Directing collagen fibers using counter-rotating cone extrusion

Area of Science:

• Biomaterials Engineering
• Tissue Engineering
• Biophysics

Background:

• Bio-inspired tissue engineering requires mimicking the extracellular matrix's anisotropic structure and mechanical properties.
• Controlling the orientation of native insoluble collagen fibers is challenging but crucial for functional tissue equivalents.

Purpose of the Study:

• To develop a method for engineering tubular collagen constructs with defined fiber anisotropy.
• To investigate the relationship between extrusion parameters and collagen fiber alignment.
• To assess the mechanical properties of the engineered collagen constructs.

Main Methods:

• Utilized controlled counter-rotating cone extrusion technology with bovine skin collagen.
• Analyzed collagen fiber orientation using second harmonic generation microscopy and quantitative image analysis.
• Varied cone rotation speeds to influence shear forces and collagen alignment.

Main Results:

• Successfully engineered tubular collagen constructs with oriented collagen fibers and bundles.
• Demonstrated a correlation between shear forces during extrusion and the direction/extent of fiber alignment.
• Observed a gradual change in fiber direction ( +50° to -40°) within the constructs.
• Engineered constructs exhibited tunable elasticity (900-2000 kPa) and toughness (19-35 mJ) based on cone speeds.

Conclusions:

• Rotational extrusion is an enabling technology for creating and controlling the anisotropic architecture of collagen constructs.
• This method offers a pathway for fabricating tailored collagen scaffolds for tissue engineering and regenerative medicine.