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Background: Sound is a kind of mechanical stimulus and has various effects on the growth and metabolism of plants and animal cells. In previous studies, it was confirmed that sound stimulation promotes the neurodifferentiation process of mesenchymal stem cells. In this study, we examined the effect of sound on the maturation of neuroblastoma cells, SH-SY5Y cells, and investigated its effect on an ischemic mouse stroke model. In the in vitro study, SH-SY5Y cells were exposed to the sound for 3 days and then performed rt-PCR, FACS, and western blot for analysis. In the in vivo study, mesenchymal stem cells were injected into the injured area, and then rats were exposed to sound for 4 weeks. Then, immunohistochemical staining and western blotting were performed. Results: Sound upregulated the expression of presynaptic proteins synaptophysin and postsynaptic density protein 95, as well as neuronal-related proteins such as NFL, Tau, and MAP2. T-type calcium channels such as CACNA1G and CACNA1I were also induced by sound. In an experiment using the brain of ischemic mice, the expression of proteins involved in neuronal differentiation such as MAP2, NF200, and S100 was increased, while the inflammation-related proteins IFNγ, MMP9, and TNFα were decreased. In this neuronal differentiation process, both ERK and CREB, which are proteins involved in the initial signal transduction process, were activated. Conclusions: Our study demonstrates that sound, with the advantage of being non-invasive and easy to use, is an effective stimulus that induces neural differentiation and maturation on animal cells.How to cite: Cho H, Park H-J, Choi J-H, et al. Sound affects the neuronal maturation of neuroblastoma cells and the repair of damaged tissues. Electron J Biotechnol 2022;57. https://doi.org/10.1016/j.ejbt.2022.03.001

Hair loss is a chronic disorder that affects many people; however, a complete treatment has not yet been developed. Therefore, new therapeutic agents for preventing hair loss must be developed, and electromagnetic field (EMF) therapy has been proven to be a promising medical treatment in various fields, including hair loss treatment. This study evaluated the effect of extremely low-frequency electromagnetic field (ELF-EMF) intensity and exposure time by analyzing the expression of cytokines and anagen-related molecules, which influence hair activation and growth, in hair bulb spheroid (HBS) and hair follicle (HF) organ cultures. ELF-EMFs did not induce toxicity in the HBSs, as verified via the lactate dehydrogenase (LDH) assay. Moreover, an ELF-EMF intensity of 5–20 G promoted the expression of ALP, versican, β-catenin, and several cytokines (VEGF, PDGF, FGF-10, and ET-1) in HBSs. Immunohistochemical staining showed that ELF-EMF at an intensity of 5–20 G upregulated ALP and β-catenin and decreased TUNEL staining in HBS. Moreover, HFs exposed to ELF-EMF for 60 min exhibited an increase in hair length and a 1.5-fold increase in IL-4, ICAM-1, ALP, and versican mRNA expression compared to the control. Immunohistochemical staining indicated that 60 min of ELF-EMF can increase the expression of ALP and β-catenin and decreases TUNEL staining in organ cultures. Collectively, our results demonstrated that ELF-EMF exposure at a 10 G intensity for 60 min promoted hair shaft growth in HFs due to the effect of cytokines and adhesion molecules via the Wnt/β-catenin pathway. Therefore, ELF-EMF is a promising treatment for hair loss.