Synovial fluid exosome-mediated crosstalk between synoviocytes and chondrocytes in development and progression of knee osteoarthritis

• Synovial fluid exosomes mediate bidirectional signaling between synoviocytes and chondrocytes, playing a dual role in knee osteoarthritis progression by both aggravating and protecting against cartilage degeneration and synovial inflammation. • Dynamic changes in exosomal non-coding RNAs (e.g., miR-140-5p, miR-21-5p, circ_0001236) correlate with disease stage, suggesting exosomes as potential liquid biopsy biomarkers for knee osteoarthritis. • Multi-omics and single-cell sequencing combined with exosome profiling reveal that synovial fluid exosomes regulate not only the classical NF-κB pathway but also emerging pathways such as ferroptosis, pyroptosis, and immunometabolic reprogramming. • Engineered exosomes, particularly mesenchymal stem cell-derived exosomes enriched with specific miRNAs (e.g., miR-140-3p, miR-26a-5p), show promise for enhancing anti-inflammatory effects and targeted therapy in knee osteoarthritis.