Ablation of Foxl1-Cre–Labeled Hepatic Progenitor Cells and Their Descendants Impairs Recovery of Mice From Liver Injury

Abstract

BACKGROUND & AIMS Foxl1+ hepatic progenitor cells (HPCs) differentiate into cholangiocytes and hepatocytes following liver injury. We investigated the requirement for Foxl1+ HPCs in recovery from liver injury in mice. METHODS We developed mice in which we can trace and delete Foxl1-expressing HPCs and their descendants (Foxl1-Cre;RosaYFP/iDTR mice). Foxl1-Cre-negative mice were used as controls. Liver damage was induced in male mice by placing them on choline-deficient, ethionine-supplemented (CDE) diets for 15 days; mice were then placed on normal diets and allowed to recover. Liver damage was induced in female mice by placing them on 5-diethoxycarbonyl-1,4-dihydrocollidine-containing diets, followed by a recovery period. Some mice were given injections of diphtheria toxin mice during the recovery phase, to delete Foxl1-Cre–marked HPCs and their descendants. Livers were collected from all mice and analyzed by immunofluorescence, quantitative reverse transcription PCR, flow cytometry, and histologic analyses. RESULTS Foxl1-Cre-marked HPCs were required for development of cholangioctyes and hepatocytes in livers following CDE diet-induced injury. A smaller percentage of YFP+ hepatocytes contained markers of oxidative stress, DNA damage, or cell death than YFP-negative hepatocytes, indicating that YFP+ hepatocytes are newly formed cells. Injection of diphtheria toxin deleted YFP+ cells from Foxl1-Cre;RosaYFP/iDTR mice and prevented the resolution of hepatic steatosis. In mice recovering from dihydrocollidine-containing diet-induced injury, most cholangiocytes arose from Foxl1-Cre-marked HPCs. Deletion of YFP+ cells did not alter levels of markers of liver injury or liver function. CONCLUSIONS Based on studies of Foxl1-Cre;RosaYFP/iDTR mice, Foxl1+ HPCs and/or their descendants are required for development of cholangioctyes and hepatocytes in liver following CDE diet-induced injury.

Hepatocyte‐Specific β‐Catenin Deletion During Severe Liver Injury Provokes Cholangiocytes to Differentiate Into Hepatocytes

“…Excitingly, Hnf4α+/CK19+ cells have also been observed in a recent study demonstrating BEC‐derived hepatocytes during long‐term severe liver injury . Our results suggest that differentiation of BECs to hepatocytes is limited or impaired during ongoing injury and that a period of recovery is necessary to allow BEC differentiation to hepatocytes, as also shown elsewhere …”

The plastic liver: differentiated cells, stem cells, every cell?

“…Interestingly, Kordes et al observed that the proportion of cells engrafted following transplantation was dependent on the injury model used, suggesting that different progenitor sources drive regeneration in response to various types of injury, a theory consistent with other reports (7,18). If this is the case, it will be important to define the signals that activate each progenitor type in response to a specific injury.…”

Wnt/β-Catenin Signaling in Liver Development, Homeostasis, and Pathobiology

“…When hepatocyte proliferation in the rat was blocked through administration of 2-acetylaminofluorene (AAF) followed by PHx, there was a massive expansion of oval cells from the periportal region into the parenchyma, and these cells were shown to give rise to hepatocytes (142, 143). Several studies in mice with YFP labeling of LPCs have reported that 2–30% of hepatocytes were YFP-positive after a CDE diet–induced liver injury (140, 141, 144), with no detection of YFP-positive hepatocytes from other forms of liver injury, such as PHx or chronic toxic injury from carbon tetrachloride (CCl 4 ) (140). However, several reports have indicated that LPCs do not contribute to liver regeneration.…”