Elastic Fiber-Reinforced Silk Fibroin Scaffold with A Double-Crosslinking Network for Human Ear-Shaped Cartilage Regeneration

Tissue engineering provides a promising approach for regenerative medicine. The ideal engineered tissue should have the desired structure and functional properties suitable for uniform cell distribution and stable shape fidelity in the full period of in vitro culture and in vivo implantation. However, due to insufficient cell infiltration and inadequate mechanical properties, engineered tissue made from porous scaffolds may have an inconsistent cellular composition and a poor shape retainability, which seriously hinders their further clinical application. In this study, silk fibroin was integrated with silk short fibers with a physical and chemical double-crosslinking network to fabricate fiber-reinforced silk fibroin super elastic absorbent sponges (Fr-SF-SEAs). The Fr-SF-SEAs exhibited the desirable synergistic properties of a honeycomb structure, hygroscopicity and elasticity, which allowed them to undergo an unconventional cyclic compression inoculation method to significantly promote cell diffusion and achieve a uniform cell distribution at a high-density. Furthermore, the regenerated cartilage of the Fr-SF-SEAs scaffold withstood a dynamic pressure environment after subcutaneous implantation and maintained its precise original structure, ultimately achieving human-scale ear-shaped cartilage regeneration. Importantly, the SF-SEAs preparation showed valuable universality in combining chemicals with other bioactive materials or drugs with reactive groups to construct microenvironment bionic scaffolds. The established novel cell inoculation method is highly versatile and can be readily applied to various cells. Based on the design concept of dual-network Fr-SF-SEAs scaffolds, homogenous and mature cartilage was successfully regenerated with precise and complicated shapes, which hopefully provides a platform strategy for tissue engineering for various cartilage defect repairs. Graphical Abstract