Human blood platelets contract in perpendicular direction to shear flow

Soft Matter. 2019 Feb 27;15(9):2009-2019. doi: 10.1039/c8sm02136h.

Abstract

In their physiological environment, blood platelets are permanently exposed to shear forces caused by blood flow. Within this surrounding, they generate contractile forces that eventually lead to a compaction of the blood clot. Here, we present a microfluidic chamber that combines hydrogel-based traction force microscopy with a controlled shear environment, and investigate the force fields platelets generate when exposed to shear flow in a spatio-temporally resolved manner. We find that for shear rates between 14 s-1 to 33 s-1, the general contraction behavior in terms of force distribution and magnitude does not differ from no-flow conditions. The main direction of contraction, however, does respond to the externally applied stress. At high shear stress, we observe an angle of about 90° between flow direction and main contraction axis. We explain this observation by the distribution of the stress acting on the adherent cell: the observed angle provides the most stable situation for the cell experiencing the shear flow, as supported by a finite element method simulation of the stresses along the platelet boundary.

MeSH terms

  • Biomechanical Phenomena
  • Blood Platelets / cytology
  • Blood Platelets / physiology*
  • Cell Adhesion
  • Humans
  • Lab-On-A-Chip Devices
  • Shear Strength*
  • Stress, Mechanical