Development and Characterization of a Tunable PDMS Substrate Model for Investigating Elastic Properties and...

Area of Science:

• Biomaterials Science
• Cell Biology
• Biomechanics

Background:

• Intervertebral disc (IVD) degeneration is linked to aberrant mechanical loading and extracellular matrix (ECM) changes.
• This impairs annulus fibrosus (AF) integrity and necessitates advanced in vitro models for studying mechanical loading and cell-substrate interactions.

Purpose of the Study:

• To introduce a tunable stretching chamber platform for simultaneous investigation of mechanical loading and cell-substrate interactions in AF degeneration.
• To assess the impact of varying substrate stiffness and mechanical strain on AF cell behavior.

Main Methods:

• Fabrication of tunable polydimethylsiloxane (PDMS) substrates by adjusting Sylgard ratios.
• Characterization of substrate mechanical, optical, and chemical properties.
• Seeding of bovine AF cells and culture under static or cyclic strain (8% at 1 Hz) conditions.
• Assessment of cell viability, morphology, and alignment using digital image correlation (DIC) for strain analysis.

Main Results:

• PDMS formulations yielded a stiffness range of 8.72–238.00 kPa with distinct viscoelastic profiles.
• All substrates supported AF cell adhesion and viability.
• DIC revealed non-uniform strain distributions; cells maintained viability up to 14 hours and aligned perpendicular to the stretch axis within 6 hours.

Conclusions:

• The PDMS stretching platform provides a biocompatible, tunable mechanical environment mimicking physiological and pathophysiological conditions.
• Enables systematic studies on how substrate elasticity and strain modulate AF cell behavior in IVD disease.
• Highlights non-uniform strain distribution and discrepancies in effective strain transfer to the cell surface.