Triple Staining Including FOXA2 Identifies Stem Cell Lineages Undergoing Hepatic and Biliary Differentiation in Cirrhotic Human Liver

Abstract

SummaryRecent investigations have reported many markers associated with human liver stem/progenitor cells, "oval cells," and identified "niches" in diseased livers where stem cells occur. However, there has remained a need to identify entire lineages of stem cells as they differentiate into bile ducts or hepatocytes. We have used combined immunohistochemical staining for a marker of hepatic commitment and specification (FOXA2 [Forkhead box A2]), hepatocyte maturation (Albumin and HepPar1), and features of bile ducts (CK19 [cytokeratin 19]) to identify lineages of stem cells differentiating toward the hepatocytic or bile ductular compartments of end-stage cirrhotic human liver. We identified large clusters of disorganized, FOXA2 expressing, oval cells in localized liver regions surrounded by fibrotic matrix, designated as "micro-niches." Specific FOXA2-positive cells within the micro-niches organize into primitive duct structures that support both hepatocytic and bile ductular differentiation enabling identification of entire lineages of cells forming the two types of structures. We also detected expression of hsa-miR-122 in primitive ductular reactions expected for hepatocytic differentiation and hsa-miR23b cluster expression that drives liver cell fate decisions in cells undergoing lineage commitment. Our data establish the foundation for a mechanistic hypothesis on how stem cell lineages progress in specialized micro-niches in cirrhotic endstage liver disease. (J Histochem Cytochem 65:33-46, 2017)

Liver‐enriched transcription factor expression relates to chronic hepatic failure in humans

“…However, in liver samples from patients with Child-Pugh A, B, and C, a substantial number of hepatocytes became positive for FOXA2, supporting that reprogramming of biliary endothelial cells to hepatocytes or vice versa is also operative in human liver. (20,32) Our findings indicate that failure of the hepatic transcription system appears to be a pathologic finding in liver disease progression. These findings suggest that any correlation between chronic liver failure in cirrhosis in humans and HNF4a-dependent hepatic functions is not regulated at the level of HNF4a transcription but rather at the level of protein expression and/or nuclear localization.…”

“…For instance, protein expression of FOXA2 in biliary endothelial cells remained consistent in all liver samples examined in this study. However, in liver samples from patients with Child‐Pugh A, B, and C, a substantial number of hepatocytes became positive for FOXA2, supporting that reprogramming of biliary endothelial cells to hepatocytes or vice versa is also operative in human liver …”

mRNA-miRNA-lncRNA Regulatory Network in Nonalcoholic Fatty Liver Disease

“…Its members play important roles in regulating cellular proliferation [50] and differentiation [51][52][53]. As FOXA2 is expressed early during fetal liver development and not expressed in mature hepatocytes or bile duct cells, it might represent an excellent marker of early stage hepatic stem/progenitor cells, HPC [54]. Nobili et al [55] assessed the role of HPC in pediatric NAFLD comparing histologic specimens isolated from normal controls, fatty livers and NASH.…”

Transcriptional Control: A Directional Sign at the Crossroads of Adult Hepatic Progenitor Cells' Fates

“…Zhou et al revealed by NCAM, CK19, and HepPar1 staining that DR embedded in cirrhotic tissues had a distinct hepatocyte and biliary tract bipolar structure 41 . Charles et al used a multi-marker approach to detect FoxA2, HepPar1, albumin, CK19, and miRNA expression to track differentiation in the stem cell lineage during end-stage cirrhosis, indicating a bifurcation direction of HPCs differentiation 42 .…”