title: Enrichment and clonal culture of progenitor cells during mouse postnatal liver development in mice.
abstract: OBJECTIVE
  Stem and progenitor cells exist in normal postnatal livers. However, it has not been possible to clonally isolate or analyze postnatal liver stem/progenitor-like cells (PLSCs) derived from noninjured livers because of a lack of specific surface markers. This study aimed to establish a primary culture system for clone-sorted PLSCs.
  
  
  METHODS
  To investigate proliferation and differentiation of PLSCs, subpopulations of nonparenchymal cells derived from noninjured livers were purified and cultured using a single-cell culture system. Cells were grown in fetal liver cell-derived conditioned medium in the presence of the Rho-associated kinase (ROCK) inhibitor Y-27632.
  
  
  RESULTS
  We identified CD13 and CD133 as markers expressed on the PLSC-containing population in noninjured livers and established an efficient single-cell culture system to clonally analyze PLSCs. Culture of PLSCs is difficult, even using conditioned medium, but the addition of Y-27632 increased PLSC cell proliferation. The proportion of progenitor cells among nonparenchymal cells decreased during postnatal liver development; however, a PLSC population was still preserved in 3-month-old mice. Long-term cultivated cells derived from clone-sorted cells in normal livers were established and were called normal-liver-derived stem-like cells (NLS cells). NLS cells could differentiate into hepatocyte-like and cholangiocyte-like cells under appropriate culture conditions and underwent self-renewal-like activity in serial reclone-sorted culture. CD13 and CD133 were expressed on progenitor cells derived from fetal and postnatal liver, whereas CD49f (integrin alpha6 subunit) was strongly expressed only on PLSCs.
  
  
  CONCLUSIONS
  These results demonstrate the presence of progenitor cells in the CD13(+)CD49f(+)CD133(+) subpopulation of nonhematopoietic cells derived from noninjured postnatal livers.
authors.affiliation: Division of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, Institute of Medical Science, University of Tokyo, Tokyo, Japan. kamiyaa@ims.u-tokyo.ac.jp
authors.forename: Akihide
authors.initials: A
authors.lastname: Kamiya
authors.forename: Sei
authors.initials: S
authors.lastname: Kakinuma
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Nakauchi
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D002999:Clone Cells; D003114:Colony-Forming Units Assay; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022781:Hepatocytes / Q000145:classification / Q000166:cytology; D008099:Liver / Q000166:cytology* / Q000196:embryology / Q000254:growth & development; D051379:Mice; D008819:Mice, Nude; D010641:Phenotype; D011725:Pyridines / Q000494:pharmacology; D013234:Stem Cells / Q000166:cytology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors
chemical_list: D000577:Amides; D000954:Antigens, Surface; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D011725:Pyridines; C108830:Y 27632; D054460:rho-Associated Kinases