title: Platelets generated in vitro from proplatelet-displaying human megakaryocytes are functional.
abstract: An in vitro culture system demonstrating the transitions from megakaryocyte progenitors to functional platelets is described. CD34-selected cells from normal human peripheral blood are cultured under conditions that promote megakaryocyte formation. After 8 to 11 days, enriched populations of mature megakaryocytes are replated under conditions that favor the development of proplatelets. Proplatelets express the platelet-specific proteins, glycoproteins Ib and IIb (GPIb and GPIIb), and fibrinogen and also contain microtubule coils equal in size to those found in plasma-derived platelets. In addition, proplatelets have ultrastructural features in common with plasma-derived platelets. Platelet-sized particles from the proplatelet culture supernatants are examined. Ultrastructurally, these particles are identical to plasma-derived platelets. Functionally, these culture-derived platelets aggregate in response to both thrombin and adenosine diphosphate (ADP) plus fibrinogen. This aggregation is specifically inhibited by the addition of a function-blocking anti-GPIIbIIIa antibody. Culture-derived platelets stimulated with agonists also express the activation-dependent antigens P-selectin and functional fibrinogen receptor. This is the first description of an in vitro culture system that sequentially demonstrates megakaryocyte growth, development, and platelet production.
authors.affiliation: AMGEN, Inc., Thousand Oaks, CA 91320.
authors.forename: E S
authors.initials: ES
authors.lastname: Choi
authors.forename: J L
authors.initials: JL
authors.lastname: Nichol
authors.forename: M M
authors.initials: MM
authors.lastname: Hokom
authors.forename: A C
authors.initials: AC
authors.lastname: Hornkohl
authors.forename: P
authors.initials: P
authors.lastname: Hunt
mesh_terms: D000741:Anemia, Aplastic / Q000097:blood; D000818:Animals; D015703:Antigens, CD; D018952:Antigens, CD34; D001792:Blood Platelets / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D002454:Cell Differentiation; D002478:Cells, Cultured; D003470:Culture Media; D004285:Dogs / Q000097:blood; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008870:Microtubules / Q000648:ultrastructure; D019007:P-Selectin; D015539:Platelet Activation; D010974:Platelet Aggregation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000032:analysis
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D003470:Culture Media; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins