title: Effects of von Willebrand factor concentration and platelet collision on shear-induced platelet activation.
abstract: 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.
authors.affiliation: Bioengineering Department, Beihag University, Xueyuan Road NO. 37, Postcode: 100191, Haidian District, Beijing, P. R. China.
authors.forename: Zhenyue
authors.initials: Z
authors.lastname: Gao
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Yu
authors.forename: Xia
authors.initials: X
authors.lastname: Bai
authors.forename: Chun
authors.initials: C
authors.lastname: Yang
authors.forename: Fengyuan
authors.initials: F
authors.lastname: Zhuang
authors.forename: Changgeng
authors.initials: C
authors.lastname: Ruan
mesh_terms: 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*
chemical_list: 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