Hepatic Progenitor Cells in Action: Liver Regeneration or Fibrosis?

Liver injury caused by drugs, viruses, and toxins that impede the proliferation of mature hepatocytes results in the activation of hepatic progenitor cells (HPCs), which then participate in the restoration of the damaged liver tissue. HPCs are known to be bipotential cells, capable of forming both hepatocytes and cholangiocytes when regeneration by mature hepatocytes is plagued or impaired. Both clinical studies of liver disease and certain experimental animal models of liver injury conspicuously show the presence of activated HPC response and proliferation. However, in addition to regeneration, the proliferation of HPCs also determines the appearance of a ductular reaction that has been correlated with progressive portal fibrosis, suggesting intricate links between activation of HPCs and fibrogenesis. The current review highlights the role of activated HPCs in both hepatic regeneration and fibrosis during liver injury.