Manipulation of Mitochondrial Genomes in Aging and Neurodegeneration

描述（由申请人提供）：人类线粒体DNA （mtDNA）随着年龄的增长而积累突变，加速mtDNA突变的动物模型会产生晚期衰老表型，如骨质疏松症、心肌病、神经变性、脱发、贫血和生育能力下降。虽然令人信服，但这些动物模型不足以证明mtDNA是衰老表型的原因。如果mtDNA能够在体内传递到线粒体，那么mtDNA在衰老中的作用就可以直接解决。Gencia公司与弗吉尼亚大学神经退行性疾病研究中心（CSND）合作，在一期STTR中成功利用全长mtDNA转染线粒体的方法。这是通过使用一种新的线粒体转染技术，Protofection？（Protein Mediated Transfection）是Gencia Corporation开发并全资拥有的一项技术。原感染是一种DNA结合的非病毒传递载体，由工程重组蛋白组成，靶向线粒体进行DNA传递。超出I期研究目标的其他数据表明，protofection可以在体内传递和表达全长mtDNA，以表达报告蛋白（GFP，绿色荧光蛋白），并且正常mtDNA的传递可以改善由老年人受试者制成的细胞质杂交（cybrid）细胞的代谢缺陷。线粒体转染技术将mtDNA传递到线粒体的机制也被发现，并提示线粒体脂筏的存在。在这个II期STTR中，Gencia Corporation和CSND提议通过将正常mtDNA转染到老年小鼠中，并将老年小鼠的mtDNA转染到年轻小鼠中，来解决线粒体基因组损伤对衰老表型的贡献。提出的mtDNA转染实验将直接确定衰老表型的哪些方面是由mtDNA引起的，哪些方面可以通过正常mtDNA的传递来逆转。改善特定衰老表型（可能包括肌肉减少症、认知能力下降、骨质疏松症等）的疗效将成为向FDA/CBER（生物制品评估和研究中心）申请使用mtDNA基因治疗这些疾病的新药研究（IND）的基础。到2030年，65岁以上的人口将达到前所未有的20%。由于线粒体DNA的突变可能是许多衰老表型的原因，因此对线粒体DNA进行治疗可能会减轻这一负担。本二期STTR提出的研究将直接解决线粒体DNA导致哪些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.