Submitted to: Experimental Cell Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/1996
Publication Date: N/A
Citation: N/A Interpretive Summary: The pig epiblast-derived cell line, PICM-19, was characterized to further define its liver cell and bile duct cell properties. PICM-19 is a unique cell culture that was previously shown to differentiate in vitro into cells resembling ether liver cells or bile duct epithelium cells. The PICM-19 were also previously shown to secrete liver specific proteins and express liver specific messenger RNA. The present study demonstrated that the PICM-19 cells had ultrastructure, enzymatic, and transport properties similar to that of liver and bile cells and bile duct cells. Electron miscroscopic analysis showed the PICM-19 cell culture contained liver-like cells, and also contained multicellular structures closely resembling bile ductules. PICM-19 was found to have P-450 and gamma-glutamyl-transpeptidase enzyme activities nearly equivalent to liver cells and bile duct cells, respectively. PICM-19 cells transported fluoroescein into specialized intercellular structures, biliary canaliculi, in the same manner as cultured liver cells. The studies results confimred the dual liver/bile duct cell nature of the PICM-19 cell line and provivdes further evidence that PICM-19 may be a liver stem cell line. PICM-19 cells may be useful for studying liver development, for toxicological assays, for artificial liver device development, for in vivo liver cell replacement experimentation, and possibly for studies of hepatitis and malaria.
Technical Abstract: The PICM-19 pig epiblast-derived cell line was previously hypothesized to be representative of liver stem cells because of their secretion of liver- specific proteins, and their in vitro differentiation into cells resembling either parenchymal hepatocytes or bile duct epithelium. In the present study PICM-19 cells displayed in vitro ultrastructure, enzymatic, and transport characteristics typical of parenchymal hepatocytes and bile duct epithelium. The PICM-19 cells contained large oval nuclei, numerous oval to elongate mitochondria with flat cristae, extensive rough and smooth endoplasmic reticulum, Golgi complexes, lipid vacuoles, and glycogen granules. Biliary canaliculi with intraluminal projecting microvilli were delimited by the junctional apparatuses between adjacent PICM-19 cells. The PICM-19 cells rapidly transported fluorescein into their biliary canaliculi from the extracellular environment. PICM-19 cells that had differentiated into multicellular ductal structures showed high gamma- glutamyl transpeptidase (GGT) activity by histochemical staining at their apical surfaces. PICM-19 total soluble GGT activity was high, and inducible cytochrome P-450, measured by two independent assays, was nearly equivalent to that of primary cultures of pig hepatocytes. The data support the hypothesis that the PICM-19 cell line is an in vitro equivalent of liver stem cells.