title: Thy1-positive mesenchymal cells promote the maturation of CD49f-positive hepatic progenitor cells in the mouse fetal liver.
abstract: Previously, we reported a system to enrich mouse fetal hepatic progenitor cells (HPCs) by forming cell aggregates. In this study, we sorted two cell populations, CD49f(+)Thy1(-)CD45(-) cells (CD49f-positive cells) and CD49f(+/-)Thy1(+)CD45(-) cells (Thy1-positive cells), from the cell aggregates using a flow cytometer. CD49f-positive cells stained positive for endodermal specific markers such as alpha-fetoprotein (AFP), albumin (ALB), and cytokeratin 19 (CK19), and are thus thought to be HPCs. However, Thy1-positive cells were a morphologically heterogeneous population; reverse-transcription polymerase chain reaction (RT-PCR) and immunocytochemical analyses revealed the expression of mesenchymal cell markers such as alpha-smooth muscle actin, desmin, and vimentin, but not of AFP, ALB, or CK19. Therefore, Thy1-positive cells were thought to be of a mesenchymal lineage. When these two cell populations were co-cultured, the CD49f-positive colonies matured morphologically and stored a significant amount of glycogen. Furthermore, real-time RT-PCR demonstrated an increased expression of tyrosine amino transferase and tryptophan oxygenase mRNA, and transmission electron microscopy confirmed that co-cultured cells produced mature hepatocytes. However, when CD49f-positive cells were cultured alone or when the two populations were cultured separately, the CD49f-positive cells did not mature. These results indicate that CD49f-positive cells are primitive hepatic endodermal cells with the capacity to differentiate into hepatocytes, and that Thy1-positive cells promote the maturation of CD49f-positive cells by direct cell-to-cell contact. In conclusion, we were able to isolate CD49f-positive primitive hepatic endodermal cells and Thy1-positive mesenchymal cells and to demonstrate the requirement of cell-to-cell contact between these cell types for the maturation of the hepatic precursors.
authors.affiliation: Department of Gastroenterological Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Hoppo
authors.forename: Hideaki
authors.initials: H
authors.lastname: Fujii
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Hirose
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yasuchika
authors.forename: Hisaya
authors.initials: H
authors.lastname: Azuma
authors.forename: Shinji
authors.initials: S
authors.lastname: Baba
authors.forename: Masato
authors.initials: M
authors.lastname: Naito
authors.forename: Takafumi
authors.initials: T
authors.lastname: Machimoto
authors.forename: Iwao
authors.initials: I
authors.lastname: Ikai
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D022781:Hepatocytes / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D039503:Integrin alpha6 / Q000378:metabolism*; D008099:Liver / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D011247:Pregnancy; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D018800:Thy-1 Antigens / Q000378:metabolism*
chemical_list: D039503:Integrin alpha6; D018800:Thy-1 Antigens