Targeted S100A8 PP-Cas9@PLGA-apt microparticles reduced cartilage degradation and subchondral bone isomerism in osteoarthritis treatment through JAK/STAT3 pathway modulation.

Synovial inflammation caused by osteoarthritis (OA) results in the release of numerous pro-inflammatory factors that promote cartilage degradation and pathological changes of subchondral bone. Nowadays, S100A8 has been recognized as a critical factor in the progression of inflammatory diseases, but its role in OA still needs to be confirmed. At the same time, the gene editing technology has emerged as a novel therapeutic approach for OA, such as clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) technology, but application in inflammatory gene therapy still requires advanced delivery systems to ensure cell-specific targeting and biosafety. In this study, S100A8 was confirmed as a key mediator perpetuating JAK/STAT3 pathway activation in OA progression by integrated RNA bioinformatics and synovial proteomic analyses. Based on it, we developed a polyamidoamine (PAMAM)-poly (lactic-co-glycolic acid) (PLGA) (PP) nanocore electrostatically complexed with Cas9-S100A8, encapsulated within an aptamer (apt)-grafted PLGA shell structure. This multifunctional nanocarrier could reduce dendrimer toxicity to cells and protein degradation, and enhance cellular targeting and endocytic capacity. PP-Cas9-S100A8@PLGA-apt exhibited 64.4 % S100A8 knockout efficiency (p < 0.001) and sustained mRNA release (71.5 % retention at 48 h), high cell viability (>80 %), and synovium-specific uptake (98.8 % at 0.8 μg/mL), inhibiting the JAK/STAT3 pathway. In OA-induced mice, this inhibition reduced pro-inflammatory responses, cartilage degradation, and attenuated osteophyte volume. Our findings first established PP-Cas9-S100A8@PLGA-apt as an efficient and safe Cas9 delivery tool, advancing studies of JAK/STAT3 pathway inhibition and the clinical translation of gene therapy for OA.