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

Background & AimsFoxl1+ hepatic progenitor cells (HPCs) differentiate into cholangiocytes and hepatocytes after liver injury. We investigated the requirement for Foxl1+ HPCs in recovery from liver injury in mice.MethodsWe developed mice in which we could trace and delete Foxl1-expressing HPCs and their descendants (Foxl1-Cre;RosaYFP/iDTR-inducible diphtheria toxin receptor [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 then were placed on normal diets and allowed to recover. Liver damage was induced in female mice by placing them on 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)–containing diets, followed by a recovery period. Some mice were given injections of diphtheria toxin 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 polymerase chain reaction, flow cytometry, and histologic analyses.ResultsFoxl1-Cre–marked HPCs were required for the development of cholangiocytes and hepatocytes in livers after CDE diet-induced injury. A smaller percentage of yellow fluorescent protein–positive (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 DDC 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.ConclusionsBased on studies of Foxl1-Cre;RosaYFP/iDTR mice, Foxl1+ HPCs and/or their descendants are required for the development of cholangiocytes and hepatocytes in liver after CDE diet-induced injury. Foxl1+ hepatic progenitor cells (HPCs) differentiate into cholangiocytes and hepatocytes after liver injury. We investigated the requirement for Foxl1+ HPCs in recovery from liver injury in mice. We developed mice in which we could trace and delete Foxl1-expressing HPCs and their descendants (Foxl1-Cre;RosaYFP/iDTR-inducible diphtheria toxin receptor [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 then were placed on normal diets and allowed to recover. Liver damage was induced in female mice by placing them on 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)–containing diets, followed by a recovery period. Some mice were given injections of diphtheria toxin 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 polymerase chain reaction, flow cytometry, and histologic analyses. Foxl1-Cre–marked HPCs were required for the development of cholangiocytes and hepatocytes in livers after CDE diet-induced injury. A smaller percentage of yellow fluorescent protein–positive (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 DDC 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. Based on studies of Foxl1-Cre;RosaYFP/iDTR mice, Foxl1+ HPCs and/or their descendants are required for the development of cholangiocytes and hepatocytes in liver after CDE diet-induced injury.