Lipid nanoparticle-targeted mRNA formulation as a treatment for ornithine-transcarbamylase deficiency model mice
Kazuto Yamazaki, Kenji Kubara, Satoko Ishii, Keita Kondo, Yuta Suzuki, Takayuki Miyazaki, Kaoru Mitsuhashi, Masashi Ito, Kappei Tsukahara
Abstract
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 (h OTC ) 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 h OTC -mRNA/LNP at 1.0 mg/kg, the delivered h OTC mRNA levels steeply decreased with a half-life (t 1/2 ) of 7.1 h, whereas the produced hOTC protein levels retained for 5 days and then declined with a t 1/2 of 2.2 days. In OTCD model mice (high-protein diet-fed Otc spf-ash hemizygous males), a single dose of h OTC -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 h OTC mRNA for OTCD.