Effect of Cell Age and Membrane Rigidity on Red Blood Cell Shape in Capillary Flow

Abstract

Blood flow in the microcirculatory system is crucially affected by intrinsic red blood cell (RBC) properties, such as their deformability. In the smallest vessels of this network, RBCs adapt their shapes to the flow conditions. Although it is known that the age of RBCs modifies their physical properties, such as increased cytosol viscosity and altered viscoelastic membrane properties, the evolution of their shape-adapting abilities during senescence remains unclear. In this study, we investigated the effect of RBC properties on the microcapillary in vitro flow behavior and their characteristic shapes in microfluidic channels. For this, we fractioned RBCs from healthy donors according to their age. Moreover, the membranes of fresh RBCs were chemically rigidified using diamide to study the effect of isolated graded-membrane rigidity. Our results show that a fraction of stable, asymmetric, off-centered slipper-like cells at high velocities decreases with increasing age or diamide concentration. However, while old cells form an enhanced number of stable symmetric croissants at the channel centerline, this shape class is suppressed for purely rigidified cells with diamide. Our study provides further knowledge about the distinct effects of age-related changes of intrinsic cell properties on the single-cell flow behavior of RBCs in confined flows due to inter-cellular age-related cell heterogeneity.

Confinement effect on the microcapillary flow and shape of red blood cells

“… 25,27 Previous work revealed differences in the dynamic deformation behavior between control RBCs and artificially stiffened RBCs, as well as RBCs of diabetes patients in microcapillary flow. 15,48,49 In our study, the observed increase of cell elongation for stable croissants is in good agreement with previous investigations on single RBCs. 11,50 This is attributed to the two “tails” of the croissant-shaped RBC that seem to become longer and pointed [see the top row in Fig.…”

“…4(e) ]. Such pdfs with two pronounced peaks at elevated velocities have been reported before 15,31 and are also found in the most confined channel [ Fig. 4(a) ] due to the emergence of both off-centered slippers and central flowing croissants and other shapes.…”

“…This observation is in good agreement with previous work. 15 Interestingly, while we find only one off-centered peak at in the channel with and [ Fig. 4(d) ], two peaks at and appear for the slightly deeper channel with and [ Fig.…”

“…Recently, microfluidic investigations have unveiled the sensitivity of the stable croissant and slipper shapes in relation to biophysical cell properties such as RBC age and reduced membrane deformability. 15 Utilizing RBCs from healthy donors and employing density gradient centrifugation methods, it has been demonstrated that the proportion of stable asymmetric, off-centered slipper-like cells diminishes with increasing age, while aged cells exhibit an augmented prevalence of stable symmetric croissants along the microchannel centerline. Consequently, analysis of the RBC shape phase diagram facilitates the discrimination of distinct RBC sub-populations, notably revealing variations in cell age.…”

“…While experimental and numerical progress has advanced our understanding of how intrinsic cell properties, such as their deformability, cytosol viscosity, viscoelasticity of the membrane, and age, affect the RBC shape and microscale flow behavior, 15,33,34 detailed experimental investigations of how slight changes in the channel confinement affect the RBC capillary flow and the shape phase diagram remain scarce. Presently, poly(dimethylsiloxane) (PDMS) microchannels fabricated using soft lithography techniques serve as a common platform to investigate the microscale flow of biological systems.…”