[Coagulation properties of erythrocyte derived membrane microparticles]

Area of Science:

• Hematology
• Biochemistry
• Cell Biology

Background:

• Membrane microparticles (MP) are released during cell activation/damage.
• MP contain phosphatidylserine (PS) and sometimes tissue factor (TF), influencing coagulation.
• Erythrocyte-derived MP (eMP) are investigated for their procoagulant potential.

Purpose of the Study:

• To investigate the coagulation properties of erythrocyte-derived microparticles (eMP).
• To compare the procoagulant activity of eMP with MP from platelets and monocytic cells.
• To determine the role of phosphatidylserine (PS) and tissue factor (TF) in eMP coagulation activity.

Main Methods:

• eMP were generated from activated donor erythrocytes and outdated erythrocyte concentrates.
• MP counting was performed using flow cytometry.
• Coagulation activity was assessed via plasma recalcification assays, PS and TF involvement was tested using lactadherin and anti-TF antibodies, TF activity was measured chromogenically, and MP size was determined by dynamic light scattering.

Main Results:

• eMP accelerated plasma clotting, but less than platelet-derived MP (pMP) and monocytic THP-1 cell-derived MP (THP-1 MP).
• Lactadherin completely inhibited coagulation activity of all tested MP.
• Anti-TF antibodies did not affect clotting with eMP or pMP, but slowed clotting with THP-1 MP; TF activity was absent in eMP and pMP, but present in THP-1 MP.
• eMP (approx. 200 nm) were smaller than pMP and THP-1 MP (approx. 400 nm).

Conclusions:

• eMP exhibit lower procoagulant activity compared to pMP and THP-1 MP.
• The reduced activity of eMP is attributed to their smaller size and the absence of tissue factor (TF).
• Phosphatidylserine (PS) exposure is a key factor in the coagulation activity of all investigated MP types.