title: The effect of centrifugation speed and time on pre-analytical platelet activation.
abstract: BACKGROUND
  The results of laboratory analyses are affected by pre-analytical variables, and in particular can platelets be activated by shear handling stress and secrete granular substances. We therefore evaluated the effect of centrifugation speed and time on pre-analytical platelet activation.
  
  
  METHODS
  Citrate- and EDTA-anticoagulated blood from healthy volunteers were centrifuged at 80-10,000 g for 5-15 min to prepare plasma and platelet-rich plasma. Pre-analytical platelet activation was assessed by flow cytometric measurement of platelet P-selectin (CD62p) expression. Blood cell counts, mean platelet volume (MPV), immature platelet fraction (IPF), and platelet distribution width (PDW) were measured. Platelet aggregation in platelet-rich plasma induced by arachidonic acid (AA), ADP or thrombin receptor activator peptide-6 (TRAP) was tested by 96-well aggregometry.
  
  
  RESULTS
  The median percentage of platelets expressing P-selectin in citrate- and EDTA-plasma centrifuged at 2000 g for 10 min were 43% [interquartile range (IQR), 38%-53%] and 56% (IQR, 31%-78%), respectively (p=0.82). Platelet-rich plasma prepared at 100-250 g for 10 min had significantly lower platelet P-selectin expression (11%-15%), p<0.001. Platelet count in plasma samples decreased with increasing speed but platelets were only completely removed if plasma was re-centrifuged. In platelet-rich plasma, increasing centrifugation speed significantly increased platelet yield but decreased contamination from other blood cells, platelet composition was altered as platelet parameters (MPV, IPF, and PDW) was lowered. Platelet aggregation was not affected by the centrifugation speed platelet-rich plasma was prepared.
  
  
  CONCLUSIONS
  Proportional to centrifugation speed, platelets in plasma and platelet-rich plasma were activated with centrifugation speed, cell content and composition changed while platelet aggregation was unaltered.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Söderström
authors.forename: Mads
authors.initials: M
authors.lastname: Nybo
authors.forename: Christian
authors.initials: C
authors.lastname: Nielsen
authors.forename: Pernille J
authors.initials: PJ
authors.lastname: Vinholt
mesh_terms: D000328:Adult; D002498:Centrifugation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015539:Platelet Activation; D010974:Platelet Aggregation; D010976:Platelet Count; D013997:Time Factors