title: Stimulation of in vitro hematopoiesis by a murine fetal hepatocyte clone through cell-cell contact.
abstract: We have previously shown that a fetal liver-derived epithelial cell clone, FHC-4D2, could support hematopoiesis in vitro through its colony-stimulating factor (CSF) activities in a short-term culture. In this study, since FHC-4D2 cells were found capable of maintaining hematopoietic progenitors in the coculture for a long time, we examined how FHC-4D2 could exert hematopoietic supporting activity in a long-term culture by coculturing adult bone marrow (BM) cells or fetal liver (FL) cells on a monolayer of FHC-4D2 cells. This clone could maintain the colony-forming unit of granulocytes and macrophages (CFU-GM) of BM for > or = 12 weeks under the coculture condition, but the fibroblastic cell clone from the fetal liver, FHC-4A3, could not support the survival of CFU-GM, even for 1 week. In addition to BM CFU-GM, the FHC-4D2 clone also supported the survival of FL CFU-GM, burst-forming unit of erythroid cells (BFUe), and colony-forming unit of mixed progenitors (CFU-Mix) for longer than 4 weeks. When BM cells were separated by a membrane filter from the FHC-4D2 cells in the coculture, the comparable number of CFU-GM was maintained at day 3, but virtually no hematopoietic progenitors were detected at the end of the first week. CFU-GM were present in both nonadherent and adherent cells to the FHC-4D2 cells at day 3 of the coculture, but at day 7, the adherent population contained greater number of CFU-GM. CFU-GM derived from the adherent cells formed larger colonies and contained more bipotential CFU-GM than the nonadherent population. When BM cells from mice given 5-fluorouracil were cocultured with FHC-4D2 cells under the limiting dilution condition, interleukin-3 (IL-3)-responsive CFU-GM were induced from immature hematopoietic progenitor cells that were otherwise unresponsive to IL-3. From these data we conclude that the FHC-4D2 clone could generate and maintain IL-3-responsive hematopoietic progenitors via close contact and that, in the fetal liver, the contact between hepatocytes and hematopoietic cells may be critically important in inducing the differentiation of resting, IL-3-unresponsive immature hematopoietic cells into CFU-GM (progenitors responsive to IL-3) and in triggering the self-renewal of CFU-GM.
authors.affiliation: Yakult Central Institute for Microbiological Research, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nanno
authors.forename: M
authors.initials: M
authors.lastname: Hata
authors.forename: H
authors.initials: H
authors.lastname: Doi
authors.forename: S
authors.initials: S
authors.lastname: Satomi
authors.forename: H
authors.initials: H
authors.lastname: Yagi
authors.forename: T
authors.initials: T
authors.lastname: Sakata
authors.forename: R
authors.initials: R
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Itoh
mesh_terms: D000818:Animals; D002450:Cell Communication; D002999:Clone Cells; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology*; D006410:Hematopoiesis / Q000502:physiology*; D008099:Liver / Q000196:embryology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains