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BP: Fachverband Biologische Physik

BP 27: Cell Mechanics II

BP 27.1: Hauptvortrag

Donnerstag, 15. März 2018, 09:30–10:00, H 1028

Size and Mechanical Scaling of Blood Platelets — Aastha Mathur, Sandra Correia, Serge Dmitrieff, Romain Gibeaux, Iana Kalinina, Tooba Quidwai, Jonas Ries, and •Francois Nedelec — EMBL Heidelberg

Blood platelets play a major role in hemostasis, the process of stopping blood loss from injured vessels. Platelets have a discoid shape while floating free in the blood in the so-called resting state but come in various sizes, ranging from 1.6 to 5 micrometers. I will argue that their size, in this case, can be understood from the competition between the elasticity of a circular bundle of microtubules, and surface tension at the cell edge. Such a mechanical equilibrium predicts a scaling law that is verified by imaging a large number of individual platelets live, from Mouse and Human blood samples. I will then discuss the dynamics that is observed at the onset of platelet activation, on the path towards platelet adhesion and aggregation. The microtubule ring maintaining the shape of platelets initially coils but is later able to recover within 30 minutes. This can be understood as the ring is made of multiple microtubules that are dynamically connected, and can respond both elastically or viscously. Importantly, given the mechanical properties of these components, we can explain why the overall mechanical response of platelets is dependent on their size, a fact that is known to be important for the physiology of platelets in vivo.