Erythrocyte sedimentation: Fracture and collapse of a high-volume-fraction soft-colloid gel

TL;DR

This study investigates the physical mechanisms behind erythrocyte sedimentation, revealing that erythrocytes form a deformable soft-colloid gel with unique properties, and develops a theoretical model consistent with experimental observations.

Contribution

The paper demonstrates that erythrocytes form a soft-colloid gel and introduces a theoretical model for gravitational collapse aligned with experimental data.

Findings

Erythrocytes form a soft-colloid gel at high volume fractions.

Deformability and weak attraction influence gel properties.

Theoretical predictions match macroscopic measurements of interface velocity.

Abstract

The erythrocyte sedimentation rate is one of the oldest medical diagnostic methods whose physical mechanisms remain debatable up to date. Using both light microscopy and mesoscale cell-level simulations, we show that erythrocytes form a soft-colloid gel. Furthermore, the high volume fraction of erythrocytes, their deformability, and weak attraction lead to unusual properties of this gel. A theoretical model for the gravitational collapse is developed, whose predictions are in agreement with detailed macroscopic measurements of the interface velocity.