Genotoxicity evaluation using primary hepatocytes isolated from rhesus macaque (Macaca mulatta)

Comparative DNA damage induced by eight nitrosamines in primary human and macaque hepatocytes

N-nitrosamines have been increasingly detected in human drugs, raising serious safety concerns due to their potential mutagenicity and carcinogenicity. In order to expand upon the human data available on these drug impurities, we previously used metabolically competent HepaRG human hepatoma cells to evaluate the genotoxicity of eight small-molecule nitrosamines [N-cyclopentyl-4-nitrosopiperazine (CPNP), N-nitrosodibutylamine (NDBA), N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), N-nitrosodiisopropylamine (NDIPA), N-nitrosoethylisopropylamine (NEIPA), N-nitroso-N-methyl-4-aminobutyric acid (NMBA), and N-nitrosomethylphenylamine (NMPA)]. In this study, we used the comet assay to further investigate the DNA damage induced by the eight nitrosamines in primary human hepatocytes (PHHs) from three individual donors and primary macaque hepatocytes (PMHs) from freshly isolated livers of six rhesus macaques. In addition, expression of genes encoding Phase I and II metabolic enzymes and the activities of the enzymes were compared in PHHs and PMHs, and Western blot was used to analyze protein biomarkers of DNA damage and apoptosis in PMHs. All eight nitrosamines induced significant DNA damage in both PHHs and PMHs; with the exception of NDMA, higher fold increases in % tail DNA were detected in PMHs compared to PHHs. Greater interindividual variability in CYP gene expression, enzyme activities, and DNA damage responses was observed in PHHs compared to PMHs. Benchmark concentration (BMC) modeling analysis showed that PHHs had more conservative BMC50 values than PMHs for most nitrosamines tested. Nonetheless, correlation analysis demonstrated that DNA damage data generated by PMHs and 3D HepaRG spheroids were comparable to those of PHHs. Western blot analysis suggested a potential role for the ethyl group in regulating protein expression in the DNA damage and apoptosis pathways for nitrosamines. Overall, this study provides human-relevant DNA damage responses for the eight nitrosamines and indicates that differences in genotoxic potency between PHHs and PMHs are likely related to CYP enzyme activity.

Genotoxicity in Unconventional Mammalian Models of Wild, Urban, and Agricultural Ecosystems: A Systematic Review Under the One Health Approach

Background/Objectives: This systematic review evaluates unconventional mammalian models from wild, agricultural, and urban/domestic ecosystems for genotoxicity assessment under the One Health framework. Non-human primates (NHPs), cattle, and domestic dogs are analyzed as sentinel species due to their distinct environmental niches, unique human interactions, and species-specific traits. In conjunction with this, evidence is presented about the in vitro use of cells of these mammals for the genotoxicological evaluation of different chemical substances, such as veterinary drugs, environmental pollutants, and pesticides. The synthesis focuses on standardized genetic toxicology assays (e.g., chromosomal aberrations, micronucleus, comet assay) aligned with Organization for Economic Cooperation and Development (OECD) guidelines. Methods: A structured search of international literature identified studies employing OECD-compliant genotoxicity assays in NHPs, cattle, dogs, and others not listed in OECD. Data was categorized by species, assay type, chemical class evaluated, environmental context (wild, agricultural, urban), and merits of the papers. Results: NHPs, despite their phylogenetic proximity to humans, show limited genotoxicity data in contrast to biomedical research, which has been constrained by ethical concerns and fieldwork logistics. Cattle emerge as robust models in agricultural settings due to the abundance of studies on the genotoxic capacity of pesticides, veterinary drug, and environmental biomonitoring, with direct implications for food safety. Domestic dogs are recognized as powerful sentinels for human health due to shared exposomes, physiological similarities (e.g., shorter cancer latency), and reduced lifestyle confounders; however, genotoxicity studies in dogs remain sparse compared to chemical exposure monitoring or cancer research. Conclusions: This review advocates for expanded, integrated use of these models to address genotoxic threats across ecosystems, which would benefit both animal and human health. In the application of biomonitoring studies with sentinel animals, a critical gap persists: the frequent lack of integration between xenobiotic quantification in environmental and biological samples, along with genotoxicity biomarkers evaluation in sentinel populations, which hinders comprehensive environmental risk assessment.