Bile Ductular Epithelial Cells Research Articles

CRISPLD2 in Hepatic Fibrogenesis and Cholangiocellular Carcinoma Progression

Studies in the past have shown that bile ductular hyperplasia correlates with the degree of hepatic fibrosis and that myofibroblasts are a major component of cholangiocellular carcinoma (CCA). However, the mechanism of cross‐talk between bile ductular epithelial cells and hepatic stellate cells during hepatic fibrogenesis and CCA progression was not established. In this study, we identified CRISPLD2, a secretory protein reported to be critical for epithelial morphogenesis during lung and kidney development, as one of the top differentially up‐regulated genes in the liver of a mouse model of nonalcoholic steatohepatitis (NASH). A combined in situ hybridization, histochemistry, immunohistochemistry and image analysis suggested that CRISPLD2 mRNA was expressed in hepatic stellate cells accompanying bile ductules and collagen fibers in the liver of mouse model of NASH and human cirrhotic liver. Furthermore, cancer‐associated myofibroblasts express CRISPLD2 mRNA in human cholangiocarcinoma tissues. These data suggest that CRISPLD2 may play a role in the branching morphogenesis of biliary epithelial cells and participate in hepatic fibrogenesis and cholangiocellular carcinoma progression. Further characterization of the role of CRISPLD2 is important as it may serve a novel candidate for targeted therapy and/or biomarker for hepatic fibrosis and CCA.

Functional Significance of the Proliferating Bile Ductules in Primary Biliary Cirrhosis -Increased Expressions of Caveolin -1 and -2-

Purpose: Bile ductular proliferation is noted in diverse human liver diseases, particularly in primary biliary cirrhosis (PBC) and obstructive jaundice. Caveolins, caveolin-1 (CAV-1) and caveolin-2 (CAV-2) are Ca-++ and cholesterol-binding proteins involved in the regulation of several intracellular processes including cholesterol transport. The aim of the present study is to clarify how CAV-1 and -2 are expressed by immunohistochemical and Western blot analyses in human liver biopsy specimens from patients with PBC. Methods: Surgical liver biopsy specimens were obtained under laparoscope from 13 patients with PBC (12 females and 1 male, mean age 53.4 years, Scheur's stageI∼II; 6 cases, stageIII; 7). As controls, wedge biopsy specimens were obtained from normal portions of the livers of 10 patients (2 females and 8 males, mean age of 57.3 years) who underwent surgical resection for metastatic liver carcinomas. Indirect immunohistochenical staining was performed on consecutive serial sections using anti-CAV-1, anti-CAV-2 specific antibody as primary antibody and horseradish peroxidase (HRP)-conjugated anti-IgG as secondary antibody. Four-micrometer sections were cut from paraffin blocks of formalin-fixed liver tissues, deparaffinized with xylene and dehydrated by graded ethanol solutions. Bile ductules were identified by immunostaining of CK-6. Western blotting was conducted using fresh control and PBC liver tissues. Results: In control liver, the specific immunopositive reactions for CAV-1 and -2 were hardly detected on the bile ducts and ductules. In PBC, the immunopositive reactions for CAV-1 and -2 were increased on the proliferating bile ductules in the stage II and III of PBC, but sparsely noted on the interlobular bile ducts in the stage I of PBC. Particularly, the epithelial cells of the proliferating bile ductules at the interface between the portal tract and the lymphocytes-infiltrated parenchymal area were intensely immunostained for CAV-1 and -2. These results were confirmed by Western blot analysis. Conclusions: The increased expressions of CAV-1 and -2 in the proliferating bile ductular epithelial cells in PBC may be related to the homeostatic control of cholesterol transport in the regenerating bile ductules in response to the obliterative immunodestruction of the down-stream interlobular bile ducts in PBC.

Matrilysin (MMP-7) is a major matrix metalloproteinase upregulated in biliary atresia-associated liver fibrosis

Matrix metalloproteinases (MMPs) are the proteases responsible for tissue remodeling during liver fibrosis caused by various disorders including biliary atresia. However, information regarding the relative contribution of these proteases to liver fibrosis is still limited. We studied matrix metalloproteinase-2 (MMP-2), -7, -9 and -13 mRNA expressions in the liver tissue of early-stage biliary atresia at the time of Kasai's procedure, late-stage biliary atresia at the time of liver transplantation with advanced fibrosis and nondiseased control without liver fibrosis. The results of real-time quantitative reverse transcriptase-PCR analysis revealed that only MMP-2 and -7 expressions were significantly different between groups. MMP-2 was significantly higher in Liver Transplantation group than both in Control (P=0.010) and in Kasai's Procedure (P=0.001) groups, whereas the difference of MMP-2 expression between Control and Kasai's Procedure was not significant. However, the relative expression level of MMP-7 was sequentially elevated when comparing Control, Kasai's Procedure and Liver Transplantation groups, and there was significant (P=0.019) difference when comparing Control and Liver Transplantation groups. Moreover, the fold difference in MMP-7 mRNA was much higher than that in MMP-2 mRNA between groups. The expressions of MMP-7 were further confirmed by agarose gel electrophoresis and Western blotting. Immunohistochemical analysis revealed a significant positive correlation of the scores of MMP-7 immunostaining with the stages of liver fibrosis. In situ hybridization demonstrated that the bile ductular epithelial cells, Kupffer cells and hepatocytes were the major producers of matrix metalloproteinase-7 in the liver. Our results imply that MMP-7 is a major MMP associated with the tissue remodeling during the progression of liver fibrosis in biliary atresia.

Reconstruction of Ductular Structure by Rat Bile Ductular Epithelial Cells(Micro- and Nano-biomechanics)

Reconstruction of Ductular Structure by Rat Bile Ductular Epithelial Cells(Micro- and Nano-biomechanics)

Biliary atresia.

Biliary atresia.

Induction of arginase II in livers of bile duct-ligated rats

Nitric oxide (NO) has been implicated in playing a role in liver cirrhosis, but the regulatory mechanisms are still unclear. As arginase shares a common substrate with NO synthase (NOS), the aim of this study was to investigate the expression of arginase I and II in cirrhotic liver. Liver cirrhosis was induced in rats by chronic bile duct ligation (BDL). Controls were sham-operated. Competitive polymerase chain reaction was performed to assay the expression of messenger RNA of arginase I and II. Protein expression was detected by immunohistochemistry and western-blotting. The level of arginine in plasma was lower in BDL rats, while the ornithine level in plasma was correspondingly higher ( r−0.96, P<0.0001). Arginase I messenger RNA was reduced significantly in BDL rats (3.34±0.32 vs. 1.32±0.21×10 4 attomole/μg of total RNA, sham vs. BDL, P<0.001), as well as arginase I protein. In contrast, arginase II mRNA was induced in the livers of BDL rats, with negligible expression in controls (0.35±0.11 vs. 3.64±0.54 attomole/μg of total RNA, sham vs. BDL, P<0.001). Arginase II protein was localized in some hepatocytes and hyperplastic bile ductular epithelial cells of cirrhotic livers but not in control livers. In conclusion, arginase II was induced in BDL livers, while the expression of arginase I was down-regulated. These data suggest that arginase I and II are regulated differently and may have different functions in the livers of BDL rats. Reduction of arginase I in BDL livers may be responsible for the lowering of arginine levels in the plasma, while induction of arginase II could be important in regulating NO synthesis as well as other important mechanisms involved in liver cirrhosis.

Establishment of a novel rat cholangiocarcinoma cell culture model.

Furan cholangiocarcinogenesis in rat liver is proving to be a unique and useful animal model for investigating important aspects of the cellular and molecular pathogenesis of cholangiocarcinoma potentially relevant to the human disease. We now describe the first culture model of rat cholangiocarcinoma cells derived from a transplantable cholangiocarcinoma originally induced in the liver of a furan-treated rat. An epithelial cell isolate highly enriched in viable cholangiocarcinoma cells was consistently obtained from transplantable cholangiocarcinoma tissue utilizing a similar procedure to that recently developed by us to establish a new rat hyperplastic bile ductular epithelial cell culture model characterized by the appearance of polarized bile ducts in vitro. Primary cholangiocarcinoma cell cultures could be readily established with these isolated cells and, in addition, we established from one such culture a novel rat cholangiocarcinoma cell line designated C611B. Cultured C611B cholangiocarcinoma cells retained a number of important characteristic features of the carcinoma cells of the parent tumor, including marked expression of the tyrosine kinase growth factor receptor proteins c-Met and c-Neu. Under basal culture conditions, the C611B cell line exhibited a cell doubling time of approximately 24 h and was aneuploid, with a predominant chromosomal count of 43. Moreover, C611B cells on collagen gels were 100% tumorigenic when transplanted into inguinal fat pads of syngeneic rats. All tumors formed at the transplantation site were cytokeratin 19-positive, mucin-producing tubular adenocarcinomas whose histological and phenotypic features closely resembled those of the furan-induced parent transplantable rat cholangiocarcinoma. Based on our findings, we believe that this novel rat cholangiocarcinoma cell culture model can serve as a valuable resource for investigating aberrant growth properties and tumor progression in biliary cancer.

Human natural tumor necrosis factor alpha induces multiple endocrine and hematologic disorders in rats.

Slc:Wistar male rats treated with human natural tumor necrosis factor alpha (hn TNF-alpha, 3 X 10(5) Japan reference units/kg intravenously) for 3 months showed histologic vacuolation of basophils in the anterior pituitary, hyperplasia of the thyroidal follicular epithelium, and hyperplasia of the testicular interstitial cells. The vacuolated basophils were immunohistochemically shown to be thyrotrophs. In addition, there were decreases in plasma levels of triiodothyronine (T3), thyroxin (T4), and testosterone, and an increase in thyroid-stimulating hormone (TSH). The number of lymphocytes in the marginal zones of lymphoid follicles in spleen and lymph nodes and B-lymphocytes in the peripheral blood decreased. Hyperplasia of hematopoietic cells in the bone marrow and decreases in both leukocytes and erythrocytes in the peripheral blood were prominent. Hyperplasia of bile ductular epithelial cells with periportal mononuclear cell infiltration in the liver and increased cellularity in alveolar walls in the lung were also characteristic. In in vitro studies, hn TNF-alpha inhibited both proliferation and peroxidase activity of thyroid follicular epithelial cells. These findings demonstrate that hn TNF-alpha may induce histologic vacuolation of thyrotrophs by causing a decrease in plasma levels of T3 and T4; hyperplasia of the thyroid follicular epithelium, which may be attributed to the increased plasma level of TSH; hyperplasia of testicular interstitial cells, by lowering the plasma level of testosterone; hyperplasia of bile ductular epithelial cells; hyperplasia of hematopoietic cells in bone marrow; and the increase in cellularity in pulmonary alveolar walls. In addition, hn TNF-alpha may suppress the differentiation of B-lymphocytes.

Transforming growth factor betas and their receptors in human liver cirrhosis.

Transforming growth factor betas (TGF-betas) are a group of homologous polypeptides that exert pleiotropic effects on various cell types and stimulate the formation of extracellular matrix and fibrosis. To evaluate whether TGF-beta isoforms (TGF-beta1, TGF-beta2 and TGF-beta3) and their receptors (types I-III) are also of importance in the pathophysiology of liver cirrhosis, we analysed their concomitant expression and localization in human liver cirrhosis. Cirrhotic liver tissue samples were obtained from 17 patients (four women, 13 men) with a median age of 41 years (range 22-67). Normal liver tissues from ten patients (seven women, three men) with a median age of 55 years (range 45-75) served as controls. The tissues were fixed in Bouin's solution and paraffin-embedded for histological analysis. For RNA analysis, freshly obtained tissue samples were snap-frozen in liquid nitrogen and stored at -80 degrees C until analysed. Northern blot analysis was used to examine the expression of TGF-beta1, beta2 and beta3 and their receptors, type I (TbetaR-I), type II (TbetaR-II) and type III (TbetaR-III). Immunohistochemistry was performed to determine the localization of the corresponding proteins in the normal and the cirrhotic liver. Northern blot analysis revealed enhanced expression (P < 0.05) of TGF-beta1 (twofold increase), TGF-beta2 (threefold increase) and TGF-beta3 (8.5-fold increase) and of TbetaR-II (threefold increase) mRNA in liver cirrhosis in comparison with normal controls. In contrast, TbetaR-I (ALK-5) and TbetaR-III mRNA expression showed no significant changes. No TGF-beta isoform immunoreactivity was present in hepatocytes in either normal livers or in liver cirrhosis. However, in liver cirrhosis, intense TGF-beta1 immunoreactivity was present in bile duct and ductular epithelial cells (including ductular proliferations) and in inflammatory cells. In a few sinusoidal lining cells, faint TGF-beta1 and moderate TGF-beta2 immunoreactivity was present. TGF-beta3 immunostaining was present in bile duct and ductular epithelial cells, in inflammatory cells and in fibroblast-like spindle cells in liver cirrhosis. For TbetaR-I and TbetaR-II, the immunoreactivity was localized in hepatocytes and biliary cells in normal and cirrhotic liver tissues, with higher intensity for TbetaR-II in the cirrhotic liver. Enhanced expression of all three TGF-bea isoforms and of TbetaR-II in liver cirrhosis suggests their involvement in this fibrotic disorder. The higher immunoreactivity of the three TGF-beta isoforms in the bile duct epithelial cells in cirrhotic tissues suggests a possible role of these cells in the pathogenesis of liver cirrhosis.

Partial cloning of rat CD34 cDNA and expression during stem cell- dependent liver regeneration in the adult rat

The sialomucin CD34 is expressed on human and mouse hematopoietic stem cells and is used as an important marker for isolating the hematopoietic stem/progenitor cells. The involvement of hepatic stem cells in liver regeneration under certain conditions in adult rats is now well supported. The objective of the present research was to explore the idea that CD34 might also be expressed on hepatic stem cell progeny. Polymerase chain reaction (PCR)-based cloning of rat CD34 was partially accomplished. During the hepatic stem cell activation (2- acetylaminofluorene/partial hepatectomy [AAF/PH] model), the CD34 transcripts were increased and reached the peak level between 9 and 12 days after partial hepatectomy when the progenitor cells (e.g., oval cells, early hepatocytes in basophilic foci, and intestinal type of cells) are most abundant. Both in situ hybridization and immunohistochemistry, using anti-mouse CD34 antibody, which recognizes the cytoplasmic domain, clearly showed the expression of CD34 on oval cells as well as on endothelial cells of large hepatic vessels. In addition, bile ductular epithelial (BDE) cells both in the AAF/PH model and in normal liver expressed CD34, suggesting a close relationship between BDE cells and the hepatic stem-cell compartment. Taken together, the data indicate that CD34 would, similar to its role in the hematopoietic system, be an important probe for characterizing the cellular biology of the hepatic stem-cell compartment. (Hepatology 1997 Sep;26(3):720-7)

A new rat bile ductular epithelial cell culture model characterized by the appearance of polarized bile ducts in vitro.

The rat treated with bile duct ligation (BDL) and furan is a unique animal model of massive bile ductular hyperplasia in which normal liver parenchyma is largely replaced with well-differentiated proliferated bile ductules. We have now developed a simple cell isolation procedure to obtain and culture viable bile ductular epithelial cells in high numbers and with a high degree of purity from the livers of BDL/furan-treated rats. Primary monolayer cell cultures were readily established when the isolated bile ductular epithelial cells were cultured in plastic tissue culture wells coated with rat tail tendon type I collagen plus bovine plasma fibronectin. Under these conditions, epidermal growth factor (EGF) was mitogenic for the cultured cells, and they retained phenotypic features typical of hyperplastic bile ductular epithelium but did not show evidence of ductal morphogenesis in vitro. In contrast, when the isolated bile ductular cells were cultured for 7 to 16 days in the presence of 25 ng EGF/mL and 10% fetal bovine serum on type I collagen gels, they formed into branching ductal structures whose ultrastructural features very closely resembled those of polarized hyperplastic bile ductules/ducts in vivo. Histological preparations of these gel cultures further showed that numerous ductal structures with defined lumens were present. Phenotypically, these ductal structures were completely surrounded by a thickened basement membrane that was strongly immunoreactive for laminin. Like their in vivo biliary cell counterparts, the epithelial cells comprising these ductal structures in culture also exhibited strong immunocytochemical staining reactions for cytokeratins 8 and 19, for glutathione S-transferase pi 7, and for luminal gamma-glutamyl transpeptidase, but they did not express immunoreactive albumin or alpha-fetoprotein. Occasional epithelial cells of the ductal structures, when examined in 10-day-old primary gel culture, showed strong nuclear staining for incorporated 5-bromo-2'deoxyuridine, indicating active cell proliferation. Our results support the development of a novel biliary epithelial cell culture model that has the potential of serving as a powerful tool for investigation of factors that regulate hyperplastic bile ductular morphogenesis, cell proliferation, and polarized cell functions in a structural form in vitro that mimics that of hyperplastic bile ductules induced in vivo.

A new rat bile ductular epithelial cell culture model characterized by the appearance of polarized bile ducts in vitro

The rat treated with bile duct ligation (BDL) and furan is a unique animal model of massive bile ductular hyperplasia in which normal liver parenchyma is largely replaced with well-differentiated proliferated bile ductules. We have now developed a simple cell isolation procedure to obtain and culture viable bile ductular epithelial cells in high numbers and with a high degree of purity from the livers of BDL/furan-treated rats. Primary monolayer cell cultures were readily established when the isolated bile ductular epithelial cells were cultured in plastic tissue culture wells coated with rat tail tendon type I collagen plus bovine plasma fibronectin. Under these conditions, epidermal growth factor (EGF) was mitogenic for the cultured cells, and they retained phenotypic features typical of hyperplastic bile ductular epithelium but did not show evidence of ductal morphogenesis in vitro. In contrast, when the isolated bile ductular cells were cultured for 7 to 16 days in the presence of 25 ng EGF/mL and 10% fetal bovine serum on type I collagen gels, they formed into branching ductal structures whose ultrastructural features very closely resembled those of polarized hyperplastic bile ductules/ducts in vivo. Histological preparations of these gel cultures further showed that numerous ductal structures with defined lumens were present. Phenotypically, these ductal structures were completely surrounded by a thickened basement membrane that was strongly immunoreactive for laminin. Like their in vivo biliary cell counterparts, the epithelial cells comprising these ductal structures in culture also exhibited strong immunocytochemical staining reactions for cytokeratins 8 and 19, for glutathione S-transferase pi 7, and for luminal gamma-glutamyl transpeptidase, but they did not express immunoreactive albumin or alpha-fetoprotein. Occasional epithelial cells of the ductal structures, when examined in 10-day-old primary gel culture, showed strong nuclear staining for incorporated 5-bromo-2'deoxyuridine, indicating active cell proliferation. Our results support the development of a novel biliary epithelial cell culture model that has the potential of serving as a powerful tool for investigation of factors that regulate hyperplastic bile ductular morphogenesis, cell proliferation, and polarized cell functions in a structural form in vitro that mimics that of hyperplastic bile ductules induced in vivo. (Hepatology 1997 Sep;26(3):537-49)

Bile ductular proliferation and altered leukotriene elimination in thioacetamide-induced fibrosis of rat liver

Background/Aims: Liver fibrosis is accompanied by both bile ductular proliferation and inflammation under various conditions. The functional consequences and the interrelationships between these changes are unknown. Altered biliary elimination and retention of cholephilic mediators may be a factor in fibrogenesis. Therefore, the relationship between fibrosis, ductular proliferation and functional changes in biliary elimination was studied. Methods: Micronodular liver fibrosis was induced by thioacetamide in rats. The relative amount of bile ductular epithelial cells was determined by microscopic morphometry. The functional changes in bile secretion and metabolism of leukotriene C4 were assessed in isolated perfused livers of treated rats. Results: Pretreatment with thioacetamide in vivo resulted in enhanced bile fluid formation in subsequently isolated and perfused livers. Infusion of isoproterenol into the portal vein stimulated bile flow. Both unstimulated and isoproterenol-stimulated bile flows were increased in fibrotic livers and were correlated with liver content of bile ductular epithelia. In contrast, biliary secretion of infused leukotriene C4 was lowered in correlation with that of taurocholate. Enhanced metabolism resulted in a shift of major fraction in bile from leukotriene C4 to leukotriene D4. Conclusions: Thioacetamide-induced liver fibrosis is associated with an increased number of functionally intact bile ductules that are responsive to isoproterenol stimulating bile fluid formation. In contrast, biliary secretion of cysteinyl-leukotrienes and taurocholate is inhibited and the relative amount of leukotriene D4 is increased. Bile ductular proliferation as well as retention and altered metabolism of leukotrienes are factors associated with the development of liver fibrosis.

Biliary proliferation and adaptation in furan-induced rat liver injury and carcinogenesis.

Distinctive intrahepatic biliary adaptation responses occur in the liver of rats subjected to select hepatotoxic and/or carcinogenic treatments with the nongenotoxic cholangiocarcinogenic agent furan. Specifically, metaplastic small intestinal-like glands closely resembling in their cellular composition the crypts of Lieberkühn of normal rat small intestine were selectively derived from putative hyperplastic bile ductule-like progenitor structures in the right and caudate liver lobes of young adult Fischer-344 male rats given furan by gavage at a daily dose of 30-45 mg/kg body weight, 5 times weekly, over a 2-6-wk treatment period. Longer term chronic administration of furan at 30 mg/kg/day for 9-19 wk resulted in the preferential development of primary hepatic adenocarcinomas, which arose at 70-100% incidences from right/caudate liver lobes and which were characterized by small intestine mucosal cell differentiation. Interestingly, the neoplastic glands of these "intestinal-type" hapatic tumors demonstrated strongly positive immunochemical reactions for both hepatocyte growth factor/scatter factor and its c-met encoded receptor and were immunohistochemically positive for transforming growth factor beta 1 (TGF-beta 1) and for mannose-6-phosphate/insulin-like growth factor II receptor, implicated in the activation of latent TGF-beta 1. In contrast, a different pattern of aberrant bile ductular cell differentiation was noted to occur in the atrophied right liver lobe of moribund Fischer-344 male rats that were chronically exposed over a 10-14-day period to a severely hepatotoxic dose of furan (60 mg/kg/day). Under this latter experimental condition, rare yet distinct cholangiolar-like structures composed of biliary epithelial cells and typically a single ductular hepatocytic cell in various stages of maturation specifically formed in association with an extensive hyperplastic bile ductular reaction. Very similar cholangiolar-like structures also appeared in areas of preexisting hyperplastic bile ductule tissue at 3-5 days following the administration of a single hepatonecrogenic dose of CCl4 to rats that 4-6 wk earlier had been subjected to a bile duct ligation. In addition, a novel rat model was developed in which furan combined in a unique synergistic manner with bile duct ligation to induce the replacement of almost all of liver with well-differentiated hyperplastic bile ductules without evidence of differentiation along either metaplastic small intestine mucosal cell or ductular hepatocyte lineages. Bile ductular epithelial cell isolated from bile duct-ligated/furan-treated rats were further observed to be organized in the form of bile duct-like structures in vitro under specific conditions of primary cell culture and in vivo following their cell transplantation into the inguinal fat pads of sygeneic recipient rats. Overall, these findings serve to exemplify the remarkable plasticity that may be exhibited by certain proliferating biliary cell populations in liver in response to specific types of severe hepatic injury and/or during cholangiocarcinogenesis.

Parathyroid hormone-related peptide is expressed and rapidly inducible in human liver cell cultures that have a bile duct phenotype

Parathyroid hormone-related peptide is the major factor responsible for hypercalcemia of malignancy. There is increasing evidence that parathyroid hormone-related peptide also plays an important role in the growth and differentiation of both neoplastic and non-neoplastic cells. Recently we found that reactive human bile ductules and cholangiocarcinomas, but not normal bile ducts, human hepatocytes nor hepatocellular carcinomas, express parathyroid hormone-related peptide and we speculated that parathyroid hormone-related peptide may function as a growth and differentiation factor for bile ductular epithelial cells. Using a specific polyclonal antibody for immunostaining and a digoxigenin-random prime-labeled probe for in situ hybridization assay, we found that only cell lines with a bile duct phenotype expressed parathyroid hormone-related peptide and its mRNA.HepG2 cells with hepatocellular phenotype (CK19-, CK7-, CK8+, CK18+, albumin+) do not express parathyroid hormone-related peptide. However, A16 (HepG2 drived cell line) expressing bile duct marker CK19, also expressed parathyroid hormone-related peptide, while hepatocyte markers CK8, CK18, CALLA and albumin were negative. In addition, the H1 cell line (adult human hepatocyte immortalized in our laboratory by SV40 DNA transfection, passaged at least 40 times and cultured for 13 months) expressed bile duct marker CK7 and parathyroid hormone-related peptide, while hepatocyte markers CK8, CK18, CALLA and albumin were negative.Previous studies demonstrated that parathyroid hormone-related peptide gene expression in keratinocytes can be modulated by serum, growth factors and cycloheximide although there is a species and cellular specificity. In this study, we found that parathyroid hormone-related peptide-expression was rapidly induced by respectively, sodium butyrate, dexamethasone, cycloheximide and epidermal growth factor: in cell line A16 from 10–12% (control) to a value ranging from 24 to 29%, and in H1 cell line from 5–6% (control) to a value ranging from 14 to 17%. These results support the concept that parathyroid hormone-related peptide is a member of the early response gene family and is involved in the regulation of cellular growth and/or differentiation of human bile ductular epithelial cells.

Isolation, Biochemical Characterization, Long-Term Culture, and Phenotype Modulation of Oval Cells from Carcinogen-Fed Rats

Oval cells are liver epithelial cells that proliferate during hepatocarcinogenesis and chemically induced severe liver injury. It has been suggested that these cells represent hepatic stem cells which might play an important role in the histogenesis of cholangiocellular as well as hepatocellular carcinomas. In order to test this hypothesis highly purified oval cell preparations and propagable oval cell lines are needed. In the present study the isolation, biochemical characterization, and longterm culture of oval cells from rats fed a choline-deficient/DL-ethionine-supplemented diet for 6, 14, or 22 weeks are described. The freshly isolated oval cells were γ-glutamyltranspeptidase-positive, cytokeratin 7-, 8-, 18-, and 19-positive, albumin-positive, peroxidase-negative, and α-fetoprotein-negative and expressed lactate dehydrogenase isoenzymes 1-5. In addition, low but clearly measurable glucose-6-phosphatase and high γ-glutamyltranspeptidase and alkaline phosphatase activities (when compared to activities in untreated liver parenchymal cells) were measured in oval cells. Three oval cell lines, OC/CDE 6, OC/CDE 14, and OC/CDE 22, were established. They contained small and large epithelial cells replicating to form uniform monolayers with a cobblestone appearance; furthermore, a very low number of mononucleated giant cells were also present in the three cell lines. OC/CDE 6, OC/CDE 14, and OC/CDE 22 cells were γ-glutamyltranspeptidase-negative, were transiently albumin-positive, maintained the glucose-6-phosphatase activity levels measured in freshly isolated oval cells, and expressed lactate dehydrogenase isoenzymes 2-5. After exposure of the cultured oval cells to dimethyl sulfoxide or sodium butyrate, 35-40% of the cells reexpressed albumin, and glucose-6-phosphatase activity was enhanced; in addition, sodium butyrate strongly increased γ-glutamyltranspeptidase and alkaline phosphatase activities. In conclusion, oval cells express phenotypic markers of liver parenchymal as well as bile duct epithelial cells and possess a certain intrinsic plasticity. In order to test if the oval cells indeed represent an intermediate step in the differentiation of certain cells within the bile duct and ductular epithelial cell compartment to parenchymal cells, the three cell lines described herein will be transformed in vitro and their potential to give rise to cholangiocellular and/or hepatocellular carcinomas will be verified in vivo.

Characterization of rat hyperplastic bile ductular epithelial cells in culture andin vivo

A novel intrahepatic biliary cell culture/in vivo transplantation system has been developed with an essentially pure population of bile ductular epithelial cells isolated from rat liver 6-12 weeks after bile duct ligation. In primary culture, these cells retain staining strongly for gamma-glutamyltranspeptidase and glutathione S-transferase P. The cytoplasm of cultured bile ductular cells reacts with an anti-laminin antibody, but loses immunoreactivity with a monoclonal anti-cytokeratin 19 antibody. Semiconservative DNA synthesis in the cultured cells was dependent upon the continued presence of 10% fetal calf serum in the medium. Replicating bile ductular cells could be subcultured for a finite number of passages. In addition, freshly isolated bile ductular epithelial cells gave rise to well differentiated bile ductular structures when transplanted into the interscapular fat pads of syngeneic recipient rats.

17β-hydroxysteroid UDP-glucuronosyl transferase is expressed in bile ductular epithelial cells under physiological conditions

Using an improved procedure to isolate pure bile ductular epithelial cells from rat liver, we were able to define UDP-glucuronosyl transferase (UDPGT) isozymes expressed in these cells under physiological conditions. The cells contained mRNA for a 17 beta-hydroxysteroid, a 3 alpha-hydroxysteroid and a phenol UDPGT. Concomitantly, a distinct pattern of UDPGT-immunoreactive proteins was expressed, including a putative 17 beta-hydroxysteroid UDPGT. The presence of this UDPGT isozyme was confirmed by a high level of testosterone glucuronidation activity. This is the first demonstration of a metabolic pathway in bile ductular epithelial cells that is primarily dedicated to the processing of endogenous compounds.

Papillary cystic tumor of the liver. A case report with ultrastructural observation

A case of primary tumor of the liver with pathologic features strikingly similar to those of the papillary cystic tumor of the pancreas in a 41-year-old woman is presented. Two large, well-demarcated, solid and cystic tumors with extensive hemorrhage and necrosis were located in the right and left lobes, measuring 30 x 27 x 7.5 cm and 5.5 x 4.0 x 2.5 cm, respectively. Microscopically, both tumor masses showed two basic patterns of cellular arrangement. One was a papillary pattern with fairly prominent fibrovascular stalks covered with one to three cell layers of tall to cuboidal cells. The other pattern was that of solid growth with microcystic degeneration. Ultrastructurally, the tumor cells were polyhedral and their oval shaped nuclei were occasionally indented. The cytoplasmic organelles varied in amount, and immature cell junctions and intercellular spaces were rarely present. A few cells contained zymogen-like secretory granules and annulate lamellae. The pancreas was free of tumor. To our knowledge, this tumor is a unique clinicopathologic entity of hepatic origin, and its similarity to the pancreatic papillary cystic tumor in clinical, gross, microscopic, and ultrastructural features together with their closely related organogenesis, suggests that this tumor derives from pluripotential cells transdifferentiating toward the pancreatic acinar cells and ductular cells, with the latter being indistinguishable from intrahepatic small bile ductular epithelial cells.

Cholesterol and Bile Acid Metabolism in Cultures of Primary Rat Bile Ductular Epithelial Cells

The role of hepatocytes in bile acid and cholesterol metabolism has been extensively studied. By contrast, nothing is known about the role of bile ductular epithelial cells in cholesterol and bile acid metabolism. The purpose of the current studies was to establish whether bile ductular epithelial cells synthesize cholesterol, bile acids or both and to determine whether these cells are capable of metabolizing (hydroxylating, conjugating) bile acids. Bile ductular epithelial cells were isolated from rat liver after ligation of the common bile duct for 6 to 8 wk. Bile ductular epithelial cells were essentially free (greater than 99%) of hepatocytes and were histochemically positive (greater than 80%) for gamma-glutamyl transpeptidase activity. Cholestatic hepatocytes were simultaneously isolated and characterized with regard to their ability to synthesize and metabolize bile acids. Incubation of bile ductular epithelial cells with [14C]-acetate resulted in rapid labeling of cellular cholesterol, suggesting that these cells have a complete cholesterol biosynthetic pathway. The addition of [4-14C]-cholesterol to bile ductular epithelial cells did not lead to detectable synthesis of [14C]-bile acids. [24-14C]-Cholic acid, [24-14C]-deoxycholic acid, [24-14C]-lithocholic acid and [3H]-ursodeoxycholic acid were individually added to bile ductular epithelial cells and incubated for 24 or 48 hr. Bile acid metabolites were extracted and separated by C-18 reverse-phase high-performance liquid chromatography or thin-layer chromatography. Bile ductular epithelial cells conjugated deoxycholic acid, ursodeoxycholic acid and lithocholic acid to glycine and taurine. Surprisingly, no conjugation of cholic acid was detected. Conjugated lithocholic acid was further metabolized to highly polar metabolite(s), possibly beta-muricholic acid.(ABSTRACT TRUNCATED AT 250 WORDS)