Kawamoto Kohei, Izumikawa Masahiko, Beyer Lisa A, Atkin Graham M, Raphael Yehoash
Department of Otolaryngology, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi, Osaka 570-8506, Japan.
Hear Res. 2009 Jan;247(1):17-26. doi: 10.1016/j.heares.2008.08.010. Epub 2008 Sep 7.
Whereas most epithelial tissues turn-over and regenerate after a traumatic lesion, this restorative ability is diminished in the sensory epithelia of the inner ear; it is absent in the cochlea and exists only in a limited capacity in the vestibular epithelium. The extent of regeneration in vestibular hair cells has been characterized for several mammalian species including guinea pig, rat, and chinchilla, but not yet in mouse. As the fundamental model species for investigating hereditary disease, the mouse can be studied using a wide variety of genetic and molecular tools. To design a mouse model for vestibular hair cell regeneration research, an aminoglycoside-induced method of complete hair cell elimination was developed in our lab and applied to the murine utricle. Loss of utricular hair cells was observed using scanning electron microscopy, and corroborated by a loss of fluorescent signal in utricles from transgenic mice with GFP-positive hair cells. Regenerative capability was characterized at several time points up to six months following insult. Using scanning electron microscopy, we observed that as early as two weeks after insult, a few immature hair cells, demonstrating the characteristic immature morphology indicative of regeneration, could be seen in the utricle. As time progressed, larger numbers of immature hair cells could be seen along with some mature cells resembling surface morphology of type II hair cells. By six months post-lesion, numerous regenerated hair cells were present in the utricle, however, neither their number nor their appearance was normal. A BrdU assay suggested that at least some of the regeneration of mouse vestibular hair cells involved mitosis. Our results demonstrate that the vestibular sensory epithelium in mice can spontaneously regenerate, elucidate the time course of this process, and identify involvement of mitosis in some cases. These data establish a road map of the murine vestibular regenerative process, which can be used for elucidating the molecular events that govern this process.
虽然大多数上皮组织在受到创伤性损伤后会更新和再生，但内耳感觉上皮的这种修复能力会减弱；在耳蜗中不存在这种能力，在前庭上皮中仅以有限的能力存在。包括豚鼠、大鼠和毛丝鼠在内的几种哺乳动物前庭毛细胞的再生程度已得到表征，但小鼠尚未进行研究。作为研究遗传性疾病的基础模式物种，可以使用多种遗传和分子工具对小鼠进行研究。为了设计用于前庭毛细胞再生研究的小鼠模型，我们实验室开发了一种氨基糖苷诱导的完全消除毛细胞的方法，并将其应用于小鼠椭圆囊。使用扫描电子显微镜观察到椭圆囊毛细胞的损失，并通过具有绿色荧光蛋白阳性毛细胞的转基因小鼠椭圆囊中荧光信号的损失得到证实。在损伤后的几个时间点直至六个月对再生能力进行了表征。使用扫描电子显微镜，我们观察到早在损伤后两周，在椭圆囊中就可以看到一些未成熟的毛细胞，这些细胞表现出指示再生的特征性未成熟形态。随着时间的推移，可以看到更多数量的未成熟毛细胞以及一些类似于II型毛细胞表面形态的成熟细胞。损伤后六个月，椭圆囊中存在大量再生的毛细胞，然而，它们的数量和外观都不正常。一项BrdU检测表明，小鼠前庭毛细胞的至少一些再生涉及有丝分裂。我们的结果表明，小鼠的前庭感觉上皮可以自发再生，阐明了这一过程的时间进程，并确定在某些情况下有丝分裂的参与。这些数据建立了小鼠前庭再生过程的路线图，可用于阐明控制这一过程的分子事件。
