Increased Cell Traction-Induced Prestress in Dynamically Cultured Microtissues

Area of Science:

• Biomedical Engineering
• Mechanobiology
• Cardiovascular Research

Background:

• Prestress significantly impacts cardiovascular tissue functionality, influencing mechanical properties, growth, and remodeling.
• The development of tissue prestress is complex, with cell-generated traction forces via actin stress fibers being a key mechanism.
• Microtissue gauge platforms enable monitoring of prestress responses to perturbations.

Purpose of the Study:

• To investigate how dynamic cyclic stretching affects microtissue prestress.
• To elucidate the role of cell-generated traction forces in the development of tissue prestress.
• To assess the reversibility and regulation of cell-generated prestress.

Main Methods:

• Combined a microfabricated tissue gauge platform with a Flexcell system for dynamic cyclic stretching of microtissues.
• Validated the setup to accurately quantify dynamic microtissue stretch.
• Applied dynamic loading for 24 hours and monitored prestress, including experiments with ROCK-inhibitor.

Main Results:

• Dynamic cyclic stretching for 24 hours more than doubled microtissue prestress compared to static controls.
• ROCK-inhibitor addition completely abolished prestress, confirming its origin from cell-generated traction forces.
• Prestress levels were restored upon removal of the ROCK-inhibitor or return to static loading.

Conclusions:

• Cell-generated prestress is a highly controlled parameter regulated by actin stress fibers acting as a mechanostat.
• Dynamic loading regimes significantly enhance tissue prestress, with implications for cardiovascular tissue mechanics.
• Findings are critical for mechanical testing of cardiovascular tissues and designing tissue engineering therapies.