title: Flk-2 is a marker in hematopoietic stem cell differentiation: a simple method to isolate long-term stem cells.
abstract: Clonogenic multipotent mouse hematopoietic stem cells (HSCs) and progenitor cells are contained within the c-kit(+) (K) lineage(-/lo) (L) Sca-1(+) (S) population of hematopoietic cells; long-term (LT) and short-term (ST) HSCs are Thy-1.1(lo). c-kit is a member of the receptor tyrosine kinase family, a class of receptors that are important in the proliferation and differentiation of hematopoietic cells. To establish whether the Flk-2/Flt3 receptor tyrosine kinase was expressed on the most primitive LT-HSCs, we sorted highly purified multipotent stem and progenitor cells on the basis of Flk-2 surface expression and used them in competitive reconstitution assays. Low numbers of Flk-2(-) HSCs gave rise to long-term multilineage reconstitution in the majority of recipients, whereas the transfer of Flk-2(+) multipotent cells resulted in mostly short-term multilineage reconstitution. The KLS subset of adult mouse bone marrow was analyzed for Flk-2 and Thy-1.1 expression. Three phenotypically and functionally distinct populations were isolated: Thy(lo) Flk-2(-) (LT-HSCs), Thy(lo) Flk-2(+) (ST-HSCs), and Thy(-) Flk-2(+) multipotent progenitors. The loss of Thy-1.1 and gain of Flk-2 expression marks the loss of self-renewal in HSC maturation. The addition of Flk-2 antibody to the lineage mix allows direct isolation of LT-HSC from adult bone marrow as c-kit(+) lin(-) Sca-1(+) Flk-2(-) from many strains of mice. Fetal liver HSCs are contained within Flk-2(-) and Flk-2(+) KTLS cells.
authors.affiliation: Departments of Pathology and Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305-5324, USA. juliech@stanford.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Christensen
authors.forename: I L
authors.initials: IL
authors.lastname: Weissman
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism; D015415:Biomarkers; D002454:Cell Differentiation; D002469:Cell Separation / Q000379:methods*; D005333:Fetus / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D006410:Hematopoiesis; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D018800:Thy-1 Antigens / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D000950:Antigens, Ly; D015415:Biomarkers; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D018800:Thy-1 Antigens; C497971:Flt3 protein, mouse; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3