Liver stem cells and possible clinical applications.

The discovery of several sources of hepatic progenitors in extra-hepatic organs and tissues, both in animal models and in humans, supports opportunities to isolate, grow and expand them in vitro. Microenvironment factors involved in regulating proliferation and commitment of liver cell precursors have been identified and better characterization of liver stem cell pathobiology would greatly improve the understanding of liver differentiation/ regeneration processes, especially those leading to hepatocarcinogenesis. The goal of these researches has been to discover the most available, suitable and easy-to-use pluripotent stem cells (PSC) sources for cell-based therapies in genetic and acquired liver diseases, therapies which to date have required liver transplantation. This report reviews the efforts, so far, to either investigate the presence of PSC in hepatic and extra-hepatic districts or evaluate their capacity to differentiate in vitro and to restore in vivo liver function.