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Coagulation activities of plasma microparticles
M A Howard1, M Coghlan, R David
1Department of Medicine, Monash Medical School, Prahran, Victoria, Australia.
Abstract:
An evaluation of the effect of plasma microparticles (MP) on in vitro coagulation has been undertaken using platelet rich (PRP), platelet poor (PPP) and platelet free (PFP) plasmas prepared by differential centrifugation. MP provide coagulant material which shortens the activated partial thromboplastin time (APTT) and dilute simplastin time (DSTT) which is different from that contributed by commercial phospholipid preparations. The amount of platelet factor three (PF3) available in plasma is directly correlated with the centrifugal force used in its preparation and is present in large amounts in the MP pellet remaining after preparation of PFP. Factor VIII (F.VIII:C) and von Willebrand factor (vWf) were associated with the MP fraction but could be separated from MP on sucrose gradients. The effect of MP on the APTT was independent of the F.VIII:C/vWf and was not solely due to their PF3 content. Plasma prepared for routine coagulation assays contains MP which contribute to the APTT and DSTT and should be considered in their assessment. High speed centrifugation of plasma reduces the F.VIII:C/vWf:Ag/RCoF levels and this may contribute to losses of these proteins during preparative procedures utilising high speed centrifugation.
Insights
Plasma microparticles (MPs) significantly impact in vitro coagulation tests, shortening activated partial thromboplastin time (APTT) and dilute simplastin time (DSTT). These MPs, distinct from commercial phospholipids, influence routine coagulation assays.
Area of Science:
- Hematology
- Biochemistry
- Coagulation Science
Background:
- Plasma microparticles (MPs) are known to influence hemostasis.
- Their precise contribution to routine coagulation assays requires further elucidation.
Purpose of the Study:
- To evaluate the effect of plasma microparticles (MPs) on in vitro coagulation.
- To differentiate the coagulant activity of MPs from commercial phospholipid preparations.
Main Methods:
- Preparation of platelet-rich (PRP), platelet-poor (PPP), and platelet-free (PFP) plasmas via differential centrifugation.
- Assessment of activated partial thromboplastin time (APTT) and dilute simplastin time (DSTT).
- Analysis of Factor VIII (F.VIII:C) and von Willebrand factor (vWf) association with MPs using sucrose gradients.
Main Results:
- MPs significantly shortened APTT and DSTT, independent of commercial phospholipids.
- Platelet factor 3 (PF3) availability correlated with centrifugation force and was abundant in the MP fraction.
- Factor VIII (F.VIII:C) and von Willebrand factor (vWf) were associated with MPs but separable.
- The procoagulant effect of MPs on APTT was independent of F.VIII:C/vWf and not solely due to PF3.
Conclusions:
- Plasma microparticles (MPs) are integral components of routine coagulation assays, affecting APTT and DSTT.
- High-speed centrifugation reduces F.VIII:C and vWf levels, impacting protein recovery during plasma preparation.