Lipid nanoparticle-targeted mRNA formulation as a treatment for ornithine-transcarbamylase deficiency model mice

• Published in: Molecular therapy. Nucleic acids Vol. 33; pp. 210 - 226
• Main Authors: Yamazaki, Kazuto, Kubara, Kenji, Ishii, Satoko, Kondo, Keita, Suzuki, Yuta, Miyazaki, Takayuki, Mitsuhashi, Kaoru, Ito, Masashi, Tsukahara, Kappei
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.09.2023; American Society of Gene & Cell Therapy; Elsevier
• Subjects: cryo-electron microscopy; homotrimer conformation; lipid nanoparticles; messenger RNA therapy; mitochondria localization; MT: delivery strategies: ornithine transcarbamylase; Original; Otcspf-ash mice; lipid nanoparticles; MT: delivery strategies: ornithine transcarbamylase; mitochondria localization; Otcspf-ash mice; messenger RNA therapy; homotrimer conformation; cryo-electron microscopy
• ISSN: 2162-2531; 2162-2531
• DOI: 10.1016/j.omtn.2023.06.023

Ornithine transcarbamylase (OTC) plays a significant role in the urea cycle, a metabolic pathway functioning in the liver to detoxify ammonia. OTC deficiency (OTCD) is the most prevalent urea cycle disorder. Here, we show that intravenously delivered human OTC (hOTC) mRNA by lipid nanoparticles (LNP) was an effective treatment for OTCD by restoring the urea cycle. We observed a homotrimer conformation of hOTC proteins produced by the mRNA-LNP in cells by cryo-electron microscopy. The immunohistochemistry revealed the mitochondria localization of produced hOTC proteins in hepatocytes in mice. In livers of mice intravenously injected with hOTC-mRNA/LNP at 1.0 mg/kg, the delivered hOTC mRNA levels steeply decreased with a half-life (t1/2) of 7.1 h, whereas the produced hOTC protein levels retained for 5 days and then declined with a t1/2 of 2.2 days. In OTCD model mice (high-protein diet-fed Otcspf-ash hemizygous males), a single dose of hOTC-mRNA/LNP at 3.0 mg/kg ameliorated hyperammonemia and weight loss with prolonged survival rate (22 days) compared with that of untreated mice (11 days). Weekly repeated doses at 0.3 and 1.0 mg/kg were well tolerated in wild-type mice and showed a dose-dependent amelioration of survival rate in OTCD mice, thus, showing the therapeutic potential of LNP-formulated hOTC mRNA for OTCD. [Display omitted] Yamazaki et al. used LNP to formulate hOTC-mRNA for delivery to hepatocytes to treat OTCD. hOTC proteins produced by hOTC-mRNA/LNP in cells shows the trimeric conformation and mitochondrial localization. Single and multiple doses of hOTC-mRNA/LNP demonstrated efficacy in an OTCD mouse model.