Collagen Gels with Different Fibrillar Microarchitectures Elicit Different Cellular Responses

Area of Science:

• Biomaterials Science
• Cell Biology
• Tissue Engineering

Background:

• The extracellular matrix (ECM) comprises fibrillar proteins with diverse architectures and mechanical properties across tissues.
• Understanding how ECM fibril characteristics influence cell behavior is crucial for biomaterial design.

Purpose of the Study:

• To investigate the impact of collagen fibril properties on human mesenchymal stem cell (hMSC) dynamics and differentiation.
• To correlate cell responses with both local microarchitecture and bulk mechanical properties of engineered collagen gels.

Main Methods:

• Systematic polymerization of collagen gels at varying temperatures to create substrates with tunable mechanics and defined microarchitecture.
• Assessing hMSC spreading, proliferation, migration, and differentiation on these engineered substrates.
• Analyzing cellular traction force transmission, focal adhesion formation, and matrix remodeling.

Main Results:

• High fiber stiffness and short fiber lengths limited cellular force transmission, suppressing hMSC spreading, proliferation, and migration.
• Cells on stiff, short fibers exhibited reduced focal adhesion formation and altered lineage preferences.
• Enhanced cell spreading, proliferation, and migration correlated with fiber recruitment, matrix deformation, and increased collagen density.
• Cells on more compliant matrices showed a preference for osteogenic differentiation and greater focal adhesion development.

Conclusions:

• Fibrillar properties, not just bulk mechanics, critically regulate cell mechanotransduction and behavior.
• Tailoring collagen fibril architecture is essential for designing biomimetic materials that guide stem cell fate.
• Findings provide design criteria for advanced tissue engineering scaffolds and biomaterials.