title: [Positive and negative regulation of megakaryocytopoiesis].
abstract: Megakaryocytopoiesis concerns the commitment of hematopoietic stem cells towards the megakaryocyte lineage, the proliferation and maturation of megakaryocyte progenitors, leading to platelet formation. Normal megakaryocytopoiesis requires an equilibrium between positive and negative regulators. Thrombopoietin, recently cloned, is the main growth factor for the megakaryocyte lineage, enhancing all the steps of megakaryocyte development: proliferation, maturation, ploidisation, platelet formation. Several other factors have a direct (interleukin 3, 6, 11, 13, GMCSF, erythropoietin) or indirect (interleukin 1, stem cell factor) positive effect. Factors inhibiting megakaryocytopoiesis are synthetized by the megakaryocytes themselves (platelet factor 4, transforming growth factor beta), or have many other effects (alpha-interferon, thrombin) or correspond to a novel molecule (anagrelide). Heparin and other glycosaminoglycans positively modulate megakaryocytopoiesis by acting synergistically with some growth factors and by neutralizing some inhibitors. These progresses in the knowledge of normal and pathological megakaryocytopoiesis should lead to considerable therapeutic advances.
authors.affiliation: Institut des Vaisseaux et du Sang, Paris.
authors.forename: S
authors.initials: S
authors.lastname: Bellucci
authors.forename: Z C
authors.initials: ZC
authors.lastname: Han
authors.forename: J P
authors.initials: JP
authors.lastname: Caen
mesh_terms: D000818:Animals; D002455:Cell Division; D016207:Cytokines / Q000502:physiology; D006025:Glycosaminoglycans / Q000502:physiology; D006410:Hematopoiesis / Q000502:physiology*; D066298:In Vitro Techniques; D008533:Megakaryocytes / Q000378:metabolism* / Q000502:physiology*; D010978:Platelet Factor 4 / Q000502:physiology; D013926:Thrombopoietin / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology
chemical_list: D016207:Cytokines; D006025:Glycosaminoglycans; D016212:Transforming Growth Factor beta; D010978:Platelet Factor 4; D013926:Thrombopoietin
vernacular_title: Régulation positive et négative de la mégacaryocytopoïèse.