty liver and the influence of immunosuppression.

Prolonged oxidative stress and delayed tissue repair exacerbate acetaminophen-induced liver injury in aged mice

The liver gradually loses its regenerative capabilities with aging. However, it remains unknown whether aging affects drug-induced liver injury. Here, we used acetaminophen induced acute liver injury model to compare tissue injury and regeneration of aged mice (>80 weeks old) with young ones (8-10 weeks old). The mortality of aged mice after acetaminophen injury was higher than that of young mice. Transient increase of serum GOT and decrease of reduced glutathione (GSH) were not returned to original levels in aged mice even at 48 hours. In addition, Foxm1b and its targets Ccnd1 and Cdk1 were upregulated in young but not in aged mice after 48 hours. Moreover, an apoptosis-related gene, Cidea, was upregulated specifically in aged livers, which was consistent with increased number of TUNEL⁺ hepatocytes. Unexpectedly, damaged hepatocytes were retained in aged liver tissue, which may be caused by impaired recruitment of macrophages to the damaged area, without increases in Ccl2 after acetaminophen injury. Collectively, prolonged oxidative stress due to delayed recovery of GSH and the retention of damaged hepatocytes may suppress tissue repair and hepatocyte proliferation, resulting in exacerbation of acetaminophen injury in aged mice. Thus, aging is a risk factor conferring susceptibility against drug-induced liver injury.

Radiological Simultaneous Portohepatic Vein Embolization (RASPE) Before Major Hepatectomy: A Better Way to Optimize Liver Hypertrophy Compared to Portal Vein Embolization

OBJECTIVE

The aim of this retrospective study was to compare portal vein embolization (PVE) and radiologica simultaneous portohepatic vein embolization (RASPE) for future liver remnant (FLR) growth in terms of feasibility, safety, and efficacy.

SUMMARY OF BACKGROUND DATA

After portal vein embolization (PVE), 15% of patients remain ineligible for hepatic resection due to insufficient hypertrophy of the FLR. RASPE has been proposed to induce FLR growth.

MATERIALS AND METHODS

Between 2016 and 2018, 73 patients were included in the study. RASPE was proposed for patients with a ratio of FLR to total liver volume (FLR/TLV) of <25% (RASPE group). This group was compared to patients who underwent PVE for a FLR/TLV <30% (PVE group). Patients in the 2 groups were matched for age, sex, type of tumor, and number of chemotherapy treatments. FLR was assessed by computed tomography before and 4 weeks after the procedure.

RESULTS

The technical success rate in both groups was 100%. Morbidity post-embolization, and the time between embolization and surgery were similar between the groups. In the PVE group, the FLR/TLV ratio before embolization was 31.03% (range: 18.33%-38.95%) versus 22.91% (range: 16.55-32.15) in the RASPE group (P < 0.0001). Four weeks after the procedure, the liver volume increased by 28.98% (range: 9.31%-61.23%) in the PVE group and by 61.18% (range: 23.18%-201.56%) in the RASPE group (P < 0.0001). Seven patients in the PVE group, but none in the RASPE group, had postoperative liver failure (P = 0.012).

CONCLUSIONS

RASPE can be considered as "radiological associating liver partition and portal vein ligation for staged hepatectomy." RASPE induced safe and profound growth of the FLR and was more efficient than PVE. RASPE also allowed for extended hepatectomy with less risk of post-operative liver failure.

Nos2 deficiency enhances carbon tetrachloride-induced liver injury in aged mice

Objective(s):

As a multifunctional molecule, NO has different effects on liver injury. The present work aimed to investigate the effects of Nos2 knockout (KO) on acute liver injury in aged mice treated with carbon tetrachloride (CCl₄).

Materials and Methods:

The acute liver injury model was produced by CCl₄ at 10 ml/kg body weight in 24-month-old Nos2 KO mice and wild type (WT) mice groups. The histological changes, transaminase and glutathione (GSH) contents, and the expressions of liver function genes superoxide dismutase (SOD2) and butyrylcholinesterase (BCHE), as well as apoptosis- and inflammation-associated genes were detected at 0, 6, 16, 20, 28, and 48 hr, respectively.

Results:

Compared with WT aged mice, there are more fat droplets in liver tissues of Nos2 KO aged mice, and the serum levels of ALT and AST were elevated in the KO group; in addition, there was a decrease in the expression of SOD2 and BCHE and GSH content at multiple time-points. Furthermore, the expression of apoptosis protein CASPASE-3 was elevated from 20 to 48 hr, the same as CASPASE-9 at 28 and 48 hr and pro-apoptotic protein BAX at 6 and 28 hr, while the expression of apoptosis inhibitory protein BCL2 declined at 6 and 28 hr; at the same time the mRNA expressions of genes related to inflammation were increased at different extents in liver extracts of Nos2 KO aged mice.

Conclusion:

Nos2 KO exacerbated liver injury probably by elevated oxidative stress, apoptosis and inflammation response in CCl₄-induced aged mice liver intoxication model.

Aging Suppresses Sphingosine-1-Phosphate Chaperone ApoM in Circulation Resulting in Maladaptive Organ Repair

Here, we show that the liver-derived apolipoprotein M (ApoM) protects the lung and kidney from pro-fibrotic insults and that this circulating factor is attenuated in aged mice. Aged mouse hepatocytes exhibit transcriptional suppression of ApoM. This leads to reduced sphingosine-1-phosphate (S1P) signaling via the S1P receptor 1 (S1PR1) in the vascular endothelial cells of lung and kidney. Suboptimal S1PR1 angiocrine signaling causes reduced resistance to injury-induced vascular leak and leads to organ fibrosis. Plasma transfusion from Apom transgenic mice but not Apom knockout mice blocked fibrosis in the lung. Similarly, infusion of recombinant therapeutics, ApoM-Fc fusion protein enhanced kidney and lung regeneration and attenuated fibrosis in aged mouse after injury. Furthermore, we identified that aging alters Sirtuin-1-hepatic nuclear factor 4α circuit in hepatocytes to downregulate ApoM. These data reveal an integrative organ adaptation that involves circulating S1P chaperone ApoM⁺ high density lipoprotein (HDL), which signals via endothelial niche S1PR1 to spur regeneration over fibrosis.

Implications of liver donor age on ischemia reperfusion injury and clinical outcomes

The aging process causes detrimental changes in a variety of organ systems. These changes include: lesser ability to cope with stress, impaired repair mechanisms and decreased cellular functional reserve capacity. Not surprisingly, aging has been associated with increased susceptibility of donor heart and kidneys grafts to ischemia reperfusion injury (IRI). In the context of liver transplantation, however, the effect of donor age seems to be less influential in predisposing the graft to IRI. In fact, a widely comprehensive understanding of IRI in the aged liver has yet to be agreed upon in the literature. Nevertheless, there have been many reported implications of increased liver donor age with poor clinical outcomes besides IRI. These other poor outcomes include: earlier HCV recurrence, increased rates of acute rejection and greater resistance to tolerance induction. While these other correlations have been identified, it is important to re-emphasize the fact that a unified consensus in regard to liver donor age and IRI has not yet been reached among researchers in this field. Many researchers have even demonstrated that the extent of IRI in aged livers can be ameliorated by careful donor selection, strict allocation or novel therapeutic modalities to decrease IRI. Thus, the goals of this review paper are twofold: 1) To delineate and summarize the conflicting data in regard to liver donor age and IRI. 2) Suggest that careful donor selection, appropriate allocation and strategic effort to minimize IRI can reduce the frequency of a variety of poor outcomes with aged liver donations.

Liver regeneration in aged mice: new insights

The regenerative capacity of the liver after resection is reduced with aging. Recent studies on rodents revealed that both intracellular and extracellular factors are involved in the impairment of liver mass recovery during aging. Among the intracellular factors, age-dependent decrease of BubR1 (budding uninhibited by benzimidazole-related 1), YAP (Yes-associated protein) and SIRT1 (Sirtuin-1) have been associated to dampening of tissue reconstitution and inhibition of cell cycle genes following partial hepatectomy. Extra-cellular factors, such as age-dependent changes in hepatic stellate cells affect liver regeneration through inhibition of progenitor cells and reduction of liver perfusion. Furthermore, chronic release of pro-inflammatory proteins by senescent cells (SASP) affects cell proliferation suggesting that senescent cell clearance might improve tissue regeneration. Accordingly, young plasma restores liver regeneration in aged animals through autophagy re-establishment. This review will discuss how intracellular and extracellular factors cooperate to guarantee a proper liver regeneration and the possible causes of its impairment during aging. The possibility that an improvement of the liver regenerative capacity in elderly might be achieved through elimination of senescent cells via autophagy or by administration of direct mitogenic agents devoid of cytotoxicity will also be entertained.

Oxidative post-translational modifications in histones

Epigenetic regulation is attracting much attention because it explains many of the effects that the external environment induces in organisms. Changes in the cellular redox status and even more specifically in its nuclear redox compartment is one of these examples. Redox changes can induce modulation of the epigenetic regulation in cells. Here we present a few cases where reactive oxygen or nitrogen species induces epigenetic marks in histones. Posttranslational modification of these proteins like histone nitrosylation, carbonylation, or glutathionylation together with other mechanisms not reviewed here are the cornerstones of redox-related epigenetic regulation. We currently face a new field of research with potential important consequences for the treatment of many pathologies.

2018 Korean Liver Cancer Association-National Cancer Center Korea Practice Guidelines for the Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer globally and the fourth most common cancer in men in Korea, where the prevalence of chronic hepatitis B infection is high in middle-aged and elderly patients. These practice guidelines will provide useful and constructive advice for the clinical management of patients with HCC. A total of 44 experts in hepatology, oncology, surgery, radiology, and radiation oncology in the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2014 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions.

Epigenetic Compensation Promotes Liver Regeneration

Two major functions of the epigenome are to regulate gene expression and to suppress transposons. It is unclear how these functions are balanced during physiological challenges requiring tissue regeneration, where exquisite coordination of gene expression is essential. Transcriptomic analysis of seven time points following partial hepatectomy identified the epigenetic regulator UHRF1, which is essential for DNA methylation, as dynamically expressed during liver regeneration in mice. UHRF1 deletion in hepatocytes (Uhrf1HepKO) caused genome-wide DNA hypomethylation but, surprisingly, had no measurable effect on gene or transposon expression or liver homeostasis. Partial hepatectomy of Uhrf1HepKO livers resulted in early and sustained activation of proregenerative genes and enhanced liver regeneration. This was attributed to redistribution of H3K27me3 from promoters to transposons, effectively silencing them and, consequently, alleviating repression of liver regeneration genes, priming them for expression in Uhrf1HepKO livers. Thus, epigenetic compensation safeguards the genome against transposon activation, indirectly affecting gene regulation.

The Hippo Signaling Pathway in Regenerative Medicine

The major role of Hippo signaling is to inhibit their downstream effectors YAP/TAZ for organ size control during development and regeneration (Nat Rev Drug Discov 13(1):63-79, 2014; Dev Cell 19(4):491-505, 2010; Cell 163(4):811-828, 2015). We and others have demonstrated that the genetic disruption of kinases Mst1 and Mst2 (Mst1/2), the core components of Hippo signaling, results in YAP activation and sustained liver growth, thereby leading to an eight- to tenfold increase in liver size within 3 months and occurrence of liver cancer within 5 months (Curr Biol 17(23):2054-2060, 2007; Cancer Cell 16(5):425-438, 2009; Cell 130(6):1120-1133, 2007; Cancer Cell 31(5):669-684 e667, 2017; Nat Commun 6:6239, 2015; Cell Rep 3(5):1663-1677, 2013). XMU-MP-1, an Mst1/2 inhibitor, is able to augment mouse liver and intestinal repair and regeneration in both acute and chronic injury mouse models (Sci Transl Med 8:352ra108, 2016).In addition, YAP-deficient mice show an impaired intestinal regenerative response after DSS treatment or gamma irradiation (Proc Natl Acad Sci U S A 108(49):E1312-1320, 2011; Nature 493(7430):106-110, 2013; Genes Dev 24(21):2383-2388, 2010; J Vis Exp (111), 2010). IBS008738, a TAZ activator, facilitates muscle repair after cardiotoxin-induced muscle injury (Mol Cell Biol. 2014;34(9):1607-21). Deletion of Salvador (Sav) in mouse hearts enhances cardiomyocyte regeneration with reduced fibrosis and recovery of pumping function after myocardial infarction (MI) or resection of mouse cardiac apex (Development 140(23):4683-4690, 2013; Sci Signal 8(375):ra41, 2015; Nature 550(7675):260-264, 2017). This chapter provides a detailed description of procedures and important considerations when performing the protocols for the respective assays used to determine the effects of Hippo signaling on tissue repair and regeneration.

2018 Korean Liver Cancer Association-National Cancer Center Korea Practice Guidelines for the Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer globally and the fourth most common cancer in men in Korea, where the prevalence of chronic hepatitis B infection is high in middle-aged and elderly patients. These practice guidelines will provide useful and constructive advice for the clinical management of patients with HCC. A total of 44 experts in hepatology, oncology, surgery, radiology and radiation oncology in the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2014 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions.

Structural-functional modifications of the liver to chronic radioactive exposure in pygmy wood mouse (Apodemus uralensis) within the East-Urals Radioactive Trace

The hepatic parameters (contents of glycogen, total lipids, nuclear and cytoplasmic proteins, DNA and RNA, fructose-6-phosphate, water, lipid peroxidation products, as well as activities of succinate dehydrogenase and glucose phosphate isomerase), radiometric data, and the relative population abundance of the pygmy wood mouse (Apodemus uralensis Pall., 1811) inhabiting natural (Middle Urals, Southern Urals, and Trans-Urals) areas and radioactivity territory (the EURT zone after of the Kyshtym accident in the South Urals in 1957) were analysed. Structural-functional modifications of the liver in A. uralensis from the EURT area are presented, taking into account irradiation power by dose-forming radionuclides (external and internal exposure to ¹³⁷Cs and ⁹⁰Sr), population size, and reproductive status (sexually immature and sexually mature yearlings, representing different ontogenetic patterns). The sexually immature mice from the EURT area can be considered to be the more sensitive (reactive) intrapopulation group to synergistic factors, such as radiation burden and population overabundance. The extent of structural-functional hepatic modification under current conditions of radionuclide exposure, in addition to the 60 year long effect of radioactive contamination in the EURT, can exceed the level of natural (geographic) variation observed in this species in the Urals region, which points to a long term evolutionary-ecological process.

A New Proposal of Criteria for the Future Remnant Liver Volume in Older Patients Undergoing Major Hepatectomy for Biliary Tract Cancer

OBJECTIVE

To evaluate whether advanced age increases the risk of severe complications after major hepatectomy with bile duct resection (BDR) in patients with biliary tract cancer, and to establish new criteria for the percentage of the future remnant liver volume (%FLV) in older patients undergoing this operation.

BACKGROUND

Advanced age is reported to inhibit liver regeneration and suppress immune function; however, little is known about the risk of aging in high-stress surgery, such as biliary tract surgery.

METHODS

Consecutive patients who underwent major hepatectomy with BDR between 2000 and 2013 were retrospectively reviewed. Severe postoperative complications were defined as Clavien-Dindo grade ≥IV.

RESULTS

In 225 patients undergoing major hepatectomy with BDR, advanced age was significantly correlated with the incidence of severe postoperative complications, with cut-off value of 69 years. In comparing postoperative complications, the incidences of hyperbilirubinemia, liver failure, respiratory failure, sepsis, severe complications, and operation-related death were more frequent in the older group. Moreover, advanced age (≥69 years) was an independent risk factor associated with severe complications after major hepatectomy with BDR. Delayed liver regeneration was the reason for the age-related risks. The incidence of severe postoperative complications in older patients was significantly decreased if %FLV was set at ≥45%.

CONCLUSIONS

Advanced age is a strong independent risk factor for severe complications after major hepatectomy with BDR. To decrease the risk of advanced age, the minimum limit of %FLV for this operation should be set at ≥45% in patients aged ≥69 years.

Liver hypertrophy: Underlying mechanisms and promoting procedures before major hepatectomy

Various procedures can promote hypertrophy of the future liver remnant (FLR) before major hepatectomy to prevent postoperative liver failure. The pathophysiological situation following portal vein embolization (PVE), hepatic artery ligation/embolization or hepatectomy remains unclear. On one hand, the main mechanisms of hepatic regeneration appear to be driven by hepatic hypoxia (involving the hepatic arterial buffer response), an increased portal blood flow inducing shear stress and the involvement of several mediators (inflammatory cytokines, vasoregulators, growth factors, eicosanoids and several hormones). On the other hand, several factors are associated with impaired liver regeneration, such as biliary obstruction, malnutrition, diabetes mellitus, male gender, age, ethanol and viral infection. All these mechanisms may explain the varying degrees of hypertrophy observed following a surgical or radiological procedure promoting hypertrophy the FLR. Radiological procedures include left and right portal vein embolization (extended or not to segment 4), sequential PVE and hepatic vein embolization (HVE), and more recently combined PVE and HVE. Surgical procedures include associated liver partition and portal vein ligation for staged hepatectomy, and more recently the combined portal embolization and arterial ligation procedure. This review aimed to clarify the pathophysiology of liver regeneration; it also describes radiological or surgical procedures employed to improve liver regeneration in terms of volumetric changes, the feasibility of the second step and the benefits and drawbacks of each procedure.

Prospective evaluation of the International Study Group for Liver Surgery definition of post hepatectomy liver failure after liver resection: an international multicentre study

BACKGROUND

The International Study Group for Liver Surgery (ISGLS) definition of post hepatectomy liver failure (PHLF) was developed to be consistent, widely applicable, and to include severity stratification. This international multicentre collaborative study aimed to prospectively validate the ISGLS definition of PHLF.

METHODS

11 HPB centres from 7 countries developed a standardised reporting form. Prospectively acquired anonymised data on liver resections performed between 01 July 2010 and 30 June 2011 was collected. A multivariate analysis was undertaken of clinically important variables.

RESULTS

Of the 949 patients included, 86 (9%) met PHLF requirements. On multivariate analyses, age ≥70 years, pre-operative chemotherapy, steatosis, resection of >3 segments, vascular reconstruction and intraoperative blood loss >300 ml significantly increased the risk of PHLF. Receiver operator curve (ROC) analysis of INR and serum bilirubin relationship with PHLF demonstrated post-operative day 3 and 5 INR performed equally in predicting PHLF, and day 5 bilirubin was the strongest predictor of PHLF. Combining ISGLS grades B and C groups resulted in a high sensitivity for predicting mortality compared to the 50-50 rule and Peak bilirubin >7 mg/dl.

CONCLUSIONS

The ISGLS definition performed well in this prospective validation study, and may be the optimal definition for PHLF in future research to allow for comparability of data.

TMIGD1 acts as a tumor suppressor through regulation of p21Cip1/p27Kip1 in renal cancer

Renal cell carcinoma (RCC) is a high-risk metastasizing tumor with a poor prognosis and poorly understood mechanism. In this study, we demonstrate that transmembrane and immunoglobulin domain-containing 1 (TMIGD1) is a novel tumor suppressor that is highly expressed in normal renal tubular epithelial cells, but it is downregulated in human renal cancer. We have identified CCAAT/enhancer-binding proteinβ (C/EBPβ, also called LAP) as a key transcriptional regulator of TMIGD1, whose loss of expression is responsible for downregulation of TMIGD1 in RCC. Transcriptionally active C/EBPβ/LAP physically interacted with and increased TMIGD1 promoter activity and expression of TMIGD1. Re-introduction of TMIGD1 into renal tumor cells significantly inhibited tumor growth and metastatic behaviors such as morphogenic branching and cell migration. Restoring TMIGD1 expression in renal tumor cells stimulated phosphorylation of p38MAK, induced expression of p21CIP1 (cyclin-dependent kinase inhibitor 1), and p27KIP1 (cyclin-dependent kinase inhibitor 1B) expression, key cell cycle inhibitor proteins involved in regulation of the cell cycle. The present study identifies TMIGD1 as a novel candidate tumor suppressor gene and provides important insight into pathobiology of RCC that could lead to a better diagnosis and possible novel therapy for RCC.

The Fountain of Youth: A Tale of Parabiosis, Stem Cells, and Rejuvenation

Transfusion (or drinking) of blood or of its components has been thought as a rejuvenation method since ancient times. Parabiosis, the procedure of joining two animals so that they share each others blood circulation, has revitalized the concept of blood as a putative drug. Since 2005, a number of papers have reported the anti-ageing effect of heterochronic parabiosis, which is joining an aged mouse to a young partner. The hallmark of aging is the decline of regenerative properties in most tissues, partially attributed to impaired function of stem and progenitor cells. In the parabiosis experiments, it was elegantly shown that factors derived from the young systemic environment are able to activate molecular signaling pathways in hepatic, muscle or neural stem cells of the old parabiont leading to increased tissue regeneration. Eventually, further studies have brought to identify some soluble factors in part responsible for these rejuvenating effects, including the chemokine CCL11, the growth differentiation factor 11, a member of the TGF-β superfamily, and oxytocin. The question about giving whole blood or specific factors in helping rejuvenation is open, as well as the mechanisms of action of these factors, deserving further studies to be translated into the life of (old) human beings.

Engineered fibroblast growth factor 19 protects from acetaminophen-induced liver injury and stimulates aged liver regeneration in mice

The liver displays a remarkable regenerative capacity triggered upon tissue injury or resection. However, liver regeneration can be overwhelmed by excessive parenchymal destruction or diminished by pre-existing conditions hampering repair. Fibroblast growth factor 19 (FGF19, rodent FGF15) is an enterokine that regulates liver bile acid and lipid metabolism, and stimulates hepatocellular protein synthesis and proliferation. FGF19/15 is also important for liver regeneration after partial hepatectomy (PH). Therefore recombinant FGF19 would be an ideal molecule to stimulate liver regeneration, but its applicability may be curtailed by its short half-life. We developed a chimaeric molecule termed Fibapo in which FGF19 is covalently coupled to apolipoprotein A-I. Fibapo retains FGF19 biological activities but has significantly increased half-life and hepatotropism. Here we evaluated the pro-regenerative activity of Fibapo in two clinically relevant models where liver regeneration may be impaired: acetaminophen (APAP) poisoning, and PH in aged mice. The only approved therapy for APAP intoxication is N-acetylcysteine (NAC) and no drugs are available to stimulate liver regeneration. We demonstrate that Fibapo reduced liver injury and boosted regeneration in APAP-intoxicated mice. Fibapo improved survival of APAP-poisoned mice when given at later time points, when NAC is ineffective. Mechanistically, Fibapo accelerated recovery of hepatic glutathione levels, potentiated cell growth-related pathways and increased functional liver mass. When Fibapo was administered to old mice prior to PH, liver regeneration was markedly increased. The exacerbated injury developing in these mice upon PH was attenuated, and the hepatic biosynthetic capacity was enhanced. Fibapo reversed metabolic and molecular alterations that impede regeneration in aged livers. It reduced liver steatosis and downregulated p21 and hepatocyte nuclear factor 4 α (Hnf4α) levels, whereas it stimulated Foxm1b gene expression. Together our findings indicate that FGF19 variants retaining the metabolic and growth-promoting effects of this enterokine may be valuable for the stimulation of liver regeneration.

Impaired liver regeneration in aged mice can be rescued by silencing Hippo core kinases MST1 and MST2

The liver has an intrinsic capacity to regenerate in response to injury or surgical resection. Nevertheless, circumstances in which hepatocytes are unresponsive to proliferative signals result in impaired regeneration and hepatic failure. As the Hippo pathway has a canonical role in the maintenance of liver size, we investigated whether it could serve as a therapeutic target to support regeneration. Using a standard two‐thirds partial hepatectomy (PH) model in young and aged mice, we demonstrate that the Hippo pathway is modulated across the phases of liver regeneration. The activity of the core kinases MST1 and LATS1 increased during the early hypertrophic phase and returned to steady state levels in the proliferative phase, coinciding with activation of YAP1 target genes and hepatocyte proliferation. Moreover, following PH in aged mice, we demonstrate that Hippo signaling is anomalous in non‐regenerating livers. We provide pre‐clinical evidence that silencing the Hippo core kinases MST1 and MST2 with siRNA provokes hepatocyte proliferation in quiescent livers and rescues liver regeneration in aged mice following PH. Our data suggest that targeting the Hippo core kinases MST1/2 has therapeutic potential to improve regeneration in non‐regenerative disorders.

Proliferation‑inhibiting pathways in liver regeneration (Review)

Liver regeneration, an orchestrated process, is the primary compensatory mechanism following liver injury caused by various factors. The process of liver regeneration consists of three stages: Initiation, proliferation and termination. Proliferation‑promoting factors, which stimulate the recovery of mitosis in quiescent hepatocytes, are essential in the initiation and proliferation steps of liver regeneration. Proliferation‑promoting factors act as the 'motor' of liver regeneration, whereas proliferation inhibitors arrest cell proliferation when the remnant liver reaches a suitable size. Certain proliferation inhibitors are also expressed and activated in the first two steps of liver regeneration. Anti‑proliferation factors, acting as a 'brake', control the speed of proliferation and determine the terminal point of liver regeneration. Furthermore, anti‑proliferation factors function as a 'steering‑wheel', ensuring that the regeneration process proceeds in the right direction by preventing proliferation in the wrong direction, as occurs in oncogenesis. Therefore, proliferation inhibitors to ensure safe and stable liver regeneration are as important as proliferation‑promoting factors. Cytokines, including transforming growth factor‑β and interleukin‑1, and tumor suppressor genes, including p53 and p21, are important members of the proliferation inhibitor family in liver regeneration. Certain anti‑proliferation factors are involved in the process of gene expression and protein modification. The suppression of liver regeneration led by metabolism, hormone activity and pathological performance have been reviewed previously. However, less is known regarding the proliferation inhibitors of liver regeneration and further investigations are required. Detailed information regarding the majority of known anti‑proliferation signaling pathways also remains fragmented. The present review aimed to understand the signalling pathways that inhbit proliferation in the process of liver regeneration.

Efficacy of Preoperative Portal Vein Embolization Among Patients with Hepatocellular Carcinoma, Biliary Tract Cancer, and Colorectal Liver Metastases: A Comparative Study Based on Single-Center Experience of 319 Cases

BACKGROUND

Efficacy of preoperative portal vein embolization (PVE) has been established; however, differences of outcomes among diseases, including hepatocellular carcinoma (HCC), biliary tract cancer (BTC), and colorectal liver metastases (CLM), are unclear.

METHODS

Subjects included patients in a prospectively collected database undergoing PVE (from 1995 to 2013). A future liver remnant (FLR) volume ≥40% is the minimal requirement for patients with an indocyanine green retention rate at 15 min (ICGR15) <10%, and stricter criteria (FLR volume ≥50%) have been applied for patients with 20% > ICGR15 ≥ 10%. Patient characteristics and survivals were compared among those three diseases, and predictors of dropout and better FLR hypertrophy were determined.

RESULTS

In 319 consecutive patients undergoing PVE for HCC (n = 70), BTC (n = 172), and CLM (n = 77), the degree of hypertrophy did not significantly differ by cancer types (median 10, 9.6, and 10%, respectively). Eighty percent (256 of 319) of patients completed subsequent hepatectomy after a median waiting interval of 24 days (range 5-90), while dropout after PVE was more common in BTC or CLM (odds ratio 2.75, p = 0.018), mainly because of disease progression. Ninety-day liver-related mortality after hepatectomy was 0% in the entire cohort, and 5-year overall survival of patients with HCC, BTC, and CLM was 56, 50, and 51%, respectively (p = 0.948). No patients who dropped out survived more than 2.5 years after PVE.

CONCLUSION

PVE produced equivalent FLR hypertrophy among the three diseases as long as liver function was fulfilling the preset criteria; however, the completion rate of subsequent hepatectomy was highest in HCC. PVE followed by hepatectomy was a safe and feasible strategy for otherwise unresectable disease irrespective of cancer types.

[Comparative analysis of static scintigraphy and computerized tomography in assessment of remnant liver volume after advanced hepatic resection]

AIM

To perform a comparative analysis of computerized tomographic volumetry and scintigraphic liver volumetry in assessment of remnant liver volume after advanced hepatic resection.

MATERIAL AND METHODS

Static hepatobiliary scintigraphy and CT volumetry were performed in 45 patients with various liver tumors who underwent advanced hepatectomies (more than three segments).

RESULTS

There were no any significant differences in volumetric parameters obtained by CT and scintigraphic volumetry.

CONCLUSION

Scintigraphic volumetry data are similar to those of CT volumetry in evaluation of future remnant liver volume. Scintigraphic volumetry may be used as an alternative in assessment of future remnant liver volume after advanced hepatic resections.