Effects of platelet count on clot contraction and dynamic viscoelastic properties. PRP was diluted with autologous PFP to final platelet concentrations of <75 000/µL, 125 000 to 150 000/µL, 250 000 to 300 000/µL, and >500 000/µL. Samples were incubated with 2 mM CaCl2 and 1 U/mL thrombin. The plots show the effect of platelet count on the kinetics of clot contraction (A), the final extent of contraction (B), and the ratio of viscous to elastic components of the blood clot (tan δ = G″/G′) (C). *P < .05; **P < .01; ***P < .001. (C) Significance comparison for <75 000/µL and >500 000/µL.