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Extracellular Vesicle Tissue Factor Activity Assay
Published on: December 29, 2023
Truncated and microparticle-free soluble tissue factor bound to peripheral monocytes preferentially activate factor
Mohammad M H Khan1, Takashi Hattori, Stefan Niewiarowski
1Harrison Department of Surgical Research, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-3325, USA.
Thrombosis and Haemostasis
|March 10, 2006
Summary
Stimulated mononuclear cells efficiently activate truncated tissue factor (rsTF) and soluble plasma tissue factor (pTF) to factor VIIa (fVIIa). This interaction is crucial for TF-driven coagulation, especially in disease states.
Area of Science:
- Biochemistry
- Hematology
- Cell Biology
Background:
- Soluble plasma tissue factor (TF) is present at low levels in healthy individuals but elevated in various diseases.
- TF plays a critical role in the coagulation cascade, initiating the extrinsic pathway.
- Understanding TF's interactions with blood cells is vital for comprehending thrombotic disorders.
Purpose of the Study:
- To investigate the hypothesis that truncated TF (rsTF) and soluble plasma TF (pTF) at low concentrations interact with monocytes and platelets.
- To determine the efficiency of rsTF and pTF in converting factor VII (fVII) to factor VIIa (fVIIa) in the presence of different blood cells.
- To identify the cellular component most effective in TF-mediated fVII activation.
Main Methods:
- rsTF and pTF were isolated from pericardial wound plasma of cardiac surgery patients.
- Tissue factor levels were quantified using ELISA.
- The conversion of fVII to fVIIa was assessed using rsTF/pTF with isolated erythrocytes, platelets, mononuclear cells, and polymorphonuclear neutrophils, as well as TF-bearing microparticles.
Main Results:
- rsTF binds to erythrocytes, platelets, mononuclear cells, and polymorphonuclear neutrophils.
- Mononuclear cells demonstrated the highest rate of fVII conversion with rsTF, followed by platelets, then polymorphonuclear neutrophils; erythrocytes showed no conversion.
- Stimulated mononuclear cells were the most efficient platform for activating rsTF or pTF at low concentrations, converting nearly all available fVII to fVIIa with pTF.
- Platelets also converted fVII to fVIIa but less efficiently than mononuclear cells.
- TF-bearing microparticles did not activate fVII in the absence of leukocytes or platelets.
Conclusions:
- Stimulated mononuclear cells provide the most efficient cellular platform for the activation of low-concentration rsTF and pTF.
- Mononuclear cells are more effective than platelets in converting fVII to fVIIa in the presence of TF.
- These findings highlight the significant role of mononuclear cells in TF-driven coagulation initiation, particularly in pathological conditions.
