title: A comparison of long-term repopulating hematopoietic stem cells in fetal liver and adult bone marrow from the mouse.
abstract: Previous studies have shown that stem cells able to competitively reconstitute the hematopoietic system of lethally irradiated mice (competitive repopulating units [CRU]) can be obtained in highly purified form from adult mouse bone marrow (BM) by the isolation of cells with a Sca-1+Lin-WGA+ phenotype. We now report on the phenotypic characteristics of CRU from day-14.5 murine fetal liver (FL). Our results confirm previous reports of similarities between the two CRU populations but also reveal a few striking differences. Both were found to express the Sca-1 antigen (SCA-1+ and surface molecules that bind wheat germ agglutinin (WGA+), and both show an absence or low expression of a number of markers characteristic of mature hematopoietic cells: B220, Gr-1,ly-1 and Ter119 (together termed Lin*-). Limiting dilution analysis of recipients transplanted with purified Sca-1+Lin*- FL cells with intermediate forward- and side-scatter properties showed that the frequency of CRU in this FL subpopulation was one in 39 cells. This represents an enrichment of approximately 450-fold over the labeled but unseparated FL starting population (one in 17,300 total FL cells). These FL CRU also resembled their counterparts in adult BM in that they expressed high levels of MHC class I and CD43 and intermediate levels of heat-stable antigen (HSA) and c-kit and did not express, or expressed at a low level, Thy-1.2, CD71, and the antigen recognized by the Fall-3 monoclonal antibody (mAb). In contrast, a high percentage of the Sca-1+Lin*- cells isolated from 14.5-day-old FL stained with the AA4.1, anti-Mac-1, and the anti-CD45RB mAbs and retained Rhodamine 123 (Rh123(bright)), whereas the Sca-1+Lin-WGA+ CRU-containing fraction of adult BM cells was found to be AA4.1-, Mac-1-, CD45RB-, and Rh123(dull). These differences in phenotype between CRU in FL and adult BM indicate changes that occur during ontogeny in cells that are similar with respect to their totipotentiality and long-term repopulating potential and complement parallel observations of functional differences between these two populations of CRU.
authors.affiliation: Terry Fox Laboratory, BC Cancer Agency, University of British Columbia, Vancouver, Canada.
authors.forename: V I
authors.initials: VI
authors.lastname: Rebel
authors.forename: C L
authors.initials: CL
authors.lastname: Miller
authors.forename: G R
authors.initials: GR
authors.lastname: Thornbury
authors.forename: W H
authors.initials: WH
authors.lastname: Dragowska
authors.forename: C J
authors.initials: CJ
authors.lastname: Eaves
authors.forename: P M
authors.initials: PM
authors.lastname: Lansdorp
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D000950:Antigens, Ly / Q000032:analysis; D001854:Bone Marrow Cells; D002469:Cell Separation; D006183:H-2 Antigens / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D016130:Immunophenotyping; D008099:Liver / Q000196:embryology*; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D011990:Receptors, Transferrin; D014909:Wheat Germ Agglutinins
chemical_list: D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000950:Antigens, Ly; C068126:CD71 antigen; D006183:H-2 Antigens; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D011990:Receptors, Transferrin; D014909:Wheat Germ Agglutinins