Self-complementary rAAV9 Systemic Gene Delivery Treatment for MPS Type IIIA

描述（由申请人提供）：目前没有治疗溶酶体贮积病粘多糖病IIIA (MPS IIIA) （Sanfilippo A）相关的神经退行性疾病的破坏性影响。遗传这种单基因疾病的儿童在出生时通常没有症状，但在1-4岁时开始出现严重的行为问题，包括攻击性和睡眠障碍，以及认知能力下降，最终发展为痴呆症。患者通常存活到成年早期，需要强烈的支持性护理。基因治疗可以有效地治疗疾病的根本原因，即编码n -磺酰基氨基磺酸水解酶（SGSH）的基因缺失，并在细胞水平上纠正病理，导致溶酶体中积累的糖胺聚糖（GAGs）被清除。由于MPS IIIA的神经病理是全局性的，影响大脑的所有区域，因此有效的基因传递到中枢神经系统（CNS）是治疗这种疾病和许多其他溶酶体贮积病的最大障碍。该项目的近期目标是开发一种基因治疗程序来治疗MPS IIIA疾病。最近观察到，来自血清型9 （AAV9）的重组腺相关病毒（rAAV）载体，与任何其他已知的病毒载体不同，在小鼠和其他动物体内静脉注射后，能够从血液中穿过血脑屏障（BBB）。这一特点为治疗MPS IIIA提供了一种均质中枢神经系统基因传递的新方法。由于人类SGSH编码区很小，因此可以通过使用rAAV载体的衍生物——自互补AAV （self-complementary AAV, scAAV）来最大限度地增加CNS内载体转导细胞的数量和分布。在许多组织中，scAAV载体绕过了将亲本病毒的单链DNA转化为双链DNA进行基因表达的要求，并将转导效率提高了几个数量级。本提案的具体目的是：1)比较scAAV和单链AAV载体在MPSIIIA小鼠中hSGSH的表达和治疗效果；2)检验疾病晚期的治疗效果，以反映治疗MPSIIIA患者群体的临床现实。该研究策略的基本原理是将AAV9的新型基因传递特性与scAAV和紧凑启动子的高效率相结合，最大限度地提高成功治疗中枢神经系统病理以及与该疾病相关的相对较轻的躯体疾病的可能性。这项提议的研究意义重大，因为它解决了对一系列神经系统疾病进行有效基因治疗的最大障碍。该项目的成功完成预计将对MPS IIIA患者群体产生直接影响，并有一个有效的治疗程序，以推进临床试验过程。

DESCRIPTION (provided by applicant): There is currently no treatment for the devastating impacts of neurodegeneration associated with the lysosomal storage disease, mucopolysaccharidosis IIIA (MPS IIIA) (Sanfilippo A). Children inheriting this monogenetic disorder are typically asymptomatic at birth, but at age 1-4 begin to develop severe behavioral problems including aggression and sleep disturbances, and cognitive deterioration that progresses to dementia. Patients usually survive to early adulthood and require intense supportive care. Gene therapy can effectively treat the root cause of the disease, a deficiency in the gene encoding N-sulfoglucosamine sulfohydrolase (SGSH), and correct the pathology at the cellular level, leading to clearance of accumulated glycosaminoglycans (GAGs) in lysosomes. Because the neuropathology of MPS IIIA is global, affecting all areas of the brain, effective gene delivery to the central nervous system (CNS) is the greatest obstacle to treatment for this, and many other lysosomal storage diseases. The immediate goal of this project is to develop a gene therapy procedure to treat MPS IIIA disease. It has been observed recently that recombinant adeno-associated virus (rAAV) vectors derived from serotype 9 (AAV9), unlike any other known viral vector, are able to cross the blood-brain barrier (BBB) from the bloodstream after intravenous injection in mice and other animals. This feature provides a novel means of homogeneous CNS gene delivery for the treatment of MPS IIIA. Because the human SGSH coding region is small, the number and distribution of vector-transduced cells within the CNS can be maximized by using a derivative of rAAV vectors, self-complementary AAV (scAAV). scAAV vectors bypass the requirement for converting the single-stranded DNA of the parent virus into double-strand DNA for gene expression, and multiply transduction efficiency by orders of magnitude in many tissues. The specific aims of this proposal are to 1) Compare scAAV and single-strand AAV vectors for hSGSH expression and therapeutic effect in MPSIIIA mice and 2) Test therapeutic efficacy in later stages of the disease to reflect the clinical realities of treatng the MPS IIIA patient population. The rationale for the research strategy is that it combines the novel gene delivery properties of AAV9 with the high efficiency of scAAV and compact promoters to maximize the probability of successfully treating CNS pathology, as well as the relatively milder somatic disorders associated with this disease. The proposed research is significant because it addresses the greatest obstacles to effective gene therapy treatment for a range of neurological disorders. Successful completion of the project is expected to have an immediate impact on the MPS IIIA patient population, with a working therapeutic procedure in hand to advance to the clinical testing process.