Effects of mechanical trauma to the human tympanic membrane: an experimental study using transmission electron microscopy

Abstract

Hypothesis: To examine the cellular events following induced superficial lesions of the human tympanic membrane (TM). Such information could lead to enhanced appreciation of repair mechanisms and novel strategies to restore TM perforations.

Background: Persistent perforation of the TM in chronic otitis media is a major global health problem and frequently necessitates surgical intervention. Most TM perforations heal spontaneously and swiftly, but sometimes healing fails. The underlying mechanisms and the reason for incomplete repair are often elusive, although some mechanisms have been proposed.

Methods: Here, five healthy adult human TMs were sampled during vestibular schwannoma surgery. Three days before harvesting, three TMs were superficially lesioned, including the epithelial and sub-epithelial layers, using a needle and two TMs served as controls. Light and transmission electron microscopy were performed.

Results: Surrounding lesion showed distinct ultrastructural changes. This included a keratinocyte frontier with electron-dense cells with abundant ribosomes and nuclei metamorphosis. Beneath, were activated fibroblasts and invaded/transformed free cells and signs of increased transcellular activity of adjacent blood vessels.

Conclusions: The study describes dynamic morphological events of a human lesioned TM. The human model may be used for further investigations and understanding of TM healing mechanisms.

Chinese abstract

假设: 检查人类鼓膜 (TM) 在表面损伤之后的细胞事件。这种信息可能会让我们进一步了解修复机制, 找到治疗TM穿孔的新方法。

背景: 慢性中耳炎的TM持续穿孔是一个全球性的主要健康问题, 常常需要外科手术。大多数TM穿孔自发迅速愈合, 但有时会愈合不了。尽管已经提出了一些机制, 但其基本机制和不完全修复的原因往往难以捉摸。

方法: 在前庭神经鞘瘤手术中对5个健康成年人TM进行取样。在取样前三天, 三个TM表面用针刺伤, 包括上皮和次上皮层。两个TM作为对照。使用了光和透射电子显微镜。

结果: 病变周围显示明显的超微结构变化。这包括具有大量核糖体和核变态的电子密集细胞的角质细胞边缘。在其之下是激活成纤维细胞和入侵/转化的游离细胞以及相邻血管的跨细胞活性增加的迹象。

结论: 本研究描述了人类受伤TM的动态的形态事件。人体模型可用于进一步研究和了解TM愈合机制。

Keywords:

• Human
• tympanic membrane
• ultrastructure
• perforation
• healing

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Regional Research Council of the Uppsala-Örebro Region, ALF grants from Uppsala University Hospital and Uppsala University and by the “Tysta Skolan” Foundation, the Swedish Deafness Foundation (HRF).