Modular Parallel Plate Flow Chamber with Tunable Substrate Mechanics and Defined Shear Stress.

Area of Science:

• Biomaterials Science
• Cell Biology
• Biophysics

Background:

• * Current *in vitro* models often study extracellular matrix (ECM) stiffness and fluid shear stress (FSS) independently.
• * This limits understanding of cellular mechanotransduction in response to multiple cues.
• * A need exists for models that can independently control and apply multiple mechanical stimuli.

Purpose of the Study:

• * To develop and validate a novel parallel plate flow chamber with a tunable polyacrylamide (PAA) substratum.
• * To enable independent control of substrate stiffness and FSS for studying cellular responses.
• * To investigate the synergistic effects of simultaneous mechanical cues on cell behavior.

Main Methods:

• * Fabricated a parallel plate flow chamber with a PAA substratum.
• * Characterized PAA mechanical properties and confirmed support for Madin-Darby canine kidney cell growth.
• * Validated controlled FSS application using particle image velocimetry.
• * Analyzed F-actin organization to quantify cellular responses.

Main Results:

• * The PAA substratum demonstrated controllable mechanical properties across various stiffnesses.
• * The flow chamber design maintained predictable fluid channel height for accurate FSS application.
• * Substrate stiffness and FSS synergistically increased F-actin filament length.
• * Stiffness and FSS showed independent effects on F-actin filament width.

Conclusions:

• * The developed model effectively allows independent and tunable control of substrate stiffness and FSS.
• * This system provides a valuable tool for investigating the impact of concurrent mechanical forces on cellular behavior.
• * Findings highlight the synergistic relationship between ECM stiffness and FSS in regulating cell cytoskeletal organization.