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Updated: Jun 23, 2026
Extracellular Vesicle Tissue Factor Activity Assay
Published on: December 29, 2023
Levels of microparticle tissue factor activity correlate with coagulation activation in endotoxemic mice
J-G Wang1, D Manly, D Kirchhofer
1Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Background:
Tissue factor (TF) is present in blood in various forms, including small membrane vesicles called microparticles (MPs). Elevated levels of these MPs appear to play a role in the pathogenesis of thrombosis in a variety of diseases, including sepsis.
Objective:
Measure levels of MP TF activity and activation of coagulation in control and endotoxemic mice.
Materials And Methods:
MPs were prepared from plasma by centrifugation. The procoagulant activity (PCA) of MPs was measured using a two-stage chromogenic assay. We also measured levels of thrombin-antithrombin and the number of MPs.
Results:
Lipopolysaccharide (LPS) increased MP PCA in wild-type mice; this PCA was significantly reduced by an anti-mouse TF antibody (1H1) but not with an anti-human TF antibody (HTF-1). Conversely, in mice expressing only human TF, MP PCA was inhibited by HTF-1 but not 1H1. MPs from wild-type mice had 6-fold higher levels of PCA using mouse factor (F)VIIa compared with human FVIIa, which is consistent with reported species-specific differences in FVIIa. Mice expressing low levels of human TF had significantly lower levels of MP TF activity and TAT than mice expressing high levels of human TF; however, there were similar levels of phosphatidylserine (PS)-positive MPs. Importantly, levels of MP TF activity in wild-type mice correlated with levels of TAT but not with PS-positive MPs in endotoxemic mice.
Conclusion:
These results suggest that the levels of TF-positive MPs can be used as a biomarker for evaluating the risk of disseminated intravascular coagulation in endotoxemia.
Insights
Tissue factor (TF) microparticles (MPs) indicate thrombosis risk. MP TF activity levels correlate with coagulation activation, serving as a biomarker for disseminated intravascular coagulation in endotoxemia.
Area of Science:
- Biochemistry
- Hematology
- Immunology
Background:
- Tissue factor (TF) is present in blood as microparticles (MPs).
- Elevated MP levels are implicated in thrombosis pathogenesis, particularly in sepsis.
- Understanding MP TF activity is crucial for thrombosis research.
Purpose of the Study:
- To quantify MP TF activity and coagulation activation in control versus endotoxemic mice.
- To investigate the role of mouse versus human TF in MP procoagulant activity (PCA).
- To assess the correlation between MP TF activity, thrombin-antithrombin (TAT) levels, and phosphatidylserine (PS)-positive MPs.
Main Methods:
- Microparticles (MPs) were isolated from plasma via centrifugation.
- Procoagulant activity (PCA) of MPs was determined using a two-stage chromogenic assay.
- Levels of thrombin-antithrombin (TAT) and phosphatidylserine (PS)-positive MPs were measured.
Main Results:
- Lipopolysaccharide (LPS) induced MP PCA in wild-type mice, inhibited by anti-mouse TF antibody.
- Species-specific differences in TF activity were observed, with higher PCA using mouse FVIIa.
- MP TF activity correlated with TAT levels but not PS-positive MPs in endotoxemic mice.
Conclusions:
- TF-positive MPs can serve as a biomarker for disseminated intravascular coagulation (DIC) risk.
- MP TF activity is a sensitive indicator of coagulation activation in endotoxemia.
- These findings advance the understanding of TF-mediated thrombosis in inflammatory conditions.
