Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Neurosci Lett. 2013 Feb 8;534:18-23. doi: 10.1016/j.neulet.2012.12.001. Epub 2012 Dec 10.
Because of their limited regenerative potential, cochlear hair cell loss is one of the major causes of permanent hearing loss in mammals. However, recent studies have shown that postnatal cochlear epithelia retain the progenitor cells that form otospheres. Otospheres are capable of self-renewing and differentiating into inner ear cell lineages, thereby suggesting a promising source for hair cell regeneration. We investigated retention of the progenitor cell phenotype in otospheres after ex vivo expansion, which is crucial for transplantation approaches. Reverse transcriptase-polymerase chain reaction and immunocytochemical analyses showed that otospheres derived from neonatal mice retained expression of stem and cochlear cell markers. After in vitro differentiation, otosphere-consisting cells differentiated into hair cell phenotypes after ex vivo expansion. However, the capacity of otospheres for self-renewal weakened with subsequent generations of ex vivo expansion. Our results indicate that ex vivo expanded-otospheres are useful experimental tools for studying hair cell regeneration in transplantation approaches and that the mechanisms for retention of the progenitor cell phenotype in otospheres should be investigated.
由于其有限的再生潜力，耳蜗毛细胞的损失是哺乳动物永久性听力损失的主要原因之一。然而，最近的研究表明，出生后的耳蜗上皮细胞保留了形成球体的祖细胞。球体能够自我更新并分化为内耳细胞谱系，从而为毛细胞的再生提供了有希望的来源。我们研究了球体在体外扩增后保留祖细胞表型的情况，这对于移植方法至关重要。逆转录聚合酶链反应和免疫细胞化学分析表明，来自新生小鼠的球体保留了干细胞和耳蜗细胞标志物的表达。在体外分化后，球体组成细胞在体外扩增后分化为毛细胞表型。然而，随着体外扩增的代次增加，球体的自我更新能力减弱。我们的结果表明，体外扩增的球体是研究移植方法中毛细胞再生的有用实验工具，并且应该研究球体中保留祖细胞表型的机制。
