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Annie Viallat - Dynamics of blood cells in the microcirculation

Speaker : Annie Viallat, Laboratoire Adhesion & Inflammation, CNRS UMR 7333, INSERM U 1067 , Aix-Marseille Université, Marseille, France

When : Thursday 27 september at 11am

Where : Salle CO23 (grande salle de réunions du CBP rez-de-chaussée LR6)

Title : Dynamics of blood cells in the microcirculation

Red and white blood cells are the major component of blood. In one human body 35 trillion red blood cells circulate within 100 000 kms of small capillaries. The viscoelastic structure of blood cells determines their deformation and their regimes of motion in the microcirculation, and greatly influences flow and mass transport in both health and disease. We give two examples of the coupling between cell rheology and motion in simple and biomimetic flows. Red blood cells in shear flow. We will highlight the role of the viscous contribution of the cytoskeleton and the cytoplasm of the red blood cell to its fluid-like or rigid-like motion in shear flow. Then we will show that a red blood cell has a shape memory, which generates a specific dynamics and we will explore the role of the cytoskeleton elasticity on the cell motion. Evolution of a red blood Cell orbit with the shear rate (observation along the flow gradient) Monocytes in a model pulmonary bed. Leukocytes, which circulate through the lung blood capillaries, must deform to enter in the narrowest vessels. Their transport is governed by the interplay between cellular rheology, hydrodynamic stress and geometrical confinement. Inflammatory mediators expressed during acute inflammatory syndromes may stiffen leukocytes, which get massively trapped in the lungs and cause severe damages. However, this transport is not understood due to the difficulty to perform in-vivo experiments in the lungs. We use a microfluidic device that mimics the pulmonary bed to explore the transport of monocytes under physiological pressures. We explore the different stages of cell transport through the model capillary network. We highlight a transient non-periodic stage of motion during which the cell spontaneously accelerates before reaching a final stationary regime, and we discuss this regime in terms of rheological response of the cell to the periodic mechanical stress applied by the capillaries.

Typical trajectory of a monocyte in a model capillary network.

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