Human Hepatic Progenitor Cells Research Articles

Human hepatic progenitor cells express vasoactive intestinal peptide receptor type 2 and receive nerve endings

We recently showed that human hepatic progenitor cells (HPCs) express muscarinic acetylcholine (Ach) receptor subtype 3 and that--following liver transplantation--HPC numbers are significantly reduced. To further elaborate on this, we examined whether HPC also express receptors for vasoactive intestinal peptide (VIP), which, besides Ach, also is an important parasympathetic neurotransmitter. VIP expressing nerves are known to be present in the liver. We performed immunohistochemistry for VIP receptor subtypes 1 and 2 (VIPR1 and 2), on sections of normal and diseased human liver (n=17), and double staining for VIPR2 and known HPC markers. We performed RT-PCR for VIPR1 and 2 on total RNA from purified rat HPC. To document the probability of direct interaction, we also performed double immunostaining for nerve markers and HPC markers on human liver sections. VIPR2 immunostaining was clearly positive in HPC and reactive bile ductules on paraffin-embedded and frozen tissue sections. We could not demonstrate VIPR1 protein expression in the liver, with either of two VIPR1 antibodies tested. The presence of VIPR2 mRNA in HPC was confirmed by RT-PCR. Nerve endings were shown to abut on reactive bile ductules. We show here for the first time that HPC express VIPR2 and receive nerve endings. These features, and the fact that HPC numbers are influenced by the presence or absence of the autonomic innervation of the liver, suggest a direct interaction.

Characterization of cells in the developing human liver

Human hepatic progenitor cells (HPCs) have been shown to co-express the hematopoietic stem cell (HSC) markers, CD117 and CD34. These cells differentiate not only into hepatocytes and cholangiocytes but also into pancreatic ductal and acinar cells under certain conditions. The fetal liver (FL) is rich in precursor/stem cells; however, little is known about (i) the markers expressed by liver cells during fetal development and (ii) whether an equivalent to the adult liver stem-like progenitors exists in the FL. Here, (i) FL tissue obtained from human 5–18-week-old fetuses were evaluated by means of flow cytometry, immunocyto-, and histochemistry for the emergence of cells expressing and co-expressing known hematopoietic, hepatic, and pancreatic cell markers, and (ii) isolated putative HPCs were phenotypically and molecularly characterized. We report that (i) red blood and endothelial cell precursors were most abundant in early gestation. Cells expressing HSC and pancreatic markers were found in the first trimester, while cells expressing hepatic markers appeared in the second trimester. Very few committed cells were present in FLs obtained early in the first trimester. In addition, cells expressing pancreatic markers co-expressed the HSC marker CD117. (ii) Isolated CD117+/CD34+/CD90− cells in vitro expressed both the genes and proteins for the hepatic markers such as albumin, alpha feto protein (AFP), α1-antitrypsin, and cytokeratin 19 (CK19). Our study suggests that hepatoblast and ductal plate/bile duct development mainly occurs during the second trimester. FLs in gestation weeks 5–9 had the highest numbers of precursor cells and the least committed cells. Cells that differentiate into Alb+ or CK19+ can be isolated from early FLs and may be appropriate progenitors for establishing novel systems to investigate basic mechanisms for cell therapy.

371 Human hepatic progenitor cells: Molecular basis for their engraftment

371 Human hepatic progenitor cells: Molecular basis for their engraftment

Morphological and biochemical characterization of a human liver in a uPA‐SCID mouse chimera†‡

A small animal model harboring a functional human liver cell xenograft would be a useful tool to study human liver cell biology, drug metabolism, and infections with hepatotropic viruses. Here we describe the repopulation, organization, and function of human hepatocytes in a mouse recipient and the infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) of the transplanted cells. Homozygous urokinase plasminogen activator (uPA)-SCID mice underwent transplantation with primary human hepatocytes, and at different times animals were bled and sacrificed to analyze plasma and liver tissue, respectively. The plasma of mice that were successfully transplanted contained albumin and an additional 21 human proteins. Liver histology showed progressive and massive replacement of diseased mouse tissue by human hepatocytes. These cells were accumulating glycogen but appeared otherwise normal and showed no signs of damage or death. They formed functional bile canaliculi that connected to mouse canaliculi. Besides mature hepatocytes, human hepatic progenitor cells that were differentiating into mature hepatocytes could be identified within liver parenchyma. Infection of chimeric mice with HBV or HCV resulted in an active infection that did not alter the liver function and architecture. Electron microscopy showed the presence of viral and subviral structures in HBV infected hepatocytes. In conclusion, human hepatocytes repopulate the uPA(+/+)-SCID mouse liver in a very organized fashion with preservation of normal cell function. The presence of human hepatic progenitor cells in these chimeric animals necessitates a critical review of the observations and conclusions made in experiments with isolated "mature" hepatocytes. Supplementary material for this article can be found on the HEPATOLOGY website (http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Efficient gene transfer system for human fetal hepatic progenitor cells utilizing developed new isolation and culture system: Kentaro Yasuchika, Kyoto University Graduate School of Medicine, Kyoto Japan; Tetsuro Hirose, Kyoto University Institute for Frontier Medical Sciences, Kyoto Japan; Takahisa Fujikawa, Hideaki Fujii, Shoshiro Oe, Hisaya Azuma, Iwao Ikai, Yoshio Yamaoka, Kyoto University Graduate School of Medicine, Kyoto Japan

Efficient gene transfer system for human fetal hepatic progenitor cells utilizing developed new isolation and culture system: Kentaro Yasuchika, Kyoto University Graduate School of Medicine, Kyoto Japan; Tetsuro Hirose, Kyoto University Institute for Frontier Medical Sciences, Kyoto Japan; Takahisa Fujikawa, Hideaki Fujii, Shoshiro Oe, Hisaya Azuma, Iwao Ikai, Yoshio Yamaoka, Kyoto University Graduate School of Medicine, Kyoto Japan

Origin and characterization of a human bipotent liver progenitor cell line

Background & Aims: Liver progenitor cells may be important in carcinogenesis resulting from human chronic liver diseases. The HepaRG cell line has been established from a liver tumor associated with chronic hepatitis C. We observed that these cells showed an evident morphological heterogeneity, displaying both hepatocyte-like and biliary-like epithelial phenotypes. Our goal was to determine whether they could share some features with liver progenitor cells. Methods: Phenotypic studies using immunofluorescence, immunoblotting, and flow cytometry were performed at different culture stages. Results: HepaRG cells progressively exhibited polarized and functional hepatocytes and bile duct-like cell features under defined conditions. Cytokeratin 18 and 19 coexpression was, however, observed all along the maturation process together with oval cell-specific markers (M2-PK, OV-1, OV-6, and CD34); kinetics and expression profiles were dependent on the cell population. In addition, a strong commitment toward the hepatocytic lineage could be observed in the presence of epidermal growth factor. Immunohistochemistry on the fibrotic liver showing the atypical ductular reaction from which HepaRG cells originated displayed a comparable immunophenotype specifically restricted to bile neoductules. Conclusions: HepaRG cells constitute the first described human hepatic bipotent progenitor cell line regarding phenotype and histological origin.

Progenitor cells in diseased human liver.

Hepatic progenitor cells are immature epithelial cells that reside in the smallest ramifications of the biliary tree in human liver. These cells are capable of differentiating toward the biliary and the hepatocytic lineages and represent the human counterpart of the oval cells in murine liver. An increased number of progenitor cells (referred to as "activation") and differentiation of the same toward hepatocytes or bile duct epithelial cells, or both, is a component of virtually all human liver diseases. The extent of progenitor cell activation and the direction of differentiation are correlated with the severity of the disease and the type of mature epithelial cell (hepatocyte or bile duct epithelial cell), respectively, that is damaged. Analogous to findings in animal models of hepatocarcinogenesis, human hepatic progenitor cells most likely can give rise to hepatocellular carcinoma. The factors that govern human hepatic progenitor cell activation and differentiation are beginning to be identified.

Hepatic progenitor cells in human liver diseases.

The canals of Hering and bile ductules in human liver contain hepatic progenitor cells that can differentiate towards the biliary and hepatocytic lineage. Proliferation and differentiation of hepatic progenitor cells is referred to as 'activation' and this process occurs to a variable degree in almost all human liver diseases. Several studies indicate that hepatic progenitor cell activation in diseased liver is regulated by neural and neuroendocrine factors such as the vagal innervation. Analogous to oval cells in animal liver, there is evidence that human hepatic progenitor cells may be able to give rise to hepatocellular carcinoma and other liver tumors.

The vagal nerve stimulates growth of the human and rat hepatic progenitor cell compartment, via muscarinic acetylcholine receptor 3

The vagal nerve stimulates growth of the human and rat hepatic progenitor cell compartment, via muscarinic acetylcholine receptor 3

Hepatic progenitor cells in hepatocellular adenomas.

Hepatocellular adenoma is a benign tumor of the liver that has a small but not negligible risk of malignant transformation into hepatocellular carcinoma. In analogy with the established role of oval cells in hepatocarcinogenesis in rodent models, human hepatic progenitor cells may have a function in the development of liver tumors. To investigate this issue, we performed immunohistochemistry on biopsies of 10 consecutively resected hepatocellular adenomas using markers for hepatic progenitor cells. Sections of paraffin-embedded and frozen biopsies were stained using antibodies against cytokeratins 7, 8, 18, and 19, chromogranin-A, OV-6, and neural cell adhesion molecule. Hepatic progenitor cells were observed in five of 10 hepatocellular adenomas. These five tumors also contained cells with an immunohistochemical phenotype intermediate between hepatic progenitor cells and hepatocytes. Hepatic progenitor cells and intermediate hepatocyte-like cells were scattered throughout the tumors with a density that varied from area to area. Ultrastructural examination confirmed the presence of hepatic progenitor cells. Our study shows that hepatic progenitor cells are present in a considerable proportion of hepatocellular adenomas, supporting the hypothesis that human hepatic progenitor cells can play a role in the development of hepatocellular tumors.

Human hepatic progenitor cells and reactive bile ductules express the muscarinic acetylcholine receptor type 3

Human hepatic progenitor cells and reactive bile ductules express the muscarinic acetylcholine receptor type 3

Human hepatic progenitor cells and reactive bile ductules express the muscarinic acetylcholine receptor type 3

Human hepatic progenitor cells and reactive bile ductules express the muscarinic acetylcholine receptor type 3

“Blastosphere”: A new culture method for human fetal hepatic progenitor cells

“Blastosphere”: A new culture method for human fetal hepatic progenitor cells

“Blastosphere”: A new culture method for human fetal hepatic progenitor cells

“Blastosphere”: A new culture method for human fetal hepatic progenitor cells

Expression of the stem cell factor receptor c-kit in normal and diseased pediatric liver: identification of a human hepatic progenitor cell?

The stem cell factor (SCF)/c-kit ligand/receptor system has been implicated in stem (oval) cell activation following liver injury in the rat. The aim of this study was to determine the role of the SCF/c-kit system in pediatric human liver during acute and chronic liver injury. Tissue was obtained from hepatectomy specimens of patients undergoing liver transplantation for extrahepatic biliary atresia (EHBA) and fulminant hepatic failure (FHF). Specific expression of mRNA for c-kit and beta-actin was measured by ribonuclease protection and by immunohistochemistry to localize c-kit in tissue sections. Expression of c-kit was detected at relatively consistent levels in normal and cirrhotic (EHBA) livers. However, in FHF, c-kit mRNA levels were elevated in 3 of 6 specimens. Immunolocalization highlighted the presence of small numbers of c-kit-positive cells in the portal tracts of normal livers with increased numbers in cirrhotic livers. The highest c-kit staining, however, was observed in FHF, in which, in addition to the cells in the portal tracts, discrete c-kit-positive cells were also found integrated into bile ducts. Colocalization studies demonstrated some of the c-kit-positive cells to be of mast cell, leukocyte, and hematopoietic cell origin. However, there remained a subset that was also negative for these markers. The up-regulation of c-kit receptor expression in diseased livers suggests an involvement of this receptor/ligand system in hepatic repair mechanisms, and we speculate that c-kit-positive cells may represent a hepatic progenitor cell population. The origin and growth/differentiation potential of these c-kit-positive cells is under investigation.