Publications (3)18.87 Total impact

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    ABSTRACT: The identification of human CD34-negative (CD34(-)) hematopoietic stem cells (HSCs) provides a new concept for the hierarchy in the human HSC compartment. This study investigated the long-term repopulating capacity and redistribution kinetics of human cord blood-derived CD34(-) severe combined immunodeficiency (SCID)-repopulating cells (SRCs) and compared them with those of CD34(+)CD38(+) and CD34(+)CD38(-) SRCs using the intra-bone marrow injection (IBMI) to clarify the characteristics of CD34(-) SRCs. On the basis of the limiting dilution analyses data, estimated numbers of CD34(+)CD38(+), CD34(+)CD38(-), and CD34(-) SRCs were transplanted to NOD/SCID mice by IBMI. The human cell repopulation at the site of injection and the other bones were serially investigated. Interestingly, CD34(+)CD38(+), CD34(+)CD38(-), and CD34(-) SRCs began to migrate to other bones 2 and 5 weeks after the transplantation, respectively. Accordingly, the initiation of migration seemed to differ between the CD34(+) and CD34(-) SRCs. In addition, CD34(+)CD38(+) SRCs only sustained a short-term repopulation. However, both CD34(+)CD38(-) and CD34(-) SRCs had longer-term repopulation capacity. Taken together, these findings showed that CD34(-) SRCs show different in vivo kinetics, thus suggesting that the identified CD34(-) SRCs are a distinct class of primitive HSCs in comparison to the CD34(+)CD38(+) and CD34(+)CD38(-) SRCs.
    No preview · Article · Oct 2009 · Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K
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    ABSTRACT: Recently, we have identified human cord blood (CB)-derived CD34-negative (CD34(-)) severe combined immunodeficiency (SCID)-repopulating cells (SRCs) using the intra-bone marrow injection (IBMI) method (Blood 2003;101:2924). In contrast to murine CD34(-) Kit(+)Sca-1(+)Lineage(-) (KSL) cells, human CB-derived Lin(-)CD34(-) cells did not express detectable levels of c-kit by flow cytometry. In this study, we have investigated the function of flt3 in our identified human CB-derived CD34(-) SRCs. Both CD34(+)flt3(+/-) cells showed SRC activity. In the CD34(-) cell fraction, only CD34(-)flt3(-) cells showed distinct SRC activity by IBMI. Although CD34(+)flt3(+) cells showed a rather weak secondary repopulating activity, CD34(+)flt3(-) cells repopulated many more secondary recipient mice. However, CD34(-)flt3(-) cells repopulated all of the secondary recipients, and the repopulating rate was much higher. Next, we cocultured CD34(-)flt3(-) cells with the murine stromal cell line HESS-5. After 1 week, significant numbers of CD34(+)flt3(+/-) cells were generated, and they showed distinct SRC activity. These results indicated that CB-derived CD34(-)flt3(-) cells produced CD34(+)flt3(-) as well as CD34(+)flt3(+) SRCs in vitro. The present study has demonstrated for the first time that CB-derived CD34(-) SRCs, like murine CD34(-) KSL cells, do not express flt3. On the basis of these data, we propose that the immunophenotype of very primitive long-term repopulating human hematopoietic stem cells is Lin(-)CD34(-)c-kit(-)flt3(-). Disclosure of potential conflicts of interest is found at the end of this article.
    Preview · Article · Jul 2007 · Stem Cells
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    ABSTRACT: Using the intra-bone marrow injection (IBMI) technique, we recently identified human cord blood-derived CD34- severe combined immunodeficiency (SCID)-repopulating cells (SRCs) with extensive lymphomyeloid reconstituting ability. In this study, we further investigated the hematopoietic stem cell (HSC) characteristics of these cells in terms of proliferative and migratory potentials. The absolute numbers of CD45+ and CD34+ cells generated by 1 CD34- SRC are significantly higher than those generated by 1 CD34+ SRC. It is interesting that CD34- SRCs have significantly higher migratory and proliferative abilities than CD34+ SRCs. Moreover, only 2 CD34- SRCs transplanted to primary recipients consistently showed secondary reconstituting capacity. This finding suggested the more homogenous nature of CD34- SRCs than that of the population of CD34+ SRCs. These results provided further evidence that CD34- SRCs are functionally different from CD34+ SRCs and that they are a distinct class of primitive HSCs.
    No preview · Article · Jun 2004 · International Journal of Hematology