The GM2-gangliosidoses are neurological diseases causing premature death, thus developing effective treatment protocols is urgent. GM2-gangliosidoses result from deficiency of a lysosomal enzyme β-hexosaminidase (Hex) and subsequent accumulation of GM2 gangliosides. Genetic changes in HEXA, encoding the Hex α subunit, or HEXB, encoding the Hex β subunit, causes Tay-Sachs disease and Sandhoff disease, respectively. Previous studies have showed that a modified human Hex µ subunit (HEXM) can treat both Tay-Sachs and Sandhoff diseases by forming a homodimer to degrade GM2 gangliosides. To this end, we applied this HEXM subunit in our PS813 gene editing system to treat neonatal Sandhoff mice. Through AAV delivery of the CRISPR system, a promoterless HEXM cDNA will be integrated into the albumin safe harbor locus, and lysosomal enzyme will be expressed and secreted from edited hepatocytes. 4 months after the i.v. of AAV vectors, plasma MUGS and MUG activities reached up to 144- and 17-fold of wild-type levels (n = 10, p < 0.0001), respectively. More importantly, MUGS and MUG activities in the brain also increased significantly compared with untreated Sandhoff mice (p < 0.001). Further, HPLC-MS/MS analysis showed that GM2 gangliosides in multiple tissues, except the brain, of treated mice were reduced to normal levels. Rotarod analysis showed that coordination and motor memory of treated mice were improved (p < 0.05). Histological analysis of H&E stained tissues showed reduced cellular vacuolation in the brain and liver of treated Sandhoff mice. These results demonstrate the potential of developing a treatment of in vivo genome editing for Tay-Sachs and Sandhoff patients.

中文翻译：

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一种治疗 Tay-Sachs 和 Sandhoff 疾病的新型基因编辑系统。

GM2-神经节苷脂病是导致过早死亡的神经系统疾病，因此迫切需要制定有效的治疗方案。GM2-神经节苷脂沉积症是由于溶酶体酶β-氨基己糖苷酶（Hex）的缺乏和随后的GM2神经节苷脂的积累引起的。编码 Hex α 亚基的 HEXA 或编码 Hex β 亚基的 HEXB 的遗传变化分别导致 Tay-Sachs 病和 Sandhoff 病。先前的研究表明，经过修饰的人类 Hex µ 亚基 (HEXM) 可以通过形成同型二聚体来降解 GM2 神经节苷脂，从而治疗 Tay-Sachs 和 Sandhoff 疾病。为此，我们在 PS813 基因编辑系统中应用了这个 HEXM 亚基来治疗新生 Sandhoff 小鼠。通过 CRISPR 系统的 AAV 递送，无启动子的 HEXM cDNA 将被整合到白蛋白安全港基因座中，溶酶体酶将从编辑后的肝细胞中表达和分泌。静脉注射 AAV 载体 4 个月后，血浆 MUGS 和 MUG 活性分别达到野生型水平的 144 倍和 17 倍（n = 10，p < 0.0001）。更重要的是，与未经治疗的 Sandhoff 小鼠相比，大脑中的 MUGS 和 MUG 活动也显着增加（p < 0.001）。此外，HPLC-MS/MS 分析表明，除大脑外，接受治疗的小鼠多个组织中的 GM2 神经节苷脂降低至正常水平。旋转棒分析表明，治疗小鼠的协调性和运动记忆得到改善（p < 0.05）。H&E 染色组织的组织学分析显示，经过处理的 Sandhoff 小鼠大脑和肝脏中的细胞空泡化减少。