The rapid progress achieved in the development of many biopharmaceuticals had a tremendous impact on the therapy of many metabolic/genetic disorders. This type of fruitful approach, called protein replacement therapy (PRT), aimed to either replace the deficient or malfunctional protein in human tissues that act either in plasma membrane or via a specific cell surface receptor. However, there are also many metabolic/genetic disorders attributed to either deficient or malfunctional proteins acting intracellularly. The recent developments of Protein Transduction Domain (PTD) technology offer new opportunities by allowing the intracellular delivery of recombinant proteins of a given therapeutic interest into different subcellular sites and organelles, such as mitochondria and other entities. Towards this pathway, we applied successfully PTD Technology as a protein therapeutic approach, in vitro, in SCO2 deficient primary fibroblasts, derived from patient with mutations in human SCO2 gene, responsible for fatal, infantile cardioencephalomyopathy and cytochrome c oxidase deficiency.

In this work, we radiolabeled the recombinant TAT-L-Sco2 fusion protein with technetium-99 m to assess its in vivo biodistribution and fate, by increasing the sensitivity of detection of even low levels of the transduced recombinant protein. The biodistribution pattern of [^99mTc]Tc-TAT-L-Sco2 in mice demonstrated fast blood clearance, significant hepatobiliary and renal clearance. In addition, western blot analysis detected the recombinant TAT-L-Sco2 protein in the isolated mitochondria of several mouse tissues, including heart, muscle and brain. These results pave the way to further consider this PTD-mediated Protein Therapy Approach as a potentially alternative treatment of genetic/metabolic disorders.

许多生物药物开发中取得的快速进展对许多代谢/遗传疾病的治疗产生了巨大影响。这种称为蛋白质替代疗法（PRT）的卓有成效的方法旨在替代人体组织中通过质膜或通过细胞膜起作用的蛋白质不足或功能异常。特定的细胞表面受体。然而，也有许多代谢/遗传性疾病归因于细胞内起作用的蛋白质不足或功能异常。蛋白质转导域（PTD）技术的最新发展通过允许将给定治疗兴趣的重组蛋白在细胞内递送到不同的亚细胞部位和细胞器（例如线粒体和其他实体）中提供了新的机会。朝着这一途径，我们成功地将PTD技术作为一种蛋白质治疗方法，在体外用于SCO2缺乏型原代成纤维细胞，该细胞源自人SCO2基因突变的患者，其负责致命，婴儿型心肌病和细胞色素c 氧化酶缺乏症。

在这项工作中，我们通过使用99m radio对重组TAT-L-Sco2融合蛋白进行了放射性标记，以通过提高甚至检测低水平转导重组蛋白的灵敏度来评估其在体内的生物分布和命运。[ ^99m Tc] Tc-TAT-L-Sco2在小鼠中的生物分布模式显示出快速的血液清除，显着的肝胆和肾脏清除。此外，蛋白质印迹分析在几种小鼠组织（包括心脏，肌肉和大脑）的分离的线粒体中检测到了重组TAT-L-Sco2蛋白。这些结果为进一步将这种PTD介导的蛋白质治疗方法视为遗传/代谢性疾病的潜在替代疗法铺平了道路。