Hepatic progenitor cells: their role and functional significance in the new classification of primary liver cancers.

Hepatic progenitor cells (HPCs) are bipotential cells residing in normal liver. Their proliferation is observed in reactive conditions of the liver and in primary liver cancers. The observation that some hepatocellular carcinomas (HCCs) express a biliary-like immunophenotype has led to the identification of HPCs in HCC. Accumulating evidence suggests that HPCs play a role as the cell of origin in a variety of primary liver cancers. This has led to the development of revolutionary concepts in hepatocarcinogenesis. In this article, the role and significance of HPCs in HCC, including its classification, are summarized and discussed.