Li Yang, Watanabe Kotaro, Fujioka Masato, Ogawa Kaoru
Department of Otorhinolaryngology, School of Medicine, Keio University,35 Shinanomachi, Shinjuku-ku, Tokyo, Japan.
Department of Otolaryngology-Head and Neck Surgery, the Second Affiliated Hospital, Xi'an Jiaotong University, Xi Wu Lu, Xi'an, China.
PLoS One. 2017 Jun 20;12(6):e0179293. doi: 10.1371/journal.pone.0179293. eCollection 2017.
Cochlear spiral ligament fibrocytes (SLFs) play essential roles in the physiology of hearing including ion recycling and the generation of endocochlear potential. In adult animals, SLFs can repopulate after damages, yet little is known about the characteristics of proliferating cells that support SLFs' self-renewal. Here we report in detail about the characteristics of cycling cells in the spiral ligament (SL). Fifteen P6 mice and six noise-exposed P28 mice were injected with 5-bromo-2'-deoxyuridine (BrdU) for 7 days and we chased BrdU retaining cells for as long as 60 days. Immunohistochemistry revealed that the BrdU positive IB4 (an endotherial marker) negative cells expressed an early SLF marker Pou3f4 but negative for cleaved-Caspase 3. Marker studies revealed that type 3 SLFs displayed significantly higher percentage of BrdU+ cells compared to other subtypes. Notably, the cells retained BrdU until P72, demonstrating they were dividing slowly. In the noise-damaged mice, in contrast to the loss of the other types, the number of type 3 SLFs did not altered and the BrdU incorporating- phosphorylated Histone H3 positive type 3 cells were increased from day 1 to 14 after noise exposure. Furthermore, the cells repopulating type 1 area, where the cells diminished profoundly after damage, were positive for the type 3 SLF markers. Collectively, in the latral wall of the cochlea, type 3 SLFs have the stem cell capacity and may contribute to the endogenous regeneration of lateral wall spiral ligament. Manipulating type 3 cells may be employed for potential regenerative therapies.
耳蜗螺旋韧带纤维细胞（SLFs）在听力生理过程中发挥着重要作用，包括离子循环和内淋巴电位的产生。在成年动物中，SLFs受损后能够再生，然而对于支持SLFs自我更新的增殖细胞的特征却知之甚少。在此，我们详细报告了螺旋韧带（SL）中循环细胞的特征。给15只P6小鼠和6只经噪声暴露的P28小鼠注射5-溴-2'-脱氧尿苷（BrdU），持续7天，并对保留BrdU的细胞追踪长达60天。免疫组织化学显示，BrdU阳性、IB4（一种内皮标记物）阴性的细胞表达早期SLF标记物Pou3f4，但裂解型半胱天冬酶3呈阴性。标记研究表明，与其他亚型相比，3型SLFs显示出显著更高比例的BrdU+细胞。值得注意的是，这些细胞在P72时仍保留BrdU，表明它们分裂缓慢。在噪声损伤的小鼠中，与其他类型细胞的减少相反，3型SLFs的数量没有改变，并且在噪声暴露后第1天到第14天，掺入BrdU的磷酸化组蛋白H3阳性的3型细胞数量增加。此外，在受损后细胞大量减少的1型区域重新填充的细胞对3型SLF标记物呈阳性。总体而言，在耳蜗外侧壁，3型SLFs具有干细胞能力，可能有助于外侧壁螺旋韧带的内源性再生。操纵3型细胞可用于潜在的再生治疗。
