Margination of artificially stiffened red blood cells

TL;DR

This study investigates how artificially increased stiffness in red blood cells affects their margination behavior in blood flow, revealing complex dependencies on vessel geometry, flow rate, and hematocrit that challenge previous assumptions.

Contribution

It provides experimental and numerical insights into the role of cell stiffness in margination, highlighting non-monotonic effects and the influence of vessel geometry.

Findings

Stiffened RBCs show a central peak and corner peaks in distribution.

Segregation depends on channel geometry and flow conditions.

Higher flow rates do not necessarily enhance margination.

Abstract

Margination, a fundamental process in which leukocytes migrate from the flowing blood to the vessel wall, is well-documented in physiology. However, it is still an open question on how the differences in cell size and stiffness of white and red cells contribute to this phenomenon. To investigate the specific influence of cell stiffness, we conduct experimental and numerical studies on the segregation of a binary mixture of artificially stiffened red blood cells within a suspension of healthy cells. The resulting distribution of stiffened cells within the channel is found to depend on the channel geometry, as demonstrated with slit, rectangular, and cylindrical cross-sections. Notably, an unexpected central peak in the distribution of stiffened RBCs, accompanied by fourfold peaks at the corners, emerges in agreement with simulations. Our results unveil a non-monotonic variation in segregation/margination concerning hematocrit and flow rate, challenging the prevailing belief that higher flow rates lead to enhanced margination.