Characterization of engineered tissue development under biaxial stretch using nonlinear optical microscopy.

Area of Science:

• Biomedical Engineering
• Cell Biology
• Materials Science

Background:

• Cells sense and respond to mechanical stimuli to maintain or remodel the extracellular matrix in tissues.
• Understanding these stimuli is crucial for tissue morphogenesis, wound healing, and tissue engineering.
• Current knowledge of cellular responses to multiaxial loading in soft tissues is limited.

Purpose of the Study:

• To investigate the precise mechanical stimuli cells sense and respond to during extracellular matrix remodeling in multiaxially loaded tissues.
• To develop a system for characterizing matrix organization under defined mechanical conditions.
• To differentiate the contributions of applied stretches, cell-mediated tractions, and matrix remodeling to matrix organization.

Main Methods:

• Custom tissue culture device designed to impart well-defined biaxial stretches on fibroblast-seeded collagen gels.
• Integration of the tissue culture device with a nonlinear optical microscopy (NLOM) system for microscopic characterization.
• Utilized a cruciform gel geometry for direct comparison of uniaxial and biaxial loading conditions.
• Performed sequential NLOM measurements over 6 days under various conditions (stretched, unloaded, decellularized).

Main Results:

• The custom device successfully imparted biaxial stretches and allowed for microscopic characterization of matrix organization.
• NLOM enabled visualization of collagen fiber orientations and their changes over time.
• The study delineated the distinct contributions of applied stretches, cell-mediated tractions, and matrix remodeling to the observed matrix distributions.
• Dynamic tissue properties in culture were visualized using intravital NLOM and novel bioreactors.

Conclusions:

• The developed system enables the visualization of dynamic tissue properties in culture.
• This approach provides insights into how cells sense and respond to mechanical stimuli in tissue remodeling.
• The findings support advancements in soft tissue engineering, wound healing, and understanding tissue morphogenesis.