A Novel Organ of Corti Explant Model for the Study of Cochlear Implantation Trauma
A Novel Organ of Corti Explant Model for the Study of Cochlear Implantation Trauma
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DOI：
10.1002/ar.22585
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发表时间：
2012-11-01
影响因子：
2
通讯作者：
Van De Water, Thomas R. i
中科院分区：
文献类型：
--
作者：
Bas, Esperanza;Gupta, Chhavi;Van De Water, Thomas R. i
本研究建立了一种新的电极插入损伤性毛细胞（HC）损伤和丢失的体外模型，并将其应用于耳保护药物的疗效检测。作为深度耳聋的一种治疗方法，人工耳蜗（CI）是通过外科手术插入一个电极阵列，为听神经提供电刺激。将CI电极插入鼓膜造成的机械损伤可导致炎症和高水平的氧化应激，从而引发听觉hc的凋亡和耳蜗内纤维化。HC细胞凋亡和耳蜗内纤维化被认为是CI功能预后不良的原因。为了进一步了解电极插入损伤（EIT）后HC细胞凋亡和鼓膜纤维化的分子机制，以及既往研究中观察到的地塞米松（DXM）的耳保护作用，我们设计了电极插入损伤（EIT）体外模型。在这里，我们提出并表征了一种新的，可重复的体外模型，用于研究EIT过程后发生的细胞和分子事件。取3日龄大鼠耳蜗造口术，将耳蜗分为3组：(1)对照组，(2)EIT组，(3)EIT + DXM （20 μ g/mL）。在第2组和第3组中，通过圆形窗口附近的小耳蜗造口引入直径0.28 mm的单丝钓鱼线，允许在110度到150度之间插入。在不同时间点对所有外植体进行HC计数、促炎细胞因子（如TNFa和IL-1 β）、促炎诱导酶（如iNOS和COX-2）和生长因子（如TGF β 1、TGF β 3和CTGF）基因表达、氧化应激（如CellROX）以及凋亡通路（如caspase-3、凋亡诱导因子和内切酶G）分析。这个EIT体外模型的结果显示，伤口愈合的开始，其中炎症反应随后是增殖纤维化阶段。此外，DXM治疗EIT外植体抑制炎症反应，促进无疤痕伤口愈合过程。本文描述的新型体外模型将提高我们对CI插入创伤的机制和保护策略（如ddxm治疗）的理解。Anat Rec, 2012。(C) 2012 Wiley期刊公司
This study presents a novel in vitro model of electrode insertion trauma-induced hair cell (HC) damage and loss and its application for testing the efficacy of otoprotective drugs. In the cochlear implant (CI) procedure as a treatment for profound deafness, an electrode array is surgically inserted to provide electrical stimulation to the auditory nerve. Mechanical trauma from insertion of a CI electrode into the scala tympani can lead to inflammation and a high level of oxidative stress, which can initiate the apoptosis of auditory HCs and intracochlear fibrosis. HC apoptosis and intracochlear fibrosis are thought to be causes of poor CI functional outcomes. In order to gain insight into the molecular mechanisms that initiate HC apoptosis and scala tympani fibrosis following electrode insertion trauma (EIT), and the otoprotective effects of dexamethasone (DXM) observed in previous studies, an in vitro model of EIT was designed. Here we present and characterize a novel, reproducible in vitro model for the study of cellular and molecular events that occur following an EIT procedure. Cochleae from 3-day-old rats were subjected to a cochleostomy and were then divided into three groups: (1) control, (2) EIT, and (3) EIT + DXM (20 mu g/mL). In Groups 2 and 3, a 0.28-mm diameter monofilament fishing line was introduced through the small cochleostomy located next to the round window area, allowing for an insertion of between 110 degrees and 150 degrees. HC counts, gene expression for pro-inflammatory cytokines (i.e., TNFa and IL-1 beta), pro-inflammatory inducible enzymes (i.e., iNOS and COX-2) and growth factors (i.e., TGF beta 1, TGF beta 3 and CTGF), oxidative stress (i.e., CellROX), and analyses of apoptosis pathways (i.e., caspase-3, apoptosis induced factor and Endonuclease G) were carried out on all explants at different time points. The results of this EIT in vitro model show the initiation of wound healing in which an inflammatory response is followed by a proliferative-fibrosis phase. Moreover, DXM treatment of EIT explants inhibited the inflammatory response and promoted a nonscarring wound healing process. The novel in vitro model described here will improve our understanding of mechanisms underlying CI insertion trauma and protective strategies such as DXM treatment. Anat Rec, 2012. (C) 2012 Wiley Periodicals, Inc.