Development of long-termed implants: In vivo and in vitro characterisation of the interactions of inner ear cells with platinum corrosion products in the context of cochlear implant stimulation

长期植入物的开发：在人工耳蜗刺激的背景下内耳细胞与铂腐蚀产物相互作用的体内和体外表征

• 批准号: 450597484
• 负责人: Professor Dr. Martin Durisin
• 金额: --
• 依托单位: Institut für Neuroanatomie und Zellbiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/450597484?language=en
• 关键词: Development; long; termed; implants; vivo

So far, it was supposed that an increase of electrical impedance extending 10 kΩ following cochlear implant insertion was due to technical defects of the electrode, induction of inflammatory processes and/or formation of scar tissue along the electrode. Recent studies, however, reported eroded surfaces of the platinum (Pt) electrode contacts as the reason for high impedances. Furthermore, the presence of Pt oxides, Pt protein complexes and particular Pt could be demonstrated at the electrode-nerve-interface and in the inner ear tissues. Whereas the cytotoxicity of of ionic Pt is well documented, the toxic potential of particular Pt depends not only on the particle size, concentration and cell type, but also on its susceptibility to oxidation by hydrolytic enzymes in the lysosomes following internalization. It is supposed that the oxidation product of the Pt particles may form complexes with DNA and subsequently induce DNA strand breakings. In fact, long-term effects of Pt corrosion, compositions of its corrosion products as well as their interactions with neural tissues are not well understood. Especially, molecular mechanisms of cell death induced by Pt corrosion products need to be clarified to enable protection of neuronal tissues against oxidative stress induced cell damage and manufacturing of electrodes preventing extensive corrosion product release.Current studies demonstrate that cisplatin mediated ototoxicity is not only triggered by apoptotic pathways, but also via necroptosis and autophagy. However, Pt corrosion products have not been identified as inductors for necroptosis or autophagy related signal pathways. Thus, detailed in vitro-analysis of cell death related signal pathways induced by the Pt corrosion products are in the focus of the project described herein. For this, in vitro cell culture models of primary rat spiral ganglion neurons, HEI-OC1 cell line of the immortalized mouse organ of Corti cells and organotypic cultivation of the rat organ of Corti will be established to characterize and quantify cytotoxic effects following administration of Pt nanoparticles and Pt corrosion products. Hereby, electrical stimulation of Pt wires will be used as source of corrosion products. Determination of the Pt concentration inducing cell death of 50 % of the cell culture constitutes the basis of the examination of the molecular mechanisms of Pt triggred oxidative stress and subsequent cell death. The obtained data will allow the examination of potential inhibitors/inductors of the cross points in apoptosis/necroptosis/autophagy signaling to prevent severe cell damage following Pt exposure. Consequently, the in vitro data has to be evaluated in vivo using rats as animal model.

到目前为止，假设耳蜗植入体插入后电阻抗增加超过10 kΩ是由于电极的技术缺陷、炎症过程的诱导和/或沿电极沿着形成瘢痕组织。然而，最近的研究报告了铂（Pt）电极触点的腐蚀表面是高阻抗的原因。此外，铂氧化物，铂蛋白复合物和特定的铂的存在下，可以证明在电极神经界面和内耳组织。尽管离子Pt的细胞毒性已得到充分证明，但特定Pt的潜在毒性不仅取决于颗粒大小、浓度和细胞类型，还取决于其在内化后对溶酶体中水解酶氧化的敏感性。据推测，铂颗粒的氧化产物可能与DNA形成复合物并随后诱导DNA链断裂。事实上，铂腐蚀的长期影响，其腐蚀产物的组成以及它们与神经组织的相互作用还没有很好地了解。特别是，需要阐明铂腐蚀产物诱导细胞死亡的分子机制，以保护神经元组织免受氧化应激诱导的细胞损伤，并制造防止大量腐蚀产物释放的电极。目前的研究表明，顺铂介导的耳毒性不仅由细胞凋亡途径触发，还通过坏死性细胞凋亡和自噬。然而，铂腐蚀产物尚未被确定为坏死性凋亡或自噬相关信号通路的诱导剂。因此，由Pt腐蚀产物诱导的细胞死亡相关信号通路的详细体外分析是本文所述项目的重点。为此，将建立原代大鼠螺旋神经节神经元、永生化小鼠Corti器官细胞的HEI-OC 1细胞系和大鼠Corti器官的器官型培养的体外细胞培养模型，以表征和量化Pt纳米颗粒和Pt腐蚀产物给药后的细胞毒性效应。因此，铂丝的电刺激将用作腐蚀产物的来源。诱导50%细胞培养物细胞死亡的Pt浓度的测定构成了检查Pt诱导的氧化应激和随后细胞死亡的分子机制的基础。获得的数据将允许检查细胞凋亡/坏死性凋亡/自噬信号传导中交叉点的潜在抑制剂/诱导剂，以防止Pt暴露后的严重细胞损伤。因此，必须使用大鼠作为动物模型在体内评价体外数据。