InterPore2026

From anomalous transport of red blood cells in microvascular networks to oxygen delivery in the brain

19 May 2026, 14:35

15m

Oral Presentation (MS09) Pore-Scale Physics and Modeling MS09

Speaker

Hugo Blons (CNRS)

Description

Fluid flow and solute transport in microvascular networks plays a central role in oxygen delivery and metabolic waste clearance in the brain [1]. The distribution of blood travel times, the times needed for blood to flow from one arteriolar end to a venular end, has been identified as a key property for the extraction of oxygen by brain tissue [2]. Broad travel time distributions can potentially lead to diseases by disturbing oxygen delivery and waste clearance. This mechanism has been formalized through a Continuous Time Random Walk framework linking the blood travel time distribution to the microvascular networks topology [3]. This stochastic model demonstrates the emergence of critical hypoxic areas induced by anomalous transport, characterizing the emergence of power law distributed travel times. However, current models of blood travel time distributions and oxygen transport have neglected oxygen confinement in red blood cells (RBC) and the oxygen-hemoglobin reaction.

Here we investigate the role of the bi-phasic nature of blood (plasma and RBCs) in anomalous transport through brain microvascular network. We use a highly-resolved network simulation to compute pressures, blood flow rates, and the ratio of RBC flow to blood flow (discharge hematocrit HD ) in a microvascular networks of a mm3 of mouse cortex. We thus simulate the non-proportional distribution of RBCs at diverging bifurcations, phase separation, induced by interactions of RBC with flow in capillaries [4] we show that RBCs exigit a lower probability of low blood flow values than passive particles in blood (Fig. 1A), which tend to reduce the effect of anomalous transport on oxygen delivery. However, the heterogeneity of hematocrit resulting from phase separation (Fig. 1B), induces a variability of oxygen concentration that is independent of travel times and increases the number of critical vessels (Fig. 1C). We further discuss the role of the non-linear binding of oxygen to hemoglobin in oxygen delivery.

Figure 1: A) Probability density functions (PDF) of blood flow (Blue: blood particles; Red: RBC; Dark lines: analytical solutions, dashed for blood, full for RBC). B) Map of HD in a microvascular network of mouse cortex, inlets at HD = 0.4. C) PDF of oxygen normalized by the inlet values (Dark: for blood in monophasic fluid. Red: total oxygen in biphasic blood; Blue: oxygen in plasma).

[1] Timothy W Secomb. Blood flow in the microcirculation. Annual Review of Fluid Mechanics, 49(1):443–461, 2017.
[2] Sune N. Jespersen and Leif Ostergaard. The roles of cerebral blood flow, capillary transit time heterogeneity, and oxygen tension in brain oxygenation and metabolism. Journal of Cerebral Blood Flow & Metabolism, 32(2):264–277, 2012. URL http://www.nature.com/jcbfm/journal/v32/n2/abs/jcbfm2011153a.html.
[3] Florian Goirand, Tanguy Le Borgne, and Sylvie Lorthois. Network-driven anomalous transport is a fundamental component of brain microvascular dysfunction. Nature Communications, 12(1):7295, December 2021. ISSN 2041- 1723. doi: 10.1038/s41467-021-27534-8. URL https://www.nature.com/articles/s41467-021-27534-8.
[4] A. R. Pries, Timothy W. Secomb, P. Gaehtgens, and J. F. Gross. Blood flow in microvascular networks. Experiments and simulation. Circulation research, 67(4):826–834, 1990. URL http://circres.ahajournals.org/content/67/4/826.short.