Novel Gene Delivery Development for Spinal Muscular Atrophy

描述（由申请人提供）：脊髓性肌萎缩症（SMA）是一种遗传性疾病，其特征是位于沿着脊髓全长的下运动神经元（LMN）缺失。SMA是由运动神经元存活（SMN）蛋白表达减少引起的。这种疾病的发病率为1/6000，一般来说，症状越早，患者的寿命越短。到目前为止，还没有有效的治疗方法，特别是对于这种致命疾病的最严重形式。许多证据支持运动神经元中SMN蛋白量的增加可以减轻疾病的严重程度。迄今为止，治疗方法主要集中于评估用于增加SMN水平或增强残余SMN功能的药物。尽管进行了多年的筛选，但尚未确定任何药物可完全有效地提高SMN水平以进行恢复性治疗。鉴于已知的遗传缺陷，其中SMN水平降低，基因替代策略可能为SMA患者提供希望。病毒载体的新增强表现出对许多神经系统疾病的重大承诺。该提案旨在开发基于无毒、长期表达载体系统的新型基因递送平台;腺相关病毒（AAV）。虽然基因和药物递送到脊髓仍然是一个挑战，但我们最近发现了AAV血清型9在血管递送后将基因高效递送到新生小鼠的脊髓运动神经元的独特能力。事实上，在脊髓的某些区域，超过90%的运动神经元被AAV 9-GFP标记基因靶向，这表明AAV 9有可能成为SMA的有效基因递送平台。此外，我们已经证明了AAV 9在将基因递送到整个身体的骨骼肌方面是有效的初步结果。考虑到AAV 9靶向运动神经元和骨骼肌，这些结果是有意义的，运动神经元和骨骼肌在这种疾病中受到显著影响。我们的提案旨在进一步加强这一交付平台，以努力开发成功的SMA治疗策略。这项工作将为SMA患者将SMN基因替代策略转化为临床提供重要信息，并为开发研究性新药（IND）申请提供所需信息。该提案的目的是NINDS发展计划的具体目标，以将有前途的疗法推向临床。目的1：优化AAV 9-GFP对新生动物的血管注射，以最大限度地将基因递送至下运动神经元。目标二：在2型SMA小鼠模型中评估表达SMN的AAV 9用于新生儿基因置换的最佳递送，以改善功能和存活。 公共卫生相关性：脊髓性肌萎缩症（SMA）是一种遗传性疾病，其特征是位于沿着整个脊髓长度的下运动神经元（LMN）丢失。迄今为止，治疗方法主要集中于评估用于增加SMN水平或增强残余SMN功能的药物。尽管进行了多年的筛选，但尚未确定任何药物可完全有效地提高SMN水平以进行恢复性治疗。鉴于已知的遗传缺陷，其中SMN水平降低，基因替代策略可能为SMA患者提供希望。我们已经发现了一种新的递送平台，用于高效靶向新生动物的运动神经元。我们将开发这些发现，以便将其转化为人类SMA临床试验。

DESCRIPTION (provided by applicant): Spinal muscular atrophy (SMA) is a genetic disorder characterized by the loss of lower motor neurons (LMNs) residing along the entire length of the spinal cord. SMA is caused by a reduction in the expression of the survival motor neuron (SMN) protein. The disease has an incidence of 1 in 6000, and in general, the earlier the symptoms, the shorter lifespan of patients. To date there are no effective therapies, particularly for the most severe forms of this lethal disease. Many lines of evidence support that increased amounts of SMN protein in motor neurons lessen disease severity. To date, therapeutic approaches have mainly focused on evaluating drugs for increasing SMN levels or enhance residual SMN function. Despite years of screening, no drugs have been identified to be fully effective for increasing SMN levels for a restorative therapy. Given the known genetic defect, in which SMN levels are decreased, gene replacement strategies may offer promise for SMA patients. New enhancements in viral vectors are demonstrating significant promise for a number of neurological disorders. This proposal seeks to develop novel gene delivery platforms based on a non-toxic, long-term expressing vector system; adeno-associated virus (AAV). While gene and drug delivery to the spinal cord has remained a challenge, we have recently discovered a unique ability for AAV serotype 9 to be highly efficient at delivering genes to spinal cord motor neurons of new born mice following vascular delivery. Indeed, in some areas of the spinal cord, over 90% of motor neurons were targeted by an AAV9-GFP marker gene, demonstrating the potential for AAV9 to be an effective gene delivery platform for SMA. Furthermore, we have demonstrated preliminary results that AAV9 is efficient at delivering genes to skeletal muscle across the entire body. These results are meaningful given that AAV9 targets both motor neurons and skeletal muscles, which are significantly affected in this disease. Our proposal seeks to further enhance this delivery platform in efforts to develop successful treatment strategies in SMA. This work will provide important information for translating an SMN gene replacement strategy to the clinic for SMA patients and provide needed information in efforts to develop an Investigational New Drug (IND) application. The aims of this proposal are specific goals for this NINDS developmental program to advance promising therapies to the clinic. Aim 1: Optimize vascular injection of AAV9-GFP to neonatal animals for maximal gene delivery to lower motor neurons. Aim 2: Evaluate optimal delivery of AAV9 expressing SMN for neonatal gene replacement in a mouse model of Type 2 SMA for improved function and survival. PUBLIC HEALTH RELEVANCE: Spinal muscular atrophy (SMA) is a genetic disorder characterized by the loss of lower motor neurons (LMNs) residing along the entire length of the spinal cord. To date, therapeutic approaches have mainly focused on evaluating drugs for increasing SMN levels or enhance residual SMN function. Despite years of screening, no drugs have been identified to be fully effective for increasing SMN levels for a restorative therapy. Given the known genetic defect, in which SMN levels are decreased, gene replacement strategies may offer promise for SMA patients. We have discovered a novel delivery platform for highly efficient targeting of motor neurons in neonatal animals. We will develop these findings for the potential to translate into human SMA clinical trials.