Large Animal Model of Spinal Muscular Atrophy

项目概述/摘要：本申请提出了利用基因靶向胚胎成纤维细胞的体细胞核移植和育种来产生脊髓性肌萎缩症（SMA） （pSMN1-/-; hSMN2）猪模型。事实证明，转基因动物的生产极大地有助于我们对人类疾病的理解。利用小鼠胚胎干细胞进行基因靶向是最发达和最常用的方法，并为包括SMA在内的人类疾病提供了模型。如果没有这些小鼠模型，我们对疾病过程和基因功能的理解是不可能发生的。然而，在包括药物发现、基因和干细胞治疗在内的各种转化领域，越来越多的证据表明，大型动物模型为神经肌肉、神经退行性疾病以及其他疾病的治疗方法的发现和测试提供了更相关的“工具”[38,55,62 -69]。脊髓性肌萎缩症（SMA）是一种神经退行性疾病，大型动物模型的建立将极大地促进其转化研究。随着SMA领域进入更多的转化研究，一个关键的问题是我们目前从细胞模型和小动物SMA模型中获得的知识如何转化为人类治疗。在SMA转化研究中，越来越明显的是，关键问题需要通过实验解决，包括：提供给定治疗及其有效性的最佳方法、位置和最大有效剂量。一个更大的SMA动物将提供一个很好的实验工具，开始系统地解决这些问题。最后，SMA小鼠模型的一个令人烦恼的并发症是，在考虑SMA治疗时，疾病进展的窗口期相对较短。猪动物模型将更有可能概括人类疾病的治疗窗口期。由于一些关键的原因，猪特别适合转基因模型。从物理角度来看，动物与人类和猪的新陈代谢和器官系统的规模非常相似，寿命也更相似，这表明这些疗法更有可能直接应用于人类。例如，猪从脊髓到肢体肌肉的长度更像一个孩子，而不是老鼠。此外，更大的猪的尺寸允许更直接的操作（手术和生化），可能需要一些人类治疗。需要强调的是，这一建议并不意味着任何目前的SMA模型都有缺陷，相反，一个大型SMA动物模型将使我们能够解决新的和独特的问题，重点是开发和筛选有效的治疗方法。虽然这不是该提议的主要理由，但大型猪SMA模型将允许在临床试验之前研究治疗安全性和毒理学。

DESCRIPTION (provided by applicant): Project summary/abstract: This application proposes the generation of a swine model of Spinal Muscular Atrophy (SMA) (pSMN1-/-; hSMN2) using somatic cell nuclear transfer of gene targeted fetal fibroblasts and breeding. The production of transgenic animals has proven tremendously beneficial to our understanding of human disease. Gene targeting using murine embryonic stem cells is the most developed and utilized approach and has provided models of human diseases including SMA. Our understanding of disease processes and gene function could not have occurred without these mouse models. However, increasing evidence in a variety of translational fields including drug discovery and gene and stem cell therapies suggest that large animal models provide more relevant "tools" for the discovery and testing of therapeutics for neuromuscular, neurodegenerative as well as other diseases [38, 55, 62-69]. Spinal Muscular Atrophy (SMA) is a neurodegenerative disease whose translational studies would greatly benefit from the development of a large animal model. As the SMA field moves into more translational studies, one critical question is how our current knowledge obtained from cellular models and small animal SMA models translate into human therapies. It has become increasingly evident in SMA translational studies that critical questions need to be experimentally addressed, including: the best methodology, location and the maximum effective dose to deliver a given therapeutic and its effectiveness. A larger SMA animal would provide an excellent experimental tool to begin to systematically address these questions. Lastly, one of the vexing complications with SMA mice models is the relatively short window of disease progression when considering SMA therapies. The pig animal model will more likely recapitulate the therapeutic window for the human disease. Swine are exceptionally well-suited transgenic models for a number of critical reasons. From a physical standpoint, the scale of the animal and the human and swine metabolisms and organ systems are remarkably similar as well having more similar lifespans, suggesting that the therapies will more likely be directly translated into the human context. For example, the length from the spinal cord to a limb muscle in the swine is more similar to a child than that of a mouse. Additionally, the larger size of the swine permits more direct manipulations (surgical and biochemical) that may be required for some human therapies. It is important to stress that this proposal does not imply that any of the current SMA models are deficient, rather a large animal model of SMA will allow us to address new and distinct questions focused on the development and screening of efficacious therapeutics. And while not the primary rationale for this proposal, a large pig SMA model will allow the study of therapeutic safety and toxicology before clinical trials. PUBLIC HEALTH RELEVANCE: As the Spinal Muscular Atrophy (SMA) field moves into more translational studies one critical question is how our current knowledge obtained from cellular models and small animal models translate into human therapies. This proposal is aimed at developing a large animal model of SMA model in order to better understand the effectiveness of drug, stem cell and gene therapies. Pigs are well-suited animal models for a number of critical reasons including the similarity between human and pig metabolism and organ systems; therefore the development of a pig SMA model would provide unique benefits for the SMA community as the field pushes toward a cure.