title: Generation of platelet-derived microparticles in patients undergoing cardiac surgery is not affected by complement activation.
abstract: OBJECTIVE
  The mechanisms causing the presence of platelet-derived microparticles in the circulation are unknown. In vitro platelets release platelet-derived microparticles in response to complement activation. This study evaluates the relationship between complement activation and levels of circulating platelet-derived microparticles in patients undergoing cardiac surgery.
  
  
  METHODS
  Prospectively, 71 patients were included who underwent elective coronary artery bypass grafting with cardiopulmonary bypass. The patients were randomly allocated to one of the 3 groups: uncoated oxygenator, UnModified Surface (n = 25) or oxygenator coated with either BioPassive Surface (n = 25) or BioActive Surface (n = 21). Platelet-derived microparticles and terminal complement complexes were determined before bypass and after induction of anesthesia, 15 minutes after the start of cardiopulmonary bypass, at the end of cardiopulmonary bypass, and 30 minutes after administration of protamine sulfate.
  
  
  RESULTS
  Demographic and cardiopulmonary bypass data were similar for the 3 groups. At the end of cardiopulmonary bypass, platelet-derived microparticle numbers were decreased in all 3 groups. No significant differences were observed among the groups at any sampling point. At the end of cardiopulmonary bypass, terminal complement complex concentrations were increased in all groups (P <.001), and significant differences among the groups were present (P =.002).
  
  
  CONCLUSIONS
  Despite significant complement activation, no increase in numbers of circulating platelet-derived microparticles was found in the systemic blood of patients undergoing cardiac surgery with cardiopulmonary bypass. Thus complement activation in vivo does not necessarily affect generation of platelet-derived microparticles.
authors.affiliation: Department of Cardio-thoracic Surgery, Academic Medical Center of the University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. J.M.vandenGoor@AMC.UVA.nl
authors.forename: Jeanette M
authors.initials: JM
authors.lastname: van den Goor
authors.forename: Albert
authors.initials: A
authors.lastname: van den Brink
authors.forename: Rienk
authors.initials: R
authors.lastname: Nieuwland
authors.forename: Willem
authors.initials: W
authors.lastname: van Oeveren
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rutten
authors.forename: Robert
authors.initials: R
authors.lastname: Tepaske
authors.forename: Jan G
authors.initials: JG
authors.lastname: Tijssen
authors.forename: Augueste
authors.initials: A
authors.lastname: Sturk
authors.forename: Bas A
authors.initials: BA
authors.lastname: de Mol
authors.forename: León
authors.initials: L
authors.lastname: Eijsman
mesh_terms: D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000502:physiology*; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D002462:Cell Membrane / Q000502:physiology; D003167:Complement Activation / Q000502:physiology*; D001026:Coronary Artery Bypass; D017558:Elective Surgical Procedures; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011479:Protamines / Q000494:pharmacology
chemical_list: D011479:Protamines