title: Organization of haematopoietic stem cells and their relationship to mastocytopoiesis.
abstract: Haematopoiesis is a dynamic process in which differentiated blood cells are regularly replaced by the proliferation and differentiation of stem cells. Two types of haematopoietic stem cells (HSC) can be distinguished: totiopotent HSC capable of giving rise to cells of all haematopoietic lineages, and pluripotent HSC capable of giving rise only to the myeloid lineages. HSC are characterized by their capacity for self-renewal and differentiation in committed stem cells determined towards one of the haematopoietic lineages. These committed stem cells, also named progenitor cells or colony-forming units (CFU), have the capacity to give rise, in semi-solid medium, to colonies composed of differentiated cells. It has recently been shown that mast cells originate from a pluripotent HSC and that CFU Baso/Masto can be detected from murine and human bone marrow and blood cells. The in vivo regulation of the proliferation and differentiation of HSC is not well known. Several studies have emphasized the role of the haematopoietic microenvironment and of long- and short-range factors in such regulation. The in vitro growth of HSC is strictly dependent on growth factors, also named CSF (colony-stimulating factors) and interleukin (IL), in particular IL3. IL3 is a glycoprotein which induces the proliferation and differentiation of pluripotent and committed HSC and which seems to have a preferential role in mast cell regulation.
mesh_terms: D000818:Animals; D003114:Colony-Forming Units Assay; D003115:Colony-Stimulating Factors / Q000502:physiology; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D066298:In Vitro Techniques; D007377:Interleukin-3 / Q000502:physiology; D008407:Mast Cells / Q000166:cytology*; D008954:Models, Biological
chemical_list: D003115:Colony-Stimulating Factors; D007377:Interleukin-3