Growth and differentiation of colony-forming human hepatocytes in vitro

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Background/Aims: Parenchymal hepatocytes (PHs) of rat contain colony-forming parenchymal hepatocytes (CF-PHs) as a small fraction. We aimed to demonstrate the presence of CF-PHs in humans and characterize them with respect to growth and differentiation potential. Methods: Human PHs were co-cultured with Swiss 3T3 cells in the medium containing human serum, EGF, nicontinamide, and ascorbic acid 2- phosphate. To examine differentiation potential hepatocytes were cultured on gels of Matrigel Matrix. Results: Few PHs formed colonies, the colony-forming efficiency being as low as 0.01-0.09%.0 The CF-PHs could be subcultured up to 7 passages. They showed a liver epithelial cell-like morphology, and immunocytochemically positive for albumin (ALB), cytokeratin (CK) 7, 8, 18, and 19 in a pre- and early phase-confluence, whereas they showed a typical differentiated hepatocyte-like morphology, and positive for α1-antitrypsin, but negative for CK7 and 19 in condensed regions at confluence. The CF-PHs at late confluence expressed mRNAs of ALB, HNF4, and isoforms of cytochrome P450 at low levels. However, when cultured on Matrigel, these cells expressed them at high levels comparable to those of original PHs. Conclusions: We concluded that the human liver contains highly replicative hepatic progenitor-like cells as a minute population that retain a normal differentiation potential.