Hearing loss is one of the major worldwide health problems that seriously affects human social and cognitive development. In the auditory system, three components outer ear, middle ear and inner ear are essential for the hearing mechanism. In the inner ear, sensory hair cells and ganglion neuronal cells are the essential supporters for hearing mechanism. Damage to these cells can be caused by long-term exposure of excessive noise, ototoxic drugs (aminoglycosides), ear tumors, infections, heredity and aging. Since mammalian cochlear hair cells do not regenerate naturally, some therapeutic interventions may be required to replace the damaged or lost cells. Cochlear implants and hearing aids are the temporary solutions for people suffering from severe hearing loss. The current discoveries in gene therapy may provide a deeper understanding in essential genes for the inner ear regeneration. Stem cell migration, survival and differentiation to supporting cells, cochlear hair cells and spiral ganglion neurons are the important foundation in understanding stem cell therapy. Moreover, mesenchymal stem cells (MSCs) from different sources (bone marrow, umbilical cord, adipose tissue and placenta) could be used in inner ear therapy. Transplanted MSCs in the inner ear can recruit homing factors at the damaged sites to induce transdifferentiation into inner hair cells and ganglion neurons or regeneration of sensory hair cells, thus enhancing the cochlear function. This review summarizes the potential application of mesenchymal stem cells in hearing restoration and combining stem cell and molecular therapeutic strategies can also be used in the recovery of cochlear function.

中文翻译：

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间充质干细胞在耳蜗再生中的治疗应用


听力损失是全球主要健康问题之一，严重影响人类社会和认知发展。在听觉系统中，外耳、中耳和内耳三个部分对于听觉机制至关重要。在内耳中，感觉毛细胞和神经节神经元细胞是听觉机制的重要支持者。这些细胞的损伤可能是由长期暴露于过量噪音、耳毒性药物（氨基糖苷类）、耳部肿瘤、感染、遗传和衰老引起的。由于哺乳动物耳蜗毛细胞不能自然再生，因此可能需要一些治疗干预措施来替换受损或丢失的细胞。人工耳蜗和助听器是严重听力损失患者的临时解决方案。目前基因治疗的发现可能有助于更深入地了解内耳再生的必需基因。干细胞迁移、存活和分化为支持细胞、耳蜗毛细胞和螺旋神经节神经元是了解干细胞治疗的重要基础。此外，不同来源（骨髓、脐带、脂肪组织和胎盘）的间充质干细胞（MSC）可用于内耳治疗。移植到内耳的间充质干细胞可以在受损部位招募归巢因子，诱导其转分化为内毛细胞和神经节神经元或感觉毛细胞再生，从而增强耳蜗功能。本综述总结了间充质干细胞在听力恢复中的潜在应用，并且干细胞和分子治疗策略相结合也可用于耳蜗功能的恢复。