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Updated: May 8, 2026
03:53
Extracellular Vesicle Tissue Factor Activity Assay
Published on: December 29, 2023
Microparticle-associated tissue factor is recycled by endothelial cells resulting in enhanced surface tissue factor
M E W Collier1, P-M Mah, Y Xiao
1Dr. Camille Ettelaie, Biomedical Section, Department of Biological Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX, UK, Tel.: +44 1482 465528, Fax: +44 1482 465458,
Thrombosis and Haemostasis
|August 16, 2013
Summary
Endothelial cells internalize tissue factor (TF)-positive microparticles, recycling TF to their surface. This process, involving phosphatidylserine exposure, significantly increases the cells' procoagulant potential.
Area of Science:
- Cell Biology
- Hemostasis
- Biochemistry
Background:
- Tissue factor (TF) is a key initiator of the coagulation cascade.
- Microparticles (MPs) carrying TF can modulate endothelial cell function.
- The fate and functional impact of TF on endothelial cells after MP uptake are not fully understood.
Purpose of the Study:
- To investigate the uptake and recycling of TF from microparticles by endothelial cells.
- To determine the functional consequences of TF recycling on endothelial cell procoagulant activity.
- To elucidate the cellular mechanisms involved in TF trafficking after microparticle interaction.
Main Methods:
- Incubation of human dermal blood endothelial cells (HDBECs) with TF-positive microparticles.
- Measurement of cell surface TF antigen and TF activity using antigen assays and thrombin generation assays.
- Analysis of phosphatidylserine exposure, TF mRNA levels, and the effect of endocytosis inhibitors.
- Tracking TF localization using TF-GFP fusion proteins and Rab GTPase markers (Rab4, Rab5, Rab9, Rab11).
- siRNA-mediated knockdown of Rab11 to assess its role in TF recycling.
Main Results:
- HDBECs showed two peaks of cell surface TF antigen after incubation with TF-positive MPs, with the second peak correlating with high TF activity due to phosphatidylserine exposure.
- No de novo TF mRNA expression was observed, and TF appearance was independent of protein synthesis but dependent on endocytosis.
- TF co-localized with early (Rab4, Rab5), late (Rab9), and recycling (Rab11) endosomal markers, indicating a trafficking pathway.
- Inhibition of Rab11 function reduced the reappearance of TF on the cell surface.
Conclusions:
- Endothelial cells internalize TF-positive microparticles and recycle the TF moiety to the cell surface via an endosomal pathway involving Rab11.
- The recycling of TF, coupled with phosphatidylserine exposure, significantly enhances the procoagulant potential of endothelial cells.
- This mechanism highlights a novel way microparticles can contribute to thrombosis and hemostasis.
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