Double network hydrogels encapsulating genetically modified dedifferentiated chondrocytes for auricular cartilage regeneration

Microtia profoundly affects patients' appearance and psychological well-being. Tissue engineering ear cartilage scaffolds have emerged as the most promising solution for ear reconstruction. However, constructing tissue engineering ear cartilage scaffolds requires multiple passaging of chondrocytes, resulting in their dedifferentiation and loss of their special phenotypes and functions. To tackle these issues, here we employ guanidinobenzoic acid (GBA) modified generation 5 polyamidoamine (PAMAM) dendrimers (PG) as a Runx1 plasmid carrier to construct PG/pRunx1 polyplex nanoparticles. The PG/pRunx1 polyplexes are transfected into human auricular chondrocytes, significantly mitigating chondrocyte dedifferentiation and enhancing cartilage regeneration during the <i>in vitro</i> culture. Furthermore, we develop highly porous double-network hydrogels based on methacrylate-functionalized and oxidized chondroitin sulfate and carbohydrazide-modified gelatin and the hydrogels possessed both dynamic adaptability and mechanical support characteristics by reversible dynamic covalent crosslinking and static covalent crosslinking, serving as an ideal scaffold for tissue engineering. Consequently, chondrocytes treated with PG/pRunx1 polyplex nanoparticles are incorporated into the hydrogels to construct tissue-engineered auricular cartilage scaffolds. After subcutaneous implantation in nude mice, the scaffolds containing chondrocytes treated with PG/pRunx1 nanoparticles showed more mature cartilaginous tissue, characterized by prominent ECM deposition and enhanced chondrogenesis. Therefore, this research provides a novel strategy for the development of tissue-engineered auricular cartilage scaffolds.