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Healthy red blood cells flow in an ordered pattern, unlike diseased ones

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Healthy red blood cells (RBCs) under flow settle into an ordered spatial pattern, whereas pathological RBCs succumb to disorder, offering a simple visual diagnosis to detect RBC pathologies.

Half of the blood volume is made of RBCs, the other half consists of plasma. Other blood elements (white cells, platelets) contribute to less than 1 %. Blood flow is thus governed by RBCs and their mutual interactions via the fluid plasma. Understanding RBC assemblies under flow is essential to decipher many blood and cardiovascular pathologies, the main cause of mortality in the world. Furthermore, it opens a path to simple and efficient tools to detect blood diseases. The paper reports experiments and simulations, revealing that, in contrast to the common assumption of disordered blood flow, RBCs under shear flow can assemble into a two-dimensional crystal with various patterns (Fig. 1). A healthy RBC is quite soft and flexible, a property which is shown here to be essential to the emergence of order. Order is suppressed (Fig. 2) when RBCs are hardened, as in diseases, such as sickle cell anemia. Therefore, this work provides a method to discriminate between healthy and diseased RBCs, which could be useful in a medical setting for diagnosis and testing/developing therapies to alleviate disease symptoms.

Figure 2 : Suspension désordonnée de globules rouges dans un canal mimant un vaisseau sanguin (simulations numériques).
Figure 1:Des globules rouges ordonnés (expériences).
Figure 3 : Des globules rouges pathologiques montrent du désordre (expériences).

Voir en ligne : Blood crystal : emergent order of red blood cells under wall-confined shear flow, Phys. Rev. Lett., Zaiyi Shen, Thomas M. Fischer, Alexander Farutin, Petia M. Vlahovska, Jens Harting and Chaouqi Misbah