Mechanically conditioned cell sheets cultured on thermo-responsive surfaces promote bone regeneration

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Cell sheet-based scaffold-free technology is promising for tissue engineering.
• Challenges include poor mechanical strength and insufficient extracellular matrix in harvested cell sheets.
• Mechanical loading enhances extracellular matrix production but lacks effective application methods for cell sheets.

Purpose of the Study:

• To develop and optimize thermo-responsive elastomer substrates for cell sheet culturing and mechanical conditioning.
• To investigate the impact of mechanical stimulation on cell sheet properties and bone regeneration.
• To create high-quality cell sheets for bone tissue engineering applications.

Main Methods:

• Preparation of thermo-responsive poly(N-isopropyl acrylamide) (PNIPAAm) grafted poly(dimethylsiloxane) (PDMS) substrates.
• Culturing MC3T3-E1 cells on substrates under cyclic mechanical stretching.
• Harvesting cell sheets via temperature reduction and evaluating their characteristics.
• Assessing new bone formation after implanting conditioned cell sheets into mouse calvarial defects.

Main Results:

• Optimized PNIPAAm grafting improved cell behavior on substrates.
• Mechanical conditioning significantly increased extracellular matrix content and cell sheet thickness.
• Up-regulation of osteogenic gene expression and matrix components was confirmed.
• Mechanically conditioned cell sheets markedly enhanced new bone formation in vivo.

Conclusions:

• Thermo-responsive elastomer substrates combined with mechanical conditioning effectively produce high-quality cell sheets.
• This approach shows significant potential for advancing bone tissue engineering.
• The developed method addresses key limitations in current cell sheet technology.