Effect of synovial fibroblast (SFB)-derived exosomes in cartilage explants. Mouse femoral head cartilage explants cultured with exosomes from non-stimulated SFB or IL-1β-stimulated SFB. Exosomes were isolated from SFB-conditioned medium using ExoQuick™ reagent. Proteoglycan release into the conditioned medium from cartilage was analyzed. Exosomes from IL-1β-stimulated SFB induced significantly more proteoglycan release than exosomes from non-stimulated SFB. Data are the means ± standard error of the mean. Comparison of mean values was performed by the Steel test; *P <0.05 versus control (Cont). Cont, isolated exosomes from fresh-DMEM with 10% FBS; Exo -IL-1β, exosomes from non-stimulated SFB; Exo + IL-1β, exosomes from IL-1β-stimulated SFB.