Translational Research for Retinal Degeneration Therapies

项目摘要 . 提出了一个多研究者、多中心的计划，以开发一种基于基因的视网膜治疗遗传性视网膜病变。 使用自然发生的犬模型研究ABCA 4基因突变引起的视网膜黄斑病变。一 这些具有ABCA 4双等位基因截短突变的患者的亚组显示在治疗期间中央视锥细胞的丢失。 随后是感光细胞变性的“爆炸性”离心进展， 周边视觉功能障碍该提案建立在当前赠款期间取得的成功的基础上 在将RPGR-XLRP的基于AAV的基因治疗转移到人类临床试验的过程中， 并在犬模型中验证另一种严重和早发性纤毛病变NPHP 5的新型基因疗法， LCA。在狗身上的实验结果表明，即使是在视网膜的中央，富含视锥细胞的视网膜也可以被靶向和拯救。 当干预发生在锥疾病的后期阶段时，这一发现与本建议高度相关。我们 最近发现了犬ABCA 4基因的功能缺失突变， 表型与人ABCA 4-CRD具有惊人的相似性：脂褐素在富含视锥细胞的 中央视网膜随后在以后的生活中发生全视网膜变性。我们将利用这一模式的可用性 提高我们对ABCA 4疾病的理解，并开发一种纳米颗粒介导的基因疗法， 以适应这种基因的大尺寸递送。我们的建议分为四个目标：1- 在犬模型中建立疾病的自然史; 2-优化 可以有效地抑制啮齿动物和狗中的视锥细胞、视杆细胞和RPE; 3-确定最佳的递送途径， 剂量，并引导载体靶向富含视锥细胞的犬中央视网膜，为4-概念验证做准备 在视锥细胞疾病/变性的早期和晚期阶段治疗的ABCA 4突变型犬中的研究。虽然测试 系统是ABCA 4突变的狗模型，所解决的治疗问题广泛适用于其他 由大尺寸基因突变引起的视网膜病变，其传递可能受益于发育和 验证了这个纳米颗粒递送平台。本提案中描述的研究代表了 继续一组视觉科学家之间的长期合作，在大学 宾夕法尼亚州已经将视网膜基因治疗带到了RPE 65-LCA，CNGB 3- 色盲和RPGR-XLRP。这一新计划将大大受益于联合专业知识， 来自三个学术机构（宾夕法尼亚大学、约翰霍普金斯大学）的研究人员联合会 大学和哥伦比亚大学），将提供必要的知识，在ABCA 4生物学， 纳米颗粒介导的DNA转移，小型和大型动物模型，以及人类ABCA 4疾病，以解决 目前对这种最常见形式的遗传性视网膜变性的治疗的未满足的医疗需求。

PROJECT SUMMARY . A multi-investigator, multi-center plan is proposed to develop a gene-based retinal therapy for inherited retinal maculopathies caused by mutations in the ABCA4 gene using a naturally-occurring canine model. A subgroup of these patients with ABCA4 bi-allelic truncation mutations show a loss of central cones during childhood that is followed by an “explosive” centrifugal progression of photoreceptor degeneration leading also to peripheral visual malfunction. The proposal builds on success achieved during the current grant period in moving AAV-based gene therapy for RPGR-XLRP to a human clinical trial, as well as developing and validating in a canine model a novel gene therapy for another severe and early-onset ciliopathy, NPHP5- LCA. Results in the dog have shown that the cone-rich central retina can be targeted and rescued even when intervention occurs at late stages of cone disease, a finding that is highly relevant to this proposal. We have recently identified a loss of function mutation in the canine ABCA4 gene that causes a retinal phenotype with striking similarities with human ABCA4-CRD: early accumulation of lipofuscin in the cone-rich central retina followed by pan-retinal degeneration later in life. We will capitalize on availability of this model to improve our understanding of ABCA4 disease and develop a nanoparticle-mediated gene therapy that can accommodate delivery of the large size of this gene. Our proposal is divided into four aims that will: 1- establish the natural history of disease in the canine model; 2- optimize a lead nanoparticle construct that can efficiently transduce cones, rods and RPE in rodents and dogs; 3- identify the optimal route of delivery, dose, and lead vector to target the cone-rich canine central retina, in preparation for 4- proof of concept studies in ABCA4-mutant dogs treated at early and later stages of cone disease/degeneration. While the test system is the ABCA4-mutant dog model, the therapeutic questions that are addressed apply broadly to other retinopathies caused by mutations in large size genes whose delivery may benefit from the development and validation of this nanoparticle delivery platform. The research studies described in this proposal represent a continuation of a longstanding collaboration between a group of vision scientists at the University of Pennsylvania that already have brought retinal gene therapy to the clinic for RPE65-LCA, CNGB3- achromatopsia , and RPGR-XLRP. This new program will greatly benefit from the joint expertise of a consortium of investigators from three academic institutions (University of Pennsylvania, Johns Hopkins University, and Columbia University) that will provide the necessary knowledge in ABCA4 biology, nanoparticle-mediated DNA transfer, small and large animal models, and human ABCA4 disease, to address the current unmet medical need for a treatment for this most common form of inherited retinal degeneration.