Effects of von Willebrand factor concentration and platelet collision on shear-induced platelet activation.
The binding of plasma von Willebrand factor (vWF) to platelet glycoprotein (GP) Ibalpha in a high shear stress field, and subsequent integrin-GPIIb/IIIa-vWF conjunction induces platelet aggregation (SIPA). However, the specific biomechanical mechanism of the vWF-GPIb interaction still remains to be elucidated. A parallel-plate rectangular flow chamber was built to simulate a stenopeic artery flow pattern. Using the flow chamber, we examined shear-induced platelet activation (SIPAct) at different vWF concentrations (5-25 microg/ml) and several simulated stenotic high shear rates. P-selectin expression on the platelets and annexin V binding to the platelets were used as two markers of platelet activation. At different localized shear rates (3,000 s(-1)-9,500 s(-1)), the percentage of annexin V and P-selectin positive cells increased from 8.3 +/- 0.4% to 22.3 +/- 1.8% ( p 0.05) and from 17.4 +/- 0.5% to 33.5 +/- 2.5% (p 0.05), respectively. As the vWF concentration increased from 5 microg/ml to 25 microg/ml, the annexin V binding rate increased from 7.2 +/- 0.6% to 53.4 +/- 3.8% (p 0.05), and P-selectin expression increased from 16.5 +/- 1.2% to 65.9 +/- 5.2% (p 0.05). A test in a uniform shear field using cone-plate viscometer rheometry showed that the platelet activation rate was proportional to the platelet concentration. This result suggests that platelet collision is one of the impact factors of SIPAct.
Gao
Zhenyue
Z
Bioengineering Department, Beihag University, Xueyuan Road NO. 37, Postcode: 100191, Haidian District, Beijing, P. R. China.
Liu
Fang
F
Yu
Ziqiang
Z
Bai
Xia
X
Yang
Chun
C
Zhuang
Fengyuan
F
Ruan
Changgeng
C
D017304:Annexin A5 / Q000378:metabolism; D001792:Blood Platelets / Q000378:metabolism*; D003251:Constriction, Pathologic; D005434:Flow Cytometry; D018056:Hemorheology; D006801:Humans; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D019007:P-Selectin / Q000378:metabolism; D015539:Platelet Activation; D010974:Platelet Aggregation; D019038:Platelet Glycoprotein GPIb-IX Complex; D011673:Pulsatile Flow; D013314:Stress, Mechanical; D013927:Thrombosis / Q000097:blood; D014841:von Willebrand Factor / Q000378:metabolism*
D017304:Annexin A5; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D019007:P-Selectin; D019038:Platelet Glycoprotein GPIb-IX Complex; C094990:adhesion receptor; D014841:von Willebrand Factor