title: Hemopoietic stem cell heterogeneity: use of cell cycle-specific drugs to look for age-associated alterations.
abstract: Hemopoietic tissue is vulnerable to perturbations, and data show that it is an appropriate tissue in which to look for age-associated alterations. This tissue has a high regenerative capacity, is composed of a heterogeneous population of stem cells that are capable of self renewal or differentiation, or both, and is sustained by a pool of resting cells. The heterogeneity of bone marrow has made characterization of the cellular elements difficult. Techniques commonly used to identify and quantify the various maturation levels of hemopoietic stem cells and the limitations of these techniques are discussed. Most techniques used to assay age-associated changes in bone marrow have not differentiated between specific cellular alterations or shifts in the distribution of the cellular elements. In particular, it has been difficult to determine the stability of the non-dividing stem cell because of the low incidence of this cell (6 per 1000) and the lack of a specific assay for this important cell type. The use of cell cycle-specific drugs has provided quantitative information on specific subpopulations of hemopoietic stem cells and seems to be the most promising approach towards determining qualitative and quantitative differences in the hemopoietic stem cells of young and old individuals.
mesh_terms: D000375:Aging; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001853:Bone Marrow / Q000187:drug effects / Q000502:physiology; D016026:Bone Marrow Transplantation; D002066:Busulfan / Q000494:pharmacology; D002453:Cell Cycle; D002454:Cell Differentiation; D002458:Cell Fractionation; D003114:Colony-Forming Units Assay; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D051379:Mice; D012038:Regeneration; D013866:Thioguanine / Q000494:pharmacology; D013936:Thymidine / Q000494:pharmacology; D014184:Transplantation, Homologous
chemical_list: D000970:Antineoplastic Agents; D013866:Thioguanine; D002066:Busulfan; D013936:Thymidine