title: Stepwise development of hematopoietic stem cells from embryonic stem cells.
abstract: The cellular ontogeny of hematopoietic stem cells (HSCs) remains poorly understood because their isolation from and their identification in early developing small embryos are difficult. We attempted to dissect early developmental stages of HSCs using an in vitro mouse embryonic stem cell (ESC) differentiation system combined with inducible HOXB4 expression. Here we report the identification of pre-HSCs and an embryonic type of HSCs (embryonic HSCs) as intermediate cells between ESCs and HSCs. Both pre-HSCs and embryonic HSCs were isolated by their c-Kit(+)CD41(+)CD45(-) phenotype. Pre-HSCs did not engraft in irradiated adult mice. After co-culture with OP9 stromal cells and conditional expression of HOXB4, pre-HSCs gave rise to embryonic HSCs capable of engraftment and long-term reconstitution in irradiated adult mice. Blast colony assays revealed that most hemangioblast activity was detected apart from the pre-HSC population, implying the early divergence of pre-HSCs from hemangioblasts. Gene expression profiling suggests that a particular set of transcripts closely associated with adult HSCs is involved in the transition of pre-HSC to embryonic HSCs. We propose an HSC developmental model in which pre-HSCs and embryonic HSCs sequentially give rise to adult types of HSCs in a stepwise manner.
authors.affiliation: Division of Stem Cell Therapy, Center for Stem Cell and Regenerative Medicine, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Takayuki
authors.initials: T
authors.lastname: Isagawa
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Nishimura
authors.forename: Takunori
authors.initials: T
authors.lastname: Ogaeri
authors.forename: Koji
authors.initials: K
authors.lastname: Eto
authors.forename: Satsuki
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Miyazaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Aburatani
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Nakauchi
authors.forename: Hideo
authors.initials: H
authors.lastname: Ema
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D053595:Embryonic Stem Cells / Q000166:cytology*; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D051379:Mice; D020133:Reverse Transcriptase Polymerase Chain Reaction