Plasmonic Retinal Prosthesis

摘要 在各种恢复视力的方法中，包括光遗传刺激和干细胞治疗，只有 基于电极的视网膜假体已经验证了它的临床前景。然而，它受制于基本的 局限性：植入装置需要复杂的手术，既有数量有限的，也有固定的 刺激部位的位置，最重要的是，空间分辨率低，因为电流传播到 像视网膜这样的传导媒介。十年前，红外光的光热刺激开启了这种可能性 没有光遗传学的帮助，而是红外线对水的强烈吸收，可以远程激活神经元 导致整体组织加热和相关的不良反应。要实现细胞分辨率，就需要“远程”神经 在没有整体加热的情况下活化，我们已经证明了结合使用金纳米颗粒和近... 红外光(可以忽略不计地被水吸收)可以通过表面等离子体共振产生高度局域的热， 这可以通过产生电容膜电流和/或开启温度敏感来激活神经元 离子通道。我们还表明，适当的纳米颗粒的化学偶联进一步增强了 近红外刺激的疗效。然而，这种有希望的神经调节方法还没有 展示了它作为视网膜假体的潜力。在这里，我们建议开发、优化和验证这本小说 这项技术被称为等离子视网膜假体，并以几个重要的优势构成了其潜力 与基于电极的视网膜假体相比：(1)它不需要任何装置植入，但 仅涉及玻璃体内注射金纳米棒(AuNRs)；(2)单细胞分辨率可在 活体；(3)刺激位置或靶向神经节细胞可自由调节；(4)可激活的数目 每单位时间的神经元可以高达每秒100,000个神经元(在我们的试验设置中)；以及(5)性能 随着相关技术的进步，安装后是否可以进一步升级，因为每个关键组件 位于眼睛之外。我们将通过理论研究，体外优化， 体内验证，并进行长期测试。首先，因为在任何新的神经接口中都必须有一个 精确的系统模型为了优化设计，我们将提出我们的数学神经元模型 调查目前正在辩论的两个机制，并确定以下各项的初始参数 动物实验(目标1)。接下来，使用我们集成了扫描激光系统的定制实验装置 和荧光显微镜，我们将开发和优化视网膜神经节神经元的单细胞刺激 小鼠视网膜外植体带有遗传编码的钙离子指示物，随后显示两者的图案化 多神经元刺激与AUNR化学优化(目标2)。最后，我们将整合我们的 在体内验证视网膜图案化近红外刺激诱导的实验和理论工作 与自然视觉刺激相似的视觉皮质神经激活，参数进一步优化， 并将进行纵向实验，以观察和量化其长期疗效和毒性(目标3)。

SUMMARY Among various approaches to restore vision, including optogenetic stimulation and stem cell therapy, only the electrode-based retinal prosthesis has validated its clinical promises. However, it suffers from fundamental limitations: it requires a complicated surgery for device implantation, has both the limited number and fixed location of stimulation sites, and above all, has a low spatial resolution since electric currents spread in conductive media like the retina. A decade ago, photothermal stimulation with infrared light opened the possibility of ‘remotely’ activating neurons without the aid of optogenetics, but the strong water absorption of infrared light leads to bulk tissue heating and associated adverse effects. To enable cellular-resolution, ‘remote’ neural activation without the bulk heating, we have demonstrated that a combined use of gold nanoparticles and near- infrared light (negligibly absorbed by water) can produce highly-localized heat via surface plasmon resonance, and this can activate neurons by generating capacitive membrane currents and/or opening temperature-sensitive ion channels. We also have shown that appropriate chemical conjugation of nanoparticles further enhances the efficacy of near-infrared stimulation. This promising neuromodulation approach, however, has yet not demonstrated its potential as a retinal prosthesis. Here, we propose to develop, optimize, and validate this novel technology, termed plasmonic retinal prosthesis, and compose its potential with several important advantages when compared to the electrode-based retinal prostheses: (1) it does not require any device implantation but only involves intravitreal injection of gold nanorods (AuNRs); (2) the single-cell resolution can be achieved in vivo; (3) stimulation locations or targeted ganglion cells are freely adjustable; (4) the number of activatable neurons per unit time can be as high as 100,000 neurons per second (in our pilot setup); and (5) the performance is further upgradable after ‘installation’ as the relevant technologies advance because every key component locates outside the eye. We will develop this promising technology through theoretical study, ex vivo optimization, in vivo validation, and long-term testing. First, since it is essential in any novel neural interface to have an accurate model of the system in order to optimize the design, we will advance our mathematical neuron model to investigate two mechanisms currently under debate and determine the initial parameters for the following animal experiments (Aim 1). Next, using our custom experimental setup that integrates a scanning laser system and fluorescence microscope, we will develop and optimize single-cell stimulation of retinal ganglion neurons in retina explants of mice with genetically-encoded Ca2+ indicators, followed by both the demonstration of patterned multi-neuron stimulation and the optimization of AuNR chemistry (Aim 2). Finally, we will integrate our experimental and theoretical work to validate in vivo that patterned near-infrared stimulation of the retina induces neural activation in the visual cortex similar to natural visual stimuli, with the parameters being further optimized, and will perform a longitudinal experiment to observe and quantify its long-term efficacy and toxicity (Aim 3).