1998 Fiscal Year Final Research Report Summary
Characterization of the hematopoietic stem cell and search for the molecules responsible for stem cell self-renewal.
| Project/Area Number |
08407028
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hematology
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| Research Institution | University of Tsukuba |
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Principal Investigator |
NAKAUCHI Hiromitsu Univ.of Tsukuba, Inst.Of Basic Medical Sciences, Professor, 基礎医学系, 教授 (40175485)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHAMA Yousuke Univ.of Tsukuba, Inst.Of Basic Medical Sciences, Assistant Professor, 基礎医学系, 講師 (20183858)
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| Project Period (FY) |
1996 – 1998
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| Keywords | hematopoietic stem cell / CD34 / hematopoietic Progenitor cells / cell cycle / lineage commitment |
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| Research Abstract |
1) We have determinedthe phenotype of hematopoietic stem cells (HSC) and hematopoietic progenitor cells in adult mouse bone marrow. They were CD34^-c-Kit^+Sca-1^+ Lineage marker(Lin)^- and CD34^+ c-Kit^+Sca-1^+Lin^-, respectively. By combining these two populations, we have developeda sensitive stem cell assay nameda progenitor rescue assay. Using this assay, we were able to show a single HSC can reconstitute bone marrow of a lethally irradiated mouse for over 300 days.
2) In 6 week-old mice, CD34^-c-Kit^+ Sca-1^+Li^- HSC can be found at a frequency of 1 in 25000-20000 bone marrow cells. However, in older mice, both relative frequency and absolute number of HSC were increased significantly. HPP-CFU as well as long-term marrow repopulation assays also supported this finding.
3) Propidium iodide staining of the purified HSC revealedthat over 97% of them were in G0G1 phase. Long-termBrdU uptake experiment showed that over 70% of HSC take up BrdU within the first two weeks. These data indicate that majority of HSC contribute to hematopoiesis but they devide rather infrequently.
4) Paired-daughtercell experiment demonstratedthat commitment of HSC appear to be stochastic although among paired-daughtercolonies, cells of certain lineages appeared significantly higher incidence suggesting non-randomfashion of the lineage commitment.
5) We happenedto find out that mouse HSC are CD34-low/negative. It is thereforecritically important to examine if there are CD34-low/negative HSC in human. Establishment of a solid assay system for humanHSC is necessary.
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