AAV Mediated Gene Transfer to the CNS for MPS I

描述（由申请人提供）：粘多糖病I型（MPS I）是一种常染色体隐性储存疾病，由a- l -伊杜糖醛酸酶（IDUA）缺乏引起，导致糖胺聚糖（GAG）储存物质的系统性积累，肝脾肥大，骨骼发育不良，心肺阻塞，进行性神经功能损害和15岁死亡。目前治疗MPS I的方法是酶替代疗法（ERT）和异体造血干细胞移植（HSCT），但这些治疗的神经系统有效性受到提供给大脑的IDUA酶的数量的限制。在这项提议中，我们提供的初步数据显示，在新生儿（4-6日龄）MPS I小鼠脑室内注射腺相关病毒血清型8 （AAV8）载体转导人类IDUA基因10个月后，大脑所有区域的IDUA酶表达水平异常高（正常水平的2- 40倍）。这种高水平的IDUA表达阻止了GAG储存物质的积累，并完全阻止了未经治疗的动物在Morris水迷宫空间导航和记忆测试中出现的神经认知缺陷的出现。这些前所未有的结果表明，AAV介导的IDUA基因直接转移到CNS具有克服目前ERT和HSCT治疗MPS的局限性的潜力。ReGenX， LLC是开发用于治疗人类疾病的AAV载体的领先公司。在这个I期STTR项目中，我们建议将ReGenX AAV载体技术与明尼苏达大学在治疗溶酶体贮存病方面的经验相结合，以解决在开发AAV介导的IDUA基因转移到CNS治疗人类MPS I的过程中必须面临的关键挑战：(I)哪种AAV血清型在介导基因转移到人类神经元细胞中最有效？为了解决这个问题，我们将比较AAV8、AAV9和AAVrh的有效性。人类神经元原代培养和脑组织切片的基因转移效率。（ii）是否存在一种侵入性较小的AAV载体给药途径，可用于在大脑中实现有效和广泛的IDUA表达，并且更容易被IDUA缺乏患者及其家属接受？为了解决这个问题，我们将评估鞘内、鼻内和血管内（血脑屏障破坏）AAV载体给药途径对人IDUA基因在中枢神经系统中的传递和表达的有效性。这些研究结果将直接影响AAV介导的IDUA基因转移到CNS作为改善MPS I治疗方法的发展，也将对AAV介导的基因转移到CNS治疗相关代谢和神经疾病具有重要意义。

DESCRIPTION (provided by applicant): Mucopolysaccharidosis type I (MPS I) is an autosomal recessive storage disease caused by the absence of a-L-iduronidase (IDUA), resulting in systemic accumulation of glycosaminoglycan (GAG) storage materials, hepatosplenomegaly, skeletal dysplasias, cardiopulmonary obstruction, progressive neurologic impairment and death by age 15. MPS I is currently treated by enzyme replacement therapy (ERT) and by allogeneic hematopoietic stem cell transplantation (HSCT), but the neurologic effectiveness of these treatments is limited by the amount of IDUA enzyme provided to the brain. In this proposal, we present preliminary data demonstrating extraordinarily high levels of IDUA enzyme expression (2- to 40-fold normal) in all areas of the brain 10 months after intracerebroventricular infusion of neonatal (4-6 day old) MPS I mice with an adeno-associated virus serotype 8 (AAV8) vector transducing the human IDUA gene. This high level of IDUA expression prevented accumulation of GAG storage material, and completely prevented emergence of neurocognitive deficits exhibited by untreated animals in a Morris water maze test of spatial navigation and memory. These unprecedented results demonstrate that AAV-mediated IDUA gene transfer directly to the CNS has the potential to overcome the current limitations of ERT and HSCT in the treatment of MPS I. ReGenX, LLC, is a leading company in the development of AAV vectors for treatment of human disease. In this Phase I STTR project, we propose to combine ReGenX AAV vector technology with the University of Minnesota's experience in the treatment of lysosomal storage diseases to address key challenges that must be faced in the development of AAV mediated IDUA gene transfer to the CNS for treatment of MPS I in humans: (i) Which AAV serotype is most effective in mediating gene transfer into human neuronal cells? To address this question, we will compare the effectiveness of AAV8, AAV9 and AAVrh.10 for gene transfer efficiency in human neuronal primary cultures and brain tissue slices. (ii) Is there a less invasive route of AAV vector administration that can be used to achieve effective and widespread IDUA expression in the brain, and that would be more acceptable to IDUA-deficient patients and their families? To address this question, we will evaluate the effectiveness of intrathecal, intranasal, and endovascular (with blood brain barrier disruption) routes of AAV vector administration for human IDUA gene delivery and expression in the CNS. Results from these studies will directly impact the development of AAV-mediated IDUA gene transfer to the CNS as an approach for improved therapy of MPS I, and will also have significance for the application of AAV mediated gene transfer to the CNS for related metabolic and neurologic diseases. PUBLIC HEALTH RELEVANCE: Lysosomal storage disorders are a rare group of inherited diseases in which patients suffer from skeletal abnormalities, heart and breathing problems, mental retardation and death. It is envisioned in this grant application that one way to treat these diseases would be to restore the missing gene in patients' central nervous system (in the brain) to prevent neurodegeneration.