Cartilage structure-inspired nanofiber-hydrogel composite with robust proliferation and stable chondral lineage-specific differentiation function to orchestrate cartilage regeneration for artificial tracheal construction.

Abstract

Tissue engineering strategies hold promise for constructing biomimetic tracheal substitutes to repair circumferential tracheal defects. However, current strategies for constructing off-the-shelf cartilage analogs for artificial trachea grafts face challenges of chondrocyte scarcity and inadequate culture strategies, which require extensive cell expansion and prolonged <i>in vitro</i> culture to generate robust neo-cartilage. To address these issues, we developed a nanofiber-hydrogel composite with superior mechanical performance by incorporating fragment oxidized bacterial cellulose (BC) nanofibers into a gelatin methacryloyl (GelMA) hydrogel network. Additionally, a biomaterial system was developed based on this composite, featuring dual-release functionality of fibroblast growth factor (FGF) and transforming growth factor beta (TGF-β) to facilitate step-wise maturation of neo-cartilage tissue. This process includes early-stage proliferation followed by second-stage extracellular matrix (ECM) deposition, driving the transition from proliferation to chondrogenesis. By encapsulating chondrocytes within the biomaterial system, mature neo-cartilage tissues with typical cartilage lacunae structures and abundant homogeneous cartilage-specific ECM deposition were successfully regenerated <i>in vitro</i> and <i>in vivo</i>. Furthermore, with a tailor-made growth factor-releasing strategy, the biomaterial system with low cell seeding density achieved biochemically and biomechanically functional neo-cartilage tissue regeneration, comparable to that achieved with high cell seeding density in the nanofiber-hydrogel composite. Based on the current biomaterial system, mature and functional cartilage-ring analogs were successfully constructed and applied to repair tracheal defects. Overall, the biomaterial system developed in this study provides a promising strategy for engineering transplantable, high-quality cartilage substitutes, with translational potential for artificial trachea construction.