Red blood cells show five-stage deformation in bifurcated microvessels

Red blood cells (RBCs) are not rigid structures; they can change shape as they circulate through the bloodstream, buffeted by endless shifts in fluid flow and dynamics. Those changes affect not only how the cells travel individually, but the overall flow of blood, especially in the continually bifurcating structures of the microvasculature.

Using a sophisticated three-dimensional modeling technique called smoothed dissipative particle dynamics (SDPD), researchers report in the Journal of Applied Physics on how a RBC moves and deforms through diverging-converging bifurcated microvessels. The results also include how it responds to those changes, including properties of shape, shear modulus, and bending modulus.

The authors used the SDPD technique because it combines the best features of smoothed particle hydrodynamics (SPH) and dissipative particle dynamics (DPD), with a stronger connection to actual physical conditions at the mesoscale. They found that a RBC undergoes a five-stage deformation process as it approaches, encounters, passes through, and exits a diverging-converging bifurcated microvessel, changing its shape and properties in a predictable pattern.

It begins to deform as it approaches the bifurcation conjunction, then stays at that point for a while (relatively speaking) before slipping into one of the branches, with a preference for a wider branch with a higher flow rate. As the RBC passes through to the bifurcation convergence, it stretches and deforms further until returning to the parent microvessel, where its shape continues to undergo some fluctuation.

The work provides new insight into the dynamics of both healthy and diseased RBCs in microvascular networks from a three-dimensional view, which is important in the understanding of disease processes such as tumor cell circulation and thrombus formation.

Source: “Three-dimensional motion and deformation of a red blood cell in bifurcated microvessels,” by Ting Ye, Lina Peng, and Yu Li, Journal of Applied Physics (2018). The article can be accessed at https://doi.org/10.1063/1.5013174 .