Potential of in vivo stress reporter models to reduce animal use and provide mechanistic insights in toxicity studies

Abstract

Chemical risk assessment ensures protection from the toxic effects of drugs and manmade chemicals. To comply with regulatory guidance, studies in complex organisms are required, as well as mechanistic studies to establish the relevance of any toxicities observed to man. Although in vitro toxicity models are improving, in vivo studies remain central to this process. Such studies are invariably time-consuming and often involve large numbers of animals. New regulatory frameworks recommend the implementation of “smart” in vivo approaches to toxicity testing that can effectively assess safety for humans and comply with societal expectations for reduction in animal use. A major obstacle in reducing the animals required is the time-consuming and complexity of the pathological endpoints used as markers of toxicity. Such endpoints are prone to inter-animal variability, subjectivity and require harmonisation between testing sites. As a consequence, large numbers of animals per experimental group are required. To address this issue, we propose the implementation of sophisticated stress response reporter mice that we have developed. These reporter models provide early biomarkers of toxic potential in a highly reproducible manner at single-cell resolution, which can also be measured non-invasively and have been extensively validated in academic research as early biomarkers of stress responses for a wide range of chemicals at human-relevant exposures. In this report, we describe a new and previously generated models in our lab, provide the methodology required for their use and discuss how they have been used to inform on toxic risk. We propose our in vivo approach is more informative (refinement) and reduces the animal use (reduction) compared to traditional toxicity testing. These models could be incorporated into tiered toxicity testing and used in combination with in vitro assays to generate quantitative adverse outcome pathways and inform on toxic potential.

Novelin vivoTDP-43 stress reporter models to accelerate drug development in ALS

“…These included the spinal cord, cortex and hippocampus (Figure 1 and Figure S2). Positive β-gal staining was observed in hTDP-43 wt -HOTT het mice as previously described in dentate gyrus and cortex regions (13). Differential expression of the reporter was not observed between the experimental groups in areas of spinal cord (Figure 1).…”

“…hTDP-43 animals were purchased from Jackson Lab (B6;SJL-Tg(Thy1-TARDBP)4Singh/J; strain number 012836) and they were described before (11). hTDP-43_p21 and hTDP-43_Hmox1 reporter mice were generated by crossing hTDP-43 heterozygous (hTDP43 het ) mice into heterozygous Hmox1 (HOTT het ) or p21 (p21 het ) reporter mice (13). Mice were housed in open-top cages in temperature-controlled rooms at 21°C, with 45-65% relative humidity and 12h/12h light/dark cycle.…”

“…This model provides an opportunity to study TDP-43-driven pathology and cell stress in a short timeframe. We have developed a portfolio of reporter mouse models in which the activation of cellular cytoprotective pathways, including inflammation/oxidative stress (NRF2-Hmox1 reporter) and senescence/DNA damage (p53-p21 reporter), can be monitored at single-cell resolution across all organs, tissues, and cell types (13)(14)(15). Moreover, the measurements can also be performed non-invasively and in real-time.…”

Potential of in vivo stress reporter models to reduce animal use and provide mechanistic insights in toxicity studies

“…figshare: F1000R-NC3R Publication - Potential of in vivo stress reporter models to reduce animal use and provide mechanistic insights in toxicity studies, https://doi.org/10.6084/m9.figshare.c.6049598.v2 . 21 …”

“…Underlying data figshare: F1000R-NC3R Publication -Potential of in vivo stress reporter models to reduce animal use and provide mechanistic insights in toxicity studies, https://doi.org/10.6084/m9.figshare.c.6049598.v2. 21 Reporting guidelines figshare: ARRIVE Essential 10 Checklist for "Potential of in vivo stress reporter models to reduce animal use and provide mechanistic insights in toxicity studies", https://doi.org/10.6084/m9.figshare.20528352.v1. 22 Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).…”