Successful isolation of liver progenitor cells by aldehyde dehydrogenase activity from naïve mice.

The role of progenitor cells in liver repair and fibrosis has been extensively described but their purification remains challenging, hampering their characterization and use in regenerative medicine. To address this issue, we developed an easy and reproducible liver progenitor cell (LPC) isolation strategy based on aldehyde dehydrogenase (ALDH) activity, a common feature shared by many progenitor cells. We demonstrate that a subset of non-parenchymal mouse liver cells displays high levels of ALDH activity, enabling the isolation of these cells by fluorescence activated cell sorting. Immunocytochemistry and qPCR analyses on freshly isolated ALDH(+) cells reveal an enrichment in cells expressing liver stem-cell markers such as EpCAM, CK19, CD133 and Sox9. In culture, the ALDH(+) population can give rise to functional hepatocyte-like cells as illustrated by albumin and urea secretion and cytochrome P450 activity. ALDH1A1 expression can be detected in canals of Hering and bile duct epithelial cells and is increased upon liver injury. Finally, we could show that the isolation and differentiation towards hepatocyte-like cells of LPCs with high ALDH activity is also successfully applicable to human liver samples. (HEPATOLOGY 2011.) CONCLUSIONS: High ALDH activity is a feature of LPCs that can be taken advantage of to isolate these cells from untreated mouse as well as from human liver tissues. This novel protocol is practically relevant, as it provides an easy and non-toxic method to isolate liver stem cells from normal tissue for potential therapeutic purposes.