Scaffold‐free three‐dimensional cartilage regeneration based on cartilaginous organoids bioassembly technology

Cartilage tissue engineering is a promising strategy to repair damaged tissue and reconstruct organ function, but the scaffold‐free cartilage regeneration technology is currently limited in its ability to construct three‐dimensional (3D) shapes, maintain the chondrogenic phenotype, and express cartilage‐specific extracellular matrix (ECM). Recently, cartilaginous organoids (COs), multicellular aggregates with spheroid architecture, have shown great potential in miniaturized cartilage developmental models in vitro. However, high‐efficiency and transferable in vivo organoid‐based 3D cartilage regeneration technology for preclinical research needs further exploration. In this study, we develop novel cartilaginous organoids bioassembly (COBA) strategy to achieve scaffold‐free 3D cartilage regeneration, which displays batch‐to‐batch efficiency, structural integration, and functional reconstruction. For underlying molecule mechanism, cellular adhesion proteins significantly regulate cell aggregation and cytoskeleton reorganization to form cartilaginous spheroids, and the hypoxic microenvironment created by high‐density cell aggregates synergistically activates hypoxia‐inducible factor‐1α‐mediated glycolytic metabolism reprogramming to maintain the chondrogenic phenotype and promote cartilage‐specific ECM deposition. Furthermore, separated COs can integrate into a complete and continuous cartilage tissue through the COBA approach, and thus facilitate raising the nasal dorsa in goats after minimally invasive injection. This study thus demonstrates the promise of COBA technology to achieve scaffold‐free 3D cartilage regeneration for organoid‐based translational applications.