Aberrant cytokeratin 7 expression of centrilobular hepatocytes: a clinicopathological study

Glutamine synthetase staining patterns in cirrhosis

Advanced liver fibrosis can regress following the elimination of causative injuries. Glutamine synthetase (GS) immunohistochemical expression is normally in centrizonal perivenular hepatocytes but can be present in periportal hepatocytes in cases of regressed cirrhosis. This study identified periportal staining and investigated the spectrum of GS staining patterns seen in a range of cirrhotic livers with varying disease processes. The hematoxylin and eosin and GS-stained slides of 88 liver resection/explant specimens with advanced fibrosis cases by different causes were reviewed, and trichrome and orcein stains were used to classify cases as progressive, indeterminate, or regressive. Periportal GS staining was seen in 97% of regressive cases and 84% progressive or indeterminate cases. Liver resection specimens with periportal GS staining showed a variety of patterns, including predominantly perivenular, predominantly periseptal, and perinodular staining. The GS periseptal pattern is more common in regressed cirrhosis compared to progressive cases. The perinodular staining was seen in 16 cases resulting from various etiologies, including biliary atresia, steatotic liver disease, primary biliary cholangitis, and viral hepatitis, 75% of which demonstrated cholestasis. This study further subclassified GS staining patterns of "periportal" pattern in cirrhotic liver. Compared to orcein/trichrome staining, GS immunohistochemical staining is not as useful in distinguishing regressed cases from non-regressed cases.

Nodular regenerative hyperplasia: The role of the CK7 immunohistochemistry pattern of expression in diagnosis

OBJECTIVES

Nodular regenerative hyperplasia (NRH) is a rare vascular disorder of the liver. Clinically, patients present with portal hypertension with or without a cholestatic pattern of injury. Histologically, the liver parenchyma is composed of small nodules of hypertrophic hepatocytes surrounded by atrophic hepatocytes without significant fibrosis. Nodular regenerative hyperplasia is a difficult diagnosis on biopsy specimens, but biopsy remains the gold standard for diagnosis. In this retrospective review, cytokeratin 7 (CK7) immunohistochemistry (IHC) was used to aid in the diagnosis and further characterization of NRH and NRH-like changes.

METHODS

The H&E-stained slides, reticulin, and CK IHC were reviewed for 22 cases. The percentage of hepatocytes staining for CK7 (0%-100%), the location of staining (centrilobular hepatic progenitor cells vs periportal/bile ductular reaction), and the pattern of staining distribution (patchy or diffuse) were recorded for comparison.

RESULTS

Of the 22 cases, 9 were CK7 positive. Cases of NRH, however, expressed various degrees of CK7 positivity in centrilobular hepatic progenitor cells, unlike NRH-like changes, which were either CK7 negative or CK7 positive in periportal hepatocytes or in areas of bile ductular reaction.

CONCLUSIONS

In cases with the appropriate clinical history and histology, CK7 immunohistochemistry can be performed to distinguish nodular regenerative hyperplasia (primary) and NRH-like changes (secondary). In difficult cases, CK7 positivity in centrilobular hepatic progenitor cells can help confirm the diagnosis of NRH. These data support NRH as a true entity with a distinct pathophysiology from NRH-like changes.

Patient with a novel syndrome with multiple benign hepatic lesions and extrahepatic neoplasms

Simultaneous occurrence of benign hepatic lesions of different types is a sporadic phenomenon. To the best of our knowledge, we report the first clinical case of a syndrome with simultaneous manifestations of three different entities of benign liver tumors (hepatocellular adenoma, focal nodular hyperplasia and hemangioma) with a novel mutation detected in the liver adenoma and in the presence of a number of further extrahepatic organ neoplasms. Furthermore, we describe for the first time the presence of liver epithelial cells of hepatocytic phenotype expressing cytokeratin 7 (CK7) at the border of the adenoma. These findings may be important for explaining pathogenesis of benign as well as malignant tumors based on genetic and histopathological features.

Quantitative Evaluation by Digital Pathology of Immunohistochemical Expression of CK7, CK19, and EpCAM in Advanced Stages of NASH

(1) Background: Nonalcoholic Steatohepatitis/Nonalcoholic Fatty Liver Disease (NASH/NAFLD) is the most recurrent chronic liver disease. NASH could present with a cholestatic (C) or hepatic (H) pattern of damage. Recently, we observed that increased Epithelial Cell Adhesion Molecule (EpCAM) expression was the main immunohistochemical feature to distinguish C from H pattern in NASH. (2) Methods: In the present study, we used digital pathology to compare the quantitative results of digital image analysis by QuPath software (Q-results), with the semi-quantitative results of observer assessment (S-results) for cytokeratin 7 and 19, (CK7, CK19) as well as EpCAM expression. Patients were classified into H or C group on the basis of the ratio between alanine transaminase (ALT) and alkaline phosphatase (ALP) values, using the "R-ratio formula". (3) Results: Q- and S-results showed a significant correlation for all markers (p < 0.05). Q-EpCAM expression was significantly higher in the C group than in the H group (p < 0.05). Importantly ALP, an indicator of hepatobiliary disorder, was the only biochemical parameter significantly correlated with Q-EpCAM. Instead, Q-CK7, but not Q-CK19, correlated only with γGlutamyl-Transferase (γGT). Of note, Stage 4 fibrosis correlated with Q-EpCAM, Q-CK19, and ALP but not with γGT or ALT. Conclusions: Image analysis confirms the relation between cholestatic-like pattern, associated with a worse prognosis, with increased ALP values, EpCAM positive biliary metaplasia, and advanced fibrosis. These preliminary data could be useful for the implementation of AI algorithms for the assessment of cholestatic NASH.

Farnesoid X receptor is an important target for the treatment of disorders of bile acid and fatty acid metabolism in mice with nonalcoholic fatty liver disease combined with cholestasis

BACKGROUND AND AIM

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been rising globally. NAFLD patients combined with cholestasis have more obvious liver fibrosis, impaired bile acid (BA), and fatty acid (FA) metabolism and severer liver injury; however, its therapeutic options are limited, and the underlying metabolic mechanisms are understood. Here, we aimed to investigate the effects of farnesoid X receptor (FXR) on BA and FA metabolism in NAFLD combined with cholestasis and related signaling pathways.

METHODS

A mouse model of NAFLD combined with cholestasis was established by joint intervention with high-fat diet (HFD) and alpha-naphthylisothiocyanate. The effects of FXR on BA and FA metabolism were evaluated by serum biochemical analysis. Liver damage was identified by histopathology. The expression of nuclear hormone receptor, membrane receptor, FA transmembrane transporter, and BA transporter protein in mice were measured by western blot.

RESULTS

NAFLD mice combined with cholestasis developed more severe cholestasis and dysregulated BA and FA metabolism. Meanwhile, the expression of FXR protein was decreased in NAFLD mice combined with cholestasis compared to the controls. Fxr-/- mice showed liver injury. HFD aggravated the liver injury with decreased BSEP expression, increased expression of NTCP, LXRα, SREBP-1c, FAS, ACC1, and CD36, and significantly increased BA and FA accumulation.

CONCLUSION

All the results suggested that FXR plays a key role in both FA and BA metabolism in NAFLD combined with cholestasis and thus may be a potential target for the treatment of disorders of BA and FA metabolism in NAFLD combined with cholestasis.

Ductular reaction in non-alcoholic fatty liver disease: When Macbeth is perverted

Non-alcoholic fatty liver disease (NAFLD) or metabolic (dysfunction)-associated fatty liver disease is the leading cause of chronic liver diseases defined as a disease spectrum comprising hepatic steatosis, non-alcoholic steatohepatitis (NASH), liver fibrosis, cirrhosis, and hepatic carcinoma. NASH, characterized by hepatocyte injury, steatosis, inflammation, and fibrosis, is associated with NAFLD prognosis. Ductular reaction (DR) is a common compensatory reaction associated with liver injury, which involves the hepatic progenitor cells (HPCs), hepatic stellate cells, myofibroblasts, inflammatory cells (such as macrophages), and their secreted substances. Recently, several studies have shown that the extent of DR parallels the stage of NASH and fibrosis. This review summarizes previous research on the correlation between DR and NASH, the potential interplay mechanism driving HPC differentiation, and NASH progression.

Aberrant cytokeratin 7 expression by hepatocytes can predict the ductopenia grade in primary biliary cholangitis

Background

Aberrant cytokeratin 7 expression by hepatocytes (CK7⁺Hs) is the hallmark characteristic of cholestasis diseases, especially in ductopenia diseases such as primary biliary cholangitis (PBC). This study attempted to evaluate the differences and relationships between the clinical and histological features of aberrant cytokeratin 7 (CK7) expression by hepatocytes in PBC patients.

Methods

The clinicopathological data of patients diagnosed with PBC at the Second Hospital of Nanjing between January 2016 and September 2018 were analysed with SPSS 20.0.

Results

Eighty-nine PBC patients who underwent liver biopsy were enrolled in this study, and 15, 29 and 45 patients had aberrant CK7 expression by hepatocytes (CK7⁺Hs (2 +), CK7⁺Hs (1 +), and CK7⁻Hs, respectively). There were significant differences in TB, DB, ALP, TA, IgM, interface activity, and ductopenia grade between patients with CK7⁻Hs and CK7⁺Hs (2 +) (P < 0.05). The ductopenia grade was also significantly different between patients with CK7⁺Hs (2 +) and CK7⁺Hs (1 +) according to sex (P < 0.05). Upon merging the data of CK7⁺Hs (2 +) and CK7⁺Hs (1 +) into CK7⁺Hs, we found significant differences in AMA, AMA-M2, anti-gp210, TB, DB, ALP, TA, IgM, fibrosis, and ductopenia grade between CK7⁺Hs and CK7⁻Hs (P < 0.05). The odds ratios (ORs) (and 95% confidence intervals (CIs)) of CK7⁺Hs according to anti-gp210, ductopenia grade, and interface activity were 6.413 (95% CI 1.363–30.162), 4.145 (95% CI 1.898–9.052) and 3.247 (95% CI 1.556–6.775), respectively (P < 0.05). Spearman's rank correlation according to interface activity and ductopenia grade in patients with CK7⁺Hs (2 + , 1 + , 0) was r = 0.359 (P = 0.001) and r = 0.396 (P < 0.001), respectively.

Conclusion

CK7⁺Hs serves as a cholestasis index of PBC and are associated with the ductopenia grade and interface activity. Aberrant cytokeratin 7 expression by hepatocytes can predict the ductopenia grade in primary biliary cholangitis.

In Vitro Differentiation of Human Amniotic Epithelial Cells into Hepatocyte-like Cells

Human amniotic epithelial cells (hAECs) represent an interesting clinical alternative to human embryonic (hESCs) and induced pluripotent (hiPSCs) stem cells in regenerative medicine. The potential of hAECs can be enhanced ex vivo by their partial pre-differentiation. The aim of this study was to evaluate the effectiveness of 18-day differentiation of hAECs into endodermal cells, hepatic precursor cells, and cells showing functional features of hepatocytes using culture media supplemented with high (100 ng/mL) concentrations of EGF or HGF. The cells obtained after differentiation showed changes in morphology and increased expression of AFP, ALB, CYP3A4, CYP3A7, and GSTP1 genes. HGF was more effective than EGF in increasing the expression of liver-specific genes in hAECs. However, EGF stimulated the differentiation process more efficiently and yielded more hepatocyte-like cells capable of synthesizing α-fetoprotein during differentiation. Additionally, after 18 days, GST transferases, albumin, and CYP P450s, which proved their partial functionality, were expressed. In summary, HGF and EGF at a dose of 100 ng/mL can be successfully used to obtain hepatocyte-like cells between days 7 and 18 of hAEC differentiation. However, the effectiveness of this process is lower compared with hiPSC differentiation; therefore, optimization of the composition of the medium requires further research.

Liver abnormalities in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a cardiopulmonary disease with high mortality. In recent years, it has been recognized that PAH is a multi-organ system disease, involving the systemic circulation, kidneys, skeletal muscles, and the central nervous system, among others. Right heart failure produces congestive hepatopathy, a disease state that has direct consequences on liver biochemistry, histology, and systemic glucose and lipid metabolism. This article aims to summarize the consequences of congestive hepatopathy with an emphasis on liver biochemistry, histology, and PAH-targeted therapy. Furthermore, PAH-specific changes in glucose and lipid metabolism will be discussed.

Keratin 7 expression in hepatic cholestatic diseases

We evaluated keratin 7 (K7) hepatocellular expression in 92 patients with common types of acute and chronic cholestatic diseases caused by bile duct obstruction/destruction or parenchymal lesions [acute hepatitis (n=20), mixed/pure cholestasis (n=16), primary biliary cholangitis-PBC (n=35), primary sclerosing cholangitis-PSC (n=10), vanishing bile duct syndrome (n=3), complete large bile duct obstruction due to space-occupying lesions (n=8)]. K7 immunohistochemical hepatocellular expression and ductular reaction (DR) were semi-quantitatively assessed. Results were correlated with liver enzyme serum levels, cholestasis type, histological features, hepatocellular Ki67 labelling index (LI) and HepPar1 expression. Hepatocellular K7 expression was detected in 87% (81/92) cases and in all cholestatic disease types with lowest incidence in pure/mixed cholestasis and highest in incomplete bile duct obstruction (iBDO), reaching 100% in PSC. K7-positive hepatocytes had low Ki67 LI (0-5%) retaining HepPar1 expression, irrespective of disease type. PSC cases had high K7 hepatocellular expression even with intact bile ducts, a feature that may aid differential diagnosis of cholestatic syndromes. K7 hepatocellular expression significantly correlated with cholestasis type, bile duct loss and fibrosis stage. It was higher in milder acute cholestatic hepatitis showing inverse correlation with hepatocyte proliferation and serum transaminase levels. In iBDO, younger age independently correlated with high K7 expression, while serum GGT levels showed a nearly significant correlation. Correlation with DR findings implied that K7-positive hepatocytes may result through metaplasia. In conclusion, K7 hepatocellular expression is a sensitive though non-specific marker of cholestasis. It may represent a cytoprotective reaction of resting hepatocytes in cholestasis of longer duration especially in younger patients.

Co-growth of Stem Cells With Target Tissue Culture as an Easy and Effective Method of Directed Differentiation

The long-term co-culture of mouse embryonic stem cells (mESC) with rat endothelial cells (EC) was tested for contact differentiation into the endothelial lineage. Serial passaging of rat ECs mixed with mESC in ratio 10:1 resulted in the emergence of a homogeneous cell population expressing mouse endothelial surface markers CD102, CD29, CD31. Rat endothelial surface marker RECA-1 completely disappeared from the co-cultured population after 2 months of weekly passaging. Co-incubation of mESC with rat ECs without cell-to-cell contact did not result in the conversion of mESC into ECs. After co-cultivation of adult mesenchymal stem cells from human endometrium (eMSC) with pre-hepatocyte-like cells of human hepatocarcinoma Huh7 the resulting co-culture expressed mature liver markers (oval cell antigen and cytokeratin 7), none of which were expressed by any of co-cultivated cultures, thus proving that even an immature (proliferating) pre-hepatocyte-like line can induce hepatic differentiation of stem cells. In conclusion, we have developed conditions where long-term co-proliferation of embryonic or adult SC with fully or partially differentiated cells results in stem cell progeny expressing markers of target tissue. In the case of endothelial differentiation, the template population quickly disappeared from the resulted culture and the pure endothelial population of stem cell progeny emerged. This approach demonstrates the expected fate of stem cells during various in vivo SC-therapies and also might be used as an effective in vitro differentiation method to develop the pure endothelium and, potentially, other tissue types of desirable genetic background.

Epithelial Plasticity during Liver Injury and Regeneration

Following injury, the liver's epithelial cells regenerate efficiently with rapid proliferation of hepatocytes and biliary cells. However, when proliferation of resident epithelial cells is impaired, alternative regeneration mechanisms can occur. Intricate lineage-tracing strategies and experimental models of regenerative stress have revealed a degree of plasticity between hepatocytes and biliary cells. New technologies such as single-cell omics, in combination with functional studies, will be instrumental to uncover the remaining unknowns in the field. In this review, we evaluate the experimental and clinical evidence for epithelial plasticity in the liver and how this influences the development of therapeutic strategies for chronic liver disease.

Establishment of rat liver cancer cell lines with different metastatic potential

The gloomy outcome of liver cancer is mainly due to the high rates of metastasis and recurrence, even after curative resection for early stage liver cancer. Our study was conducted to find the animal model suitable for the study of liver cancer metastasis. In our study, two liver cancer cells were obtained from N-nitrosodiethylamine (DEN) and N-nitrosomorpholine (NMOR) induced rats, and they were cultivated, screened and cloning cultivated. Bionomics of cells was analyzed. The results show that 2 cells had different metastatic potentiality. They were named Wrh-f2 and Wrh-s2, and they have the characteristics of Hepatocellular carcinoma cells. The bionomics of 2 cells showed: (1) The chromosome karyotype analysis showed that the mode of Wrh-f2 was 80–83 and Wrh-s2 was 55–57; (2) AFP positive cytoplasmic staining was observed in Wrh-f2 and Wrh-s2. Cytokeratin (CK) 7 and CK8 positive staining was present in Wrh-f2. CK8 positive staining was present in Wrh-s2; (3) The numbers of Wrh-f2 and Wrh-s2 that passed through the Transwells were 98 ± 12 and 55 ± 15;(4) Wrh-f2 had the significant higher colony formation (78%) than Wrh-s2(8%) (P < 0.01). (5) The animal models generated solid tumours when 2 cells were inoculated to nude mouse and rat. And Wrh-f2 developed stable pulmonary metastasis. The established cell lines with different metastatic potential showed obvious advantages over liver cancer in mimicking the biological properties of malignant liver cancer tumors. It provided a suitable model for the mechanism of liver cancer metastasis in vivo and in vitro.

Nodular regenerative hyperplasia - An under-recognized vascular disorder of liver

INTRODUCTION

Nodular regenerative hyperplasia (NRH) is a rare hepatic vascular disorder which is often associated with wide variety of systemic diseases. Intrahepatic microvascular injury and subsequent altered perfusion state leads to development of non-cirrhotic portal hypertension in many of these patients. Diagnosis of NRH often remains unsuspected clinically and liver biopsy is essential for the diagnosis and exclusion of fibrosis. We herein, present clinicopathological features of 22 NRH cases. In addition we assessed CK7 and CD34 expression in hepatocytes and sinusoidal endothelial cells respectively.

RESULTS

Most of the cases were associated with systemic disorders, predominantly immunological, inflammatory and drug-related injuries. Signs and symptoms of portal hypertension were found in 86.4 % patients. Majority of the patients showed a predominant mild cholestatic pattern of liver function tests. Nearly all the (21/22) cases showed CK7 positivity in centrizonal hepatocytes which ranged from <10 % cells to diffuse perivenular positivity extending into the midzonal areas. CD34 positivity in sinusoidal endothelial cells was seen in all the cases, which was prominent in periportal areas in all cases; while perivenular (n = 20) and midzonal (n = 14) areas also showed CD34 positive sinusoidal endothelial cells.

CONCLUSION

This study highlights the role of pathologist in the diagnosis of NRH and stresses upon the need for awareness of NRH as a cause of unexplained portal hypertension in patients with underlying systemic diseases. The altered perfusion state in NRH leads to phenotypic shift in centrizonal atrophic hepatocytes and sinusoidal endothelial cells (as depicted by IHC) which may be responsible for development of portal hypertension.

Human endometrial stem cells: High-yield isolation and characterization

BACKGROUND

Menstrual blood is only recently and still poorly studied, but it is an abundant and noninvasive source of highly proliferative mesenchymal stromal cells (MSCs). However, no appropriate isolation method has been reported due to its high viscosity and high content of clots and desquamated epithelium.

METHODS

We studied three different isolation approaches and their combinations: ammonium-containing lysing buffer, distilled water and gradient-density centrifugation. We tested the proliferative capacity, morphology, surface markers and pluripotency of the resulting cells.

RESULTS

Our isolation method yields up to four million nucleated cells per milliliter of initial blood, of which about 0.2-0.3% are colony-forming cells expressing standard mesenchymal markers CD90, CD105 and CD73, but not expressing CD45, CD34, CD117, CD133 or HLA-G. The cells have high proliferative potential (doubling in 26 h) and the ability to differentiate into adipocytes and osteocytes. Early endometrial MSCs (eMSCs) express epithelial marker cytokeratin 7 (CK7). CK7 is easily induced in later passages in a prohepatic environment. We show for the first time that a satisfactory and stable yield of eMSCs is observed throughout the whole menstrual period (5 consecutive days) of a healthy woman.

DISCUSSION

The new cost/yield adequate method allows isolation from menstrual blood a relatively homogenous pool of highly proliferative MSCs, which seem to be the best candidates for internal organ therapy due to their proepithelial background (early expression of CK7 and its easy induction in later passages) and for mass cryobanking due to their high yield and availability.

Centrilobular ductular reaction correlates with fibrosis stage and fibrosis progression in non-alcoholic steatohepatitis

There is increasing interest in the role of ductular reaction as part of the pathogenesis and characteristic histology of non-alcoholic steatohepatitis. However, earlier studies did not separately assess the contribution of periportal and centrilobular zone ductular reaction over the spectrum of non-alcoholic steatohepatitis, and their clinical significance remains unclear. We herein analyzed the character of ductular reaction in each hepatic zone in non-alcoholic steatohepatitis biopsies and for the first time evaluated the prognostic value of ductular reaction in baseline biopsies as a predictor of progression of fibrosis in subsequent biopsies. A total of 90 non-alcoholic steatohepatitis liver biopsies were included in the cohort. The relationships among ductular reaction, grade, stage, and other common histopathologic findings in non-alcoholic steatohepatitis were analyzed in a cross-sectional manner. Among these patients, a total of 47 patients underwent sequential liver biopsies in the absence of effective treatment. The frequency of ductular reaction and the other histopathologic parameters in the initial biopsies were analyzed as predictors of progression of fibrosis in the second biopsies in a longitudinal analysis. Centrilobular ductular reaction was identified in 90% of patients and 38% of centrilobular zones. The prevalence of centrilobular ductular reaction increased as non-alcoholic steatohepatitis grade increased (P=0.0002) and also as stage of fibrosis increased (P<0.0001) in the cross-sectional study. In the longitudinal study, the frequency of centrilobular ductular reaction in the initial biopsies was significantly higher in the group of progressors and correlated with the rate of fibrosis progression (P=0.02). Centrilobular ductular reaction is common in non-alcoholic steatohepatitis and its presence correlates significantly with increasing necroinflammatory activity and fibrosis stage. Development of centrilobular ductular reaction appears to predict progression of fibrosis in subsequent biopsies.

In hepatic venous outflow obstruction, alcoholic liver disease, and nonalcoholic fatty liver disease, centrilobular scars, CD34+ vessels, and keratin 7+ hepatocytes are in close proximity

For hepatic venous outflow obstruction, alcoholic liver injury, and nonalcoholic fatty liver disease, the term "centrizonal injury disease" (CID) is used, because injury patterns in all three entities are similar. To elucidate CID-related CD34+ vessels (sinusoids and/or microvessels) and keratin 7+ hepatocytes (K7+ Hs), we examined a series of 41 liver tissue specimens obtained at autopsy and surgery, consisting of 32 CID cases and 9 controls. Centrizonal scars were found in 21 CID cases, and these were associated with centrizonal CD34+ vessels (P = 0.009) and centrizonal K7+ Hs (P < 0.001). Centrizonal coexistence of CD34+ vessels and K7+ Hs was observed in 22 CID cases (P = 0.057). These findings suggest close centrizonal proximity of scar, CD34+ vessels, and K7+ Hs in CID. However, centrizonal K7+ Hs without CD34+ vessels were observed in 21 CID cases. CD34+ vessels were detectable in all control samples and may represent the normal vascular bed. In 29 CID cases, centrizonal CD34+ vessel density was higher than that in controls. However, most appeared to be continuous with periportal and/or interlobular CD34+ vessels, and those CD34+ vessels restricted to centrizonal regions were focal and limited in seven CID cases. Centrizonal CD34+ vessels were associated with venoportal adhesions (P = 0.027). Our findings suggest that CID induces both venoportal adhesion-related structural distortion and expansion of normally present CD34+ vessels, which may result in increased centrizonal CD34+ vessel density.

Expression kinetics of hepatic progenitor markers in cellular models of human liver development recapitulating hepatocyte and biliary cell fate commitment

Due to the limitations of research using human embryos and the lack of a biological model of human liver development, the roles of the various markers associated with liver stem or progenitor cell potential in humans are largely speculative, and based on studies utilizing animal models and certain patient tissues. Human pluripotent stem cell-based in vitro multistage hepatic differentiation systems may serve as good surrogate models for mimicking normal human liver development, pathogenesis and injury/regeneration studies. Here, we describe the implications of various liver stem or progenitor cell markers and their bipotency (i.e. hepatocytic- and biliary-epithelial cell differentiation), based on the pluripotent stem cell-derived model of human liver development. Future studies using the human cellular model(s) of liver and biliary development will provide more human relevant biological and/or pathological roles of distinct markers expressed in heterogeneous liver stem/progenitor cell populations.

Histological Spectrum of Idiopathic Noncirrhotic Portal Hypertension in Liver Biopsies From Dialysis Patients

Objectives. Liver biopsy is performed for various indications in dialysis patients. Being a less-common subset, the hepatic pathology in renal dialysis is not well documented. Idiopathic noncirrhotic portal hypertension (INCPH) is a clinical entity associated with unexplained portal hypertension and/or a spectrum of histopathological vascular changes in the liver. After encountering INCPH and vascular changes of INCPH in 2 renal dialysis patients, we sought to further investigate this noteworthy association. Materials and methods. A random search for patients on hemodialysis or peritoneal dialysis with liver biopsy was performed. Hematoxylin and eosin, reticulin, trichrome, and CK7 stains were performed on formalin-fixed, paraffin-embedded tissue sections. Histopathological features were reviewed, and the results were correlated with clinical findings. Results. In all, 13 liver biopsies were retrieved. The mean cumulative duration of dialysis was 50 months (range = 17 months to 11 years). All patients had multiple comorbidities. Indications for biopsy were a combination of abnormal liver function tests (6), portal hypertension (4), ascites (3), and possible cirrhosis (3). Two patients with portal hypertension underwent multiple liver biopsies for diagnostic purposes. All (100%) biopsies showed some histological features of INCPH, including narrowed portal venous lumen (9), increased portal vascular channels (8), shunt vessels (3), dilated sinusoids (9), regenerative nodule (5), and features of venous outflow obstruction (3). No cirrhosis was identified. Conclusion. Liver biopsies from patients on dialysis demonstrate histopathological vascular changes of INCPH. Some (31%) patients present with portal hypertension without cirrhosis. The histological changes may be reflective of underlying risk factors for INCPH in this group.

Phenotypic and functional analyses show stem cell-derived hepatocyte-like cells better mimic fetal rather than adult hepatocytes

BACKGROUND & AIMS

Hepatocyte-like cells (HLCs), differentiated from pluripotent stem cells by the use of soluble factors, can model human liver function and toxicity. However, at present HLC maturity and whether any deficit represents a true fetal state or aberrant differentiation is unclear and compounded by comparison to potentially deteriorated adult hepatocytes. Therefore, we generated HLCs from multiple lineages, using two different protocols, for direct comparison with fresh fetal and adult hepatocytes.

METHODS

Protocols were developed for robust differentiation. Multiple transcript, protein and functional analyses compared HLCs to fresh human fetal and adult hepatocytes.

RESULTS

HLCs were comparable to those of other laboratories by multiple parameters. Transcriptional changes during differentiation mimicked human embryogenesis and showed more similarity to pericentral than periportal hepatocytes. Unbiased proteomics demonstrated greater proximity to liver than 30 other human organs or tissues. However, by comparison to fresh material, HLC maturity was proven by transcript, protein and function to be fetal-like and short of the adult phenotype. The expression of 81% phase 1 enzymes in HLCs was significantly upregulated and half were statistically not different from fetal hepatocytes. HLCs secreted albumin and metabolized testosterone (CYP3A) and dextrorphan (CYP2D6) like fetal hepatocytes. In seven bespoke tests, devised by principal components analysis to distinguish fetal from adult hepatocytes, HLCs from two different source laboratories consistently demonstrated fetal characteristics.

CONCLUSIONS

HLCs from different sources are broadly comparable with unbiased proteomic evidence for faithful differentiation down the liver lineage. This current phenotype mimics human fetal rather than adult hepatocytes.

Aberrant centrizonal features in chronic hepatic venous outflow obstruction: centrilobular mimicry of portal-based disease

Chronic hepatic venous outflow obstruction is characterized by centrizonal scarring but may also display features that can lead to portal tract mimicry and misdiagnosis as biliary disease, especially given elevated cholestatic liver profiles in these patients. However, these histopathologic features have not been systematically described. We graded the numbers of centrizonal arterioles, ductules, keratin 7+ hepatocytes, CD34+ microvessels, and capillarized sinusoids in 61 cases of chronic venous outflow obstruction and assessed changes in metabolic zonation by glutamine synthetase staining. Centrizonal arterioles and ductules were present in 82.0% and 72.1% of cases, respectively, and correlated with fibrosis. Centrizonal CD34+ microvessels and sinusoidal capillarization were closely associated and present in 25 (92.6%) and 26 (96.3%) of 27 cases, respectively. Centrizonal capillarized sinusoids and microvessels, which were present in all cases with advanced fibrosis, were demonstrated in 90% and 80% of the cases without significant fibrosis, respectively. The results suggest that capillarization and/or microvessel formation precede and may contribute to centrizonal scarring, whereas arterialization likely reflects vascular remodeling associated with progressive fibrosis. Centrizonal ductules were often immature, being either keratin 7+/keratin 19- (36.4%) or keratin 7-/keratin 19- (10.0%). Centrizonal keratin 7+ intermediate-phenotype hepatocytes were present in 25 (92.5%) of 27 cases. Lastly, 22 (91.7%) of 24 cases showed loss of metabolic zonation, with reversed zonation in 2 (8.3%) cases. Together, the findings indicate that vascular and lobular reorganization in chronic venous outflow obstruction may result in mimicry of central zones as portal tracts. Recognition of these changes is essential to prevent misdiagnosis of this condition as biliary tract disease.

Central portalization correlates with fibrosis but not with risk factors for nonalcoholic steatohepatitis in steatotic chronic hepatitis C

Concomitant steatosis in chronic hepatitis C is associated with fibrosis and unfavorable treatment outcome. Central zone injury in nonalcoholic steatohepatitis (NASH) manifests as central portalization, with centrizonal microvessels and ductular reaction. We investigated whether central portalization in steatotic HCV biopsies would identify patients with metabolic risk factors for NASH. Liver biopsies with chronic hepatitis C and >10% steatosis (n = 65) were evaluated for the degree of steatosis, zonation of steatosis, fibrosis, and nonalcoholic fatty liver disease (NAFLD) activity score. The presence of centrizonal microvessels, sinusoidal capillarization, ductular reaction, and CK7 positive intermediate-phenotype hepatocytes were evaluated by CD34 and CK7 immunostain. The degree of steatosis and fibrosis showed a positive correlation. Additional positive correlations were noted between centrizonal angiogenesis and NAFLD activity score and central portalization and fibrosis. However, neither central portalization nor zonation of steatosis identified patients with metabolic risk factors for NASH. Therefore, central portalization cannot be used as a surrogate marker to identify patients with metabolic risk factors for NASH in steatotic HCV biopsies. The mechanism of centrizonal injury in steatotic HCV hepatitis is not solely attributable to the metabolic risk factors for NASH.

Liver pathology in infantile mitochondrial DNA depletion syndrome

Mitochondrial DNA (mtDNA) depletion syndrome is a relatively novel cause of hepatic dysfunction in the pediatric population. It is caused by mutations in either mtDNA or nuclear DNA (nDNA) that result in a quantitative reduction in mtDNA and, in turn, dysfunctional oxidative phosphorylation. In infants, it results in the hepatocerebral phenotype, characterized by hyperbilirubinemia, coagulopathy, lactic acidosis, hypoglycemia, lethargy, encephalopathy, developmental delay, and hypotonia. Three infants diagnosed with mtDNA depletion syndrome at The Children's Hospital of Philadelphia were identified, and their clinical presentation, disease course, and histologic and ultrastructural features of liver samples (pre- and postmortem) were characterized. While a different mutant gene was identified in each child, they all showed clinical evidence of metabolic dysfunction soon after birth and expired by 1 year of age. Steatosis, cholestasis, and cytoplasmic crowding by atypical mitochondria were consistent pathologic liver findings. Other findings included hepatocyte hypereosinophilia, fibrosis, and hemosiderosis. This analysis provides insight into the important clinical signs/symptoms and histopathologic and ultrastructural features of mtDNA depletion syndrome in infants and young children. Knowledge of these characteristics will facilitate early recognition and appropriate treatment of this rare disorder. Additionally, ultrastructural evaluation of liver samples by electron microscopy is an important diagnostic component of hepatic dysfunction caused by metabolic abnormalities. This type of analysis should be routinely employed in the setting of unexplained cholestasis, especially when accompanied by steatosis and hepatocyte hypereosinophilia.