Adeno-associated Viral Vector Modification for Targeted Motor Neuron Therapy

描述(申请人提供)：运动神经元疾病(MND)，如肌萎缩侧索硬化症(ALS)和脊髓肌萎缩症(SMA)，是一种进行性神经退行性疾病，具有上运动神经元(MN)和/或下运动神经元(MN)变性的共同特征。尽管MND的分子机制尚不完全清楚，但所有形式最终都会导致运动神经元的死亡。对于MND的治疗策略，使用营养因子或抗凋亡蛋白可以提供MN保护，而不考虑具体的损伤机制。目前，基因治疗是利用慢病毒和腺相关病毒(AAV)载体在MND中提供这些治疗的最有前途的候选方法之一。由于AAV载体具有诱人的安全性，各种临床试验正在进行中或计划应用于包括ALS在内的神经退行性疾病。尽管AAV载体具有诱人的特性，但它对骨骼肌具有很高的亲和力，而且对轴突终末的趋向性有限，阻碍了IM注射后MN基因的传递。这些限制阻止了通过肌肉注射AAV.IGF-I治疗ALS的临床试验的积极发展。为了克服这一障碍，我们通过插入具有高MN亲和力和逆行转运的新多肽(Tet1)来修饰载体的衣壳，增加了AAV介导的MN基因的传递。本资助旨在寻找最佳靶向AAV载体，以增强MN基因的传递，并证明与前一代载体相比，ALS大鼠模型的存活率有所提高。大幅度改进的逆行递送将促使ALS基因治疗临床试验的积极发展。我们的应用将试图证明：1.AAV帽基因的衣壳突变，将新的神经元结合肽整合到病毒的外壳中，可以提高MN基因的传递效率和特异性。2.靶向AAV介导的IGF-I基因表达对SOD大鼠MNS有保护作用。3.通过动脉和鞘内注射等不同的递送途径，插入多肽可能会增强神经元的递送。 公共卫生相关性：运动神经元疾病(MND)的死亡和残疾，如肌萎缩侧索硬化症(ALS)，是由神经系统中称为运动神经元(MN)的细胞死亡造成的。在目前的应用中，我们将设计病毒，以安全和增强的治疗基因输送到运动神经元。这些病毒在简单的肌肉注射后将能够将基因输送到脊髓，为ALS的基因治疗提供了一种安全的方法。

DESCRIPTION (provided by applicant): Motor neuron diseases (MND), such as Amyotrophic Lateral Sclerosis (ALS) and Spinal Muscular Atrophy (SMA), are progressive neurodegenerative disorders that share the common characteristic of upper and/or lower motor neuron (MN) degeneration. Although the molecular mechanisms underlying MND are not entirely clear, all forms ultimately lead to apoptotic motor neuron death. Therapeutic strategies for MND, using trophic factors, or anti-apoptotic proteins can confer MN protection regardless of the specific mechanism of injury. Currently, gene therapy is one of the most promising candidates to deliver these treatments in MND, using lentiviral and adeno-associated viral (AAV) vectors. Because of the attractive safety profile of AAV vectors a variety of clinical trials are ongoing or planned for application to neurodegenerative diseases including ALS. Despite their appealing characteristics, AAV vectors have high affinity for skeletal muscle, as well as limited tropism for axon terminals, impeding MN gene delivery after IM injection. These limitations halted the aggressive development of a clinical trial for the treatment of ALS through intramuscular AAV.IGF-I injection. To overcome this barrier, we have modified the vector's capsid through the insertion of a novel peptide (Tet1) with high MN affinity and retrograde transport, increasing AAV mediated MN gene delivery. The present grant seeks support to identify the optimal targeted AAV vector for enhanced MN gene delivery, and demonstrate improved survival in the rat model of ALS compared to the earlier generation vector. Substantially improved retrograde delivery will prompt a return to the aggressive development of a clinical trial for ALS gene therapy. Our application will attempt to demonstrate that: 1. Capsid Mutation of the AAV Cap gene, incorporating novel neuronal binding peptides into the virus' coat, can increase the efficiency and specificity of MN gene delivery. 2. Targeted AAV-mediated IGF-I gene expression will protect MNs in SOD1 rats. 3. Peptide insertion may enhance neuronal delivery following alternative delivery routes, such as intra-arterial and intrathecal injections. PUBLIC HEALTH RELEVANCE: Death and disability in Motor neuron diseases (MND), such as Amyotrophic Lateral Sclerosis (ALS), result from death of cells in the nervous system called motor neurons (MN). In the present application, we will engineer viruses for safe and enhanced delivery of therapeutic genes to motor neurons. These viruses will be capable of delivering genes to the spinal cord after simple muscle injection, providing a safe approach to gene therapy for ALS.