Relative number and proliferation kinetics of hemopoietic stem cells in the mouse.
A model calculation of the hemopoiesis of the mouse based on known hematologic data leads to the conclusion that approximately 3% of all nucleated bone marrow cells are stem cells (pluripotent plus committed stem cells). By a new 125IUdR labeling technique on radiation chimeras, a relative number of 2%-7% stem cells was determined. In previous studies with test systems for stem cells using colony formation in vivo or in vitro, a relative number of stem cells of at least one order of magnitude lower has been estimated. In this study the stem cells are found to have a turnover time of about 4.3 days in the donor mice. This turnover time remained unchanged even after transfusion of marrow cells into lethally irradiated recipient mice. Radiosensitivity determinations yielded a D0 of 80 rad for stem cells in S-phase and D0 of 185 rad for stem cells distributed throughout the entire cell cycle. The respective extrapolation numbers were 1.23 and 1.14. Experiments using an 3H-TdR suicide technique revealed different cell cycle parameters for bone marrow stem cells seeding to the spleens and to the femurs of lethally irradiated recipients, primarily a shortening of S-phase in cells seeding to femurs. The method described here provides a new approach to hematologic stem cell research.
D000818:Animals; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D002452:Cell Count; D002455:Cell Division; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D007700:Kinetics; D008433:Mathematics; D051379:Mice; D008954:Models, Biological