The influence of the endothelial surface layer on the motion of red blood cells

The endothelial lining of blood vessels presents a large surface area for exchanging materials between blood and tissues. The endothelial surface layer (ESL) plays a critical role in regulating vascular permeability, hindering leukocyte adhesion as well as inhibiting coagulation during inflammation. Once the ESL is pathologically altered, the changes in its topography are believed to cause vascular hyperpermeability and induce thrombus formation during sepsis. The occurrence of these biological phenomena requires Red Blood Cells (RBCs) stay within close proximity to the ESL, initiating RBC-layer interaction. To investigate the influence of various physical properties of the ESL on the motion of RBCs, we construct two models to represent the ESL combined with the immersed boundary method. In particular, we focus on analyzing how lift force and drag force change over time when a RBC is placed close to the ESL as the width, roughness, and permeability of the ESL vary. Our results suggest that increase in the ESL thickness has a dominant effect in slowing down the motion of RBCs for all physically-relevant permeability values, hindering the migration of RBCs from the layer; whereas effect of the roughness is minimal.