A novel in vitro flow system for changing flow direction on endothelial cells

Area of Science:

• Biomedical Engineering
• Cell Biology
• Fluid Dynamics

Background:

• Atherosclerotic plaques form in areas of disturbed blood flow, like bifurcations and curves.
• These disturbed flow regions exhibit complex, multi-directional shear stress due to vortices.
• Existing in vitro models cannot replicate these multi-directional flow changes.

Purpose of the Study:

• To develop a novel in vitro flow system capable of simulating multi-directional shear stress.
• To investigate endothelial cell response and re-alignment to dynamic changes in flow direction.
• To analyze the cellular mechanisms, including actin remodeling, involved in sensing altered flow.

Main Methods:

• Development of a new in vitro flow system allowing flow direction changes at any angle.
• Pre-alignment of endothelial cells under laminar shear stress.
• Rotation of the flow system to induce changes in shear stress direction (e.g., 90°).
• Microscopic analysis of cell re-alignment and actin stress fiber organization over 24 hours.

Main Results:

• Endothelial cells successfully re-aligned to the new flow direction within 24 hours after a 90° rotation.
• Cell re-alignment was mediated by the remodeling and gradual rotation of actin stress fibers.
• The developed system effectively simulated dynamic changes in shear stress direction.

Conclusions:

• The novel flow system enables the study of endothelial cell mechanosensing in response to complex, dynamic flow patterns.
• Endothelial cells exhibit adaptive re-alignment capabilities through actin cytoskeleton remodeling.
• This technology provides a platform for further research into the role of flow dynamics in vascular diseases like atherosclerosis.