DOI: 10.1097/hc9.0000000000001022 ISSN: 2471-254X

Prime editing models the MTARC1 A165T variant in human liver organoids, demonstrating reduced steatosis, inflammation, and fibrosis

Amel Ben Saad, Nahid Arghiani, Arden D. Weilheimer, Stefan D. Gentile, Benjamin J. Toles, Sudipta Tripathi, Seher Mohsin Sayed, Anil Chandraker, Alan C. Mullen
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Background:

Metabolic dysfunction–associated steatotic liver disease (MASLD) is the most prevalent cause of chronic liver disease worldwide. This progressive, multifactorial condition is characterized by hepatic steatosis, which can evolve into steatohepatitis, fibrosis, cirrhosis, and liver cancer. Genetic factors influence the development, progression, and complications in MASLD, and genome-wide association studies (GWAS) have identified single-nucleotide polymorphisms (SNPs) associated with altered risk. Mitochondrial amidoxime reducing component 1 ( MTARC1 ) rs2642438 (p.A165T) variant has been identified as protective, but the role of MTARC1 and the impact of this variant in hepatocytes remains poorly understood.

Methods:

We applied prime editing to create the rs2642438 variant in human embryonic stem cells (hESCs) before differentiation into human liver organoids (HLOs) to investigate the effect of the variant under conditions of steatotic and fibrotic injury.

Results:

Compared with HLOs formed from hESCs containing the MTARC1 reference sequence, HLOs with the rs2642438 variant show lower levels of MTARC1 protein and triglycerides and are protected from steatotic and fibrotic injury, as predicted by the phenotype observed in patients carrying the variant. The observed decrease in triglyceride levels with the variant appears to be driven more by suppression of de novo lipogenesis than stimulation of β-oxidation in the HLO model. While resmetirom, the thyroid hormone receptor-beta (THRB) agonist approved to treat patients with metabolic dysfunction–associated steatohepatitis (MASH), was effective in reducing triglyceride levels in the setting of steatotic injury in HLOs with the reference sequence, HLOs containing the variant did not show further reduction in triglyceride levels with exposure to resmetirom.

Conclusions:

Collectively, these findings establish a platform to model disease-associated SNPs in HLOs, provide insight into the activity of the MTARC1 variant, and suggest that SNP profiling may help identify patients more likely to respond to MASLD therapies.

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