title: Role of transcription factor CCAAT/enhancer-binding protein alpha in human fetal liver cell types in vitro.
abstract: OBJECTIVE
  The transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) has been shown to play an important role in liver development, cell proliferation and differentiation. It is, however, largely unknown if C/EBPα regulates cell differentiation and proliferation differently in the diverse cell types of the human liver. We investigated the role of C/EBPα in primary human fetal liver cells and liver cell subpopulations in vitro using a 3-D perfusion bioreactor as an advanced in vivo-like human organ culture model.
  
  
  METHODS
  Human fetal liver cells were investigated in vitro. C/EBPα gene expression was knocked down using siRNA or overexpressed by plasmid transfection. Cell type-specific gene expression was studied, cell populations and their proliferation were investigated, and metabolic parameters were analyzed.
  
  
  RESULTS
  When C/EBPα gene expression was knocked down, we observed a significantly reduced expression of typical endothelial, hematopoietic and mesenchymal genes such as CD31, vWF, CD90, CD45 and α-smooth muscle actin in fetal cells. The intracellular expression of hepatic proteins and genes for liver-specific serum proteins α-fetoprotein and albumin were reduced, their protein secretion was increased. Fetal endothelial cell numbers were reduced and hepatoblast numbers were increased. C/EBPα overexpression in fetal cells resulted in increased endothelial numbers, but did not affect mesenchymal cell types or hepatoblasts.
  
  
  CONCLUSIONS
  We demonstrated that the effects of C/EBPα are specific for the different human fetal liver cell types, using an advanced 3-D perfusion bioreactor as a human in vivo-like model.
authors.affiliation: Department of Surgery and Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Jörg C
authors.initials: JC
authors.lastname: Gerlach
authors.affiliation: Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Patrick
authors.initials: P
authors.lastname: Over
authors.affiliation: University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
authors.forename: Hubert G
authors.initials: HG
authors.lastname: Foka
authors.affiliation: University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
authors.forename: Morris E
authors.initials: ME
authors.lastname: Turner
authors.affiliation: University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Thompson
authors.affiliation: Department of Surgery, ISMETT - Mediterranean Institute for Transplantation and Advanced Specialized Therapies, Palermo, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Gridelli
authors.affiliation: Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Schmelzer
keywords: CCAAT/enhancer-binding protein alpha; bioreactor; hepatoblast; hepatocyte; liver