Hedgehog signaling maintains resident hepatic progenitors throughout life.

Hedgehog signaling through its receptor, Patched, activates transcription of genes, including Patched, that regulate the fate of various progenitors. Although Hedgehog signaling is required for endodermal commitment and hepatogenesis, the possibility that it regulates liver turnover in adults had not been considered because mature liver epithelial cells lack Hedgehog signaling. Herein, we show that this pathway is essential throughout life for maintaining hepatic progenitors.

Proliferation and hepatic differentiation of adult-derived progenitor cells.

Hepatic progenitor cells, capable of maturing into hepatocytes and biliary cells, are hypothesized to be involved in all forms of liver regeneration and may prove clinically useful at reconstituting damaged livers. A murine hepatic progenitor cell population from young adult liver tissue has been isolated and characterized to establish a model for the development of liver cell therapies and for analysis of immune responses after transplantation. Hepatic progenitor cells were isolated from 3- to 6-week-old C57BL/6 mice using modifications of a two-stage liver perfusion technique followed by low speed centrifugation.