Searching for hematopoietic stem cells: evidence that Thy-1.1lo Lin- Sca-1+ cells are the only stem cells in C57BL/Ka-Thy-1.1 bone marrow.
Hematopoietic stem cells (HSCs) are defined in mice by three activities: they must rescue lethally irradiated mice (radioprotection), they must self-renew, and they must restore all blood cell lineages permanently. We initially demonstrated that HSCs were contained in a rare (approximately 0.05%) subset of bone marrow cells with the following surface marker profile: Thy-1.1lo Lin- Sca-1+. These cells were capable of long-term, multi-lineage reconstitution and radioprotection of lethally irradiated mice with an enrichment that mirrors their representation in bone marrow, namely, 1,000-2,000-fold. However, the experiments reported did not exclude the possibility that stem cell activity may also reside in populations that are Thy-1.1-, Sca-1-, or Lin+. In this article stem cell activity was determined by measuring: (a) radioprotection provided by sorted cells; (b) long-term, multi-lineage reconstitution of these surviving mice; and (c) long-term, multi-lineage reconstitution by donor cells when radioprotection is provided by coinjection of congenic host bone marrow cells. Here we demonstrate that HSC activity was detected in Thy-1.1+, Sca-1+, and Lin- fractions, but not Thy-1.1-, Sca-1-, or Lin+ bone marrow cells. We conclude that Thy-1.1lo Lin- Sca-1+ cells comprise the only adult C57BL/Ka-Thy-1.1 mouse bone marrow subset that contains pluripotent HSCs.
Howard Hughes Medical Institute, Department of Pathology, Stanford University School of Medicine, California 94305.
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Uchida
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Weissman
D000818:Animals; D000941:Antigens / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis*; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D002469:Cell Separation; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D018800:Thy-1 Antigens
D000941:Antigens; D000954:Antigens, Surface; D018800:Thy-1 Antigens