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Microparticle-mediated thrombin generation assay: increased activity in patients with recurrent thrombosis
1Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
Background:
Circulating cell-derived microparticles (MP) are important players in thrombogenesis, attributed in part to tissue factor (TF) carried on them. We developed MP-mediated thrombin generation assay (TGA) and measured a series of patients with thrombosis (TBS) and normal controls (NC).
Methods:
MP were isolated from plasma of 66 patients with TBS and 34 NC. The MP were resuspended in normal pooled particle-free plasma (PFP) containing corn trypsin inhibitor (to inhibit contact pathway). MP mediated TGA yields three parameters: lag time, peak and rate. This method is not influenced by anticoagulant therapy. Of the TBS patients, 41 had only a single thrombosis (S-TBS) and 25 had recurrences (R-TBS) within a 5-year period. In parallel, MP were quantitated by flow cytometry, and cell origin was determined: endothelial cells (EMP), leukocytes (LMP), red cells (RMP) and platelets (PMP).
Results:
MP from all TBS patients exhibited higher thrombin generation than NC by all three TGA parameters. R-TBS had significantly greater TGA values than S-TBS, reflected in higher peak and rate, and shorter lag time. MP numbers were also higher in TBS vs. NC, for all MP subtypes, and were significantly higher in R-TBS than S-TBS (except LMP). All MP levels correlated with thrombin generation (P < 0.0001), most closely between PMP and peak (R = 0.47) and rate (R = 0.43).
Conclusions:
MP-mediated TGA is a novel way to assess functional procoagulant activity of MP. Enhanced MP-mediated TGA was demonstrated in TBS patients, and significantly higher activity in R-TBS. These findings support a major role of MP in thrombogenesis.
Insights
Cell-derived microparticles (MP) play a key role in blood clot formation. A new assay shows higher MP activity in thrombosis patients, especially those with recurrent events, highlighting MP's role in thrombogenesis.
Area of Science:
- Hematology
- Thrombosis Research
- Biochemistry
Background:
- Circulating cell-derived microparticles (MP) contribute to thrombogenesis, partly due to carried tissue factor (TF).
- A novel microparticle-mediated thrombin generation assay (TGA) was developed to assess MP procoagulant activity.
Purpose of the Study:
- To evaluate the functional procoagulant activity of MP in patients with thrombosis (TBS) compared to normal controls (NC).
- To investigate differences in MP-mediated TGA between patients with single thrombosis (S-TBS) and recurrent thrombosis (R-TBS).
Main Methods:
- MP were isolated from plasma of 66 TBS patients and 34 NC.
- MP-mediated TGA was performed using particle-free plasma, measuring lag time, peak, and rate.
- MP were quantified by flow cytometry to determine cell origin (EMP, LMP, RMP, PMP).
Main Results:
- TBS patients showed significantly higher MP-mediated TGA than NC across all parameters.
- R-TBS patients exhibited greater TGA values (higher peak, higher rate, shorter lag time) than S-TBS patients.
- Elevated MP levels, particularly PMP, were observed in TBS patients and correlated strongly with thrombin generation.
Conclusions:
- MP-mediated TGA is a valuable method for assessing MP functional procoagulant activity.
- Enhanced MP activity is evident in thrombosis patients, with heightened levels in those experiencing recurrent events.
- These findings underscore the significant role of microparticles in the pathogenesis of thrombogenesis.
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