The relationship between crosslinking structure and silk fibroin scaffold performance for soft tissue engineering

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Polymer Chemistry

Background:

• Silk fibroin (SF) scaffolds are promising for soft tissue engineering due to their elasticity and robustness.
• Cryogelation is a method used to prepare these SF scaffolds.
• Understanding the role of crosslinking agents like ethylene glycol diglycidyl ether (EGDE) is key to optimizing scaffold performance.

Purpose of the Study:

• To investigate the impact of varying ethylene glycol diglycidyl ether (EGDE) concentrations on the in vitro and in vivo properties of silk fibroin (SF) scaffolds.
• To determine the optimal EGDE dosage for achieving desired mechano- and bio-performance in SF scaffolds for soft tissue engineering.

Main Methods:

• Preparation of SF scaffolds using cryogelation with varying EGDE concentrations (1-5 mmol/g).
• In vitro characterization including assessment of β-sheet conformation, tensile properties, and cytotoxicity assays (NIH3T3 fibroblasts).
• In vivo subcutaneous implantation in animal models to evaluate degradation, tissue ingrowth, and foreign body reactions over 28 days.

Main Results:

• Increasing EGDE content altered β-sheet conformation, increased tensile modulus, and decreased elasticity.
• SF scaffolds with EGDE up to 5 mmol/g showed no in vitro cytotoxicity.
• Scaffolds with <3 mmol/g EGDE exhibited favorable degradation and tissue ingrowth, while higher concentrations (≥3 mmol/g) induced foreign body reactions.

Conclusions:

• The concentration of EGDE significantly influences the structural, mechanical, and biological properties of SF scaffolds.
• An optimal EGDE dosage is critical for balancing mechanical strength, degradation kinetics, and biocompatibility for soft tissue engineering applications.
• Excessive crosslinking can lead to adverse in vivo responses, highlighting the importance of precise crosslinking control.