Cholangiocyte organoids can repair bile ducts after transplantation in the human liver.

Organoid technology holds great promise for regenerative medicine but has not yet been applied to humans. We address this challenge using cholangiocyte organoids in the context of cholangiopathies, which represent a key reason for liver transplantation. Using single-cell RNA sequencing, we show that primary human cholangiocytes display transcriptional diversity that is lost in organoid culture. However, cholangiocyte organoids remain plastic and resume their in vivo signatures when transplanted back in the biliary tree. We then utilize a model of cell engraftment in human livers undergoing ex vivo normothermic perfusion to demonstrate that this property allows extrahepatic organoids to repair human intrahepatic ducts after transplantation. Our results provide proof of principle that cholangiocyte organoids can be used to repair human biliary epithelium.

Regional Differences in Human Biliary Tissues and Corresponding In Vitro-Derived Organoids.

BACKGROUND AND AIMS: Organoids provide a powerful system to study epithelia in vitro. Recently, this approach was applied successfully to the biliary tree, a series of ductular tissues responsible for the drainage of bile and pancreatic secretions. More precisely, organoids have been derived from ductal tissue located outside (extrahepatic bile ducts; EHBDs) or inside the liver (intrahepatic bile ducts; IHBDs). These organoids share many characteristics, including expression of cholangiocyte markers such as keratin (KRT) 19. However, the relationship between these organoids and their tissues of origin, and to each other, is largely unknown. APPROACH AND RESULTS: Organoids were derived from human gallbladder, common bile duct, pancreatic duct, and IHBDs using culture conditions promoting WNT signaling. The resulting IHBD and EHBD organoids expressed stem/progenitor markers leucine-rich repeat-containing G-protein-coupled receptor 5/prominin 1 and ductal markers KRT19/KRT7. However, RNA sequencing revealed that organoids conserve only a limited number of regional-specific markers corresponding to their location of origin. Of particular interest, down-regulation of biliary markers and up-regulation of cell-cycle genes were observed in organoids. IHBD and EHBD organoids diverged in their response to WNT signaling, and only IHBDs were able to express a low level of hepatocyte markers under differentiation conditions. CONCLUSIONS: Taken together, our results demonstrate that differences exist not only between extrahepatic biliary organoids and their tissue of origin, but also between IHBD and EHBD organoids. This information may help to understand the tissue specificity of cholangiopathies and also to identify targets for therapeutic development.

Histochemical Study of Heparin-positive Mast Cells in the Terminal Part of Porcine Ductus Choledochus and Papilla Duodeni Major.

The study presented in detail the localization and density of mast cells (MCs) in the intramural part of the common bile duct (CBD) and in the major duodenal papilla (MDP) of domestic swine. MCs' density (number/mm(2) ) in different layers of both of the duct and papilla was evaluated after toluidine blue staining. Their number was higher in the lamina propria mucosae than in the tunica muscularis of the studied structures. The localization of berberine-positive, (heparin containing) MCs and the ratio between them and toluidine blue-positive MCs with γ-ma metachromasia was also established. Ratios of heparin-containing MCs in comparison with all toluidine blue-positive MCs were found as follows: ductus choledochus - 32% in the subglandular connective tissue of lamina propria mucosae in the intramural part of the duct; m. sphincter ductus choledochus - 31% in the circular and 0.06% in the longitudinal muscle layer; subserosa - 59%; papilla duodeni major - 0.03% in the subepithelial connective tissue and 34% in the subglandular connective tissue of lamina propria mucosae, respectively. The established large difference in heparin-positive MCs in both the subepithelial and subglandular connective tissues of CBD and MDP, respectively, is an evidence for the existence of mucosal and connective tissue MCs.

The Density of Interstitial Cells of Cajal Is Diminished in Choledochal Cysts.

BACKGROUND AND AIMS: Interstitial cells of Cajal (ICC) have been shown to be present in the extrahepatic biliary tract of animals and humans. However, ICC distribution in choledochal cysts (CC) has not been investigated. A study was conducted to investigate the distribution of ICC in the extrahepatic biliary tract, including CC, in pediatric human specimens. METHOD: The specimens were divided into two main groups as gallbladders and common bile ducts. Gallbladders were obtained from the cholelithiasis, CC operations and autopsies. Common bile ducts were obtained from autopsies. Tissues were stained using c-kit immunohistochemical staining. ICC were assessed semi-quantitatively by applying morphological criteria and were counted as the number of cells/0.24 mm(2) in each area under light microscopy. RESULTS: A total of 35 gallbladders and 14 CC were obtained from operations. Ten gallbladders plus common bile ducts were obtained from autopsies. The mean numbers of ICC in the gallbladders of cholelithiasis and the gallbladders of CC were 12.2 ± 4.9 and 5.3 ± 1.2, respectively (p = 0.003). The mean numbers of ICC in the common bile ducts and CC were 9.8 ± 2.9 and 3.4 ± 1.4, respectively (p = 0.001). CONCLUSION: The scarcity of ICC in the extrahepatic biliary tract may be responsible for the etiopathogenesis of the CC.

In vivo and in vitro evaluation of effects of Mg-6Zn alloy on apoptosis of common bile duct epithelial cell.

Biodegradable magnesium alloy implants have attracted much attention because of their excellent biocompatibility and good mechanical properties. However, effects of Mg alloy on cell apoptosis remain unclear. The aim of this study was to investigate the effects of the Mg-6Zn alloy on the apoptosis and necrosis of common bile duct (CBD) epithelial cells. In the in vitro experiments, primary mouse extrahepatic bile epithelial cells (MEBECs) were exposed to Mg-6Zn alloy extracts with different concentrations (0, 40, 80, and 100 %). Flow cytometry analysis indicated that low concentration Mg-6Zn extract can induce apoptosis of MEBECs, and high concentration Mg-6Zn extracts may relate to necrosis and/or 'apoptotic necrosis'. Real-time PCR results showed that when MEBECs were treated with 40 % extracts for 3 days, the relative apoptotic genes including Bax, Bax/Bcl-2 ratio, NF-κB and caspase-3 were higher than those in the control group. In the in vivo experiments, Mg-6Zn alloy stents were implanted into rabbits' CBD for 1, 2, 3 weeks, respectively. Based on the hematoxylin and eosin (H&E) staining of peri-implant CBD tissue, no apoptotic bodies and necrotic cells were observed. Results of immunohistochemical staining also showed Mg-6Zn stents did not increase expression levels of apoptosis related gene such as Bax, Bcl-2, Bax/Bcl-2 ratio, TNF-α, NF-κB and caspase-3 in CBD, which indicating Mg-6Zn did not induce significant apoptosis in the in vivo experiments. The different results of in vitro and in vivo experiment may result from the low corrosion rate of Mg-6Zn alloy stents in vivo and local Mg(2+) ion concentration in CBD.

Esfinterotomía de aguja / Needle sphincterotomy

La canulación fallida del conducto biliar común durante la colangiopancreatografía retrógrada endoscópica es del 5 al 20% según la experticia del operador. El uso de guías hidrofílicas y la canulación profunda y selectiva son claves en el adecuado abordaje de la vía biliar. La inadecuada selección del paciente, papilas pequeñas o peridiverticulares, cálculo impactado, disfunción del Oddi o traumatismo repetido durante la canulación son las causas más frecuentes. La esfinterotomía de aguja en sus dos modalidades infundibulotomía y el precorte son técnicas opcionales para el abordaje del conducto biliar ante el fallo de la técnica convencional. Ambas técnicas son igualmente efectivas para el abordaje biliar en coledocolitiasis. La hiperamilasemia es más frecuente en el precorte (17.75%) en infundibulotomía (2.7%). La incidencia de pancreatitis post colangiografía es de 15% posterior a 15 o más intentos de canulación. La pancreatitis en el precorte puede alcanzar el 8% y es rara durante la infundibulotomía. El sangramiento ocurre de forma comparable con ambas técnicas. La esfinterotomía de aguja temprana en la canulación fallida disminuye la ocurrencia de pancreatitis post procedimiento. Debe ser realizada por colangiografistas expertos en la técnica y manejo de las complicaciones y contarse con los equipos y materiales adecuados

The failed cannulation of the common bile duct during endoscopic retrograde cholangiopancreatography is from 5 to 20% depending on operator expertise. The use of hydrophilic guides and the deep and selective cannulation are key to sucessfull access to the bile duct. Inadequate patient selection, small duodenal papilla or peridiverticular, impacted gallstone, Oddi dysfunction or repeated trauma during cannulation are the most common causes of failure. Needle-knife sphincterotomy in its two modalities: infundibulotomy and precut are optional techniques for accessing the bile duct when confronted with the conventional technique failure. Both techniques are equally effective for biliary choledocholithiasis. Hyperamylasemia is more common in the precut (17.75%) infundibulotomy (2.7% ). The incidence of post cholangiography pancreatitis is 15% after 15 or more cannulation attempts. Pancreatitis in precut can reach 8% and is rare during the infundibulotomy. Bleeding occurs in a similar way in both techniques. Early needle-knife use, in failed in cannulation decreases the occurrence of post procedure pancreatitis. It must be perfomed by experts in the technique that are able to manage eventual complications beside having adequate equipment and materials available

Effects of trypsin, thrombin and proteinase-activated receptors on guinea pig common bile duct motility.

Trypsin and thrombin activate proteinase-activated receptors (PARs), which modulate gastrointestinal motility. The common bile duct is exposed to many proteinases that can activate PARs, especially during infection and stone obstruction. We investigated PAR effects on common bile duct motility in vitro. Contraction and relaxation of isolated guinea pig common bile duct strips caused by PAR(1), PAR(2) and PAR(4) agonists were measured using isometric transducers. Reverse transcription polymerase chain reaction (RT-PCR) was performed to determine the expression of PAR(1) and PAR(2). Thrombin and two PAR(1) peptide agonists, TFLLR-NH(2) and SFLLRN-NH(2), evoked moderate relaxation of the carbachol-contracted common bile duct in a concentration-dependent manner. Trypsin and three PAR(2) peptide agonists, 2-furoyl-LIGRLO-NH(2), SLIGKV-NH(2) and SLIGRL-NH(2), generated moderate to marked relaxation as well. The existence of PAR(1) and PAR(2) mRNA in the common bile duct was identified by RT-PCR. Moreover, two PAR(4)-selective agonists, AYPGKF-NH(2) and GYPGQV-NH(2), produced relaxation of the common bile duct. In contrast, all PAR(1), PAR(2) and PAR(4) inactive control peptides did not elicit relaxation. This indicates that PAR(1), PAR(2) and PAR(4) mediate common bile duct relaxation. The thrombin, TFLLR-NH(2), trypsin, and AYPGKF-NH(2)-induced responses were not affected by tetrodotoxin, implying that the PAR effects are not neurally mediated. Our findings provide the first evidence that PAR(1) and PAR(2) mediate whereas agonists of PAR(4) elicit relaxation of the guinea pig common bile duct. Trypsin and thrombin relax the common bile duct. PARs may play an important role in the control of common bile duct motility.

In situ tissue engineering of the bile duct using polypropylene mesh-collagen tubes.

Multiple attempts have been made to replace biliary defects with a variety of materials. Recently, successful biliary reconstruction using the Gore-Tex vascular graft has been reported experimentally and clinically. We designed a new artificial bile duct consisting of collagen sponge and polypropylene mesh. We presently evaluated the feasibility of using this prosthesis as a scaffold for bile duct tissue regeneration in a canine model. Our prosthesis, a sponge made from porcine dermal collagen, is reinforced with a polypropylene mesh cylinder. We used the prosthesis to reconstruct the middle portion of the common bile duct in seven beagle dogs to evaluate its efficacy. While one dog died of biliary stricture 8 months after operation, six survived without problems to scheduled time points for tissue evaluation at 1 to 12 months. All prostheses had become completely incorporated into the host. A confluent epithelial lining was observed within 3 months. In cholangiograms the prosthesis displayed long-term patency in the six dogs and provided satisfactory bile drainage for up to 12 months. Our graft thus shows promise for repair of biliary defects and should lead to development of a new treatment for biliary reconstruction.

The common bile duct ligation in rat: A relevant in vivo model to study the role of mechanical stress on cell and matrix behaviour.

Common bile duct ligation leads to bile accumulation and liver fibrosis. In this model, little attention has been dedicated to the modification of the common bile duct. We have studied by histochemistry and immunohistochemistry, 3 and 5 days after ligation, the connective tissue modifications of the common bile duct wall. After bile duct ligation, compared with normal bile duct, a strong increase of the bile duct diameter, due to bile stasis, and a thickness of the bile duct wall were observed; numerous myofibroblasts expressing alpha-smooth muscle actin appeared in parallel with the detection of many proliferating connective tissue cells. These myofibroblasts secreted very early high amount of elastic fibre components, elastin and fibrillin-1. Elastic fibre increase was also observed close to the epithelial cell layer. Procollagen type III deposition was also induced 3 days after ligation but decreased thereafter, underlining that myofibroblasts modify their synthesis of extracellular matrix components to comply with the request. We show here that common bile duct ligation represents an invaluable model to study myofibroblastic differentiation and extracellular matrix adaptation produced by an acute mechanical stress.

Somatostatin stimulates the brush-tailed possum sphincter of Oddi in vitro and in vivo.

BACKGROUND & AIMS: Somatostatin, a neuropeptide and hormone, is found in the biliary tract of several species. The aim of this study was to map the distribution of somatostatin-like immunoreactive nerve fibers in the extrahepatic biliary tract of the Australian possum and to determine the pharmacological effects of somatostatin 1-14 on sphincter of Oddi activity in vitro and in vivo. METHODS: Tissue was harvested for immunohistochemistry and sphincter of Oddi for circular or longitudinal muscle contractility. In anesthetized possums, sphincter of Oddi motility was measured by manometry, and transsphincteric flow was measured gravimetrically. RESULTS: Somatostatin immunoreactivity was evident in gallbladder ganglia nerve cell bodies and in nerve fibers of the common bile duct and sphincter of Oddi. Somatostatin 1-14 increased circular and longitudinal muscle contraction amplitude 3-4-fold (P < 0.05), but only the longitudinal muscle contraction amplitude was tetrodotoxin sensitive. Somatostatin 1-14 stimulated spontaneous sphincter of Oddi motility in a tetrodotoxin-insensitive manner, increasing basal pressure, contraction frequency, and amplitude 2-4-fold (P < 0.05) and reducing transsphincteric flow to 25% of control (P < 0.0001). CONCLUSIONS: Somatostatin-like immunoreactivity is present in the extrahepatic biliary tree, and somatostatin 1-14 stimulates sphincter of Oddi smooth muscle and nerves. The major action is direct stimulation of sphincter of Oddi circular muscle, which reduces transsphincteric flow.

Isolation, culture and characterization of biliary epithelial cells from different anatomical levels of the intrahepatic and extrahepatic biliary tree from a mouse.

We developed methods to isolate biliary epithelial cells (BECs) from the gallbladder (GB), common bile duct (CBD), intrahepatic large bile duct (ILBD) and small bile duct (ISBD) of a mouse, simultaneously. ILBD and ISBD were cut from the biliary tree after collagenase perfusion of the liver. BECs from all of these biliary segments were cultured as explants on collagen gel. BECs spread from the explants and formed cellular sheets. Areas of these sheets composed entirely of BECs were cut and placed on other gels as subculture, and this continued for 10 passages. Primary and passage cultured BECs on gel were composed of a monolayer of epithelial cells. Passaged cultured BECs in gel formed a spherical cyst lined by a single epithelial layer. Ultrastructurally, microvilli were dense on the luminal surface, and junctional complex and interdigitation was identifiable on the lateral surfaces. These features were similar in both primary and passaged cultured BECs, irrespective of their anatomical origin. Major histocompatibility complex antigens and intercellular adhesion molecule-1 were induced on the basolateral cell membranes of primary and passaged cultured BECs, by interferon-gamma. Although several phenotypic, structural and probable biological features of BECs inherent to each anatomical level may be lost after culture on gel, a combination of this method, several immunological modifications in experimental animals, and addition of immunologically active substances to the culture medium will make the immunopathologic analysis of biliary diseases possible.

Secretions of the biliary mucosa in experimental clonorchiasis.

The histological change of the biliary mucosa in clonorchiasis is characterized as adenomatous hyperplasia, and cross-sectioned mucosa looks like intestinal mucosa. In addition to the glandular hyperplasia, the metaplasia of mucin secreting cells is also known. The present study investigated the presence of intestinal secretion from the biliary mucosal cells of rabbits and rats with Clonorchis sinensis infection. The rabbit was infected with 300 and the rat was infected with 100 metacercariae of C. sinensis. A part of the animals were followed up after praziquantel treatment. The rabbit livers were prepared for histochemistry to observe any endocrine secretion and the bile duct mucosa of the mice was processed for the activity of brush border membrane (BBM)-bound enzymes of the small intestine. Immunohistochemistry with the polyclonal antibodies and biotin-streptavidin-peroxidase staining kit showed no positive cells for gastrin and secretin, but a few cells were positive for serotonin. The proliferated biliary mucosa of the mice revealed no activity of disaccharidases and aminopeptidase. Only alkaline phosphatase activity was found both in the control and the infected. The hyperplastic biliary mucosal cells showed no gastrointestinal secretory functions. The serotonin secreting cells may be one of the inflammatory cells.

Postnatal development of the brush cells in the common bile duct of the rat.

The postnatal development of brush cells in the distal segment of the common bile duct of the rat was examined with respect to cell number and immunoreactivity for liver fatty acid-binding protein (L-FABP). The brush cells, distinguishable from the principal cells by scanning electron microscopy, first appeared in the common bile duct 4 weeks after birth. They showed a remarkable increase in number, with a sex difference in time, i.e., between 8 and 12 weeks in the male and between 10 and 14 weeks in the female. In both sexes, the frequency of brush cells reached approximately 30% of total epithelial cells by 16 weeks and remained constant until 40 weeks of age. Cells with positive immunoreactivity for L-FABP first appeared in small numbers at 8 weeks. Immuno-electron microscopy revealed that all immunoreactive cells were brush cells. They increased in number gradually from 16 to 40 weeks with no sex difference. At 40 weeks, the immunoreactive cells reached approximately 7.5% of total epithelial cells, corresponding to one-fourth of the number of brush cells. These results indicate that the occurrence of the brush cell population in the common bile duct is a late event in the postnatal development of the rat and that its functional maturation progresses with aging.

In vitro duct-like structure formation after isolation of bile ductular cells from a murine model.

The epithelium of the biliary tree is involved in the response to numerous liver disease processes including immunologic destruction during liver transplant rejection and liver graft-versus-host disease after bone marrow transplantation. Furthermore, very little is known concerning the function of this previously inaccessible epithelium, because attempts to isolate and culture biliary cells have been unsuccessful until recently. We present a method for the isolation and culture of bile ductular cells from mice with external bile duct obstruction. Over 85% of the isolated cells stain positive for cytokeratin 19, which is characteristic of murine biliary epithelium. Incubation with recombinant murine gamma-interferon resulted in increased class II antigen expression on the isolated cell surface. When these cells were placed, on a basement membrane matrix, they formed duct-like structures composed of cells that had the morphologic characteristics of bile ductular epithelium when examined by transmission electron microscopy. The ability to isolate murine biliary epithelium that forms duct-like structures will be useful for the in vitro study of biliary epithelial characteristics and injury.

Three-dimensional arrangement of dense connective tissue around the human major duodenal papilla. Including the ampullary region and the distal choledochal duct.

Directionally arranged dense connective tissue fibres were investigated in 21 specimens of the major duodenal papilla. Specimens were examined using a stereoscope, polarization microscopy and serial histological sections at three different planes. Directionally arranged dense connective tissue fibres spread in a deltoid pattern from the orifice of the major duodenal papilla and its intraduodenal part to the circular duodenal musculature. Connective tissue fibres crossing at different angles form a texture from the orifice of the major duodenal papilla to the distal choledochal duct. The functional significance of the dense connective tissue fibres, e.g. for the muscular system in the investigated area, is discussed as well as possible reasons for gallstone impactions.

Choledochal cysts. Oligoganglionosis in the narrow portion of the choledochus.

To investigate whether cystic dilation may be due to a reduction of postcholinergic cell bodies that leads to autonomic dysfunction, ganglion cell bodies were counted in five patients with choledochal cysts and five patients with normal choledochus. In the normal choledochus, the ganglion cell counts in the proximal and distal portions were 374.7 +/- 82.7/cm2 and 349.2 +/- 51.2/cm2, respectively. In cases of choledochal cysts, the ganglion cell counts in the dilated portion and narrow portions were 298.6 +/- 86.9/cm2 and 81.0 +/- 34.8/cm2, respectively. The cell ratio (narrow to dilated) was 0.271. Significant reductions of cell numbers were observed in all the choledochal cysts having various types of pancreatobiliary junctions. These findings indicate that the reduction in the number of ganglion cells in the narrow portion of the choledochal cysts supports the concept of oligoganglionosis in distal choledochus.

Comparison of the effects of polyglycolic acid and monofilament nylon sutures in the common bile duct of pigs.

The tissue reaction and involvement of cells in the common bile duct of young pigs after surgery with two suture materials, polyglycolic acid and monofilament nylon, have been described. By comparing the different tissue reactions to the suture materials the authors observe that the use of non-absorbable polymer sutures and their long lasting presence in living tissues, may interfere with the healing process, since the sutures tend to migrate within the common duct wall and be expelled into the lumen owing perhaps to the delayed immuno-allergic reaction which develops in the common duct wall. In contrast polyglycolic acid seems to be biologically well tolerated and well integrated as a suture material, which is reabsorbed with the help of cell enzymes producing a complete restitutio ad integrum of the wall.

Changes in morphology of the distal common bile duct associated with aging.

A gross and microscopic study has been made of the changes associated with aging in the distal common bile duct of normal humans. Grossly a progressive narrowing develops with aging at the level of the preampullary portion of the common bile duct. On the contrary, the pancreatic portion of the common bile duct has a tendency to dilatation with aging. Histologically the thickening and sclerosis of the wall in the preampullary portion represent the changes increasing in degree with aging, consisting of: 1) submucosal glandular proliferation and fibrosis, and 2) intermuscular glandular proliferation and fibrosis. On the other hand, the diffuse sclerosis in the pancreatic portion gradually occurs with aging, consisting of: 1) proliferation and fragmentation of elastic fibers, and 2) increase in collagen fibers. Factors influencing the development of these changes associated with age are discussed. The author presumes that decrease in response to an upward tendency of the intraductal pressure resulting from diffuse sclerosis in the wall of the common bile duct, in addition to a progressive narrowing of the preampullary portion, may be responsible for dilatation of the common bile duct, moreover, bile stasis and infection on the biliary tract. It is suggested therefore that these alterations with aging process in the terminal bile duct may be a responsible agent in the formation of common duct stones.