목적: Mesenchymal stem cell therapy and diagnosis are gaining attention for their remarkable characteristics.They can rapidly multiply, renew themselves, differentiate into various cell types, effectively combat oxidative stress, and have ethical advantages over embryonic and induced pluripotent stem cells.However,limitations include immune response, potential tumor growth promotion, reduced differentiation capacity, and limited migration to target areas. Studies show that the underlying cytotoxicity of nanoparticles is unbalanced reactive oxygen species, oxidative stress, and ferroptosis which likely depend on their morphology, size, dosage, and coatings. We improved mesenchymal stem cells (MSCs) homing phenomenon with high anti-inflammatory effects for restoring damaged hair cells. This study aims to investigate the antioxidative response of MSCs derived from tonsils after labeling them with positively charged iron oxide nanoparticles, with and without pretreatment using n-acetyl cysteine (NAC). Additionally, we will evaluate the therapeutic efficacy of MSC-derived exosomes loaded with nanoparticles in an ex vivo model of hearing loss. 방법:Tonsil-derived MSCs were cultured and labeled cells were exposed to PYRB doses (5, 10, and 20ug/ml) for 24h. Cell viability was assessed using an enzyme-linked immunosorbent assay. Reactive oxygen species (ROS) presence was detected with a DCFDA cellular ROS detection kit, while antioxidant activities (catalase, SOD, GSH) were measured using a colorimetric microplate reader to evaluate oxidative stress. The quantitative polymerase chain reaction was used to analyze the expression levels of the ferroptosis downstream gene PTGS2 and the transferrin receptor TFRC. Exosomes were isolated from nanoparticle-induced MSCs using the ultracentrifuge technique, both with and without NAC pretreatment. These exosome isolates were then used in ex vivo cochlear explant experiment. 결과:Cell viability decreased based on the dose and duration of exposure. Moreover, the labeling of positively charged iron oxide nanoparticles led to an increase in reactive oxygen species. However, pretreatment with N-acetylcysteine rescued the cells by reducing ROS levels. The activity of catalase and superoxide dismutase decreased, while the presence of oxidized glutathione increased and the ratio of reduced glutathione to GSSG decreased when using 10 and 20 g/ml of positively charged IONP. Interestingly, GSH levels did not show a significant difference,indicating that mesenchymal stem cells primarily responded to IONPs through catalase activity. However, pretreatment with NAC improved cell survival by affecting SOD activity and GSSG levels, rather than catalase activity.High concentrations of IONP led to increased expression of ferroptosis-related genes, suggesting cell death due to iron accumulation.NAC pretreatment did not affect exosome production but correlated with the level of reactive oxygen species. In ex vivo experiments, cochlear explant models induced by kanamycin were successfully rescued when treated with exosomes induced by NAC- pretreated nanoparticles. 결론:Human mesenchymal stem cells (hMSC) possess catalase activity, which helps maintain redox balance. When labeled with PYRB at different doses and durations, hMSC can effectively preserve redox homeostasis. Supplementing with antioxidants like NAC can also reduce oxidative stress caused by nanoparticle labeling. Exosome production is dependent on oxidative stress levels, not just cell viability. However, pretreating nanoparticles with NAC and inducing exosomes has shown promising results in restoring damaged hair cells in cochlear explants. This study presents a crucial concept for mitigating oxidative stress in mesenchymal stem cells by enhancing enzymatic activity, and it also highlights the potential of a more effective translational approach in regenerative medicine. Further research on the components of exosomes and in vivo models is warranted to fully explore this concept.