Interface integration of layered collagen scaffolds with defined matrix stiffness: implications for sheet-based...

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cellular Mechanics

Background:

• Successful sheet-based tissue engineering relies on integrating construct components.
• Matrix stiffness is a critical regulator of cellular responses like migration and collagen deposition at interfaces.
• Developing models to control interface matrix stiffness is essential for understanding tissue integration.

Purpose of the Study:

• To develop and utilize a sheet-based 3D model for controlling interface matrix stiffness.
• To investigate the impact of varying matrix stiffness on cell behavior and interface integration in bilayer hydrogel constructs.
• To assess the relationship between matrix stiffness, cell migration, interface adhesive strength, and construct fusion.

Main Methods:

• Acanular or fibroblast-seeded bilayer collagen hydrogel constructs were created.
• Plastic compression was used to increase collagen density and matrix stiffness.
• Constructs were cultured under high-stiffness (compressed day 0) or low-stiffness (compressed day 7) conditions.
• Interface adhesive strength was measured using a mechanical testing system.
• Finite element modeling was employed to analyze stress distribution at the interface.
• Cell migration and interface fusion were visualized and quantified.

Main Results:

• Cell-seeded constructs exhibited a six-fold increase in interface adhesive strength compared to acellular controls.
• No significant difference in interface adhesive strength was observed between low- and high-stiffness cultures after 1 week.
• Initial cell migration across the interface was higher in low-stiffness constructs at 24 hours, but this difference diminished by 1 week.
• Interface fusion between the two layers was observed in low-stiffness constructs but not in high-stiffness constructs after 1 week.

Conclusions:

• Controlling matrix stiffness in 3D models can modulate early cellular responses at tissue interfaces.
• While initial cell migration is affected by stiffness, long-term interface adhesive strength may not be significantly different after 1 week.
• Matrix stiffness plays a crucial role in promoting interface fusion, essential for successful tissue integration.
• This model provides a tool for studying cellular behavior at interfaces in bioengineered tissues.