title: Transplantable hematopoietic stem cells in human fetal liver have a CD34(+) side population (SP)phenotype.
abstract: Cells with a verapamil-sensitive ability to efflux Hoechst 33342 (termed side population [SP] cells) have been identified in adult marrow from several species including humans and in several tissues from adult mice. In mice, the SP phenotype appears to be a common feature of stem cells, but human SP cells have been less well characterized. We show here, for the first time to our knowledge, that SP cells are present in the second-trimester human fetal liver. They include all of the transplantable human hematopoietic stem cell activity detectable in NOD/SCID mice and also certain other, more differentiated hematopoietic cell types. Notably, the stem cell activity was confined to the CD34(+)CD38(-) SP(+) population, and isolation of these cells gave an approximately tenfold enrichment of transplantable stem cells. This subset was not, however, coenriched in hematopoietic progenitors detectable by either short- or long-term in vitro assays, indicating most of these to be distinct from transplantable stem cells. These findings suggest that the SP phenotype is an important and distinguishing property of human hematopoietic stem cells and that early in ontogeny they express CD34.
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and Department of Medical Genetics, Medicine and Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Uchida
authors.forename: T
authors.initials: T
authors.lastname: Fujisaki
authors.forename: A C
authors.initials: AC
authors.lastname: Eaves
authors.forename: C J
authors.initials: CJ
authors.lastname: Eaves
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000818:Animals; D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D015415:Biomarkers; D002469:Cell Separation; D002478:Cells, Cultured; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000276:immunology*; D022781:Hepatocytes / Q000145:classification / Q000166:cytology / Q000276:immunology; D006801:Humans; D016130:Immunophenotyping; D008099:Liver / Q000166:cytology* / Q000196:embryology*; D008562:Membrane Glycoproteins; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009244:NAD+ Nucleosidase
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D015415:Biomarkers; D008562:Membrane Glycoproteins; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; C498155:Cd38 protein, mouse; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1