Nanoparticle-based therapy for photoreceptor degeneration

 描述(由申请人提供)：通过将治疗剂封装在可生物降解的纳米颗粒中，可以提供持久的分子输送，否则这些分子会迅速清除或降解。这项建议的目的是继续评估和开发一种纳米颗粒平台，利用该平台传递抗氧化酶、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)(Nano-SOD/CAT)来治疗视网膜疾病。由活性氧(ROS)介导的氧化损伤是视网膜色素变性(RP)等视网膜疾病中感光细胞退化的重要驱动力。我们发现，在一种广泛使用的非常激进的人类RP模型-Pdeb6rd10(Rd10)小鼠中，系统注射纳米SOD/CAT显著减缓了光感受器细胞的死亡速度。为了建立在这些有希望的结果的基础上，我们将测试这一假设，即纳米-SOD/CAT在减缓许多遗传形式的RP的光感受器细胞死亡方面是有效的，并可被开发为一种减缓疾病进展的慢性疗法。在目标1中，我们将确定纳米SOD/CAT的最佳剂量，确定哪种治疗方案提供最好的结果，并将研究应用纳米SOD/CAT的有益效果是否取决于治疗开始时的年龄(疾病阶段)。在所有这些研究中，我们将使用视网膜电信号(ERG)记录和光学显微镜下的视网膜结构以及通过计算经历细胞凋亡的细胞数量来评估视网膜功能。在目标2中，我们将抑制在氧化应激引发的细胞事件中发挥主要作用的两条途径。这些研究将使用与目标1相同的结果衡量标准，并将阐明纳米超氧化物歧化酶/CAT介导的ROS减少导致光感受器保存的机制(S)。在目标3中，我们将把这一研究策略扩展到另外三个小鼠模型。虽然人类RP是由50多个基因的突变引起的，但视紫红质和外周蛋白/rds的突变在受影响的患者中占相当大的比例。因此，我们将确定纳米-SOD/CAT是否会减缓Rho或Prhp2突变所致的三种常染色体隐性或显性RP小鼠模型的退化表型。选择这些小鼠模型是因为它们的潜在遗传学和它们独特的光感受器细胞损失率，所有这些都比rd10模型中看到的要慢。因此，AIM 3将提供有关纳米SOD/CAT在具有不同表型的多种遗传形式的RP中减缓光感受器退化速度的一般潜力的重要信息，这些表型也在人类中常见。虽然纳米超氧化物歧化酶/过氧化氢酶不能纠正潜在的遗传缺陷，但显著的疾病减缓将是有意义的，因为它允许受影响的患者，特别是儿童，在更长的时间内保持有用的视力，并有可能在他们的一生中。

 DESCRIPTION (provided by applicant): By encapsulating therapeutic agents within biodegradable nanoparticles, it is possible to provide long-lasting delivery of molecules that are otherwise rapidly cleared or degraded. The purpose of this proposal is to continue evaluation and development of a nanoparticle platform with which to deliver antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) (nano-SOD/CAT) to treat retinal diseases. Oxidative damage mediated via reactive oxygen species (ROS) is an important driving force in photoreceptor degeneration as occurs in human retinal diseases such as retinitis pigmentosa (RP). We have found that "systemic delivery (intraperitoneal injection)" of nano-SOD/CAT significantly slows the rate of photoreceptor cell death in a widely used very aggressive model of human RP - the Pdeb6rd10 (rd10) mouse. To build upon these promising results, we will test the hypothesis that nano-SOD/CAT is effective in slowing the rate of photoreceptor cell death for many genetic forms of RP and can be developed as a chronic therapy to slow down disease progression. In Aim 1, we will define the optimal dose of nano-SOD/CAT, determine which treatment schedule provides the best results, and will also examine whether the beneficial effect of nano-SOD/CAT application is dependent upon the age (disease stage) when treatment begins. In all of these studies, we will evaluate retinal function using electroretinogram (ERG) recordings and retinal structure using light microscopy and by counting the number of cells undergoing apoptosis. In Aim 2, we will inhibit two pathways that play major roles in cellular events initiated by oxidative stress. These studies will use the same outcome measures as Aim 1, and will clarify the mechanism(s) by which nano-SOD/CAT mediated reduction in ROS leads to preservation of photoreceptors. In Aim 3, we will expand this research strategy to three additional mouse models. While human RP is caused by mutations in more than 50 genes, mutations in rhodopsin and peripherin/rds account for a sizeable fraction of affected patients. Therefore, we will determine whether nano-SOD/CAT will slow the degenerative phenotype in three mouse models for autosomal recessive or dominant RP due to Rho or Prhp2 mutations. These mouse models were chosen due to their underlying genetics and their distinct rates of photoreceptor cell loss, all of which are slower than that seen in the rd10 model. Aim 3 will thus provide important information about the general potential for nano-SOD/CAT to slow the rate of photoreceptor degeneration in multiple genetic forms of RP with distinct phenotypes which are also commonly seen in humans. Although nano-SOD/CAT will not correct the underlying genetic defect, significant disease slowing would be meaningful, by allowing affected patients, particularly children to retain useful vision for a substantially longer period of time and potentilly throughout their lifetime.