Pharmacokinetics of Therapeutic Nanoparticles in the CNS

描述(申请人提供)：中枢神经系统(CNS)内神经元的进行性退化对这些细胞控制的正常功能，特别是对个体的整体功能有深远的负面影响。有许多影响大脑的神经退行性疾病，包括阿尔茨海默病、帕金森病、亨廷顿病等。视网膜作为中枢神经系统的另一部分，神经元的退行性变也在许多疾病中发生，包括老年性黄斑变性、视网膜色素变性、糖尿病视网膜病变等。这些神经退行性疾病似乎都是由独特的原发缺陷引起的，这些疾病导致神经元慢性或急性暴露于活性氧中间体(ROI)。这些氧化代谢的有毒产物激活了细胞自杀途径--细胞凋亡。这一研究领域的一个普遍目标是找到破坏或清除ROI的分子，以期减缓或阻止这些疾病的发展。我们推测，特定的无机纳米颗粒由于其活性、尺寸(~5 nm)、纳米颗粒状态、不溶性和无机性，将能够进入细胞并清除ROI，从而阻止细胞凋亡的激活和细胞的死亡。我们的初步数据表明，这些特定的纳米颗粒可以破坏试管中的ROI，在培养的视网膜神经元中，并可以防止体内ROI介导的视网膜变性。该项目的总体目标是确定这些纳米颗粒的药代动力学(分布和周转)，以验证我们的假设，即只要它们存在，它们就会通过进入细胞并防止ROI增加而发挥作用。人们会问这个问题：注射后纳米氧化钙颗粒在眼睛细胞内停留多长时间？推论是纳米颗粒在任何浓度下和在较长时间内是否有毒。纳米颗粒的改良制剂也将进行测试。透射电子显微镜将被用来直接检测纳米颗粒，而白化大鼠光损伤模型将被用来检测它们保护视网膜功能的能力的保留。具体目标二将测试这样一种假设，即纳米氧化钙颗粒的作用机制是通过阻止凋亡途径的激活，而不是诱导其他救援途径。我们的数据表明，纳米颗粒还将有效地抑制各种神经退行性疾病中发生的由ROI诱导的细胞死亡的进展。它们在视网膜中的药代动力学特征对于验证它们在人类中的潜在治疗应用是非常重要的。使用这些无机纳米颗粒作为多种疾病的直接治疗代表了一种新的策略，并表明它们可能代表着一种独特的技术。美国有数以百万计的人患有某种形式的神经退行性疾病，如阿尔茨海默病、帕金森氏病、痴呆症、老年性黄斑变性、糖尿病视网膜病变等。我们的初步数据表明，我们的稀土元素无机纳米颗粒可以防止活性氧诱导的大鼠视网膜退化。为了实现我们的特定目标，对这些纳米颗粒的药代动力学(摄取、分布和消除)进行表征，对于最终抑制神经元退化和保护依赖于中枢神经系统的人类的智力、视力和整体体力活动是必要的。

DESCRIPTION (provided by applicant): Progressive degeneration of neurons within the central nervous system (CNS) has a profound negative effect on the normal functions controlled by those cells and especially on the overall functioning of the individual. There are numerous neurodegenerative diseases which affect the brain including Alzheimer's disease, Parkinson's disease, Huntington's disease, etc. Degeneration of neurons in the retina, another part of the CNS, also occurs in many diseases including Age Related Macular Degeneration, Retinitis Pigmentosa, Diabetic Retinopathy, etc. Each of these neurodegenerative diseases appears to arise from unique primary defects which result in a chronic or an acute exposure of the neurons to Reactive Oxygen Intermediates (ROI). These toxic products of oxidative metabolism activate a cell suicide pathway - apoptosis. A universal goal in this area of research has been to find molecules which destroy or scavenge ROI in anticipation that the progression of these diseases can be slowed or halted. We hypothesized that specific inorganic nanoparticles, because of their activity, size (~5nm), nanoparticle status, insolubility and inorganic nature, would be able to enter cells and scavenge ROI and thereby prevent the activation of apoptosis and the death of the cells. Our preliminary data demonstrate that these specific nanoparticles can destroy ROI in test tubes, in retinal neurons in culture and can prevent ROI-mediated retinal degeneration in vivo. The overall objective of this project is to determine the pharmacokinetics (distribution and turnover) of these nanoparticles in order to test our hypothesis that they are acting by entering cells and preventing increases in ROI for as long as they are present. Specific Aim One will ask the question: How long after injection do the nanoceria particles remain within the cells of the eye? A corollary is whether the nanoparticles are toxic at any concentration and over prolonged periods of time. Modified preparations of the nanoparticles will also be tested. Transmission electron microscopy will be used to directly detect the nanoparticles whereas the albino rat light-damage model will be used to detect the retention of their ability to protect retinal function. Specific Aim Two will test the hypothesis that the mechanism by which the nanoceria particles function is by preventing the activation of apoptotic pathways rather than inducing other rescue pathways. Our data suggest that the nanoparticles will also be effective in inhibiting the progression of ROI-induced cell death that occurs in a variety of neurodegenerative diseases. The characterization of their pharmacokinetics in the retina is very important for validating their potential therapeutic applications in humans. The use of these inorganic nanoparticles as direct therapy for multiple diseases represents a novel strategy and suggests they may represent a unique technology. There are millions of people in the USA who have some form of neurodegenerative disease such as, Alzheimer's disease, Parkinson's disease, Dementia, Age Related Macular Degeneration, Diabetic Retinopathy, etc. Our preliminary data demonstrate that our rare earth element inorganic nanoparticles prevent Reactive Oxygen Species induced retinal degeneration in rats. Achievement of our specific aims, the characterization of the pharmacokinetics (uptake, distribution, and elimination) of these nanoparticles, is necessary for the eventual inhibition of neuronal degeneration and the preservation of mental abilities, vision, and overall physical activities in humans which are dependent on the central nervous system.