title: Characterisation of a stereotypical cellular and extracellular adult liver progenitor cell niche in rodents and diseased human liver.
abstract: BACKGROUND
  Stem/progenitor cell niches in tissues regulate stem/progenitor cell differentiation and proliferation through local signalling.
  
  
  OBJECTIVE
  To examine the composition and formation of stem progenitor cell niches.
  
  
  METHODS
  The composition of the hepatic progenitor cell niche in independent models of liver injury and hepatic progenitor cell activation in rodents and humans was studied. To identify the origin of the progenitor and niche cells, sex-mismatched bone marrow transplants in mice, who had received the choline-ethionine-deficient-diet to induce liver injury and progenitor cell activation, were used. The matrix surrounding the progenitor cells was described by immunohistochemical staining and its functional role controlling progenitor cell behaviour was studied in cell culture experiments using different matrix layers.
  
  
  RESULTS
  The progenitor cell response in liver injury is intimately surrounded by myofibroblasts and macrophages, and to a lesser extent by endothelial cells. Hepatic progenitor cells are not of bone marrow origin; however, bone marrow-derived cells associate intimately with these cells and are macrophages. Laminin always surrounds the progenitor cells. In vitro studies showed that laminin aids maintenance of progenitor and biliary cell phenotype and promotes their gene expression (Dlk1, Aquaporin 1, gammaGT) while inhibiting hepatocyte differentiation and gene expression (CEPB/alpha).
  
  
  CONCLUSIONS
  During liver damage in rodents and humans a stereotypical cellular and laminin niche forms around hepatic progenitor cells. Laminin helps maintenance of undifferentiated progenitor cells. The niche links the intrahepatic progenitor cells with bone marrow-derived cells and links tissue damage with progenitor cell-mediated tissue repair.
authors.affiliation: MRC/University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh, UK.
authors.forename: Stefania
authors.initials: S
authors.lastname: Lorenzini
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Bird
authors.forename: Luke
authors.initials: L
authors.lastname: Boulter
authors.forename: Christopher
authors.initials: C
authors.lastname: Bellamy
authors.forename: Kay
authors.initials: K
authors.lastname: Samuel
authors.forename: Rebecca
authors.initials: R
authors.lastname: Aucott
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Clayton
authors.forename: Pietro
authors.initials: P
authors.lastname: Andreone
authors.forename: Mauro
authors.initials: M
authors.lastname: Bernardi
authors.forename: Mathew
authors.initials: M
authors.lastname: Golding
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Alison
authors.forename: John P
authors.initials: JP
authors.lastname: Iredale
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Forbes
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000473:pathology; D005109:Extracellular Matrix / Q000502:physiology; D005260:Female; D019698:Hepatitis C, Chronic / Q000473:pathology; D022781:Hepatocytes / Q000473:pathology*; D006801:Humans; D007797:Laminin / Q000032:analysis / Q000502:physiology; D008099:Liver / Q000737:chemistry; D008107:Liver Diseases / Q000378:metabolism / Q000473:pathology*; D008115:Liver Regeneration / Q000502:physiology; D008264:Macrophages / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D058628:Myofibroblasts / Q000473:pathology; D010641:Phenotype; D051381:Rats; D011916:Rats, Inbred F344; D012008:Recurrence; D013234:Stem Cells / Q000473:pathology*
chemical_list: D007797:Laminin