Erythrocyte-derived microparticles supporting activated protein C-mediated regulation of blood coagulation

PLoS One. 2014 Aug 19;9(8):e104200. doi: 10.1371/journal.pone.0104200. eCollection 2014.


Elevated levels of erythrocyte-derived microparticles are present in the circulation in medical conditions affecting the red blood cells. Erythrocyte-derived microparticles expose phosphatidylserine thus providing a suitable surface for procoagulant reactions leading to thrombin formation via the tenase and prothrombinase complexes. Patients with elevated levels of circulating erythrocyte-derived microparticles have increased thrombin generation in vivo. The aim of the present study was to investigate whether erythrocyte-derived microparticles are able to support the anticoagulant reactions of the protein C system. Erythrocyte-derived microparticles were isolated using ultracentrifugation after incubation of freshly prepared erythrocytes with the ionophore A23187 or from outdated erythrocyte concentrates, the different microparticles preparations yielding similar results. According to flow cytometry analysis, the microparticles exposed phoshatidylserine and bound lactadherin, annexin V, and protein S, which is a cofactor to activated protein C. The microparticles were able to assemble the tenase and prothrombinase complexes and to stimulate the formation of thrombin in plasma-based thrombin generation assay both in presence and absence of added tissue factor. The addition of activated protein C in the thrombin generation assay inhibited thrombin generation in a dose-dependent fashion. The anticoagulant effect of activated protein C in the thrombin generation assay was inhibited by a monoclonal antibody that prevents binding of protein S to microparticles and also attenuated by anti-TFPI antibodies. In the presence of erythrocyte-derived microparticles, activated protein C inhibited tenase and prothrombinase by degrading the cofactors FVIIIa and FVa, respectively. Protein S stimulated the Arg306-cleavage in FVa, whereas efficient inhibition of FVIIIa depended on the synergistic cofactor activity of protein S and FV. In summary, the erythrocyte-derived microparticle surface is suitable for the anticoagulant reactions of the protein C system, which may be important to balance the initiation and propagation of coagulation in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Annexin A5 / pharmacology
  • Antibodies / pharmacology
  • Antigens, Surface / metabolism
  • Blood Coagulation / drug effects*
  • Blood Coagulation Tests
  • Calcimycin / pharmacology
  • Cell-Derived Microparticles / chemistry
  • Cell-Derived Microparticles / drug effects*
  • Cell-Derived Microparticles / metabolism
  • Cells, Cultured
  • Erythrocytes / chemistry
  • Factor V / metabolism
  • Factor VIIIa / metabolism
  • Factor VIIIa / pharmacology
  • Factor Va / metabolism
  • Factor Va / pharmacology
  • Factor Xa / metabolism
  • Humans
  • Lipoproteins / antagonists & inhibitors
  • Lipoproteins / metabolism
  • Milk Proteins / metabolism
  • Phosphatidylserines / chemistry
  • Phosphatidylserines / metabolism
  • Protein C / metabolism
  • Protein C / pharmacology*
  • Protein S / metabolism
  • Protein S / pharmacology
  • Thrombin / biosynthesis*
  • Thromboplastin / metabolism
  • Thromboplastin / pharmacology
  • Ultracentrifugation


  • Annexin A5
  • Antibodies
  • Antigens, Surface
  • Lipoproteins
  • MFGE8 protein, human
  • Milk Proteins
  • Phosphatidylserines
  • Protein C
  • Protein S
  • lipoprotein-associated coagulation inhibitor
  • prothrombinase complex
  • Calcimycin
  • Factor Va
  • Factor VIIIa
  • Factor V
  • Thromboplastin
  • Thrombin
  • Factor Xa

Grant support

This work was supported by Swedish Research Council #71430 (, and Heart and Lung Foundation #20110251 ( The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.