From macroscopic mechanics to cell-effective stiffness within highly aligned macroporous collagen scaffolds

Area of Science:

• Biomaterials Science
• Cellular Mechanics
• Tissue Engineering

Background:

• Macroporous biomaterial scaffolds are designed for tissue regeneration, but their macroscopic mechanical properties are often prioritized over the microscopic environment experienced by cells.
• The cellular mechanical environment significantly influences cell proliferation, differentiation, and extracellular matrix formation, impacting tissue regeneration outcomes both in vitro and in vivo.

Purpose of the Study:

• To investigate how architectural features of aligned macroporous collagen scaffolds influence mechanical properties at both macroscopic and microscopic scales.
• To develop and validate a finite element model (FE-model) that relates macroscopic scaffold properties to the cell-effective stiffness experienced by adhering cells.
• To establish a predictive model for cell-effective stiffness in complex biomaterial architectures for improved tissue regeneration.

Main Methods:

• Fabrication of highly aligned macroporous collagen scaffolds using controlled freezing and freeze-drying techniques.
• Characterization of scaffold architectural features to inform the development of a predictive finite element model (FE-model).
• Validation of the FE-model through experimental mechanical compression testing and atomic force microscopy at both macro- and microscopic levels.

Main Results:

• A finite element model (FE-model) was developed to predict the cell-effective stiffness of macroporous collagen scaffolds.
• A consistent linear relationship was identified between macroscopic scaffold stiffness and cell-effective stiffness, with the latter being approximately 6.4 times higher.
• The in vitro relevance of cell-effective stiffness in controlling progenitor cell differentiation was experimentally confirmed.

Conclusions:

• The study successfully predicted cell-effective stiffness in complex biomaterial scaffolds, a critical factor for early-stage tissue regeneration.
• The developed FE-modeling approach is transferable to other macroporous biomaterial architectures, offering a versatile tool for design optimization.
• Understanding and optimizing the cell-specific mechanical environment is key to enhancing biomaterial-based tissue regeneration strategies.