An in situ gelling BMSC-laden collagen/silk fibroin double network hydrogel for cartilage regeneration

Abstract

Collagen (Col)-based injectable hydrogels are desirable scaffolds for cartilage tissue engineering. However, fabrication of Col-based injectable hydrogels with short gelation time, great biocompatibility and good mechanical properties still faces great challenges. In this work, an injectable bone marrow mesenchymal stem cell (BMSC)-encapsulated double network (DN) hydrogel was fabricated via collagen (Col), silk fibroin (SF) and poly(ethylene glycol) (PEG), in which PEG-Tetrazine (Tz) and Col-Norbornene (Nb) were used to crosslink through bioorthogonal reactions to form the first network rapidly, and ultrasonic induction was carried out to form the second SF network. The experimental results showed that the mechanical properties of the Col-PEG/SF DN hydrogel were obviously enhanced compared to those of Col-PEG or SF single network hydrogels. In vivo assays demonstrated that the Col-PEG/SF DN hydrogel could significantly repair full-thickness cartilage defects generated in a rat model after 8 weeks of implantation. These results suggested that the Col-PEG/SF DN hydrogel possesses excellent properties and is a potential treatment candidate for cartilage tissue engineering.