ALTEX

The adverse outcome pathways (AOPs) were developed to accelerate evidence-based chemical risk assessment by leveraging data from new approach methodologies. Thanks to their stressor-agnostic approach, AOPs were seen as instrumental in other fields. Here, we present AOPs that report non-chemical stressors along with the challenges encountered for their development. Challenges regarding AOPs linked to nanomaterials include non-specific molecular initiating events, limited understanding of nanomaterial biodistribution, and needs for adaptations of the in silico modeling and testing systems...

Effective repair of spinal cord injury sites remains a major clinical challenge. One promising strategy is the implantation of multifunctional bioscaffolds to enhance nerve fibre growth, guide regenerating tissue and modulate scarring/inflammation processes. Given their multifunctional nature, such implants require testing in models which replicate the complex neuropathological responses of spinal injury sites. This is often achieved using live, adult animal models of spinal injury. However, these have substantial drawbacks for developmental testing, including the requirement for large numbers of animals, costly infrastructure, high levels of expertise and complex ethical processes...

QT prolongation and the potentially fatal arrhythmia Torsades de Pointes are common causes for withdrawing or restricting drugs; however, little is known if environmental chemicals may have similar liabilities. Current in vitro-in silico models for testing proarrhythmic liabilities, using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM), provide an opportunity to address this data gap. These methods are still low- to medium-throughput and not suitable for testing the tens of thousands of chemicals in commerce...

Difficult to test substances including poorly soluble, mildly irritating, or Unknown or Variable Composition Complex reaction products or Biological Materials (UVCBs), producing weak or borderline in vivo results, face additional challenges in in vitro assays that often necessitates data integration in a weight of evidence (WOE) approach to inform skin sensitization potential. Here we present several case studies on difficult to test substances and highlight the utility of Toxicological Prioritization Index (ToxPi) as a data visualization tool to compare skin sensitization biological activity...

In vitro methods provide a key opportunity to consider human-relevant exposure scenarios for hazard identification of inhaled toxicants. Compared to in vivo tests, in vitro methods have the advantage of assessing effects of inhaled toxicants expressed by differences in dosimetry, e.g. variations in concentration (exposure intensity), exposure duration and exposure frequency, in an easier way. Variations in dosimetry can be used to obtain information on adverse effects in human relevant exposure scenarios that can be used for risk assessment...

In 2019, the US EPA Administrator issued a directive directing the agency away from reliance on vertebrate tests by 2035, whilst maintaining high quality human health and environmental risk assessments.  There is no accepted approach to achieve this. The decade long duration of the crop protection (CP) chemical R&D process therefore requires both the invention, and application, of a modernized approach to those CP chemical projects entering corporate research portfolios by the mid-2020s.  Consequently, we conducted problem formulation discussions with regulatory agency scientists which created the problem statement: "Develop, demonstrate, and implement a modern scientifically sound and robust strategy that applies appropriate and flexible exposure and effects characterization without chemical specific vertebrate tests to reliably address risk, uncertainties, and deficiencies in data and its interpretation with equivalent confidence as do the currently accepted test guidelines and meet the regulatory needs of the agencies"...

The Adverse Outcome Pathway (AOP) framework plays a crucial role in the paradigm shift of toxicity testing towards the development and use of new approach methodologies. AOPs developed for chemicals are in theory applicable to nanomaterials (NMs). However, only subtle efforts have been made to integrate information on NM-induced toxicity into existing AOPs. In a previous study, we identified AOPs in the AOP-Wiki associated with the molecular initiating events (MIEs) and key events (KEs) reported for NMs in scientific literature...

While the original definition of replacement focuses on the replacement of the use of animals in science, a more contemporary definition focuses on accelerating the development and use of predictive and robust models, based on the latest science and technologies, to address scientific questions without the use of animals. The transition to animal free innovation is on the political agenda in and outside the European Union. The Beyond Animal Testing Index (BATI) is a benchmarking instrument designed to provide insight into the activities and contribution of research institutes in the transition to animal free innovation...

At present, quality control of diphtheria vaccines by both manufacturers and national control laboratories relies heavily on in vivo assays to confirm potency. As part of the VAC2VAC project we have developed a monoclonal antibody (mAb) enzyme-linked immunosorbent assay (ELISA) to measure the relative amount and quality of diphtheria toxoid (DTxd) in Diphtheria-Tetanus based vaccines, and believe this test has the potential to play a key role in a control strategy no longer including an in vivo potency test...

Adverse outcome pathways (AOPs) provide evidence for demonstrating and assessing causality between measurable toxicological mechanisms and human or environmental adverse effects. AOPs have gained increasing attention over the past decade and are believed to provide the necessary steppingstone for more effective risk assessment of chemicals and materials and moving beyond the need for animal testing. However, as with all types of data and knowledge today, AOPs need to be reusable by machines, i.e., machine-actionable, in order to reach their full impact potential...

Bile acid homeostasis is vital for numerous metabolic and immune functions in humans. The enterohepatic circulation of bile acids is extremely efficient, with ~95% of the intestinal bile acids being reabsorbed. Disturbing intestinal bile acid uptake is expected to substantially affect intestinal and systemic bile acid levels. Here, we aimed to predict the effects of apical sodium-dependent bile acid transporter (ASBT)-inhibition on systemic plasma levels. For this, we combined the in vitro Caco-2 cell transport assays with physiologically based (PBK) modeling...

Publication of scientific findings is fundamental for research, pushing innovation and generating interventions that benefit society, but it is not without biases. Publication bias is generally recognized as journal's preference for publishing studies based on the direction and magnitude of results. However, early evidence of a newly recognized type of publication bias has emerged in which journal policy, peer reviewers, or editors request that animal data be provided to validate studies produced using nonanimal-based approaches...

In chemical safety assessment, benchmark concentrations (BMC) and their associated uncertainty are needed for the toxicological evaluation of in vitro data sets. A BMC estimation is derived from concentration-response modelling and results from various statistical decisions, which depend on factors such as experimental design and assay endpoint features. In current data practice, the experimenter is often responsible for the data analysis and therefore relies on statistical software often without being aware of the software default settings and how they can impact the outputs of data analysis...

Lung cancer is a leading cause of death worldwide, with only a fraction of patients responding to immunotherapy. The correlation between increased T-cell infiltration and positive patient outcomes has motivated the search for therapeutics promoting T-cell infiltration. While transwell and spheroid platforms have been employed, these models lack flow and endothelial barriers, and cannot faithfully model T-cell adhesion, extravasation and migration through 3D tissue. Presented here is a 3D chemotaxis assay, in a lung tumor-on-chip model with 3D endothelium (LToC-Endo), to address this need...

Since Russell and Burch introduced and defined the 3Rs, i.e., the replacement, reduction, and refinement of animal use in research, in 1959, different definitions have emerged and been implemented in guidelines and policies. Switzerland is known for having some of the most restrictive legislation regarding the use of animals, in which the 3Rs are also defined and implemented. To our knowledge, the purpose and definitions of the 3Rs used in the Swiss Animal Welfare Act, Animal Protection Ordinance and Animal Experimentation Ordinance have never been compared with Russell and Burch's original purpose and definitions...

The assessment of skin sensitising properties of chemicals has moved away from the traditional animal methods to new approach methodologies (NAM), guided by qualitative mechanistic understanding operationalised in an adverse outcome pathway (AOP). As with any AOP, the molecular initiating event (MIE) of covalent binding of a chemical to skin proteins is particularly important. This MIE has been modelled by several test methods by measuring the reaction of a test chemical with model peptides in chemico. To better understand the similarities and differences, a data repository with publicly available data for the Direct Peptide Reactivity Assay (DPRA), Amino acid Derivative Reactivity Assay (ADRA) and kinetic DPRA (kDPRA), as well as the Peroxidase Peptide Reactivity Assay (PPRA) was assembled...

Efforts have been made to replace animal experiments in safety evaluations, including in vitro-based predictions of human internal exposures, such as predicting peak plasma concentration (Cmax) values for xenobiotics and comparing these values with in vitro-based toxicity endpoints. Herein, the authors predicted the Cmax values of food-related compounds in humans, based on the existing and novel in vitro techniques. In this study, 20 food-related compounds, which have been previously reported in human pharmacokinetic or toxicokinetic studies were evaluated...

Many interventions that show promising results in preclinical development do not pass clinical tests. Part of this may be explained by poor animal-to-human translation. Using animal models with low predictability for humans is neither ethical, nor efficient. If translational success shows variation between medical research fields, analyses of common practices in these fields could identify factors contributing to successful translation. We have thus assessed translational success rates in medical research fields using two approaches: through literature and clinical trial registers...

Proper brain development is based on the orchestration of key neurodevelopmental processes (KNDP), including the formation and function of neural networks. If at least one KNDP is affected by a chemical, an adverse outcome is expected. To enable a higher testing throughput than the guideline animal experiments, a developmental neurotoxicity (DNT) in vitro testing battery (DNT IVB) comprising a variety of assays that model several KNDPs was set up. Gap analyses revealed the need for a human-based assay to assess neural network formation and function (NNF)...

Absorption in the gastrointestinal tract is a key factor in the bioavailability of chemicals after oral exposure, but is frequently assumed to have a conservative value of 100% for environmental chemicals, particularly in the context of high throughput toxicokinetics for in vitro-to-in vivo extrapolation (IVIVE). For pharmaceutical compounds, the physiological-based Advanced Compartmental Absorption and Transit (ACAT) model has been used extensively to predict gut absorption, but has not generally been applied to environmental chemicals...