Morphogenesis of primary human biliary epithelial cells: Induction in high-density culture or by coculture with autologous human hepatocytes

Abstract

Although the control of biliary ductular morphogenesis has received some attention particularly using isolated rat biliary epithelial cell models, the regulation of human bile duct formation is not well defined. In the present study, using a 3-dimensional culture model comprising primary human biliary epithelial cells (BECs) and coculture with primary human hepatocytes, we have sought to define the factors involved. We have shown that primary human BECs can be expanded on collagen gels in the absence of growth factors or serum. When plated in high density in double collagen gels, BECs established 3-dimensional structures that subsequently developed into well differentiated polarized luminal ducts. This morphogenic response occurred in the absence of hepatocyte growth factor (HGF) and epidermal growth factor. Strikingly, the addition of growth factors While the control of liver regeneration has focused on the factors that regulate the initiation of growth in primary hepatocytes (HCs) 1,2 since they are the first cell type in the liver to respond in the regenerative process, 3 less attention has been paid to the biliary epithelial cell (BEC) compartment. We know that in vivo, BECs respond to partial hepatectomy with a delay of approximately 24 hours 4 (together with the sinusoidal cell populations). Although some of the mitogenic signaling molecules have been identified, 1,3 the factors that induce biliary ductular morphogenesis, essential to the efficient regeneration of the bile drainage system, are not well characterized.Many rodent-based biliary epithelial cell studies have focused on the bile duct ligation model, which results in extensive hyperplasia of ductular epithelium and indeed is a chosen means of increasing the yield of BECs that can be isolated from liver tissue. [5][6][7] In rats, factors including epidermal growth factor (EGF), hepatocyte growth factor (HGF), somatostatin, bile acids, and cytokines have been implicated in the proliferative response 6-10 after bile duct ligation 6,7 or partial hepatectomy. 10 After bile duct ligation in mice, HGF receptors (cmet) are up-regulated and interleukin 6 (IL-6) receptors (gp-80) are induced on the proliferating ductular cells. 11 Studies on isolated intrahepatic BECs from normal rats have also proven productive. 8,12,13 Other investigators have used dissected rodent bile duct units to show that interactions of the periductal inflammatory stroma are the source of these factors 11 and to perform functional studies on intrahepatic biliary epithelium. 12,[14][15][16][17][18] Some work on the control of ductular morphogenesis in vitro has also been performed with BECs from bile ductligated rats 5,6,18 and normal rats, 15-17 but the important regulatory factors remain poorly characterized. In other systems, most notably during angiogenesis and mammary gland ductulogenesis, factors such as EGF and HGF have been shown to be the principal morphogenic factors. [19][20][21][22][23][24] Recent evidence from in vitro-based cell proliferation and motility assays has ...

Augmented expression of hepatocytes growth factor activator inhibitor type 1 (HAI-1) in intrahepatic small bile ducts in primary biliary cirrhosis

“…HGFA and c-Met were constantly expressed in small bile ducts and bile ductules in PBC and control livers. HGF-enhanced cell proliferation and wound healing in cultured BECs in the present study were as reported previously [1,7,27,32]. HGF has opposing effects on cell growth; HGF stimulates the proliferation of several tumor cell lines [5], whereas it inhibits the proliferation of a number of other tumor cell lines [26].…”

Murine gallbladder epithelial cells can differentiate into hepatocyte-like cells in vitro

“…This "clean" cell model could then be used to investigate whether such changes in differentiation occur. We and others (3,14,17,22,31,32,35) have reported the establishment of cell lines from normal gallbladder epithelia of adult dogs, humans, and mice. We therefore used genetically labeled well-differentiated murine gallbladder epithelial cells (GBEC) to examine whether differentiation into hepatocyte-like cells can be induced in vitro.…”

Liver Regenerative Medicine: Advances and Challenges

“…Then, endothelial and ductal cells form microvessels and bile ducts thereby restoring the structure of the normal liver [Stolz et al, 1999]. Furthermore, coculturing hepatocytes and biliary cells have beneficial effects on both hepatic cell lineages [Auth et al, 2001[Auth et al, , 2005. These findings have attracted investigators to start developing 3D heterologous cell systems, a prototype of the bioengineered liver.…”