Advancing the 3Rs: innovation, implementation, ethics and society

Unravelling early hematoendothelial development through the chick model: Insights and future perspectives

The chicken embryo has been an important model in advancing our understanding of early hematoendothelial development, particularly in the formation of hematopoietic stem cells (HSCs) and the endothelial-to-hematopoietic transition (EHT). The accessibility and ease of manipulation of chicken embryos have made them an invaluable tool for researching development of blood and endothelial cells. Early research using this model provided pivotal insights, demonstrating that intra-embryonic regions, such as the dorsal aorta (DA), are primary sources of HSCs, rather than the yolk sac (YS), as previously believed. The identification of intra-aortic hematopoietic clusters (IAHCs) and the process of EHT in the chicken embryo laid the foundation for similar discoveries in other vertebrate species, including mice and zebrafish. Recent advances in genetic tools, such as transgenic chickens expressing fluorescent proteins, have further enhanced the precision of cell lineage tracing and real-time imaging of dynamic cellular processes. This review highlights both historical contributions and contemporary advancements facilitated by the chicken model, underscoring its continued relevance in developmental biology. By examining key findings and methodological innovations, we aim to demonstrate the importance of the chicken embryo as a model system for understanding hematoendothelial development and its potential for informing therapeutic applications in regenerative medicine and blood disorders. Finally, we will underscore potential applications of the chicken model for comparative and omics-level studies in conjunction with other model systems and what future directions lie ahead.

Enhanced virulence of mixed-species Candida biofilms isolated from intragastric balloon patient: insights from larval model

Candida species, particularly Candida albicans and C. tropicalis, are critical members of the human microbiota and are associated with systemic infections, including candidaemia. The pathogenicity is largely attributed to virulence factors such as biofilm formation, which enhances antifungal resistance and immune evasion. Despite extensive research on single-species biofilms, the dynamics of polymicrobial biofilms, especially those involving fungal‒fungal interactions, remain poorly understood. This study investigated the virulence of monomicrobial and polymicrobial biofilms of C. albicans and C. tropicalis formed in vitro, using Zophobas morio larvae as a model. Biofilms were formed from C. albicans and C. tropicalis obtained from the gastric mucosa of a patient with an intragastric balloon (IGB). The biomass and structure of the monomicrobial and mixed-species biofilms were characterized via crystal violet staining and fluorescence microscopy techniques. The virulence of suspended, adhered, and planktonic Z. morio larvae was evaluated via survival assays, monitored over 10 days. C. albicans single biofilms presented greater biomass and structural organization than C. tropicalis, while mixed-species biofilms produced the highest biomass and density. Fluorescence microscopy revealed enhanced interspecies interactions in mixed biofilms, suggesting synergistic effects. Yeasts from single biofilms impacted less on survival rates, particularly under suspended and adhered cell conditions. These findings suggest that mixed-species biofilms exhibit increased virulence due to synergistic interactions between both species. Moreover, they also suggest distinct functional roles within biofilms, where C. tropicalis contributes to cellular proliferation and C. albicans supports matrix production, collectively enhancing biofilm robustness and pathogenic potential. This study underscores the pathogenic significance of fungal‒fungal interactions in biofilms, particularly under mixed-species conditions. The enhanced virulence observed in mixed biofilms highlights the importance of targeting interspecies dynamics in antifungal strategies. The use of alternative models such as Z. morio larvae provides valuable insights into biofilm-mediated infections and potential therapeutic interventions.

Contactless monitoring of respiratory rate variability in rats under anesthesia with a compact 24GHz microwave radar sensor

Objective

The objective of this study was to develop and validate a noncontact monitoring system for respiratory rate variability in rats under anesthesia using a 24GHz microwave radar sensor. This study aimed to address the need for stress-free monitoring techniques that comply with the 3Rs principle (Reduction, Replacement, and Refinement) in laboratory animal settings.

Methods

Utilizing a 24GHz microwave radar sensor, this system detects subtle body surface displacements induced by respiratory movements in anesthetized rats. The setup includes a 24.05 to 24.25 GHz radar module coupled with a single-board computer, specifically Raspberry Pi, for signal acquisition and processing. The experiment involved four male Wistar rats tracking the variability in their respiratory rates at various isoflurane anesthesia depths to compare the radar system's performance with reference measurements.

Results

The radar system demonstrated high accuracy in respiratory rate monitoring, with a mean difference of 0.32 breaths per minute compared to laser references. The Pearson's correlation coefficient was high (0.89, p < 0.05), indicating a strong linear relationship between the radar and reference measurements. The system also accurately reflected changes in respiratory rates corresponding to different isoflurane anesthesia levels. Variations in respiratory rates were effectively mapped across different anesthesia levels, confirming the reliability and precision of the system for real-time monitoring.

Conclusion

The microwave radar-based monitoring system significantly enhanced the animal welfare and research methodology. This system minimizes animal stress and improves the integrity of physiological data in research settings by providing a non-invasive, accurate, and reliable means of monitoring respiratory rates.

Cerebrolysin Induces Dendritic Tree Plastic Changes and BDNF Increase in the Amygdala of Male Rats with Maternal Deprivation

Several psychopathologies may be triggered, among other factors, by stress or trauma in childhood. The maternal deprivation model (MD) replicates some of the core factors that may induce the onset of different psychopathologies like structural and plasticity defects. Among other brain regions, the amygdala is susceptible to stress and trauma and plays a key role in integrating social behavior. Several molecules, such as Cerebrolysin® (CBL), have been used to treat different symptoms by reversing the underlying neurobiological plasticity-related changes. In this study, maternal deprivation (MD) was conducted on 9-day-old male Sprague-Dawley rats (n = 28; 7 rats per group: Intact, Intact + CBL, MD, and MD + CBL). At 25 postnatal days (PND), CBL treatment was administered for 10 consecutive days, and social behavior was evaluated in a three-chamber social test at 35 PND. Moreover, Sholl analysis and immunohistochemistry were carried out for dendritic intersection and brain-derived neurotrophic factor (BDNF) presence in the amygdala, respectively. CBL treatment had an augmentative effect on intact animals in terms of social behavior and incidences, but no differences between MD and CBL-treated animals. Moreover, dendritic intersections and BDNF decreased after the MD protocol but increased by CBL treatment in MD animals. Our results show that CBL could be part of the treatment in case of a traumatic or stressful event in neurodevelopment, especially in the youth age. According to this preclinical study, CBL could help reverse symptoms of different psychopathologies caused by stress or trauma, with neurobiological changes underlying its effect.

The Combination of Neurotropic Vitamins B1, B6, and B12 Enhances Neural Cell Maturation and Connectivity Superior to Single B Vitamins

Peripheral neuropathy (PN) is a prevalent condition characterized by damage to peripheral nerves, often linked to risk factors such as diabetes. This condition results from various forms of neural damage, including injury to the cell body, axons, or demyelination, frequently beginning with small and thinly or unmyelinated fibers. Such nerve damage disrupts normal signaling, leading to symptoms like numbness, tingling, and pain. Effective nerve repair and regeneration, particularly through remyelination, are essential therapeutic objectives. While vitamin B12's role in repair processes has been well established, emerging evidence suggests that other neurotropic vitamins, specifically B1 and B6, also contribute significantly to nerve health and symptom relief in PN. In this study, we demonstrate that a combination treatment of vitamins B1, B6, and B12 enhances repair and oxidative stress responses in co-cultures of neural and Schwann cells, leading to improved cell maturation and connectivity compared to vitamin B12 alone. Furthermore, proteomic analysis supports these observations at the molecular level, with enhanced cellular recycling processes like proteasome enhancement, as well as protein synthesis upregulation, needed to rebuild nerve connections and combatting oxidative stress. Our combined morphological and molecular results highlight the potential therapeutic advantage of the B1, B6, and B12 combination over vitamin B12 alone.

Screening of estrogen receptor activity of per- and polyfluoroalkyl substances based on deep learning and in vivo assessment

Over the past decades, exposure to per- and polyfluoroalkyl substances (PFAS), a group of synthetic chemicals notorious for their environmental persistence, has been shown to pose increased health risks. Despite that some PFAS were reported to have endocrine-disrupting toxicity in previous studies, accurate prediction models based on deep learning and the underlying structural characteristics related to the effect of molecular fluorination remain limited. To address these issues, we proposed a stacking deep learning architecture, GXDNet, that integrates molecular descriptors and molecular graphs to predict the estrogen receptor α (ERα) activities of compounds, enhancing the generalization ability compared to previous models. Subsequently, we screened the ERα activity of 10,067 PFAS molecules using the GXDNet model and identified potential ERα binders. The representative PFAS molecules with the top docking scores showed that the introduction of fluorinated alkane chains significantly increased the binding affinities of parent molecules with ERα, suggesting that the combination of phenol structural fragments and fluorinated alkane chains has a synergistic effect in improving the binding capacity of the ligands to ERα. The binding modes, SHapley Additive Explanations analysis, and attention map emphasized the importance of π-π stacking and hydrogen bonding interactions with the phenol group, while the fluorinated alkane chain enhanced the interaction with the hydrophobic amino acids of the active pocket. Experimental validation using zebrafish models further confirmed the ERα activity of the representative PFAS molecules. Overall, the current computational workflow is beneficial for the toxicological screening of emerging PFAS and accelerating the development of eco-friendly PFAS molecules, thereby mitigating the environmental and health risks associated with PFAS exposure.

Accelerating Animal Replacement: How Universities Can Lead - Results of a One-Day Expert Workshop in Zurich, Switzerland

This report is a result of an interdisciplinary workshop held at the Collegium Helveticum in Zurich, Switzerland in February 2024, in which ideas for accelerating NAMs (New Approach Methodologies) in Swiss universities were shared and discussed. Due to regional differences in university organisation and funding structures, not all recommendations will be transferable to all regions worldwide. All participants were qualified to contribute to the discussion, due to their knowledge and experience of the Three Rs, in particular with regard to their implementation. The workshop participants believed that universities, which play a pioneering role in so many other areas, should also exploit their innovative potential in the field of animal-free research. The workshop uncovered four areas that would need to be addressed in order to achieve a significant change in university science culture and do more justice to the Three Rs, namely: language - innovative framing (pro-replacement framing in official university statements); knowledge transfer - communicating innovative findings in teaching (redirecting curriculum); change of values within science faculties; and structured implementation and well-coordinated planning of the transformation (establishment of a 'transition unit'). Specific strategies for implementing these four areas are outlined. In addition, we discuss why the replacement of animal testing should be an essential goal for universities, why this goal has not yet been achieved, and why concerted efforts toward change are required.

Premises for digital twins reporting on Atlantic salmon wellbeing

Many species of fish, birds and mammals commonly live in human captivity; Atlantic salmon Salmo salar is one of them. The international legal status of the welfare of captive animals is slowly developing and still requires rigorous specification. For example, even though fish have complex cognition and elements of sentience, The United Nations' animal welfare principles still take a functional health-centred perspective overlooking the cognitive-affective component. Wellbeing problems remain a major source of slow growth and high mortality in intensive aquaculture of Atlantic salmon. The value system for decision making in vertebrates is based on expectations of emotional wellbeing for the options available and is linked with the individual's assessment of its future. We propose a new approach for monitoring and improving the welfare of salmon (or any other captive or wild vertebrate) based on modelling the salmon's wellbeing system by digital twins, which are simulation models that implement major bodily mechanisms of the organism. Indeed, predictions on boredom, stress and wellbeing can all be captured by a computational evolutionary model of the factors underlying behaviour. We explain how such an agent-based model of salmon digital twins can be constructed by modelling a salmon's subjective wellbeing experience along with prediction of its near future and allostasis (the bodily preparation for the expected near future). We attempt to identify the building blocks required in digital twin models to deliver early warnings about escalating issues that could eventually lead to negative effects on salmon health in aquaculture. These models would provide critical insights for optimizing production processes and could significantly reduce the reliance on animal experiments. Overall, reports of a population of digital twins could support the implementation of 3Rs - replacement, reduction, refinement - by offering actionable information to fish farmers as well as consumers, voters, politicians and regulators on relevant issues as well as guide experimental work on animal wellbeing across species.

Investigating Connectivity Deficits in Alzheimer's Disease Using a Novel 3D Bioprinted Model Designed to Quantify Neurite Outgrowth

Here, we present a novel 3D bioprinted model of the forebrain cortex designed to quantify neurite outgrowth across a hydrogel bridge. To validate this model, we cultured Alzheimer's disease (AD) forebrain cortical populations derived from human iPSCs carrying APP (amyloid precursor protein) mutations (K670M/N671L + V717F). Neurite and synapse formation were significantly impaired in 3D AD mutant cultures compared to controls, but this was not replicated in 2D, highlighting deficits in these traditional 2D cell culture models. To investigate the mechanisms underlying impaired neurite outgrowth in 3D and 2D models of AD, we assessed amyloid-β dysfunction, mitochondrial health, and oxidative stress in both conditions. In the 3D model, APP mutant cultures exhibited reduced mitochondrial membrane potential and fragmented networks, indicating dysfunction and potential cellular energy deficits. Additionally, elevated oxidative stress and proteostasis disruption were identified in the 3D AD models as indicators of cellular damage, which may be limiting neurite extension. Furthermore, transcriptomic (bulk RNA-Seq) analysis revealed distinct differences in gene expression pathways between 2D and 3D models of AD, suggesting alternate underlying mechanisms of disease pathology between the culture conditions. This study demonstrates the functionality of this novel 3D bioprinted model for quantifying neurite connectivity and identifying underlying disease mechanisms.

Ethical and academic dilemmas in authorship of clinical research publications: a medical oncologist's perspective

Authorship in clinical research carries significant academic, financial, and social implications. However, determining rightful authorship often introduces ethical and professional dilemmas, particularly in large, multidisciplinary studies, such as those common in oncology. This article explores the ethical complexities surrounding authorship in clinical research from the viewpoint of a medical oncologist. It addresses issues, such as academic jealousy, the inclusion of industry-affiliated researchers, honorary authorship, and the role of patient recruitment in authorship qualification. By examining current guidelines, ethical considerations, and practical cases, this paper aims to offer insights into fostering fair and transparent authorship practices in the field of clinical oncology.

Bridging the gap: From petri dish to patient - Advancements in translational drug discovery

Translational research serves as the bridge between basic research and practical applications in clinical settings. The journey from "bench to bedside" is fraught with challenges and complexities such as the often-observed disparity between how compounds behave in a laboratory setting versus in the complex systems of living organisms. The challenge is further compounded by the limited ability of in vitro models to mimic the specific biochemical environment of human tissues. This article explores and details the recent advancements and innovative approaches that are increasingly successful in bridging the gap between laboratory research and patient care. These advancements include, but are not limited to, sophisticated in vitro models such as organ-on-a-chip and computational models that utilize artificial intelligence to predict drug efficacy and safety. The article aims to showcase how these technologies improve the predictability of drug performance in human bodies and significantly speed up the drug development process. Furthermore, it discusses the role of biomarker discovery in preparation of more targeted and personalized therapy approaches and covers the impact of regulatory changes designed to facilitate drug approvals. Additionally, by providing detailed case studies of successful applications, we illustrate the practical impacts of these innovations on drug discovery and patient care.

Young TPI: empowering animal-free science among the next- generation of scientists

Strategies emphasizing animal-free innovation are imperative for the contemporary and future scientific research. They not only address important ethical concerns, but also should directly improve research accuracy and reliability through redirecting scientific inquiry toward more reliable and translatable methodologies. Promotion and encouragement for use of animal-free innovations among the next-generation of scientists, alongside knowledge acquisition and training in the increased capabilities of novel technologies, are fundamental for advancing science and the welfare of animals used for scientific purposes. The Dutch government has promoted initiatives such as Transitie Proefdiervrije Innovatie (TPI) to make the public aware of the current situation. However, the transition towards animal-free innovations will span over more than two generations. In this context, Young TPI emerged as the-first-of-its-kind network comprising young professionals and students dedicated to revolutionizing scientific practices by catalyzing the shift towards animal-free research. Grounded on three pillars - collaboration, awareness-raising, and networking - Young TPI has evolved into a premier youth network in the Netherlands. Boasting over 270 members spanning Dutch 49 institutions, including biotechnology startups and pharmaceutical companies and universities, Young TPI harnesses the diverse expertise of its members to propel a sustainable, future-proof transition and to promote a continuous dialogue with a wide range of stakeholders. This manuscript describes the conception, establishment, and progress of Young TPI from its start to present, detailing its strategy for communication, activities, and funding mechanisms, and ongoing endeavors to enlist new members and forge strategic alliances in pursuit of its mission.

"Killing in the Name of 3R?" The Ethics of Death in Animal Research

Changing relationships with nonhuman animals have led to important modifications in animal welfare legislations, including the protection of animal life. However, animal research regulations are largely based on welfarist assumptions, neglecting the idea that death can constitute a harm to animals. In this article, four different cases of killing animals in research contexts are identified and discussed against the background of philosophical, societal, and scientific-practical discourses: 1. Animals killed during experimentation, 2. Animals killed before research, 3. "Surplus" animals and 4. "Leftover" animals. The scientific community and, accordingly, animal research regulations such as the internationally acknowledged framework 3R ("Replace", "Reduce", "Refine") tend to aim at the reduction of "surplus" and, to some extent, "leftover" animals, whereas the first two classes are rather neglected. However, the perspective that animal death matters morally is supported by both societal moral intuitions and certain theoretical accounts in animal ethics. Therefore, we suggest the implementation of the 3Rs in regulations, so that they: 1. Make their underlying philosophical position transparent; 2. Are based on a weighing account of animal death; 3. Are applicable to procedures on living and dead animals; 4. Apply the "reduction" principle to procedures on dead animals; 5. Entail that methods using (parts of) dead animals need to be replaced by animal free methods, if possible; 6. Do not suggest replacing research on living animals by research on killed animals; 7. Include all kinds of animals, depending on the respective harm of death; 8. Are applied to the broader context of experimentation, including breeding and the fate of the animals after the experiment.

In vitro 3D skin culture and its sustainability in toxicology: a narrative review

In current toxicological research, 2D cell cultures and animal models are well- accepted and commonly employed methods. However, these approaches have many drawbacks and are distant from the actual environment in human. To embrace this, great efforts have been made to provide alternative methods for non-animal skin models in toxicology studies with the need for more mechanistically informative methods. This review focuses on the current state of knowledge regarding the in vitro 3D skin model methods, with different functional states that correspond to the sustainability in the field of toxicology testing. We discuss existing toxicology testing methods using in vitro 3D skin models which provide a better understanding of the testing requirements that are needed. The challenges and future landscape in using the in vitro 3D skin models in toxicology testing are also discussed. We are confident that the in vitro 3D skin models application may become an important tool in toxicology in the context of risk assessment.

Cerebrolysin Induces Motor Recovery Along with Plastic Changes in Motoneurons and an Increase in GAP43 Protein in the Ventral Spinal Cord Following a Kainic Acid Excitotoxic Lesion in the Rat Motor Cortex

Lesions in the motor cortex induced by contusions or pathological insults can exert the degeneration of afferent neurons lying distal to these lesions. Axon degeneration and demyelination are hallmarks of several diseases sharing pathophysiological and clinical characteristics. These conditions are very disabling due to the disruption of motor abilities, with lesions that affect this area proving to be a therapeutic challenge, which has driven increasing efforts to search for treatments. Cerebrolysin (CBL) contains a mix of pig brain-derived peptides with activity similar to neurotrophic factors. Here, the effect of cerebrolysin administration on the motor impairment produced by kainic acid (KA) lesion of the motor cortex was evaluated in Sprague-Dawley female rats (n = 27), defining its effect on motoneurons dendritic tree changes, dendritic spine density and GAP43 presence in the ventral thoracolumbar regions of the spinal cord. Ten days after the KA lesion of the motor cortex, rats were administered cerebrolysin, and their motor performance was evaluated using the "Basso, Beattie, and Bresnahan" (BBB) and Bederson scores. Cerebrolysin administration improved motor activity according to the BBB and Bederson scales, along with increased dendritic intersections and dendritic spine density on motoneurons. There was also a significant increase in GAP43 protein, suggesting that CBL may promote plastic changes through this protein, among others. Hence, this study proposes that cerebrolysin could promote motor recovery following motor cortex lesions by driving neuronal changes and dendritic spine plasticity on motoneurons and an increase in GAP43 protein, along with other mechanisms.

In Vivo Efficacy of a Nanoconjugated Glycopeptide Antibiotic in Silkworm Larvae Infected by Staphylococcus aureus

To contrast the rapid spread of antibiotic resistance in bacteria, new alternative therapeutic options are urgently needed. The use of nanoparticles as carriers for clinically relevant antibiotics represents a promising solution to potentiate their efficacy. In this study, we used Bombyx mori larvae for the first time as an animal model for testing a nanoconjugated glycopeptide antibiotic (teicoplanin) against Staphylococcus aureus infection. B. mori larvae might thus replace the use of mammalian models for preclinical tests, in agreement with the European Parliament Directive 2010/63/EU. The curative effect of teicoplanin (a last resort antibiotic against Gram-positive bacterial pathogens) conjugated to iron oxide nanoparticles was assessed by monitoring the survival rate of the larvae and some immunological markers (i.e., hemocyte viability, phenoloxidase system activation, and lysozyme activity). Human physiological conditions of infection were reproduced by performing the experiments at 37 °C. In this condition, nanoconjugated teicoplanin cured the bacterial infection at the same antibiotic concentration of the free counterpart, blocking the insect immune response without causing mortality of silkworm larvae. These results demonstrate the value and robustness of the silkworm as an infection model for testing the in vivo efficacy of nanoconjugated antimicrobial molecules.

The new paradigm in animal testing - "3Rs alternatives"

Regulatory studies have revolutionised over time. Today, the focus has shifted from animal toxicity testing to non-animal for regulatory safety testing. This move is in line with the international 3Rs (Replacement, Reduction, and Refinement) principle and has also changed the regulator's perspective. The 3R principle has stimulated changes in policy, regulations, and new approaches to safety assessment in drug development in many countries. The 3Rs approach has led to the discovery and application of new technologies and more human-relevant in vitro approaches that minimise the use of animals including non-human primates, in research and improve animal welfare. In 2016, the European Medicines Agency published the Guidelines on the principles of regulatory acceptance of 3Rs testing approaches, followed by a conceptual paper in 2023 to align with current 3R standards. Additionally, the United States Food and Drug Administration passed new legislation in 2023 that no longer requires all new human drugs to be tested on animals, which will change the current testing paradigm. This review paper provides the adoption of the 3Rs and the current regulatory perspective regarding their implementation.

Developing a Screening Strategy to Identify Hepatotoxicity and Drug Interaction Potential of Botanicals

Botanical supplements, herbal remedies, and plant-derived products are used globally. However, botanical dietary supplements are rarely subjected to robust safety testing unless there are adverse reports in post-market surveillance. Botanicals are complex and difficult to assess using current frameworks designed for single constituent substances (e.g. small molecules or discrete chemicals), making safety assessments costly and time-consuming. The liver is a primary organ of concern for potential botanical-induced hepatotoxicity and botanical-drug interactions as it plays a crucial role in xenobiotic metabolism. The NIH-funded Drug Induced Liver Injury Network noted that the number of botanical-induced liver injuries in 2017 nearly tripled from those observed in 2004-2005. New approach methodologies (NAMs) can aid in the rapid and cost-effective assessment of botanical supplements for potential hepatotoxicity. The Hepatotoxicity Working Group within the Botanical Safety Consortium is working to develop a screening strategy that can help reliably identify potential hepatotoxic botanicals and inform mechanisms of toxicity. This manuscript outlines the Hepatotoxicity Working Group's strategy and describes the assays selected and the rationale for the selection of botanicals used in case studies. The selected NAMs evaluated as a part of this effort are intended to be incorporated into a larger battery of assays to evaluate multiple endpoints related to botanical safety. This work will contribute to a botanical safety toolkit, providing researchers with tools to better understand hepatotoxicity associated with botanicals, prioritize and plan future testing as needed, and gain a deeper insight into the botanicals being tested.

Advancing toxicity studies of per- and poly-fluoroalkyl substances (pfass) through machine learning: Models, mechanisms, and future directions

Perfluorinated and perfluoroalkyl substances (PFASs), encompassing a vast array of isomeric chemicals, are recognized as typical emerging contaminants with direct or potential impacts on human health and the ecological environment. With the complex and elusive toxicological profiles of PFASs, machine learning (ML) has been increasingly employed in their toxicity studies due to its proficiency in prediction and data analytics. This integration is poised to become a predominant trend in environmental toxicology, propelled by the swift advancements in computational technology. This review diligently examines the literature to encapsulate the varied objectives of employing ML in the toxicity studies of PFASs: (1) Utilizing ML to establish Quantitative Structure-Activity Relationship (QSAR) models for PFASs with diverse toxicity endpoints, facilitating the targeted toxicity prediction of unidentified PFASs; (2) Investigating and substantiating the Adverse Outcome Pathway (AOP) through the synergy of ML and traditional toxicological methods, with this refining the toxicity assessment framework for PFASs; (3) Dissecting and elucidating the features of established ML models to advance Open Research into the toxicity of PFASs, with a primary focus on determinants and mechanisms. The discourse extends to an in-depth examination of ML studies, segregating findings based on their distinct application trajectories. Given that ML represents a nascent paradigm within PFASs research, this review delineates the collective challenges encountered in the ML-mediated study of PFAS toxicity and proffers strategic guidance for ensuing investigations.

Intuitive toxicology in the 21st century-Bridging the perspectives of the public and risk assessors in Europe

Three decades ago, several articles on the subjectivity in chemical risk judgments (i.e., labeled "intuitive toxicology") measured the divide between the public and toxicologists with different backgrounds regarding the validity of predicting health effects based on in vivo studies. Similar divides with impacts on societal discourse and chemical risk assessment practices might exist concerning alternative toxicity testing methods (i.e., in vitro and in silico). However, studies to date have focused either on the public's views of in vivo or stem cell testing or on experts' views of in vivo testing and potential alternatives (i.e., toxicologists and medical students), which do not allow for a direct investigation of potential divides. To fill this knowledge gap, we conducted two online surveys, involving members of the German-speaking public in Switzerland and European human health risk assessors, respectively. This article presents the results of these two surveys regarding the divide in the public's and risk assessors' perspectives on risk assessment based on in vivo, in vitro, and in silico testing. Particularly, the survey with the risk assessors highlights that, beyond scientific and regulatory barriers, alternatives to in vivo testing may encounter individual hurdles, such as higher uncertainty associated with them. Understanding and addressing these hurdles will be crucial to facilitate the integration of new approach methodologies into chemical risk assessment practices as well as a successful transition toward next-generation risk assessment, bringing us closer to a fit-for-purpose and more efficient regulatory landscape.

Stepwise Imperatives for Improving the Protection of Animals in Research and Education in Canada

In this paper, we review the standard-setting tools of different levels of government in Canada for overseeing the care of animals used in science against a landscape of other international efforts. We find regulatory inconsistencies, argue that the related shortcomings are detrimental to the level of care afforded to animals, and offer suggestions for a centralized and proactive approach that could close the existing gaps. Given the resources, cost, and time it would take to transform the current system into a single cohesive one, the proposed approach is a stepwise one, and begins with the addition of two new Rs-Reflection and Responsiveness-to the existing 3Rs framework: Replacement, Refinement, and Reduction. Reflection emphasizes more continuous and specific attention to progress in the research pathway as it applies to animals than is currently required by institutional review and reporting; Responsiveness speaks to the immediate action that researchers can take responsively to that ongoing evaluation.

Who cares about lab rodents?

Humanities and social sciences help advance "cultures of care" around laboratory animal science and welfare.

Lessons for the Future of NAMs from History, Philosophy and Social Studies of Science

This paper explores what we can learn from the humanities and social sciences about how standards operate in and around science, in order to understand more about how 'the gold standard' can be shifted away from the use of animals in research and testing, and toward New Approach Methodologies (NAMs). These fields allow us to consider potential futures of NAMs as alternatives, replacements, or complements to animal use in testing and research. As we demonstrate, the questions that we pose and how they are framed are as important as the answers that result. Rather than asking how to 'redefine the gold standard', norms and expectations for NAMs must be actively debated and transparently defined. These considerations would be based, in part, on what has been learned in the past from non-human animal models and systems, but also use the norms within the fields from which the NAMs derive in light of the rich broader contexts within which they are being developed. As we argue, notions such as 'a gold standard' are limited and must be replaced by contextualised standards that depend on the scientific, sociocultural and other factors that contribute to our understanding of a particular method (new or otherwise) as 'good' for a particular purpose.

Measurement of compassion fatigue in animal health care professionals: a systematic review of available instruments and their content validity

Introduction

Compassion fatigue (CF) refers to emotional or physical exhaustion and emotional reactions resulting from prolonged exposure to traumatic events, commonly experienced by professionals in caregiving roles. CF is prevalent among healthcare professionals, including those in animal care. Several Patient-Reported Outcome Measures (PROMs) were developed to measure CF, but their psychometric validity was not reviewed systematically. This study aims to identify and review the content validity of CF PROMs used in animal health care professionals.

Methods

Literature was searched in PubMed, PsycINFO, and EMBASE (1973-2023). We included studies conducted in animal health care professionals, using a PROM to measure CF, reporting at least one psychometric property of this PROM, and published as original research. For each identified PROM, additional literature search was conducted to identify PROM development and content validation studies. Three independent reviewers evaluated the content validity of each PROM using COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) methodology and summarized the quality of evidence using a modified GRADE approach. The protocol was registered in PROSPERO (CRD42023433982) and results reported following PRISMA guidelines.

Results

Initially, 1709 studies were identified. After a double screening, 17 eligible studies were included. CF was measured using six different PROMs or their modified versions. Only one PROM specifically targeted animal health care professionals: the ProQOL-5 Veterinary Medicine Version. This and three other original CF PROMs were reviewed. For all PROMs, the quality of content validity was rated as insufficient due to deficiencies in the concept and items elicitation, inadequate target population representation, and inadequate details on cognitive interview procedures. The overall evidence quality was rated as low due to a limited number of PROM validation studies, poor methodological and reporting quality, and indirect result.

Discussion

There is a scarcity of studies examining CF within the target population, and the quality of evidence for content validity of the reviewed PROMs for CF measurement is currently low. CF definition and construct description in PROM development studies suffer from vagueness and seem inadequately reflected by the content of the reviewed PROMs. Further research with a robust methodology seems necessary to address the identified flows.

Systematic review registration

Measurement of compassion fatigue in people working with animals: protocol for a systematic review. PROSPERO 2023 CRD42023433982. Available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023433982.

Embracing prospects for reducing the numbers of animals used in aquaculture research

The principles of three Rs-REPLACEMENT, REDUCTION, and REFINEMENT-govern the protection and use of animals, including fish, for research purposes in the European Union and Norway. In this paper, we discuss some straightforward steps to simplify the delivery of these principles at the idea stage and adapt some of these examples for conducting fish trials related to health and welfare. Although some of the approaches are well established in other animal science arenas, we believe there can be a timely recap of their key facets. We discuss a number of simple strategies to emphasize how a reduction in fish numbers can be achieved from initial project conception to implementation, highlighting not only their advantages but also their limitations. We also highlight the role that funding agencies can play in the implementation of the 3R principles in aquaculture research. These simple points can be used in frameworks to initiate a broader and dynamic intersectoral dialogue among stakeholders of aquaculture research on how to promote ethics and embrace opportunities for this within the tenets of the 3Rs.

Moral distress measurement in animal care workers: a systematic review

OBJECTIVES

The mental health of veterinary and other animal health professionals is significantly impacted by the psychological stressors they encounter, such as euthanasia, witnessing animal suffering and moral distress. Moral distress, initially identified in nursing, arises when individuals are aware of the right action but are hindered by institutional constraints. We aimed to review existing research on moral distress scales among animal care workers by focusing on the identification and psychometric validity of its measurement.

DESIGN

Two-step systematic review. First, we identified all moral distress scales used in animal care research in the eligible original studies. Second, we evaluated their psychometric validity, emphasising content validity, which is a critical aspect of patient-reported outcome measures (PROMs). This evaluation adhered to the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN). The results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

DATA SOURCES

PubMed, EMBASE and PsycINFO to search for eligible studies published between January 1984 and April 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included original (primary) studies that (1) were conducted in animal care workers; (2) describing either the development of a moral distress scale, or validation of a moral distress scale in its original or modified version, to assess at least one of the psychometric properties mentioned in COSMIN guidelines.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers used standardised methods to search, screen and code included studies. We considered the following information relevant for extraction: study reference, name and reference of the moral distress scale used, psychometric properties assessed and methods and results of their assessments. The collected information was then summarised in a narrative synthesis.

RESULTS

The review identified only one PROM specifically adapted for veterinary contexts: the Measure of Moral Distress for Animal Professionals (MMD-AP), derived from the Measure of Moral Distress for Healthcare Professionals (MMD-HP). Both MMD-HP and MMD-AP were evaluated for the quality of development and content validity. The development quality of both measures was deemed doubtful. According to COSMIN, MMD-HP's content validity was rated as sufficient, whereas MMD-AP's was inconsistent. However, the evidence quality for both PROMs was rated low.

CONCLUSION

This is the first systematic review focused on moral distress measurement in animal care workers. It shows that moral distress is rarely measured using standardised and evidence-based methods and that such methods should be developed and validated in the context of animal care.

PROSPERO REGISTRATION NUMBER

CRD42023422259.

Perceptions of 3R implementation in European animal research: A systematic review, meta-analysis, and meta-synthesis of barriers and facilitators

OBJECTIVES

The purpose of this systematic review was to examine how the scientific community in Europe that is involved with research with animals perceives and experiences the implementation of 3R (Replace, Reduce, Refine).

METHODS

A systematic search of the literature published in the past ten years was performed in PubMed, Web of Science and Scopus. Publications were screened for eligibility using a priori inclusion criteria, and only empirical evidence (quantitative, qualitative, or mixed methodologies) was retained. Quantitative survey items were investigated by conducting a meta-analysis, and the qualitative data was summarized using an inductive meta-synthetic approach. Included publications were assessed using the Quality Assessment for Diverse Studies tool.

RESULTS

17 publications were included (eight quantitative, seven qualitative, two mixed-methods). The meta-analysis revealed that scientists are skeptical about achieving replacement, even if they believe that 3R improve the quality of experimental results. They are optimistic concerning the impact of 3R on research costs and innovation, and see education as highly valuable for the implementation of 3R. The meta-synthesis revealed four barriers (systemic dynamics, reification process, practical issues, insufficient knowledge) and four facilitators (efficient use of animals, caring for animals, regulatory uptake, supportive workplace environment).

CONCLUSION

These findings show actionable levers at the local and systemic levels, and may inform regulators and institutions in their 3R policies.

TRIAL REGISTRATION

The protocol was registered into the PROSPERO database under the number CRD42023395769.

Why Do I Choose an Animal Model or an Alternative Method in Basic and Preclinical Biomedical Research? A Spectrum of Ethically Relevant Reasons and Their Evaluation

BACKGROUND

Research model selection decisions in basic and preclinical biomedical research have not yet been the subject of an ethical investigation. Therefore, this paper aims, (1) to identify a spectrum of reasons for choosing between animal and alternative research models (e.g., based on in vitro or in silico models) and (2) provides an ethical analysis of the selected reasons.

METHODS

In total, 13 researchers were interviewed; the interviews were analyzed qualitatively. The ethical analysis was based on the principlism approach and a value judgement model.

RESULTS

This paper presents 66 reasons underlying the choice of researchers using animal (27 reasons) or alternative models (39). Most of the reasons were assigned to the work environment (29) and scientific standards (22). Other reasons were assigned to personal attitudes (11) and animal welfare (4). Qualitative relevant normative differences are presented in the ethical analysis. Even if few reasons can be rejected outright from an ethical point of view, there are good reasons to give some more weight than others.

CONCLUSIONS

The spectrum of reasons and their ethical assessment provide a framework for reflection for researchers who may have to choose between animal models and (investing in) alternatives. This can help to reflect on and ethically justify decisions.

Post-Mortem Extracorporeal Membrane Oxygenation Perfusion Rat Model: A Feasibility Study

The development of biomedical soft- or hardware frequently includes testing in animals. However, large efforts have been made to reduce the number of animal experiments, according to the 3Rs principle. Simultaneously, a significant number of surplus animals are euthanized without scientific necessity. The primary aim of this study was to establish a post-mortem rat perfusion model using extracorporeal membrane oxygenation (ECMO) in surplus rat cadavers and generate first post vivo results concerning the oxygenation performance of a recently developed ECMO membrane oxygenator. Four rats were euthanized and connected post-mortem to a venous-arterial ECMO circulation for up to eight hours. Angiographic perfusion proofs, blood gas analyses and blood oxygenation calculations were performed. The mean preparation time for the ECMO system was 791 ± 29 s and sufficient organ perfusion could be maintained for 463 ± 26 min, proofed via angiographic imaging and a mean femoral arterial pressure of 43 ± 17 mmHg. A stable partial oxygen pressure, a 73% rise in arterial oxygen concentration and an exponentially increasing oxygen extraction ratio up to 4.75 times were shown. Considering the 3Rs, the established post-mortal ECMO perfusion rat model using surplus animals represents a promising alternative to models using live animals. Given the preserved organ perfusion, its use could be conceivable for various biomedical device testing.