Isolation and primary cultures of human intrahepatic bile ductular epithelium

An improved and easy protocol for primary epithelial cell culture from atretic tissue in biliary atresia

Biliary atresia (BA) is a lethal disease of infancy with obscure etiology. Insight into the pathogenesis of this disorder is limited by lack of availability of adequate epithelial tissue. Primary culture of human biliary epithelium may help to provide material for diagnostic and research purposes. However, culture of these cells from atretic tissue is a challenging task. We aimed to develop a reliable and easier protocol for culture of human biliary epithelial cells from excised atretic extrahepatic bile duct. An explant culture was performed using tissue obtained from 30 children with diseases of biliary tract. The culture showed florid cell growth in less than 3 weeks. Epithelial nature and biliary origin of cultured cells was confirmed using pancytokeratin and cytokeratin -7 antibodies. The protocol showed 100% success rate as cells could be cultured in all 30 patients. Moreover, the cells remained viable for a duration of over 3 months in most of the cases. This easier culture technique is likely to have an impact on the study of biliary cell pathophysiology, particularly in BA.

Increased expression of senescence-associated cell cycle regulators in the progression of biliary atresia: an immunohistochemical study

AIMS

Cellular senescence plays a role in tumour suppression and in the pathogenesis of various non-neoplastic diseases, including primary biliary cholangitis and other adult cholangiopathies. Less is known about the role of cellular senescence in cholangiopathies in children. With that in mind, we examined the expression of senescence-associated cell cycle regulators in biliary atresia, the most common form of paediatric obliterative cholangiopathy.

METHODS AND RESULTS

The expression of senescence-associated cell cycle regulators (p16^Ink4a and p21^WAF1/Cip1 ) and a ductular reaction related marker (neural cell adhesion molecule: NCAM) was examined in bile ducts and bile ductules in liver samples taken from the patients with biliary atresia [n = 80; including 23 samples at the time of the Kasai procedure (KP) and 63 obtained from the explanted liver (LT) (six cases with samples at both surgical stages of disease)] and from appropriate controls (n = 17). The degree of ductular reaction and cholestasis was significantly more extensive in LT than KP (P < 0.01). The expression of p16^INK4a and NCAM was significantly more extensive in bile ducts and bile ductules in ductular reaction in both KP and LT compared to controls and in LT compared to KP (P < 0.05). The expression of p21^WAF1/Cip1 was significantly more extensive in bile ducts and bile ductules in KP compared to both LT and controls (P < 0.01).

CONCLUSIONS

Cellular senescence may play a role in the progression of bile duct loss in biliary atresia in a manner similar to that of adult cholangiopathies.

Epithelial cell senescence: an adaptive response to pre-carcinogenic stresses?

Senescence is a cell state occurring in vitro and in vivo after successive replication cycles and/or upon exposition to various stressors. It is characterized by a strong cell cycle arrest associated with several molecular, metabolic and morphologic changes. The accumulation of senescent cells in tissues and organs with time plays a role in organismal aging and in several age-associated disorders and pathologies. Moreover, several therapeutic interventions are able to prematurely induce senescence. It is, therefore, tremendously important to characterize in-depth, the mechanisms by which senescence is induced, as well as the precise properties of senescent cells. For historical reasons, senescence is often studied with fibroblast models. Other cell types, however, much more relevant regarding the structure and function of vital organs and/or regarding pathologies, are regrettably often neglected. In this article, we will clarify what is known on senescence of epithelial cells and highlight what distinguishes it from, and what makes it like, replicative senescence of fibroblasts taken as a standard.

Efficient generation of biliary epithelial cells from rabbit intrahepatic bile duct by Y-27632 and Matrigel

Efficient culture of primary biliary epithelial cells (BECs) from adult liver is useful for both experimental studies and clinical applications of tissue engineering. However, an effective culture system for long-term proliferation of adult BECs is still unachieved. Laboratory rabbit has been used in a large number of studies; however, there are no reports of BECs from normal adult rabbit. As little as 5 g of normal rabbit liver tissue were minced, digested, and then clonally cultured in medium containing FBS and ITS. Cells were characterized by cell morphology, immunoassaying, and growth rate assay. Different combination of growth factors and substrates, including Y-27632 and Matrigel, were employed to assess their effect on cell proliferation. In the primary culture, the BECs cellular sheets consisting of cuboidal cells, as well as fibroblast-like cells and other hepatic cells, emerged with time of culture. The BECs cellular sheets were then manually split into cells clumps for further characterization. The subcultured cells had typical cell morphology of cholangiocytes, expressed the specific markers of BECs, including GGT, cytokeratin (CK18), and CK19, and possessed the capacity to form duct-like structure in three-dimensional Matrigel. Y-27632 and Matrigel-treated BECs had a steady growth rate as well as colony-formation capacity. The BECs were maintained in Y-27632 and Matrigel culture system for more than 3 mo. This is the first example, to our knowledge, of the successful culture of BECs from normal adult rabbit liver. Furthermore, our results indicate that treatment of BECs with Y-27632 and Matrigel is a simple method for efficient output of BECs.

[Physiologic and pathologic experimental models for studying cholangiocytes]

Cholangiocytes (epithelial cells lining the intra- and extrahepatic bile ducts) and hepatocytes are two major components of liver epithelia. Although cholangiocytes are less numerous than hepatocytes, they are involved in both bile secretion and diverse cellular processes such as cell-cycle phenomena, cell signaling, and interactions with other cells, matrix components, foreign organisms, and xenobiotics. Cholangiocytes are also targets in several human diseases including cholangiocarcinoma, primary sclerosing cholangitis, autoimmune cholangitis, and vanishing bile-duct syndrome. The rapid advances in experimental biology technologies are greatly expanding interest in and knowledge of the physiology and pathophysiology of cholangiocytes. This review focuses on the progress of in vivo and in vitro experimental models in elucidating the physiologic functions of cholangiocytes and the pathophysiology of various cholangiopathies. The following aspects are reviewed: isolation of cholangiocytes from the liver and their heterogeneity, various culture systems, establishment of cholangiocyte cell lines, isolation and usage of intrahepatic bile-duct units, three-dimensional modeling of the bile duct, experimental models for inducing cholangiocyte proliferation, and various cholangiopathies such as cholangiocarcinoma, primary sclerosing cholangitis, and autoimmune cholangitis.

Long-term culture of cholangiocytes from liver fibro-granulomatous lesions

BACKGROUND

Extensive bile duct proliferation is a key feature of the tissue reaction to clinical and experimental forms of liver injury. Experimental infection of mice by Schistosoma mansoni is a well-studied model of liver fibrosis with bile duct hyperplasia. However, the regulatory mechanisms of bile duct changes are not well understood. In this study we report the reproducible isolation of long-term cultures of cholangiocytes from mice livers with schistosomal fibrosis.

METHODS

We have isolated a cholangiocyte cell line from Schistosoma-induced liver granulomas using a combination of methods including selective adhesion and isopyknic centrifugation in Percoll.

RESULTS

The cell line was characterized by morphological criteria in optical and transmission electron microscopy, ability to form well differentiated ductular structures in collagen gels and by a positive staining for cytokeratin 18 and cytokeratin 19. To our knowledge, this is the first murine cholangiocyte cell line isolated from schistosomal fibrosis reported in the literature.

CONCLUSION

After 9 months and 16 passages this diploid cell line maintained differentiated characteristics and a high proliferative capacity. We believe the method described here may be a valuable tool to study bile duct changes during hepatic injury.

Frequent cellular senescence in small bile ducts in primary biliary cirrhosis: a possible role in bile duct loss

The pathogenesis of progressive bile duct loss in primary biliary cirrhosis remains unclear. In this study, the involvement of cellular senescence of biliary epithelial cells was examined in liver tissue samples from patients with primary biliary cirrhosis (n = 33), and compared with control diseased and normal livers (n = 83). In addition, cellular senescence was induced by oxidative stress in cultured mouse biliary epithelial cells. Biliary epithelial cells in small bile ducts in primary biliary cirrhosis, especially those in patients presenting with chronic non-suppurative cholangitis, frequently expressed senescence-associated beta-galactosidase, and senescence-associated p16(INK4) and p21(WAF1/CIP). In contrast, senescence-associated markers were rarely expressed in small bile ducts in control livers. The infiltration of myeloperoxidase-positive inflammatory cells into biliary epithelial cell layers was closely associated with the cellular senescence of biliary epithelial cells in early-stage PBC. Cellular senescence of cultured mouse biliary epithelial cells was induced by treatment with H2O2 via the p38MAPK-dependent pathway and nitric oxide-augmented H2O2-induced cellular senescence. Oxidative stress- and nitric oxide-mediated cellular senescence may be involved in bile duct lesions, which are followed by progressive bile duct loss in primary biliary cirrhosis.

Isolation and culture of biliary epithelial cells from bile duct remnants of patients with biliary atresia

Biliary atresia(BA), the most common cause of obstructive jaundice in infancy, has been considered to be a result of progressive destruction of the bile ducts through a necroinflammatory process. Many immunohistochemical studies of BA remnant have been done, but it has not been shown that biliary epithelial cells (BECs) can be cultured from BA remnant. For this study, we obtained bile duct remnants from three patients with biliary atresia (one male, two females) who received Kasai's operation from 2002 to 2003. The successive cultivation rate of BECs from explants was 100% (3/3 patients). Culture of BECs on collagen gel was possible up to at least four passages. Under a phase-contrast microscope, primary and passed cultured cells on collagen gel showed a cobblestone-like spread in 2 weeks. The BECs had immunoreactivity to anti-human cytokeratin 7 antibody. In this study, we proved that BECs in the remnants of BA could be cultured, and defined the maturation of biliary epithelial cells of BA by immunocytochemistry with anti-human cytokeratin 7 antibody. In conclusion, BECs in BA remnant are "alive", and their proliferation activity can be maintained.

Ductular morphogenesis and functional polarization of normal human biliary epithelial cells in three-dimensional culture

BACKGROUND/AIMS

The understanding of the physiology and function of human biliary epithelial cells (hBEC) has been improved by studies in monolayer culture systems. The aim was to develop a polarized model to elucidate the mechanisms of ductular morphogenesis and functional differentiation of hBEC.

METHODS

The morphological, phenotypic and functional properties of hBEC cultured as three-dimensional aggregates in collagen gel were assessed in medium supplemented with (or without) human hepatocyte growth factor (hHGF) and foetal bovine serum.

RESULTS

In the absence of added mitogens and serum, cells maintained as morphologically polarized aggregates, organized around a central lumen, were positive for phenotypic markers of biliary epithelium and negative for markers of other cell types. Functional markers, gamma-glutamyl-transferase, anion exchanger-2, responses to gamma interferon and forskolin induced secretion, were preserved. hHGF increased both the size and number of aggregates and induced hBEC to invade the gel and lumena forming anastomosing networks of cells.

CONCLUSIONS

Collagen gel culture in the absence of added growth factors and serum provides a model for analysis of the polarized functions of hBEC. The formation of poorly organized cords of cells in response to hHGF suggests that collagen gel culture may provide a model for the investigation of atypical ductular morphogenesis of the human biliary tract.

Replicative senescence of biliary epithelial cells precedes bile duct loss in chronic liver allograft rejection: increased expression of p21(WAF1/Cip1) as a disease marker and the influence of immunosuppressive drugs

Early chronic liver allograft rejection (CR) is characterized by distinctive cytological changes in biliary epithelial cells (BECs) that resemble cellular senescence, in vitro, and precede bile duct loss. If patients suffering from early CR are treated aggressively, the clinical and histopathological manifestations of CR can be completely reversed and bile duct loss can be prevented. We first tested whether the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR, and whether treatment reversed the expression. The percentage of p21+ BECs and the number of p21+ BECs per portal tract is significantly increased in early CR (26 +/- 17% and 3.6 +/- 3.1) compared to BECs in normal liver allograft biopsies or those with nonspecific changes (1 +/- 1% and 0.1 +/- 0.3; P: < 0.0001 and P: < 0.02), chronic hepatitis C (2 +/- 3% and 0.7 +/- 1; P: < 0.0001 and P: < 0.04) or obstructive cholangiopathy (7 +/- 7% and 0.7 +/- 0.6; P: < 0.006 and P: = 0.04). Successful treatment of early CR is associated with a decrease in the percentage of p21+ BECs and the number of p21+ BECs per portal tract. In vitro, nuclear p21(WAF1/Cip1) expression is increased in large and multinucleated BECs, and is induced by transforming growth factor (TGF)-beta. TGF-beta1 also increases expression of TGF-beta receptor II, causes phosphorylation of SMAD-2 and nuclear translocation of p21(WAF1/Cip1), which inhibits BEC growth. Because conversion from cyclosporine to tacrolimus is an effective treatment for early CR, we next tested whether these two immunosuppressive drugs directly influenced BEC growth in vitro. The results show that cyclosporine, but not tacrolimus, stimulates BEC TGF-beta1 production, which in turn, causes BEC mito-inhibition and up-regulation of nuclear p21(WAF1/Cip1). In conclusion, expression of the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR and decreases with successful recovery. Replicative senescence accounts for the characteristic BEC cytological alterations used for the diagnosis of early CR and lack of a proliferative response to injury. The ability of cyclosporine to inhibit the growth of damaged BECs likely accounts for the relative duct sparing properties of tacrolimus.

Selective and organotypic culture of intrahepatic bile duct cells from adult pig liver

Secondary culture of nontransformed bile duct epithelium has been difficult to achieve. STO feeder cell-dependent secondary cultures of adult pig bile duct cells were established from primary cultures of adult pig liver cells. Adult pig hepatocytes exhibited limited or no replication and were lost from the secondary culture at Passage 3 or 4. In contrast, adult pig bile duct cells replicated and were carried for 4-8 passages in secondary culture. A simple method to produce nearly pure pig intrahepatic bile duct cultures was first to freeze a relatively crude liver cell preparation. Upon subsequent thawing, all hepatocytes and most macrophages were lysed. Bile duct cells composed 95% of the surviving cells after the freeze/thaw, and they grew out rapidly. The bile duct cells grew on top of the STO feeder cells as closely knit epithelial, colonial outgrowths. Histocytochemical and biochemical analyses demonstrated high levels of gamma-glutamyltranspeptidase activity and low levels of P450 activity in the bile duct cultures. The bile duct cells spontaneously adopted a multicellular ductal morphology after 7-10 d in static culture which was similar to that found in in vivo pig liver. Transmission electron microscopic examination revealed complex junctions and desmosomes typical of epithelium, and lumenally projecting cilia typical of in vivo intrahepatic bile ductules. This simple method for the coculture of pig intrahepatic bile duct cells which adopt in vivo-like structure may facilitate biological studies of this important, but difficult to culture, cell type.

Dexamethasone inhibits the proliferation of hepatocytes and oval cells but not bile duct cells in rat liver

Recent advances have implicated the importance of tumor necrosis factor (TNF) and interleukin 6 (IL-6) in the regulation of liver growth. Therefore, we studied how dexamethasone, a well-known inhibitor of these cytokines, influences the proliferation of different hepatic cell populations. As we expected, dexamethasone pretreatment suppressed the expression of both TNF and IL-6 after partial hepatectomy and significantly reduced the proliferative response of the hepatocytes. Furthermore, the proliferative response of hepatocytes could be rescued by IL-6 administration. Dexamethasone also severely diminished the induction and expansion of oval cells induced by the 2-acetylaminofluorene/partial hepatectomy (AAF/PH) protocol but did not have any effect on the proliferation of the bile duct cells stimulated by bile duct ligation. The differential inhibition of these two morphologically very similar cell types may be used to characterize divergent regulatory mechanisms responsible for the proliferative response of oval cells and adult bile epithelial cells.

The immunological role of biliary epithelial cells in human liver transplant rejection

From histopathological analyses after liver transplantation it is evident that the biliary epithilium is an important target for leucocytes of the graft recipient. Besides clinical and histopathological investigations undertaken by several authors it was also endeavoured to determine the immunological impact of the biliary epithelial cells (BEC) in vitro. As for the intrahepatic BEC, in vitro studies proved to be restricted owing to difficult isolation procedures and the limited number of cells yielded from transplanted organs. Therefore, studies on cultured extrahepatic BEC served as a model for the immunological features of the biliary epithelium in transplantation. Herein, in vivo and in vitro studies dealing with BEC and immunologically mediated hepatic disorders are reviewed in order to understand better the pathogenesis after liver transplantation. Furthermore, possible underlying mechanisms of BEC-directed immunity with regard to BEC-leucocyte interactions are discussed.

Cultured human biliary epithelial cells induce allogeneic lymphocyte activation in vitro: possible relevance in liver transplant rejection

The biliary epithelium is a major target for allograft-directed immune responses during rejection crises after liver transplantation. This paper deals with in vitro studies on the immunogenetic potential of cultured biliary epithelial cells (BECs) to elicit an allogeneic cellular immune response. Therefore, BECs were cocultured with syngeneic and allogeneic lymphocytes in order to study lymphocyte activation. The respective lymphocytes [3H]thymidine incorporation was a measure for the proliferative activity. While syngeneic peripheral blood lymphocytes (PBL) never exhibited BEC-induced proliferation allogeneic PBL were significantly (P < 0.05) activated in all experiments (n = 6). In experiments with purified subpopulations CD8+ cells but not CD4+ cells proved to be activated by BECs. In time kinetics (n = 5) the maximum of the BEC-induced proliferation was on day 9 while the endothelial cell-induced proliferation was found to be 2 days earlier on day 7 after onset of the experiments (P < 0.05). BEC-induced proliferation was accompanied by induced IL-2 secretion (> 300 pg/ml) by activated lymphocytes as determined by ELISA. Stimulation of BECs with 500 U/ml interferon-gamma, 1000 U/ml interferon-alpha or blocking expression of HLA molecules on the surface membrane of BECs by monoclonal antibodies did not alter BEC-induced allogeneic lymphocyte proliferation. Monoclonal antibodies against CD8+ but not CD4+ suppressed proliferative activity of PBL and CD8+ cells by 40 and 45%, respectively. Overall, these results provide evidence that BECs may induce CD8+ lymphocyte activation in vivo and therefore might play a crucial role in triggering immune responses related to liver transplant rejection episodes.

Morphology, physiology, and biochemistry of biliary epithelia

In this review, we have emphasized the importance of cholangiocytes in biology and pathology and highlighted recent advances in experimental approaches to study these increasingly important cells. It is anticipated that major advances will continue to be made in our understanding of how these cells function and the processes which result in their dysfunction. The techniques are now available to allow major inroads in our understanding of the pathobiology of cholangiocytes.

Characterization of biliary epithelial cells isolated from needle biopsies of human liver in the presence of hepatocyte growth factor

Current methods for the isolation of intrahepatic biliary epithelial cells from human liver rely upon relatively large segments of tissue, thereby limiting studies to cells isolated from patients with end-stage disease. To investigate a greater range of diseases and those at an earlier stage, we have developed a method to isolate biliary epithelial cells from biopsy-sized fragments of human liver. Tissue explants are cultured for > 4 weeks, and, in approximately 50% of samples incubated with medium containing hepatocyte growth factor, biliary epithelial cells begin to migrate from the fragments and proliferate. With time they form confluent pavements of cells that express cytokeratin 19 and gamma-glutamyl transpeptidase and are negative for markers of non-biliary cell phenotype. After subculturing, cells can be expanded, yielding substantial numbers for subsequent study in vitro. Cells can be isolated with a similar degree of success from adult normal liver, from a variety of liver diseases, and from post-transplant liver biopsies. Overall, pediatric tissue yielded cells less frequently than adult tissue. This novel technique is likely to have a major impact on the study of biliary pathophysiology, as small fragments of tissue removed from biopsies taken for diagnostic purposes can be used.

Human biliary epithelial cells secrete and respond to cytokines and hepatocyte growth factors in vitro: interleukin-6, hepatocyte growth factor and epidermal growth factor promote DNA synthesis in vitro

Recombinant growth factors and proinflammatory cytokines were added to primary cultures of human intrahepatic biliary duct epithelia to test for their ability to stimulate DNA synthesis and elicit cytokine production. Interleukin-6 and hepatocyte and epidermal growth factors were found to increase the DNA labeling index of biliary duct epithelium from fourfold to sixfold 24 hr after their addition to primary biliary duct epithelium cultures maintained in serum-free medium. The proliferative responses to all three biliary duct epithelium mitogens peaked within 24 hr, and hepatocyte growth factor was effective over a concentration range of 1.0 to 50 ng/ml, whereas interleukin-6 was effective from 1 to 1,000 U/ml. Insulin-like growth factor, phorbol myristate acetate, interleukin-1 beta and platelet-derived growth factor BB showed mild stimulatory effects, whereas interleukin-4, gamma-interferon, phytohemagglutinin and platelet-derived growth factors AA and AB did not increase DNA synthesis in biliary duct epithelium. Interleukin-1 beta and phorbol myristate acetate were also shown to induce in a dose-dependent fashion a threefold to fivefold increase of interleukin-6 production as measured by enzyme-linked immunosorbent assay in human primary biliary duct epithelium cultures, when compared with hepatocyte growth factor, epidermal growth factor, insulin-like growth factor, phytohemagglutinin, tumor necrosis factor-alpha or platelet-derived growth factor. These results show that interleukin-6 participates in growth regulation of human biliary duct epithelium. This could be exerted in a paracrine or autocrine manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and culture of biliary epithelial cells

At one time it was thought that biliary epithelial cells simply formed the lining to the tubular conduits which constitute the biliary tract. Development of in vitro systems for culturing biliary epithelial cells has enabled functional studies which increasingly show that this is far from true, and that biliary epithelial cells do have important functional roles. Disruption of these functions may be involved in the generation of pathology. Most functional studies to date have utilised cells isolated from rat liver. Increasingly, variations are being found between human and animal cells both in terms of function and phenotype. The relevance of animal cells in the study of human disease therefore remains obscure. Human biliary tract disease has to date been studied almost exclusively by examination of histological sections. The development of improved methods for isolating highly pure biliary epithelial cells from human liver provides a new technology with which to investigate directly the dynamics of human biliary epithelial cell biology and pathobiology. It is predicted that further progress will now be made in dissecting the biology and physiology of human biliary epithelium.

Cytotoxic activity of spleen-derived T lymphocytes against autologous biliary epithelial cells in autopsy patients with primary biliary cirrhosis

Autoimmunity against biliary epithelial cells is considered to be involved in the pathogenesis of primary biliary cirrhosis (PBC). However, cytotoxic activity of T lymphocytes against biliary epithelial cells has not previously been examined. This study has demonstrated that spleen-derived T lymphocytes were cytotoxic for autologous biliary epithelial cells in all of five patients with PBC, even though it was only detectable at high effector to target ratios. Such cytotoxicity was not found in non-PBC patients. CD8-positive T lymphocytes were shown to be responsible for the cytotoxicity by negative selection, and its inhibition was dependent on the ratio of cold to hot target cells. These observations may support a current hypothesis that the pathogenesis of PBC is partly due to T cell autoimmunity directed against the bile duct epithelium.

Primary culture of human gallbladder epithelial cells

Growth requirements of epithelial cells isolated from the human gallbladder were examined. The growth of gallbladder epithelial cells (GBEC) was stimulated by medium conditioned with gallbladder fibroblasts (CM-GBF) in a dose-dependent manner. The conditioned medium derived from human embryo lung fibroblasts also showed similar growth stimulating activity for GBEC, suggesting that fibroblasts secrete a factor or factors which induce GBEC growth in vitro. CM-GBF in the presence of 10% fetal bovine serum increased GBEC growth up to 10 times the growth in the absence of CM-GBF supplement. GBEC cultured with CM-GBF showed hexagonal shape under a phase-contrast microscope, and also expressed cytokeratin and mucopolysaccharide in the cytoplasm, both of which are specific for GBEC. Electron microscopy revealed desmosomes and tight junctions between the cells and microvilli on the apical plasma membrane, suggesting that they regained morphological polarity in the medium containing CM-GBF. These results shows that CM-GBF is essential for the growth and the differentiation of GBEC in culture.

Recognition of major histocompatibility complex antigens on cultured human biliary epithelial cells by alloreactive lymphocytes

We have developed an in vitro system to study the interactions between biliary epithelium and lymphocytes using cultured human biliary epithelial cells. No class II antigens were detected by immunoperoxidase staining of the normal biliary epithelial cells, but alloactivated lymphocyte culture supernatants were able to induce class II expression. The activity of the supernatants was blocked with an anti-gamma-interferon monoclonal antibody. In addition, recombinant human gamma-interferon alone induced the expression of class II antigens and increased the intensity of class I staining of cultured biliary epithelial cells. Biliary epithelial cell-induced proliferation of alloreactive T lymphocytes demonstrated that the major histocompatibility complex molecules carry functional lymphocyte-activating determinants. The recognition of major histocompatibility complex determinants was confirmed by monoclonal antibody-blocking studies and by stimulation of an alloreactive T-cell clone. However, the biliary epithelial cells were much less potent stimulators than arterial endothelial cells tested in the same assay system.

Biliary epithelial cells from the liver of patients with primary biliary cirrhosis: isolation, characterization, and short-term culture

Since biliary epithelial cells of the middle-sized interlobular bile ducts are targets for lymphocyte-mediated damage in patients with primary biliary cirrhosis (PBC), we have developed a method for isolating and maintaining these cells in short-term tissue culture. Intrahepatic biliary epithelial cells were isolated from small segments of liver removed at the time of transplantation. Cells were separated from a collagenase digest by immunomagnetic separation using Dynabeads coupled to a monoclonal antibody (HEA 125) specific for a biliary epithelial cell surface antigen. The yield was approximately 3 x 10(5) cells/g of liver. The isolated cells were characterized morphologically and ultrastructurally using light and electron microscopy, and immunocytochemically using HEA 125 and anti-cytokeratin, anti-vimentin and anti-asialoglycoprotein receptor antibodies. By these criteria cells were judged to be identical to biliary epithelial cells from normal liver. The cells could be maintained in short-term tissue culture for up to 4 weeks without loss of biliary epithelial cell markers. Availability of interlobular biliary epithelial cells will be of value in future investigations of the pathogenetic mechanisms of PBC.

Immuno-isolation and culture of biliary epithelial cells from normal human liver

Biliary epithelial cells (BEC) lining the intra-hepatic biliary ducts are the site of damage in several immunologically mediated liver diseases. BEC are difficult to isolate since they represent only 5% of the total cell number in normal liver. In this communication, a novel method for their isolation from normal liver is presented using a monoclonal antibody (HEA125) with specificity for an epithelial cell surface glyco-protein reported to be expressed in liver only by biliary epithelium. By combining differential density centrifugation and immuno-magnetic separation using HEA125 pure BEC (10(5) cells/g fresh tissue) were prepared routinely. These cells were maintained in culture for up to 4 weeks with significant increases in cell numbers. The ability to prepare BEC from human liver offers an opportunity to develop In Vitro models to investigate the aetiology of diseases of intra-hepatic biliary epithelium.