Documents & Resources
Micronucleus Induction by 5-Methoxypsoralen in the Photo Reconstructed Skin Micronucleus Assay
March 28, 2025To address a lack of suitable non-animal tools to screen novel ingredients in personal care products for mutagenic/clastogenic activity after solar light exposure, we initiated a three-phase program to develop a new approach methodology (NAM) which integrates established UVA/UVB/visible light (UV/vis) photo-activation techniques to the reconstructed skin micronucleus (RSMN) assay. The first phase of the program established a repeat exposure photo- irradiation schedule in reconstructed human epidermal (RhE) tissues, and the second phase was conducted to identify a photo-genotoxic substance for use as a positive control in subsequent third phase studies focused upon test method evaluations. An ideal positive control should be non-mutagenic in the absence of photo-activation, but is recognized to have human-relevant photo-induced mutagenic or carcinogenic etiology or, at minimum, is known to induce micronuclei in replicating mammalian cells after photo-irradiation.
Addressing Key Factors in Cryopreservation Method Development Ensures Robust Performance for Human Precision-cut Lung Slices
March 28, 2025As new approach methodologies (NAMs) are increasingly explored to identify dependable and accurate non-animal alternatives to predict human toxicities, several 3-dimensional test systems have emerged as excellent models of the human respiratory tract. Among these, human precision-cut lung slices (hPCLS) are considered highly relevant, containing many cell types (including key immune cells), small airways, and respiratory parenchyma in a native architecture configuration. Despite their excellent representation of the deep lung, limited accessibility to fresh (non-transplantable) human donor lungs has hampered the hPCLS model as a mainstream test system for screening efforts and standardization toward regulatory applications. Hence, efforts for cold- and cryo-preservation of hPCLS have emerged as potential solutions that will enable hPCLS access in a flexible manner.
Genotoxicity Evaluation of Fragrances and Botanicals using ToxTracker Assay
March 28, 2025The ToxTracker® assay has gained attention as a second tier non-animal test method to the standard battery of in vitro genotoxicity assays by providing mechanistic insights into the modes of action including DNA damage, oxidative stress, cellular stress, protein damage, and the validated method is currently undergoing review at the OECD level for acceptance within international regulatory frameworks. As such, ToxTracker® is designed to identify both genotoxic and non-genotoxic carcinogens, thus providing industry and regulatory toxicologists with highly useful information for hazard and risk assessment purposes. Whereas ToxTracker® can be used as a confirmatory assay when chemicals show positive or equivocal results in Ames and/or micronucleus tests, the test method is also used for rapid and cost-effective screening of chemicals to identify potential DNA mutagens. The test method is reported to have a wide chemical applicability domain; accordingly, this study was focused on evaluating chemicals found to have genotoxic potential either from classic genetox test methods or have compelling evidence of in vivo carcinogenic activity.
Transfer and Refinement of the Reactive Oxygen Species (ROS) Assay to Evaluate Photoreactivity Potential
March 28, 2025Photoreactivity evaluation is one of the initial screenings in a photosafety assessment that can identify compounds which may have the potential to produce various types of adverse photo reactions, including photoirritation (or phototoxicity), photoallergy, and photogenotoxicity. The Reactive Oxygen Species (ROS) Photoreactivity Assay, adopted under OECD Test Guideline (TG) 495, is an in chemico test system that measures the amount of ROS generated by a test compound upon exposure to simulated sunlight. The generation of ROS is determined through measurement of singlet oxygen (SO) and superoxide anion (SA) produced through the bleaching of p-nitrosodimethylaniline (RNO) and the reduction of nitroblue tetrazolium (NBT) in respective reaction mixtures.
Optimizations of the Reconstructed Human Epidermis-Based Phototoxicity Testing to Evaluate the Safety of Long-Lasting Cosmetic Products
January 10, 2025The safety of cosmetic products coming in contact with consumers’ skin is often assessed using New Approach Methodologies, which include Reconstructed human Epidermis (RhE) tissue models that have demonstrated utility as reliable test systems. In our manuscript, we evaluated the phototoxicity potential of long-lasting cosmetic products, such as lipsticks and foundations containing UV-absorbing ingredients. given their design to persist on application areas of skin, technical challenges were encountered in the experiments using RhE tissues as the products could not be entirely removed at the end of the exposure period. (more…)
A Proof-of-Concept for Safety Evaluation of Inhalation Exposure to Known Respiratory Irritants Using In Vitro and In Silico Methods
January 8, 2025There is increased interest in developing non-animal test systems for inhalation exposure safety assessments. However, defined methodologies are absent for predicting local respiratory effects from inhalation exposure to irritants. The current study introduces a concept for applying in vitro and in silico methods for inhalation exposure safety assess- ment. (more…)
Building Confidence and Transparency Into a New Validation Paradigm
November 26, 2024For the last two decades, validation management organizations have evaluated new test methods according to the OECD’s Guidance Document 34: Guidance Document On The Validation And International Acceptance Of New Or Updated Test Methods For Hazard Assessment (“GD 34”, 2005, https://doi.org/10.1787/20777876; now under revision).
Human relevance of in vivo and in vitro skin irritation tests for hazard classification of pesticides
September 24, 2024Test methods to inform hazard characterization and labeling of pesticides to protect human health are typically conducted using laboratory animals, and for skin irritation/corrosion the rabbit Draize test is currently required by many regulatory agencies. Although the Draize test is generally regarded to provide protective classifications for human health, new approach methodologies (NAMs) have been developed that offer more human relevant models that circumvent the uncertainty associated with species differences that exist between rabbits and humans. (more…)
The Fibrotic Phenotype of Human Precision-Cut Lung Slices Is Maintained after Cryopreservation
September 24, 2024Human precision-cut lung slices (hPCLS) prepared from fibrotic lungs recapitulate the pathophysiological hallmarks of fibrosis. These hallmark features can also be induced by treating non-fibrotic hPCLS with a fibrotic cocktail (FC). As a result, the fibrotic and fibrosis-induced hPCLS are rapidly emerging as preferred models for disease modeling and drug discovery. However, current hPCLS models are limited by tissue viability in culture, as they are usually only viable for one week after harvesting. (more…)
Deriving a point of departure for assessing the skin sensitization risk of wearable device constituents with in vitro methods
September 24, 2024Wearable devices are in contact with the skin for extended periods. As such, the device constituents should be evaluated for their skin sensitization potential, and a Point of Departure (PoD) should be derived to conduct a proper risk assessment. Without historical in vivo data, the PoD must be derived with New Approach Methods (NAMs). To accomplish this, regression models trained on LLNA data that use data inputs from OECD-validated in vitro tests were used to derive a predicted EC3 value, the LLNA value used to classify skin sensitization potency, for three adhesive monomers (Isobornyl acrylate (IBOA), N, N- Dimethylacrylamide (NNDMA), and Acryloylmorpholine (ACMO) and one dye (Solvent Orange 60 (SO60)). (more…)