Bioinspired scaffold recapitulating chondrogenic ontogeny and microenvironment for functional cartilage regeneration

Focal articular cartilage defects often progress to osteoarthritis, imposing a substantial global health burden. Current neglect of cartilage developmental regulation and cartilage microenvironment compromises therapeutic efficacy. We developed an innovation CE-SKP/CPH/P2G3 scaffold which effectively repairs focal cartilage defects and emulates native cartilage ontogeny: the superficial CE-SKP hydrogel layer recruits SMSCs and promotes chondrogenesis; the middle CPH hydrogel layer induces chondrocyte hypertrophic calcification, forming cartilage calcified layer; and the basal P2G3 nanofiber membrane isolates subchondral cells, enforcing a top-down developmental sequence and preserving a localized hypoxic niche. In vitro characterization confirms that the porosity, swelling ratio, biodegradation rate, and biocompatibility are optimal for sequential SMSC recruitment, cartilage differentiation, hypertrophic mineralization, and cells isolation. In vivo, the biomimetic tri-layer scaffold promotes regeneration of both cartilage and calcified cartilage by recapitulating the native ontogenetic progression from cartilage to calcified cartilage within the in vivo microenvironment, successfully restoring the normal physiological structure of articular cartilage by 24 weeks post-implantation. ScRNA-seq revealed SMSCs and a novel chondrocyte subpopulation CHON_5 as key repair populations, SMSCs mediated early repair via hypoxia response and migration, while CHON_5 promoted ECM remodeling, synergistically enhancing regeneration in late repair stage. Furthermore, we identified FGF signaling (FGF2-FGFR1/2 and FGF18-FGFR1/2 pairs) was crucial for MSC-CHON_5 communication during sequential cartilage regeneration. Overall, by recapitulating native developmental dynamics and microenvironmental cues, this scaffold offers a novel and effective strategy for functional cartilage regeneration and osteoarthritis treatment.