TABLE 4.

Highlights of good practices for preclinical in vivo research on NP

1. Product translational relevance and replicability:

a. Equivalent product formulation. NPs used in preclinical studies should use similar or analogous formulation(s) to the intended human studies.

b. Biotransformation. Track the actual bioactives, which may be generated from precursors in the NP by the host or the host’s gut microbiota. Either or both may transform NP constituents to active or inactive compounds. These transformations may differ between models and humans, and amongst humans, and affect replicability of results.

c. Dose-ranging. Doses used in models should be comparable to anticipated human dosage. Initial dose ranges may be based on traditional use or MPS dose-response studies, derived using PBPK modeling, or from preclinical in vivo studies using appropriate scaling approaches. A clinical study is still required to establish dose-response, assess safety, and determine PK and PD in the target population.

2. Model translational relevance:

a. Model selection. Consider the translational relevance for the specific research question of different species and strains, humanized, outbred, wildling, and/or genetically modified models. Heterogeneity in the model organisms may contribute to the ability to predict responders vs. non-responders.

b. Documentation. Document as much as possible. Endogenous (e.g., age, sex, physiological/health status, genetic), and external factors (e.g., environment, including background diet, exposure history, enclosure size and enrichment, circadian timing, season, duration and timing of exposure relative to outcome assessment, handlers and handling methods) may affect outcomes. Make these records findable, accessible, interoperable, reusable (FAIR) (100).

3. Validated methods for de-risking the NPCT (see also Fig. 1): Develop and use validated assays to assess achievement of go/no-go criteria based on as many components of the mechanistic model as possible (see Fig. 1), e.g, achievement of effective concentrations of the bioactive component(s) at in vivo targets, target occupancy, and modulation of relevant biological networks.

4. Specimen collection, analysis, archiving. Collect and appropriately document and store specimens needed for assays described in point 3, and as applicable, fecal or other relevant samples to facilitate assessment of any association of the gut microbiota with differential responses. In analyses, include approaches to control for known artefacts, such as reagent contamination that can strongly affect outcomes in low biomass microbiome specimens (195).