Mouse precision-cut liver and kidney slices: an optimized ex vivo model for organotoxicity testing.

As excretion organs, the kidneys and liver are exposed to high concentrations of potentially toxic substances. While animal models remain the gold standard for organ-specific toxicity testing, meaningful alternative ex vivo approaches are essential in order to align with the 3 R principles (refinement, reduction, replacement). Precision-cut tissue slices (PCTS) retain native tissue architecture, cellular heterogeneity, the interplay of different cell types, and metabolic capacity, offering a promising link between in vitro and in vivo models. Here, we aimed to establish an optimized protocol for preparation and cultivation of precision-cut kidney and liver slices (PCKS and PCLS) from mice for use in substance-oriented toxicity testing. Key parameters - including slice thickness, media composition and oxygenation, glucose levels, and incubation time - were refined to preserve tissue viability and metabolic function. Five known prototypical toxins - acetaminophen, cyclosporin A, cisplatin, arsenic trioxide, and aristolochic acid I - were tested. While PCKS showed comparable sensitivity to established kidney cell lines, PCLS achieved IC50 values closely matching in vivo toxicity data. High reproducibility across different experimenters was achieved, highlighting the robustness of the model. In conclusion, the optimization of this ex vivo system makes this valuable, reproducible, and ethically approved platform for testing nephrotoxicity and hepatotoxicity accessible to more laboratories, for example for dose finding or compound prioritization, thereby supporting 3 R-conform preclinical drug screening as well as hazard identification and potentially reducing reliance on animal experiments.