Posters & Presentations
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.
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).
Approaches to Evaluation of Solvents for use in Photosafety Testing
March 20, 2024New Approach Methodologies (NAMs) are routinely used in photosafety testing to evaluate if a test compound has the potential to become more toxic upon exposure and subsequent exposure to light. Three such NAMs to address photosafety are the in chemico UV-Vis Assay, the cell-based 3T3 Neutral Red Uptake (NRU) Phototoxicity Test (PT), and the tissue-based Reconstructed human EpiDermis (RhE) Phototoxicity Test (PT), described under OECD Test Guidelines (TG) 101, 432, and 498, respectively. (more…)
Refinement and Optimization of the Photo-KeratinoSens™ Assay to Evaluate Photoallergy Potential
March 20, 2024Identification of test chemicals that have the potential to become more reactive, more toxic, or may become phototoxic upon application and subsequent exposure to sunlight is integral to photosafety testing. Several regulatory-based New Approach Methodologies (NAMs) are widely used in the evaluation of phototoxicity and skin sensitization potential. More recently, there has been an increased interest in ability to identify photoallergens. To this end, an innovative photo-KeratinoSens™ assay was established with addition of an irradiation exposure (5 J/cm2 of UVA) to the KeratinoSens™ Skin Sensitization Test (OECD TG 442D), as described in Tsujita-Inoue, et al. (2015). Twelve reference compounds were previously evaluated at IIVS under a protocol adapted from Tsujita-Inoue, et al. (2015), resulting in an accuracy of 58.3% (7/12 correctly predicted), with low sensitivity (50%, 5/10 positives correctly predicted) (Hilberer, et al., 2023).
Toxicity and Inflammatory Response to Common Magic Mouthwashes in a 3D Oral Reconstructed Tissue Model
November 8, 2023Magic Mouthwash is a general term describing oral rinses prescribed by a doctor for the treatment of pain, inflammation, or infection, commonly as a result of chemotherapy and radiation induced oral sores (oral mucositis). There is no set combination of ingredients for the preparation of a magic mouthwash, rather they are formulated for the individual needs of each patient, selecting from an array of various active ingredients. Although the ingredients most commonly used to formulate Magic Mouthwashes are considered safe as prescribed, the final formulations lack toxicity and inflammatory response data. (more…)
Safety Assessment of Monographed OTC Cold/Cough Medicine Using an In Vitro Testing Platform Based on Human Reconstructed Oral Tissues
November 8, 2023Over-the-counter (OTC) products are available to alleviate concurrent symptoms of colds and flu. They are primarily based on a combination of decongestants, antitussive and alpha adrenergic agonists, which are well-established pharmaceutical agents covered by U.S. monographs. Many of the active components of the OTC cough/cold drugs are bitter and must be masked using flavoring agents. Bayer internally employed a stringent safety testing program for OTC cough/cold medicine line extensions that require the products to be held in the mouth for a short period using an innovative testing platform based on reconstructed oral tissues. (more…)
A Laboratory Method to Measure Skin Surface Staining by Cigarette Smoke
October 20, 2023Exhaled or side-stream cigarette smoke (CS) may visually stain a consumer’s skin over time. Tobacco heating prod- ucts (THPs) and e-cigarettes (ECs) have reduced staining potential because they do not produce side-stream aerosols and their exhaled aerosols have significantly reduced levels of toxicants, particles and odour. Here we assess discolour- ation of porcine skin in vitro after exposure to particulate matter (PM) or aerosols from CS (3R4F), two THPs (glo and glo sens) and an EC (iSwitch Maxx). (more…)