Manipulation of Mitochondrial Genomes in Aging and Neurodegeneration

描述(申请人提供)：线粒体DNA(MtDNA)在人类中随着年龄的增长而积累突变，加速mtDNA突变的动物模型产生高级衰老表型，如骨质疏松症、心肌病、神经退行性变、脱发、贫血和生育能力下降。尽管这些动物模型令人信服，但它们不足以证明线粒体DNA是衰老表型的原因。如果线粒体DNA能够在体内被运送到线粒体，线粒体DNA在衰老中的作用就可以直接得到解决。Gencia公司与弗吉尼亚大学神经退行性疾病研究中心(CSND)合作，在第一阶段STTR中，成功地利用一种方法将全长mtDNA导入线粒体。这是通过使用一种新的线粒体转基因技术Protofect？(蛋白质介导的转染法)，这是一项由Gencia公司开发并独家拥有的技术。Protofect是一种DNA结合的非病毒传递载体，由一种以线粒体为靶点的工程重组蛋白组成，用于DNA传递。超出第一阶段研究目标的其他数据表明，原感染可以在体内传递和表达经改造以表达报告蛋白(GFP，绿色荧光蛋白)的全长mtDNA，并且传递正常的mtDNA可以改善由老年人制成的细胞质杂交(Cybrid)细胞中的代谢缺陷。线粒体转基因技术将线粒体DNA传递到线粒体的机制也被发现，并提示线粒体脂筏的存在。在这一第二阶段的研究中，Gencia Corporation和CSND建议通过将正常mtDNA导入老龄小鼠和将老龄小鼠的mtDNA导入幼鼠来解决线粒体基因组损伤对衰老表型的贡献。建议的线粒体DNA转染实验将直接确定衰老表型的哪些方面是由线粒体DNA引起的，哪些可以通过传递正常的线粒体DNA来逆转。改善衰老的特定表型(可能包括骨质疏松症、认知能力下降、骨质疏松症等)的有效性将成为FDA/CBER(生物制品评估和研究中心)在这些条件下使用mtDNA基因治疗的研究性新药(IND)申请的基础。到2030年，史无前例的20%的人口将超过65岁。由于线粒体DNA的突变可能与许多衰老表型有关，因此对线粒体DNA进行治疗可能会减轻这一负担。这项在第二阶段STTR中提出的研究将直接解决线粒体DNA引起的衰老表型以及这些表型是否可以逆转。

DESCRIPTION (provided by applicant): Mitochondrial DNA (mtDNA) accumulates mutations with aging in human beings and animal models of accelerated mtDNA mutagenesis produce advanced aging phenotypes such as osteoporosis, cardiomyopathy, neurodegeneration, hair loss, anemia and reduced fertility. Though compelling, these animal models are insufficient to prove that mtDNA is responsible for aging phenotypes. If mtDNA could be delivered to mitochondria in vivo, the role of mtDNA in aging could be directly addressed. In conjunction with the Center for the Study of Neurodegenerative Disease (CSND) at the University of Virginia, in a Phase I STTR, Gencia Corporation successfully utilized a method to transfect mitochondria with full-length mtDNA. This was done by using a novel mitochondrial transfection technology, Protofection? (Protein Mediated Transfection), a technology developed and solely owned by Gencia Corporation. Protofection is a DNA-binding, non-viral delivery vector consisting of an engineered recombinant protein that targets mitochondria for DNA delivery. Additional data beyond the aims of the Phase I study show that protofection can deliver and express a full-length mtDNA engineered to express a reporter protein (GFP, Green Fluorescent Protein), in vivo and that delivery of normal mtDNA can ameliorate metabolic defects in cytoplasmic hybrid (cybrid) cells made from aged human subjects. The mechanism by which the mitochondrial transfection technology delivers mtDNA to mitochondria was also discovered and suggests the existence of mitochondrial lipid rafts. In this Phase II STTR, Gencia Corporation and the CSND propose to address the contribution of mitochondrial genomic damage to aging phenotypes by transfecting normal mtDNA into aged mice and mtDNA from aged mice into young mice. The proposed mtDNA transfection experiments will directly determine which aspects of aging phenotypes are caused by mtDNA and which can be reversed by the delivery of normal mtDNA. Efficacy in ameliorating specific phenotypes of aging (which may include sarcopenia, cognitive decline, osteoporosis and others) will be the basis of Investigational New Drug (IND) applications to the FDA/CBER (Center for Biologics Evaluation and Research) for the use of mtDNA gene therapy in these conditions. By 2030, an unprecedented 20% of the population will be over age 65. Since mutations in mitochondrial DNA may be responsible for many aging phenotypes, having a therapy for mitochondrial DNA may reduce this burden. The research proposed in this Phase II STTR will directly address what aging phenotypes are caused by mitochondrial DNA and whether these phenotypes can be reversed.