KGN-functionalized PLGA-nHA scaffold modulate TGF-β and Hippo pathways for osteochondral repair

• 3D-printed gradient porosity scaffold: 302 μm cartilage, 500 μm bone. • Kartogenin was covalently grafted onto a thermosensitive hydrogel with 48.3%. • Uniform hydroxyapatite coating boosted bone growth and neutralized acidic byproducts. Given the complexity of the osteochondral repair process, this study developed a composite scaffold system (KGN-Gel/PLGA nHA ) comprising a 3D-printed gradient-porosity PLGA scaffold (cartilage layer: 302 μm, calcified layer: dense, bone layer: 500 μm) uniformly coated with nano-hydroxyapatite (nHA), and a thermosensitive hydrogel (KGN-Gel) with covalently grafted Kartogenin (KGN, grafting rate 48.3%). Rabbit bone marrow mesenchymal stem cells (BMSCs) encapsulated in KGN-Gel were injected into the cartilage layer pores for in situ gelation. The system synergistically modulated TGF-β/Smad2/3 and Hippo signaling pathway crosstalk, promoting chondrogenic and osteogenic gene expression. In a rabbit osteochondral defect model, the scaffold achieved spatially specific repair with upper-layer cartilage and lower-layer bone regeneration. This integrated strategy provides a promising approach for osteochondral tissue engineering.