title: Hepatic progenitor cells in human fetal liver express the oval cell marker Thy-1.
abstract: Hepatic progenitor cells play a major role in regenerating diseased liver. In rodents, progenitors forming hepatocytes or cholangiocytes are identified by the stem cell marker Thy-1. The aim of this study was to ascertain whether progenitor cells expressing Thy-1 could be identified in human fetal liver. Midtrimester human fetal liver was immunostained for Thy-1, cytokeratins 18 and 19, vimentin, CD34, CD45, and fibrinogen. Thy-1+ and Thy-1+CD34+ populations were purified using fluorescence-activated cell sorting (FACS). Immunofluorescence and mRNA expression were used to examine the bipotential nature of purified stem cells. We found that Thy-1+ cells were concentrated in portal tracts but were also scattered in parenchyma. In FACS-prepared cells, 0.18-3.08% (median 0.65%, n = 14) of cells were Thy-1+. Immunophenotyping revealed that some Thy-1+ cells coexpressed cytokeratins 18 and 19, others, fibrinogen and cytokeratin 19. RT-PCR demonstrated that Thy-1+ cells expressed mRNA for Thy-1, cytokeratin 18, and cytokeratin 19, and Thy-1+CD34+ cells expressed mRNA for alpha-fetoprotein, transferrin, and hepatocyte nuclear factor-4alpha. Thy-1+ cells were identified in fetal liver. These cells expressed several lineage markers, including coexpression of biliary and hepatocellular proteins and mRNA. These data suggest that Thy-1 is a marker of liver stem cells in human fetal liver.
authors.affiliation: Tissue Injury and Repair Group, Department of Clinical and Surgical Sciences (Surgery), University of Edinburgh Medical School, Edinburgh, EH16 4SB, UK. n.m.masson@btinternet.com
authors.forename: Neil M
authors.initials: NM
authors.lastname: Masson
authors.forename: Ian S
authors.initials: IS
authors.lastname: Currie
authors.forename: John D
authors.initials: JD
authors.lastname: Terrace
authors.forename: O James
authors.initials: OJ
authors.lastname: Garden
authors.forename: Rowan W
authors.initials: RW
authors.lastname: Parks
authors.forename: James A
authors.initials: JA
authors.lastname: Ross
mesh_terms: D002454:Cell Differentiation; D002478:Cells, Cultured; D022781:Hepatocytes / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D018800:Thy-1 Antigens / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D018800:Thy-1 Antigens