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Specific activation of platelets by surface-adsorbed plasma proteins
Journal of Biomaterials Science. Polymer Edition
|September 2, 1998
Summary
This study isolated pure human platelets and tested their activation on surfaces coated with plasma proteins. Immobilized von Willebrand factor (vWF) specifically triggered platelet activation, indicated by CD62P exposure.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Platelet activation is crucial for hemostasis and thrombosis.
- Understanding platelet interactions with surface-bound proteins is key to elucidating these processes.
- Specific plasma proteins can trigger distinct platelet responses.
Purpose of the Study:
- To investigate human platelet activation by adsorbed plasma proteins on a hydrophobic surface.
- To determine the specific role of von Willebrand factor (vWF) in platelet activation.
- To characterize platelet responses including cell spreading, microparticle formation, and CD62P exposure.
Main Methods:
- Human platelets isolated via Percoll density gradient centrifugation with reversible inactivation.
- Platelet purity (>99%) and viability confirmed by flow cytometry and fluorescein diacetate hydrolysis.
- Incubation of purified platelets with adsorbed plasma proteins on glass, followed by analysis of activation markers.
Main Results:
- Surface-immobilized immunoglobulin G (IgG) induced microparticle release and cell lysis.
- Surface-immobilized vWF specifically induced CD62P (P-selectin) exposure, indicating alpha-granule release.
- Specificity of vWF response confirmed using plasma from normal and factor VIII-deficient individuals.
Conclusions:
- Platelets can be effectively isolated and maintained with high purity and viability.
- Surface-bound vWF is a potent activator of human platelets, leading to CD62P exposure.
- This model system allows for the study of specific protein-ligand interactions in platelet activation.