Platelet surface P-selectin molecules increased after exposing platelet to a high shear flow.
BACKGROUND
P-selectin is known to play a crucial role in leucocyte recruitment at sites of vascular injury. Although platelet surface expression of P-selectin molecules are well known to occur after platelet stimulation by chemical agonists such as alpha-thrombin, it is still uncertain whether P-selectin expression occurs in the process of the more physiological platelet activation pathway mediated by interaction between von Willebrand factor (vWF) and platelet receptor proteins, including glycoprotein (GP) Ibalpha and GP IIb/IIIa, occurring under high shear rates generated by blood flow.


METHODS
We have developed a method to detect P-selectin molecules expressed on platelet surface with flow-cytometer and monoclonal antibody, which can bind exclusively to P-selectin (WGA1), directly conjugated with fluorescein isothiocynate. This method allowed us to measure platelet surface P-selectin molecules semiquantitatively.


RESULTS
We demonstrated that a significant increase in platelet surface P-selectin molecules occur after exposing platelets to a relatively high shear rate of 10,800 s(-1). We have also demonstrated that shear-induced surface expression of P-selectin as well as microparticle release from platelets depended at least on the interaction between von Willebrand factor and glycoprotein Ibalpha, a platelet surface receptor for the former.


CONCLUSIONS
Shear-induced von Willebrand-mediated surface expression of P-selectin may play a role in leucocyte recruitment in platelet thrombi at vascular injury sites.
Goto
S
S
Division of Cardiology, Tokai University School of Medicine, Isehara, Kanagawa, Japan. shinichi@is.icc.u-tokai.ac.jp
Ichikawa
N
N
Lee
M
M
Goto
M
M
Sakai
H
H
Kim
J J
JJ
Yoshida
M
M
Handa
M
M
Ikeda
Y
Y
Handa
S
S
D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000378:metabolism* / Q000502:physiology; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D019007:P-Selectin / Q000378:metabolism*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism; D013314:Stress, Mechanical; D013927:Thrombosis / Q000209:etiology; D014841:von Willebrand Factor / Q000378:metabolism / Q000502:physiology
D000911:Antibodies, Monoclonal; D019007:P-Selectin; D019038:Platelet Glycoprotein GPIb-IX Complex; D014841:von Willebrand Factor