title: Force field evolution during human blood platelet activation.
abstract: Contraction at the cellular level is vital for living organisms. The most prominent type of contractile cells are heart muscle cells, a less-well-known example is blood platelets. Blood platelets activate and interlink at injured blood vessel sites, finally contracting to form a compact blood clot. They are ideal model cells to study the mechanisms of cellular contraction, as they are simple, having no nucleus, and their activation can be triggered and synchronized by the addition of thrombin. We have studied contraction using human blood platelets, employing traction force microscopy, a single-cell technique that enables time-resolved measurements of cellular forces on soft substrates with elasticities in the physiological range (∼4 kPa). We found that platelet contraction reaches a steady state after 25 min with total forces of ∼34 nN. These forces are considerably larger than what was previously reported for platelets in aggregates, demonstrating the importance of a single-cell approach for studies of platelet contraction. Compared with other contractile cells, we find that platelets are unique, because force fields are nearly isotropic, with forces pointing toward the center of the cell area.
authors.affiliation: University of Göttingen, Department of X-Ray Physics and Courant Research Centre Nano-Spectroscopy and X-Ray Imaging, 37077 Göttingen,  Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Schwarz Henriques
authors.forename: Rabea
authors.initials: R
authors.lastname: Sandmann
authors.forename: Alexander
authors.initials: A
authors.lastname: Strate
authors.forename: Sarah
authors.initials: S
authors.lastname: Köster
mesh_terms: D001777:Blood Coagulation / Q000502:physiology*; D001792:Blood Platelets / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D006801:Humans; D015539:Platelet Activation / Q000502:physiology*