PLGA Nanoparticle-Mediated Sustained Release of Fisetin for Intra-Articular Therapy of Temporomandibular Joint Osteoarthritis.

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative maxillofacial disorder marked by progressive cartilage degradation and subchondral bone resorption, severely compromising patients' quality of life. Intra-articular injection (IA), a standard route for conservative therapy, offers clinical advantages in safety and efficacy; however, outcomes remain limited due to short drug retention, poor tissue penetration, and variable agent efficacy, necessitating repeated administration. To overcome these limitations, fisetin-loaded poly (lactic-co-glycolic acid) nanoparticles (FST-PNP) were developed as a localized drug delivery system (DDS) for TMJOA treatment. Physicochemical analyses showed FST-PNP had uniform spherical morphology, excellent dispersibility, stability, high encapsulation efficiency, and substantial drug loading capacity. An in vitro study demonstrated more sustained and stable release from FST-PNP than free fisetin. The in vivo IA administration of FST-PNP preserved mandibular condylar osteochondral structures in TMJOA models. Notably, FST-PNP suppressed the expression of metalloproteinase-13 and a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS5) as catabolic enzymes and downregulated p16 and p21 as senescence markers, indicating synergistic anti-inflammatory and anti-senescent effects. These findings highlight FST-PNP as a DDS integrating controlled-release with multifaceted therapeutic actions, providing a promising strategy for IA therapy of TMJOA.