Animal Models

Overview of Animal Models

Animal models serve as the primary in vivo bridge between molecular hypotheses and clinical translation, and commercial offerings increasingly favor purpose-built, disease-specific systems over generic backgrounds. Current platforms span humanized models engineered to express human targets for direct pharmacological testing, immunodeficient models that support engraftment of human tumors or immune cells, and genetically modified lines that recapitulate metabolic, cardiovascular, neurodegenerative, or autoimmune disease phenotypes. Standard inbred and outbred lines remain in use as baseline platforms for toxicology and mechanistic studies where a defined genetic background matters more than a humanized target. Together, these options reflect a shift toward modular systems that can be combined with additional humanization, gene edits, or engraftment to address a specific research question.

Considerations for Model Selection

Model selection should begin with matching the genetic architecture of the model to the biological question, since a full gene knockout answers a different question than a targeted knock-in designed for species cross-reactivity. Immune status is a second key variable, as immunodeficient platforms enable efficient human cell engraftment but sacrifice the immune components needed to study immunotherapy mechanisms, while immunocompetent humanized models preserve endogenous immunity at some cost to engraftment efficiency. Investigators should also weigh the strength of available validation data, prioritizing models benchmarked against approved or clinical-stage therapeutics, since this evidence is often the best proxy for translational relevance. Finally, practical factors such as disease onset timing, breeding requirements, and husbandry burden should inform selection, particularly for chronic disease models where study timelines and cost are directly affected.