Quantitative prediction of flow dynamics and mechanical retention of surface-altered red blood cells through a splenic slit

XJ Qi and S Wang and SH Ma and KQ Han and XJ Li, PHYSICS OF FLUIDS, 33, 051902 (2021).

DOI: 10.1063/5.0050747

Normal red blood cells (RBCs) have remarkable properties of deformability, which enable them to squeeze through tiny splenic inter- endothelial slits (IESs) without any damage. Decreased surface-area-to- volume (SA/V) ratio through the loss of membrane surface is a key determinant of splenic entrapment of surface-altered RBCs due to cell aging or disease. Here, we investigate the flow dynamics and mechanical retention of the surface-altered RBCs with different extents of surface area loss, using a multiscale RBC (MS-RBC) model implemented in dissipative particle dynamics (DPD). We show that the DPD-based MS-RBC simulations can accurately reproduce the ex vivo experimentally measured rate of RBC mechanical retention when we take into account the distribution of RBC surface area (i.e., the size difference within the RBC population). We also examine the cumulative effect of the cell surface area loss on the traversal dynamics of the surface-altered RBCs, where we found that the final values of cell surface area (or the SA/V ratio) play a key role in determining the RBC traversal dynamics, regardless of the loss pathway of cell surface area. Taken together, these simulation results have implications for understanding the sensitivity of the splenic IESs to retain and clear the surface-altered RBCs with increased surface area loss, providing an insight into the fundamental flow dynamics and mechanical clearance of the surface- altered RBCs by the human spleen.

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