Formation of platelet-binding von Willebrand factor strings on non-endothelial cells
Article first published online: 1 OCT 2012
© 2012 International Society on Thrombosis and Haemostasis
Journal of Thrombosis and Haemostasis
Volume 10, Issue 10, pages 2168–2178, October 2012
How to Cite
WANG, J. W., VALENTIJN, J. A., VALENTIJN, K. M., DRAGT, B. S., VOORBERG, J., REITSMA, P. H. and EIKENBOOM, J. (2012), Formation of platelet-binding von Willebrand factor strings on non-endothelial cells. Journal of Thrombosis and Haemostasis, 10: 2168–2178. doi: 10.1111/j.1538-7836.2012.04891.x
- Issue published online: 1 OCT 2012
- Article first published online: 1 OCT 2012
- Accepted manuscript online: 20 AUG 2012 10:21AM EST
- Received 23 May 2012, accepted 10 August 2012
- von Willebrand disease;
- von Willebrand factor;
- Weibel–Palade body
Summary. Background and Objective: Von Willebrand factor (VWF) forms strings on activated vascular endothelial cells that recruit platelets and initiate clot formation. Alterations in VWF strings may disturb hemostasis. This study was aimed at developing a flexible model system for structure–function studies of VWF strings.
Methods: VWF strings were generated by inducing exocytosis of pseudo-Weibel–Palade bodies from VWF-transfected HEK293 cells, and the properties of these strings under static conditions and under flow were characterized.
Results: Upon exocytosis, VWF unfurled into strings several hundred micrometers in length. These strings could form bundles and networks, and bound platelets under flow, resembling authentic endothelial VWF strings. Anchorage of the platelet-decorated VWF strings was independent of P-selectin and integrin αVβ3. Translocation of platelets along the strings, elongation and fragmentation of the strings frequently occurred under flow. Furthermore, VWF variants with the p.Tyr87Ser and p.Cys2773Ser mutations, which are defective in multimer assembly, did not give rise to VWF strings. Also, insertion of the green fluorescent protein into VWF inhibited string formation.
Conclusions: HEK293 cells provide a flexible and useful model system for the study of VWF string formation. Our results suggest that structural changes in VWF may modulate string formation and function, and contribute to hemostatic disorders.