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BP: Fachverband Biologische Physik

BP 16: Membranes and Vesicles II

BP 16.2: Vortrag

Mittwoch, 20. März 2024, 09:45–10:00, H 0112

Physics and slowerance of the erythrocyte sedimentation rate — •Alexis Darras, Thomas John, Lars Kaestner, and Christian Wagner — Saarland University, Saarbruecken, Germany

Red blood cells (or erythrocytes) sedimentation rate (ESR) is a physical parameter of blood which is often checked in medical diagnosis. It is indeed well known that in case of inflammation, the increase in fibrinogen and other proteins induces a higher ESR. A higher ESR is clinically established as a disease marker. Recently, we demonstrated that Red Blood Cells (RBCs), when left at rest and suspended at physiological volume fractions, form percolating aggregates as wide as the container. It follows that they sediment following a so-called " gel collapse", governed by the geometry of the percolating aggregate acting as a porous material. In this talk, by comparing physical models to experimental sedimentation curves, we show how this knowledge can help to quantify physically meaningful parameters that characterize the details of the collapse dynamics. Amongst others, we provide a dependency of the maximal sedimentation velocity as a function of the initial RBC volume fraction (i.e. the hematocrit), which was a long-sought correction for ESR measurements from anemic patients. We also review how those parameters make it possible to experimentally distinguish between healthy samples and some conditions where the ESR is slowed down. In particular, this opens new perspective to use the ESR as an objective marker to detect diseases where the RBCs are deformed and/or rigidified.

Keywords: Red Blood Cells aggregation; collective behavior; ESR (Erythrocyte Sedimentation Rate); Percolating soft gel; multi-phase flow