EXO/hydrogel system for sequential regulation of endogenous hyaline cartilage regeneration

Articular cartilage repair remains a clinically significant challenge due to its limited regenerative capacity and vulnerability to inflammation-induced damage and fibrocartilage formation. Current therapeutic strategies frequently fail to enhance intrinsic repair capacity or overcome the dual barriers of injury/inflammation-driven fibrosis and insufficient hyaline cartilage regeneration, often yielding suboptimal outcomes. Here, we developed an exosome-integrated hydrogel system for temporally programmed drug delivery. Kartogenin (KGN) and halofuginone (HF) were encapsulated into human umbilical cord MSC-derived exosomes (EXO_KGN/EXO_HF). EXO_HF was specifically immobilized in GelMA hydrogel via CP05-CD63 binding, while EXO_KGN was incorporated unbound. This design achieved rapid release of EXO_KGN versus sustained retention of EXO_HF for sequential therapeutic action. The rapidly released EXO_KGN initiated bone marrow-derived mesenchymal stem cell (BMSC) migration and chondrogenic differentiation in the repair process. Concurrently, the sustained release of EXO_HF demonstrated anti-inflammatory and anti-fibrotic effects during later regenerative phases. This sequential release profile-first promoting BMSC recruitment and chondrogenesis, then suppressing inflammation and fibrocartilage formation-synergistically enhanced hyaline cartilage repair. Importantly, we identified that HF dynamically modulates inflammatory chemokines through the cGAS-STING pathway, maintaining a pro-regenerative microenvironment. In conclusion, our exosomal dual-drug hydrogel with sequential release successfully coordinated chondrogenesis promotion and inflammation/fibrosis suppression, significantly enhancing hyaline cartilage regeneration. Also revealed was HF's cGAS-STING immunomodulatory mechanism, demonstrating strong potential for clinical translation.