Scheibinger Mirko, Ellwanger Daniel C, Corrales C Eduardo, Stone Jennifer S, Heller Stefan
Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, 94305, USA.
Department of Otology and Laryngology, Harvard Medical School and Brigham and Woman's Hospital, Boston, MA, 02115, USA.
J Assoc Res Otolaryngol. 2018 Feb;19(1):17-29. doi: 10.1007/s10162-017-0646-4. Epub 2017 Nov 13.
In this study, we present a systematic characterization of hair cell loss and regeneration in the chicken utricle in vivo. A single unilateral surgical delivery of streptomycin caused robust decline of hair cell numbers in striolar as well as extrastriolar regions, which in the striola was detected very early, 6 h post-insult. During the initial 12 h of damage response, we observed global repression of DNA replication, in contrast to the natural, mitotic hair cell production in undamaged control utricles. Regeneration of hair cells in striolar and extrastriolar regions occurred via high rates of asymmetric supporting cell divisions, accompanied by delayed replenishment by symmetric division. While asymmetric division of supporting cells is the main regenerative response to aminoglycoside damage, the detection of symmetric divisions supports the concept of direct transdifferentiation where supporting cells need to be replenished after their phenotypic conversion into new hair cells. Supporting cell divisions appear to be well coordinated because total supporting cell numbers throughout the regenerative process were invariant, despite the initial large-scale loss of hair cells. We conclude that a single ototoxic drug application provides an experimental framework to study the precise onset and timing of utricle hair cell regeneration in vivo. Our findings indicate that initial triggers and signaling events occur already within a few hours after aminoglycoside exposure. Direct transdifferentiation and asymmetric division of supporting cells to generate new hair cells subsequently happen largely in parallel and persist for several days.
在本研究中，我们对鸡体内椭圆囊毛细胞的损失和再生进行了系统表征。单次单侧手术注射链霉素导致纹状区以及纹状区外区域的毛细胞数量显著下降，在纹状区，损伤后6小时就很早检测到了这种下降。在损伤反应的最初12小时内，我们观察到DNA复制受到整体抑制，这与未受损对照椭圆囊中自然的、有丝分裂的毛细胞产生情况相反。纹状区和纹状区外区域的毛细胞再生通过支持细胞的高速不对称分裂发生，同时伴随着对称分裂的延迟补充。虽然支持细胞的不对称分裂是对氨基糖苷类损伤的主要再生反应，但对称分裂的检测支持了直接转分化的概念，即支持细胞在表型转化为新的毛细胞后需要得到补充。支持细胞的分裂似乎协调良好，因为尽管最初毛细胞大量损失，但在整个再生过程中支持细胞的总数保持不变。我们得出结论，单次应用耳毒性药物提供了一个实验框架，用于研究体内椭圆囊毛细胞再生的确切起始和时间。我们的研究结果表明，初始触发因素和信号事件在氨基糖苷类暴露后的几小时内就已经发生。支持细胞直接转分化和不对称分裂以产生新的毛细胞随后在很大程度上并行发生，并持续数天。
