Efficiency and Safety of Microstimulation Via Different Electrode Materials

通过不同电极材料进行微刺激的效率和安全性

• 批准号: 10421288
• 负责人: XINYAN Tracy CUI
• 金额: $ 59.06万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10421288
• 关键词: Acute; Affect; Animals; Auditory; Autopsy; Axon; Behavior; Brain; Calcium; Calcium Signaling; Cell Membrane Permeability; Cells; Charge; Chronic; Clinical; Coculture Techniques; Connexins; Cultured Cells; Deposition; Detection; Disease; Dose; Electric Stimulation; Electrodes; Endothelial Cells; Extravasation; Frequencies; Gases; Gliosis; Health; Histology; Hour; Hyperactivity; Image; Immunohistochemistry; Implant; Implanted Electrodes; In Vitro; Inflammation; Inflammatory; Injections; Interphase; Label; Link; Measures; Medicine; Methodology; Microelectrodes; Microglia; Monitor; Morphology; Mus; Nervous System Physiology; Neurites; Neurons; Neurosciences; Permeability; Phagocytosis; Physiologic pulse; Polymers; Property; Protein Analysis; Proteins; RNA analysis; Research Personnel; Safety; Site; Structure; System; Technology; Testing; Therapeutic; Time; Tissues; Toxic effect; Visual; Width; base; bioelectronics; biomaterial compatibility; cell behavior; cell motility; cell type; density; electric impedance; experimental study; implantation; improved; in vivo; in vivo Model; in vivo imaging; interest; iridium oxide; microstimulation; multi-electrode arrays; nanocomposite; nanomaterials; neural stimulation; neuron loss; neuronal cell body; protein expression; relating to nervous system; response; restoration; safety testing; somatosensory; tool; two photon microscopy

Microstimulation has been an invaluable tool for neuroscience researchers to infer functional connections between brain structures or causal links between structure and behavior. In recent years, therapeutic microstimulation is gaining interest for the restoration of visual, auditory and somatosensory functions as well as emerging applications in bioelectronic medicine. Current neural stimulation parameters and safety limits need to be revised for microelectrodes using more systematic and advanced methodologies. Stimulations via microelectrodes often require high charge injection for effective modulation of neural tissue without exceeding the threshold to harm the tissue or the electrodes. Therefore, advanced electrode materials with high charge injection capability and stability are highly desired. We have developed several types of stimulation materials based on conducting polymer PEDOT and nanomaterial composites. These materials present different charge transfer and electrochemical properties as well as biocompatibility, and the effects of these properties on microstimulation have yet to be comprehensively characterized. This proposal aims to establish new in vitro and in vivo models to examine the efficiency and safety of stimulation via multiple electrode materials, ranging from the clinically approved Pt and Iridium Oxide (IrOx) to the emerging PEDOT nanocomposites. Another challenge with micro-stimulation is its sensitivity to host tissue responses. Implantation of electrodes causes electrode fouling, progressive neuronal loss and inflammatory gliosis immediately surrounding the implants. Loss of nearby neurons and axons leads to decreased stimulation efficacy, while electrode fouling and gliosis increase impedance. Additionally, stimulation itself may further exacerbate host tissue responses if above the safety limit, which has yet to be defined for microelectrodes and emerging electrode materials. Using in vivo imaging in fluorescently labeled mice, we will examine the acute and chronic effects of microstimulation on neurons, microglia and vasculature, while monitoring the electrode material and electrochemical products. We will use an in vitro multielectrode arrays (MEA) system to study the effects of electrical stimulation on material and cells, in order to pinpoint the mechanisms of material and tissue damage. The first aime is to assess the efficiency and safety limit of neural stimulation via different electrode materials in vivo in acute experiments. For efficiency testing, we will implant the electrodes in the cortices of GCaMP mice and use 2-photon microscopy to image the calcium signal in order to determine stimulation threshold and optimum stimulation parameter for each electrode material. as a function of stimulation parameters. Stimulation threshold and efficiency for different pulse width, interphase period, bias potential and frequency from each electrode material type will be determined. For safety testing, we will use Syn-RCaMP/Cx3Cr1-GFP mice to visualize both neuronal and microglia cells and determine the damage threshold. The second aim is to examine the effects of stimulation on electrode materials and cultured cells in vitro. Using a high-throughput in vitro MEA system in which the six microelectrode materials can be deposited, we will stimulate at safe and unsafe parameters (identified in vivo from Aim 1) for up to 12 weeks. We will assess electrode material stability and analyze the stimulated media to identify electrochemical and degradation products. The toxicity of stimulated media will be tested in cultures of neuron, microglia, endothelial cells and neuron-microglia co-culture at varying doses to determine the detrimental effects of electrochemical and degradation products on these cells. Finally, we will directly stimulate the cells cultured on MEAs and characterize cell behavior using quantitative RNA and protein analysis, neural recording/stimulation and immunohistochemistry. The third aim is to characterize the chronic safety and stability of microstimulation in vivo from different electrode materials. Stimulation will be applied one hour per day to microelectrode arrays chronically implanted in Syn-RCaMP/Cx3Cr1-GFP animals for 12 weeks. In each weekly imaging session, we will measure the in vivo impedance, CV, charge injection limit, and stimulation threshold. The neuronal response (activity, health, density), microglia (morphology, coverage and motility) and BBB integrity will be recorded, and compared over time points between material types, and to the non-stimulated sites. In addition, we will closely track the electrode health with electrochemical interrogation, imaging and explant analysis.

微刺激一直是神经科学研究人员推断功能连接的宝贵工具 在结构和行为之间的大脑结构或因果关系之间。近年来，治疗性 微刺激也引起了视觉，听觉和体感功能的恢复的兴趣 作为生物电子医学中的新兴应用。当前的神经刺激参数和安全限制 需要使用更多系统和高级方法进行微电极修订。通过 微电极通常需要高电荷注射以有效调节神经组织而不超过 损害组织或电极的阈值。因此，高电荷的高级电极材料 高度需要注入能力和稳定性。我们已经开发了几种类型的刺激材料 基于传导聚合物PEDOT和纳米材料复合材料。这些材料具有不同的费用 转移和电化学特性以及生物相容性以及这些特性对 微刺激尚未全面表征。该建议旨在建立新的体外 和体内模型，以检查通过多种电极材料刺激的效率和安全性 从临床认可的PT和氧化虹膜（Irox）到新兴的PEDOT纳米复合材料。其他 微刺激的挑战是其对宿主组织反应的敏感性。电极的植入 电极结垢，进行性神经元丧失和炎症性神经胶质发生立即围绕植入物。 附近的神经元和轴突的丧失导致刺激功效降低，而电极结垢和胶膜病 增加阻抗。另外，如果高于 安全极限，尚未定义为微电极和新兴电极材料。使用体内 在荧光标记的小鼠中成像，我们将检查微刺激对 神经元，小胶质细胞和脉管系统，同时监测电极材料和电化学产品。我们 将使用体外多电极阵列（MEA）系统研究电刺激对材料的影响 和细胞，以查明材料和组织损伤的机制。 第一个AIME是通过不同的不同 急性实验中体内电极材料。为了进行效率测试，我们将植入电极 GCAMP小鼠的皮质并使用2光子显微镜对钙信号进行成像，以确定 每种电极材料的刺激阈值和最佳刺激参数。作为 刺激参数。刺激阈值和效率不同 将确定每种电极材料类型的电势和频率。对于安全测试，我们将使用 SYN-RCAMP/CX3CR1-GFP小鼠可视化神经元和小胶质细胞，并确定损伤 临界点。 第二个目的是检查刺激对电极材料和培养的影响 细胞体外。使用高通量的体外MEA系统，其中六种微电极材料可以是 沉积后，我们将在安全且不安全的参数（从AIM 1中识别）刺激长达12周。 我们将评估电极材料稳定性并分析刺激介质以识别电化学和 降解产品。刺激培养基的毒性将在神经元的培养物中进行测试，小胶质细胞， 内皮细胞和神经元 - 神经元以不同剂量的共同培养，以确定 这些细胞上的电化学和降解产物。最后，我们将直接刺激在 使用定量RNA和蛋白质分析，神经记录/刺激来测量和表征细胞行为 和免疫组织化学。 第三个目的是表征体内微刺激的慢性安全性和稳定性 不同的电极材料。刺激每天将每天一小时应用于微电极阵列 长期植入Syn-RcAMP/CX3CR1-GFP动物12周。在每个每周的成像会议中，我们 将测量体内阻抗，简历，电荷注入极限和刺激阈值。神经元 反应（活动，健康，密度），小胶质细胞（形态，覆盖率和运动性）和BBB完整性将为 记录并将材料类型之间的时间点和与未刺激的位点进行比较。此外， 我们将通过电化学询问，成像和外植物分析密切跟踪电极健康。