title: The stem cell continuum.
abstract: Hematopoietic stem cells have been felt to exist in a hierarchical structure with a relatively fixed phenotype at each stage of differentiation. Recent studies on the phenotype of the marrow hematopoietic stem cell indicate that it is not a fixed entity, but rather that it fluctuates and shows marked heterogeneity. Past studies have shown that stem cell engraftment characteristics, adhesion protein, and gene expression varies with the phase of the cell cycle. More recently, we demonstrated that progenitor numbers and differentiation potential also vary reversibly during one cytokine-induced cell cycle transit. We have also shown high levels of conversion of marrow cells to skeletal muscle and lung cells, indicating a different level of plasticity. Recently, we demonstrated that homing to lung and conversion to lung cells in a mouse transplant model also fluctuates reversibly with cell cycle transit. This could be considered plasticity squared. These data indicate that marrow stem cells are regulated on a continuum related to the cell cycle both as to hematopoietic and to nonhematopoietic differentiation.
authors.affiliation: Department of Research and Head, Cancer Center, Roger Williams Medical Center, 825 Chalkstone Ave., Providence, RI 02908-4735, USA. pquesenberry@rwmc.org
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Quesenberry
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Colvin
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Abedi
authors.forename: Gerri
authors.initials: G
authors.lastname: Dooner
authors.forename: Mark
authors.initials: M
authors.lastname: Dooner
authors.forename: Jason
authors.initials: J
authors.lastname: Aliotta
authors.forename: Patrick
authors.initials: P
authors.lastname: Keaney
authors.forename: Luguang
authors.initials: L
authors.lastname: Luo
authors.forename: Delia
authors.initials: D
authors.lastname: Demers
authors.forename: Abigail
authors.initials: A
authors.lastname: Peterson
authors.forename: Bethany
authors.initials: B
authors.lastname: Foster
authors.forename: Deborah
authors.initials: D
authors.lastname: Greer
mesh_terms: D002453:Cell Cycle / Q000502:physiology; D006410:Hematopoiesis / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000502:physiology*