Shear stress gradient over endothelial cells in a curved microchannel system

Area of Science:

• Physiology
• Biophysics
• Microfluidics

Background:

• The microcirculation's complex fluid dynamics are critical for endothelial cell function.
• Accurate measurement of shear forces on endothelial cells is essential for understanding cellular responses.
• Existing models require validation against experimental data.

Purpose of the Study:

• To validate a scale model of microcirculation using in vitro experiments.
• To measure shear forces on endothelial cells within microchannels.
• To compare experimental findings with computational fluid dynamics (CFD) simulations.

Main Methods:

• In vitro experiments using D-shaped microchannels lined with endothelial cells.
• Tracking fluorescently labeled microspheres to determine velocity profiles.
• Utilizing computational fluid dynamics (CFD) to simulate wall shear stress gradients.
• Comparing velocity profiles with and without endothelial cell nuclei.

Main Results:

• Endothelial cell nuclei significantly altered and sharpened the microsphere velocity profile.
• Experimental data confirmed the scale model's ability to represent shear stress exposure.
• CFD simulations predicted a 2-fold greater radial than axial wall shear stress gradient over nuclei.
• Nuclear position influenced the wall shear stress gradient.

Conclusions:

• The validated scale model accurately represents microcirculatory shear forces on endothelial cells.
• Endothelial cell nuclei play a significant role in modulating local fluid dynamics.
• CFD simulations coupled with experimental data provide a powerful tool for microcirculation research.