Biophysical and biological characterisation of collagen/resilin-like protein composite fibres

Collagen type I, in various physical forms, is widely used in tissue engineering and regenerative medicine. To control the mechanical properties and biodegradability of collagen-based devices, exogenous cross-links are introduced into the 3D supramolecular structure. However, potent cross-linking methods are associated with cytotoxicity, whilst mild cross-linking methods are associated with suboptimal mechanical resilience. Herein, we assessed the influence of resilin, a super-elastic and highly stretchable protein found within structures in arthropods where energy storage and long-range elasticity are needed, on the biophysical and biological properties of mildly cross-linked extruded collagen fibres. The addition of resilin-like protein in the 4-arm poly(ethylene glycol) ether tetrasuccinimidyl glutarate cross-linked collagen fibres resulted in a significant increase of stress and strain at break values and a significant decrease of modulus values. The addition of resilin-like protein did not compromise cell metabolic activity and DNA concentration. All groups are supported parallel to the longitudinal fibre axis cell orientation. Herein we provide evidence that the addition of resilin-like protein in mildly cross-linked collagen fibres improves their biomechanical properties, without jeopardising their biological properties.