The expression of mesenchymal, neural and haematopoietic stem cell markers in adult hepatocytes proliferating in vitro

Background/Aims: Cultured adult hepatocytes may be stimulated into clonal expansion. We raise the question whether adult hepatocytes proliferating in vitro recapitulate the early process of hepatic development. Methods: A non-enzymatic method was used to isolate hepatocytes free of contamination with non-parenchymal cells. Hepatocytes were stimulated into proliferation in the presence of mitogens and conditioned media from nonparenchymal cell and hepatocyte culture supernatants. Immunofluorescence methods and PCR analysis were used to demonstrate immunophenotypical characteristics and gene expression profiles similar to those of progenitor cells. Results: Rapid growth occurred during the first 7 days of culture. Cells continued to express hepatic markers (phosphoenolpyruvate carboxykinase, cytokeratin 18, transferrin and dipeptidylpeptidase IV), but the gap junction protein connexin 32 was down-regulated. In the early stage of proliferation, cells started to express biliary and extrahepatic progenitor markers (cytokeratin 19, CD49b, CD49f, nestin, vimentin, Thyl and c-kit), followed by cytokeratin 7, connexin 43, and neural cell adhesion molecule. Co-expression of the epithelial liver progenitor marker alpha-foetoprotein with either nestin (neural marker) or Thyl (mesenchymal marker) was also demonstrated. Conclusions: Mature, hepatocytes reveal their potential to regain a spectrum of progenitor markers from different germ layers, suggesting, enormous plasticity and differentiation potential of adult liver cells. (c) 2006 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.