Liver-humanized mice

Liver-humanized mice engraft human hepatocytes into a mouse host whose liver and immune backgrounds permit repopulation.^[S1][S3] The resulting system can measure specified human-hepatocyte endpoints in vivo. It does not eliminate species differences, establish human toxicity or safety, or predict development success. This article focuses on the platform records that were verified for US commissioning.

What the human hepatocyte compartment establishes

Published platform records describe human hepatocyte expansion in Fah-/-Rag2-/-Il2rg-/- mice and human-type metabolic responses in a uPA/SCID-based system.^[S1][S3] Those findings support measuring metabolism or another prespecified hepatocyte endpoint under the reported conditions. They do not make the remainder of the animal human, and they do not establish human pharmacokinetics, drug-induced liver injury, efficacy, or safety. “Gold standard” is therefore not used.

Verified foundational papers

Both citations in the Japanese original contained bibliographic discrepancies.^[S2][S3] The blocks below replace them with the closest verified papers by the named authors. Read the full papers before using a specific method or performance claim in a protocol.

uPA/SCID paper and hepatocyte replacement^[S3]

• {'items': ['Verified paper: “Near completely humanized liver in mice shows human-type metabolic responses to drugs.”^[S3]', 'Tateno C, et al.; American Journal of Pathology, 2004;164(4):1301-1313.^[S3]']}

The verified Tateno paper reports a uPA/SCID-based liver-humanization system and human-type metabolic responses to drugs.^[S3] Cite the paper for its reported model and findings, not for the stronger original claims that it established a universal replacement-rate metric or a standard framework for pharmacokinetic studies.

Verified Katoh review^[S2]

• {'items': ['Verified paper: “Chimeric mice with humanized liver.”^[S2]', 'Katoh M, Tateno C, Yoshizato K, and Yokoi T; Toxicology, 2008;246(1):9-17.^[S2]']}

The verified record establishes a 2008 Toxicology review titled “Chimeric mice with humanized liver.”^[S2] It does not substantiate the different title in the Japanese original or, by bibliographic record alone, the claims of high predictive performance for human clearance, toxicity, or safety. Any such performance claim requires a directly supporting validation study.

Verified platform records

The verified records cover three platform families: published uPA/SCID work, published FRG work with a US commercial record, and the PXB-mouse company record.^{[S1][S3][S4][S5]} They are listed without ranking. A sponsor still has to match host genotype, donor, replacement or engraftment criterion, test article, endpoint, and study duration to the question.

Protocol decisions that govern interpretation

Put the variables that could change interpretation into the protocol: host genotype, human-hepatocyte donor and lot, qualification data, engraftment or replacement criterion, allocation across groups, test-article exposure, sampling schedule, primary endpoint, exclusions, and analysis plan. If an immune-humanized component is proposed, require separate evidence and acceptance criteria for it. Adding a human cell compartment does not establish a human safety response.

Commissioning checklist

The verified literature identifies uPA/SCID and FRG approaches, and the verified company records identify US-accessible FRG and PXB offerings.^{[S1][S3][S4][S5]} Compare them on the exact host, donor, engraftment criterion, endpoint, schedule, and current supply terms. Results establish what occurred in that chimeric mouse system. They do not show that a candidate will have human pharmacokinetics, avoid liver injury, or succeed clinically.