Local hemodynamics affect monocytic cell adhesion to a three-dimensional flow model coated with E-selectin

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Cell Biology

Background:

• Monocyte adhesion to endothelium is crucial for inflammatory responses.
• Hemodynamic forces and cell-surface interactions significantly influence monocyte adhesion.
• Previous studies show monocyte adhesion inversely correlates with wall shear stress on inert surfaces.

Purpose of the Study:

• To investigate the role of insolubilized E-selectin in mediating monocyte adhesion under varying wall shear stresses.
• To determine the effect of pulsatile versus steady flow on monocyte adhesion profiles.
• To correlate local hemodynamics with biological activity on the vessel wall in leukocyte adhesion.

Main Methods:

• Utilized a 3D axisymmetric flow model with stenosis and sudden expansion to create varied wall shear stress and flow patterns.
• Perfused pre-activated U937 cells through coated (E-selectin) and uncoated models under steady and pulsatile flow conditions.
• Employed computational fluid dynamics and particle tracking to characterize velocity fields and near-wall cell availability.

Main Results:

• Surface E-selectin significantly increased U937 cell adhesion compared to uncoated models across tested Reynolds numbers (steady flow).
• Under steady flow, E-selectin-mediated adhesion correlated with the reciprocal of wall shear stress in regions with high near-wall cell density.
• Pulsatile flow resulted in a more uniform distribution of adherent cells throughout the E-selectin-coated model.

Conclusions:

• Insolubilized E-selectin enhances monocyte adhesion, particularly at lower wall shear stresses.
• Flow patterns, specifically pulsatile flow, can alter the spatial distribution of leukocyte adhesion.
• Understanding both local hemodynamics and endothelial cell-surface interactions is critical for predicting leukocyte adhesion in vivo.