Fate tracing of mature hepatocytes in mouse liver homeostasis and regeneration
Yann Malato, … , Dirk Grimm, Holger Willenbring
Yann Malato, … , Dirk Grimm, Holger Willenbring
Published November 21, 2011
Citation Information: J Clin Invest. 2011;121(12):4850-4860. https://doi.org/10.1172/JCI59261.
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Research Article

Fate tracing of mature hepatocytes in mouse liver homeostasis and regeneration

Abstract

Recent evidence has contradicted the prevailing view that homeostasis and regeneration of the adult liver are mediated by self duplication of lineage-restricted hepatocytes and biliary epithelial cells. These new data suggest that liver progenitor cells do not function solely as a backup system in chronic liver injury; rather, they also produce hepatocytes after acute injury and are in fact the main source of new hepatocytes during normal hepatocyte turnover. In addition, other evidence suggests that hepatocytes are capable of lineage conversion, acting as precursors of biliary epithelial cells during biliary injury. To test these concepts, we generated a hepatocyte fate-tracing model based on timed and specific Cre recombinase expression and marker gene activation in all hepatocytes of adult Rosa26 reporter mice with an adenoassociated viral vector. We found that newly formed hepatocytes derived from preexisting hepatocytes in the normal liver and that liver progenitor cells contributed minimally to acute hepatocyte regeneration. Further, we found no evidence that biliary injury induced conversion of hepatocytes into biliary epithelial cells. These results therefore restore the previously prevailing paradigms of liver homeostasis and regeneration. In addition, our new vector system will be a valuable tool for timed, efficient, and specific loop out of floxed sequences in hepatocytes.

Authors

Yann Malato, Syed Naqvi, Nina Schürmann, Raymond Ng, Bruce Wang, Joan Zape, Mark A. Kay, Dirk Grimm, Holger Willenbring

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Figure 3

Hepatocyte-specific activation of EYFP expression in adult R26R-EYFP mice injected with AAV8-Ttr-Cre.

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Hepatocyte-specific activation of EYFP expression in adult R26R-EYFP mic...
Livers were coimmunostained for EYFP (red) and cell type–specific markers (green) 5 days after injection of 4 × 1011 viral genomes of AAV8-Ttr-Cre. Double-positive cells appear yellow. (A) All MUP-positive cells are also EYFP positive, which confirms that AAV8-Ttr-Cre loops out floxed sequences in all hepatocytes of adult mice. (B) In Alb-Cre, R26R-EYFP control mice, not only all hepatocytes, but also all CK19-positive biliary cells, express EYFP. (C) All cells positive for CK19 are EYFP negative, which shows that AAV8-Ttr-Cre does not loop out floxed sequences in biliary epithelial cells and liver progenitor cells. (D–F) All cells positive for F4/80 (D), desmin/α-SMA/GFAP (E), or isolectin B4 (“Lectin”) (F) are EYFP negative, which shows that AAV8-Ttr-Cre does not loop out floxed sequences in liver macrophages, stellate cells, or sinusoidal, portal vein, and central vein endothelial cells. Nuclei were stained with DAPI (blue). Original magnification, ×100, insets ×200 (A, C, and E); ×200, insets ×400 (B, D, and F). 20 liver sections from 4 mice were analyzed for each experiment.