Generation of platelet-derived microparticles in patients undergoing cardiac surgery is not affected by complement activation.
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.
van den Goor
Jeanette M
JM
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
van den Brink
Albert
A
Nieuwland
Rienk
R
van Oeveren
Willem
W
Rutten
Peter M
PM
Tepaske
Robert
R
Tijssen
Jan G
JG
Sturk
Augueste
A
de Mol
Bas A
BA
Eijsman
León
L
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
D011479:Protamines