Cell and Gene Replacement Strategies for Arginase Deficiency

项目总结/摘要 尿素循环是哺乳动物氨解毒的主要途径。精氨酸酶1缺乏症被认为是 是尿素循环障碍中最不常见的并导致高维生素B2血症。在人类中，缺乏 这种酶的临床特征是进行性精神损伤、痉挛、生长迟缓， 高氨血症的周期性发作这一建议有两个方面：1）继续推进基于基因的 利用适当的鼠模型治疗β-内酰胺酶缺乏症;病毒载体和基因组校正 将应用技术来检查动物是否可以在行为和生化方面得到纠正;以及2） 评估iPSC衍生的细胞治疗方法，将肝细胞置于生物活性支架上以供应尿素 循环函数初步数据：我们的研究小组（在其他发现中）：1）构建和 表征了重组蛋白酶1敲除小鼠; 2）证实了重组蛋白酶1的长期存活和拯救。 腺相关病毒载体; 3）证明只有低水平的尿素生成是必要的长期 存活率; 4）使用一系列行为测试表明，经过处理的腺苷酸酶敲除动物缺乏神经紧张， 系统异常，与同窝出生的小鼠相比，在学习或行为方面没有差异; 5）显示 外周代谢可导致循环血浆精氨酸的控制;和6）精氨酸酶基因的丢失 表达导致神经元的内在兴奋性和树突状结构的异常。目标1：长期 将通过病毒载体基因治疗在肌肉中表达辅酶Ⅱ酶2， 表型校正的小鼠模型中的辅酶A酶缺乏症。这种方法可以避免中和免疫 无效突变患者的反应。在目标2中，研究将检查是否在支架上生长辅助肝脏 可以提供导致高维生素B2血症表型纠正所必需的最小尿素循环功能。这 这种方法对于其他尿素循环障碍可能是成功的。随着拟议研究的顺利完成， 预计一种新的基因和细胞替代疗法将使患有 淀粉酶缺乏。

Project Summary/Abstract The urea cycle is the major pathway for detoxification of ammonia in mammals. Arginase 1 deficiency is thought to be the least common of the urea cycle disorders and results in hyperargininemia. In humans, deficiency of this enzyme is characterized clinically by progressive mental impairment, spasticity, growth retardation, and periodic episodes of hyperammonemia. This proposal is two-fold: 1) to continue to advance gene-based therapies for arginase deficiency utilizing appropriate murine models; viral vectors and genomic correction technology will be applied to examine if animals can be corrected behaviorally and biochemically; and 2) to evaluate an iPSC-derived cell therapy approach with hepatocytes placed on bioactive scaffolds to supply urea cycle function. Preliminary data: Our research group has (amongst other findings): 1) constructed and characterized the arginase 1 knockout mouse; 2) demonstrated long-term survival and rescue with recombinant adeno-associated viral vectors; 3) demonstrated that only low-level ureagenesis is necessary for long-term survival; 4) shown that, using an array of behavioral tests, that treated arginase knockout animals lack nervous system abnormalities and there is no difference in learning or behavior when compared to littermates; 5) shown that peripheral metabolism can result in control of circulating plasma arginine; and 6) loss of arginase gene expression results in abnormalities of intrinsic excitability and the dendritic arbor of neurons. In Aim 1, long-term expression of arginase 2 in muscle by viral vector gene therapy will be performed to examine for biochemical and phenotypic correction in a murine model of arginase deficiency. This approach may avoid neutralizing immune responses in patients with null mutations. In Aim 2, studies will examine if an auxiliary liver grown on scaffolds can supply the minimal urea cycle function necessary to lead to phenotypic correction of hyperargininemia. This approach may be successful for other urea cycle disorders. With successful completion of the proposed studies it is expected that a new therapy with gene and cell replacement will be one step closer for patients afflicted with arginase deficiency.