Cloning and characterization of liver progenitor cells from the scattered cell clusters in primary culture of porcine livers.

The scattered cell clusters that can differentiate into hepatocytes or biliary epithelial cells have been isolated from primary cultures of adult porcine livers. We have generated 11 clonal cell lines from this system and identified liver progenitor cells (LPCs) among the clonal lines. These clonal lines expressed c-kit, HNF-1, HNF-6, and/or CK19 mRNA. An immunocytochemical study of the clonal lines indicated that clonal line CL-11 expressed liver epithelial cell markers CK14, vimentin, CK18, and BD-1. The expression of albumin and alpha1-antitrypsin (alpha1-AT) mRNA was only upregulated in CL-11 among the clonal lines when they were grown as aggregates. Under these conditions, CL-11 also exhibited ammonia metabolic activity and several indicators that suggest hepatocytic differentiation, including the upregulation of liver-specific genes such as dipeptidyl peptidase IV, CYP1A1, and CYP3A4 mRNA, and the downregulation of biliary cell markers such as gamma-glutamyltrans-peptidase (GGT), CK19, and HNF6 mRNA. After culturing CL-11 in Matrigel, the expression of GGT and HNF6 mRNA was upregulated. These results indicate that CL-11 has dual potential: the ability to differentiate as hepatocytes or as bile duct cells. The isolation of scattered cells could provide a simple method to generate LPC lines from adult livers.