Intrathecal Gene Therapy Expressing IGF-1 for Amyotrophic Lateral Sclerosis

肌萎缩侧索硬化症（ALS）是一种毁灭性的神经肌肉疾病，每年约有1/40，000人发病。患有ALS的个体表现出肌肉控制的快速丧失、肌肉萎缩和由于呼吸衰竭而死亡。ALS的原因是运动神经元对肌肉的进行性去神经支配。目前还没有治愈这种疾病的方法，唯一批准的治疗方法对疾病进展的影响非常有限。显然，迫切需要更有效的治疗方法。一种可能的途径是使用神经保护因子，由于它们的一般作用模式，它们也可能对其他神经肌肉疾病有用。我们这个项目的长期目标是开发ALS的基因疗法。以前的研究已经调查了神经保护因子的使用。这些分子，如胰岛素样生长因子1（IGF-1），为运动神经元提供抗凋亡信号，并促进神经突生长。这些分子在动物研究中似乎很有前途。然而，临床试验表明，将剂量扩大到人类带来了艰巨的挑战。更有效的方法可能是使用基因疗法，让患者自己的细胞产生治疗因子。包括我们自己在内的几项研究表明，这种方法是有价值的。然而，这些研究使用的技术在较大的动物模型中没有很好地扩大规模。实质内注射到脊髓中仅导致局部的转基因表达，因此在人体中需要不合理的大量注射。注射到肌肉中的载体在运动神经元中的逆行转运在ALS的啮齿动物模型中也是有效的，但由于需要注射的肌肉质量，可能再次具有有限的临床适用性。在这个提议中，我们将研究在ALS的SOD 1-G93 A大鼠模型中鞘内施用表达IGF-1的基因治疗的功效。在具体目标1中，我们表明我们的基因治疗可以促进运动神经元存活并保护神经肌肉接头的完整性。此外，我们将表明，这种疗法减弱了星形胶质细胞和小胶质细胞的激活，有助于运动神经元的破坏。此外，我们将研究运动神经元对IGF-1水平升高产生耐受性的可能性，这种现象可能会限制这种疗法的长期有效性。在具体目标2中，我们将展示目标1中发现的改善转化为运动功能的改善和寿命的延长。将使用握力、旋转棒和旷场试验评价SOD 1大鼠，以评价运动功能的几个方面。此外，将测量寿命、疾病发作时的年龄和疾病进展速率以显示疗效。这项研究将提供必要的原理验证数据，以支持这种方法的未来临床试验。

DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is a devastating neuromuscular disorder striking about 1 person in 40,000 each year. Individuals with ALS exhibit rapid loss of muscle control, muscle atrophy, and death due to respiratory failure. The cause of ALS is the progressive denervation of muscle by motor neurons. There is currently no cure for this disease, and the only approved therapy has a very modest effect on the disease progression. Clearly, there is a pressing need for more effective therapies. One possible route would be to use neuroprotective factors which, due to their general mode of action, may have utility in other neuromuscular disorders as well. Our long-term objective for this project is to develop gene therapy for ALS. Previous studies have investigated the use of neuroprotective factors. These molecules, such as insulin-like growth factor 1 (IGF-1) provide anti-apoptotic signals for motor neurons as well as promoting neurite outgrowth. These molecules seemed promising in animal studies. However, clinical trials demonstrated that scaling the dose to humans poses daunting challenges. A more effective approach might be to use gene therapy to allow the patients' own cells to produce the therapeutic factor. Several studies, including our own, have shown this approach has merit. However, these studies used techniques that have not scaled up well in larger animal models. Intraparenchymal injection into the spinal cord results in only localized transgene expression and thus would require an unreasonably large number of injections in humans. Retrograde transport in motor neurons of vector injected into muscle was also effective in a rodent model of ALS, but again would likely have limited clinical applicability due to the muscle mass that would need to be injected. In this proposal we will investigate efficacy of intrathecally administered gene therapy expressing IGF-1 in the SOD1-G93A rat model of ALS. In Specific Aim 1, we show that our gene therapy can promote motor neuron survival and protect the integrity of neuromuscular junctions. In addition we will show that this therapy attenuates the activation of astrocytes and microglia that helps contribute to th destruction of motor neurons. Furthermore, we will investigate the possibility that motor neurons can develop tolerance to elevated levels of IGF-1, a phenomenon that could limit the effectiveness of this therapy long-term. In Specific Aim 2, we will show that the improvements found in Aim 1 translate into improved motor function and increased life span. SOD1 rats will be evaluated using the grip strength, rotarod, and open field tests to evaluate several aspects of motor function. In addition, life span, age at disease onset, and the rate of disease progression will be measured to show efficacy. This study will provide the proof-of-principle data necessary to support future clinical trials of this approach.