title: The bone marrow stem cell niche grows up: mesenchymal stem cells and macrophages move in.
abstract: Stem cell niches are defined as the cellular and molecular microenvironments that regulate stem cell function together with stem cell autonomous mechanisms. This includes control of the balance between quiescence, self-renewal, and differentiation, as well as the engagement of specific programs in response to stress. In mammals, the best understood niche is that harboring bone marrow hematopoietic stem cells (HSCs). Recent studies have expanded the number of cell types contributing to the HSC niche. Perivascular mesenchymal stem cells and macrophages now join the previously identified sinusoidal endothelial cells, sympathetic nerve fibers, and cells of the osteoblastic lineage to form similar, but distinct, niches that harbor dormant and self-renewing HSCs during homeostasis and mediate stem cell mobilization in response to granulocyte colony-stimulating factor.
authors.affiliation: Division of Stem Cells and Cancer, German Cancer Research Center, D-69120 Heidelberg, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Ehninger
authors.forename: Andreas
authors.initials: A
authors.lastname: Trumpp
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000254:growth & development* / Q000502:physiology; D016179:Granulocyte Colony-Stimulating Factor / Q000502:physiology; D006801:Humans; D008264:Macrophages / Q000502:physiology*; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D009000:Monocytes / Q000502:physiology; D055153:Stem Cell Niche / Q000166:cytology* / Q000502:physiology
chemical_list: D016179:Granulocyte Colony-Stimulating Factor