Transient low shear-stress preconditioning influences long-term endothelial traction and alignment under high shear...

Area of Science:

• Vascular biology
• Cellular biomechanics
• Biophysics

Background:

• Endothelial cells (ECs) respond to fluid shear stress (FSS), a critical factor in vascular health.
• High laminar FSS is generally beneficial, while low or disturbed FSS can lead to endothelial dysfunction and inflammation.
• The adaptive mechanisms of ECs to dynamic FSS changes are not fully understood.

Purpose of the Study:

• To investigate how endothelial cells adapt their traction forces during transitions from low to high fluid shear stress.
• To elucidate the long-term effects of initial shear stress exposure on endothelial cell behavior and alignment.
• To understand the influence of shear stress history on endothelial cell responses.

Main Methods:

• Utilized traction force microscopy combined with a custom flow chamber to analyze human umbilical vein endothelial cells.
• Applied controlled transitions between low and high fluid shear stress conditions.
• Employed Granger causality analysis to determine the functional relationship between traction vector orientation and cell alignment.

Main Results:

• Initial low FSS exposure resulted in a delayed but substantial increase in EC traction under subsequent high FSS.
• Direct high FSS caused a rapid traction surge followed by a significant decrease below baseline.
• The orientation of EC traction vectors was found to be dependent on the initial shear stress exposure, influencing subsequent cell alignment.

Conclusions:

• Short-term exposure to low FSS has a lasting impact on endothelial cell traction and orientation.
• The history of shear stress exposure critically dictates endothelial cell adaptive responses and alignment.
• A functional link exists between the direction of endothelial cell traction and cell orientation in response to varying shear stress patterns.