Enabling novel paradigms: a biological questions-based approach to human chemical hazard and drug safety assessment

Throughput needs, costs of time and resources, and concerns about the use of animals in hazard and safety assessment studies are fueling a growing interest in adopting new approach methodologies for use in product development and risk assessment. However, current efforts to define "next-generation risk assessment" vary considerably across commercial and regulatory sectors, and an a priori definition of the biological scope of data needed to assess hazards is generally lacking. We propose that the absence of clearly defined questions that can be answered during hazard assessment is the primary barrier to the generation of a paradigm flexible enough to be used across varying product development and approval decision contexts. Herein, we propose a biological questions-based approach (BQBA) for hazard and safety assessment to facilitate fit-for-purpose method selection and more efficient evidence-based decision-making. The key pillars of this novel approach are bioavailability, bioactivity, adversity, and susceptibility. This BQBA is compared with current hazard approaches and is applied in scenarios of varying pathobiological understanding and/or regulatory testing requirements. To further define the paradigm and key questions that allow better prediction and characterization of human health hazard, a multidisciplinary collaboration among stakeholder groups should be initiated.

The First Steps on AOPs' Concepts, Development, and Applications in Teratology

An Adverse Outcome Pathway (AOP) is an analytical model that describes, through a graphical representation, a linear sequence of biologically connected events at different levels of biological organization, causally leading to an adverse effect on human health or the environment. In general, AOPs are constructed based on five central principles: systematic development and review, chemical-agnostic, modular, networks, and living documents. Furthermore, AOPs have the potential to be used, for example, to investigate certain molecular targets; relate the regulation of specific genes or proteins among AOPs; extrapolate biological processes, pathways, or diseases from one species to another; and even predict adverse effects in particular populations. AOPs also emerge as an alternative to animal experimentation in studies of developmental malformations. It's even possible now to develop a quantitative AOP to predict teratogenic effects for some substances. However, the construction of high-quality AOPs requires standardization in the way these models are developed and reviewed, ensuring an adequate degree of flexibility and guaranteeing efficiency. The development of AOPs should strictly be based on the guidance documents developed by the OECD. Nevertheless, an important step for those developing AOPs is the choice of an apical endpoint or an initiating molecular event in order to initiate the construction of the pathway. Another crucial step is a systematic literature review based on the random combination of the blocks of information. With these two fundamental steps completed, it only remains to follow the guidance documents on Developing and Assessing Adverse Outcome Pathways and AOP Developers' Handbook supplement provided by the OECD to organize and construct an AOP. This modern approach will bring radical changes in the field of toxicity testing, regarding the prediction of apical toxic effects using molecular-level effects.

Law OKs Animal Alternatives in Preclinical Testing

The FDA Modernization Act 2.0 allows companies to submit nonanimal data using certain alternative technologies to demonstrate the safety and efficacy of investigational drugs prior to human trials. Animal rights supporters hope the law represents a shift away from animal use, but researchers caution that organ-chips and other innovations, although potentially valuable, cannot replace animal models to test drugs in development.

The Current Status and Work of Three Rs Centres and Platforms in Europe

The adoption of Directive 2010/63/EU on the protection of animals used for scientific purposes has given a major push to the formation of Three Rs initiatives in the form of centres and platforms. These centres and platforms are dedicated to the so-called Three Rs, which are the Replacement, Reduction and Refinement of animal use in experiments. ATLA's 50th Anniversary year has seen the publication of two articles on European Three Rs centres and platforms. The first of these was about the progressive rise in their numbers and about their founding history; this second part focuses on their current status and activities. This article takes a closer look at their financial and organisational structures, describes their Three Rs focus and core activities (dissemination, education, implementation, scientific quality/translatability, ethics), and presents their areas of responsibility and projects in detail. This overview of the work and diverse structures of the Three Rs centres and platforms is not only intended to bring them closer to the reader, but also to provide role models and show examples of how such Three Rs centres and platforms could be made sustainable. The Three Rs centres and platforms are very important focal points and play an immense role as facilitators of Directive 2010/63/EU 'on the ground' in their respective countries. They are also invaluable for the wide dissemination of information and for promoting the implementation of the Three Rs in general.

The chorioallantoic membrane as a bio-barrier model for the evaluation of nanoscale drug delivery systems for tumour therapy

In 2010, the European Parliament and the European Union adopted a directive on the protection of animals used for scientific purposes. The directive aims to protect animals in scientific research, with the final goal of complete replacement of procedures on live animals for scientific and educational purposes as soon as it is scientifically viable. Furthermore, the directive announces the implementation of the 3Rs principle: "When choosing methods, the principles of replacement, reduction and refinement should be implemented through a strict hierarchy of the requirement to use alternative methods." The visibility, accessibility, and the rapid growth of the chorioallantoic membrane (CAM) offers a clear advantage for various manipulations and for the simulation of different Bio-Barriers according to the 3R principle. The extensive vascularisation on the CAM provides an excellent substrate for the cultivation of tumour cells or tumour xenografts which could be used for the therapeutic evaluation of nanoscale drug delivery systems. The tumour can be targeted either by topical application, intratumoural injection or i.v. injection. Different application sites and biological barriers can be examined within a single model.

The in vivo Tetrahymena thermophila extracellular glucose drop assay for characterization of mammalian insulin activity

Insulin activity is generally determined by an in vivo rabbit blood glucose drop assay in research and industriel laboratories. The humane experimental techniques imply the use of alternative invertebrate organisms in place of animals, known as replacement rule of the 3Rs. In this study, we report an alternative in vivo extracellular glucose drop assay using unicellular invertebrate Tetrahymena thermophila to replace the use of rabbit and mouse. This assay has four major steps; growing cells, starving cells, treatment of cells and measurement of glucose drop. In this assay, 0.2 mg/ml of human, porcine and bovine insulins dropped extracellular glucose level to 16%, 14% and 12%, respectively in ten minutes. In addition, mammalian insulins respectively increased the cell area about 19%, 15%, and 16% at 6th hour with statistically significant effect on the cell growth, but not in the cell viability. The results showed that the in vivo Tetrahymena thermophila extracellular glucose drop assay could be used as an alternative assay to replace the mouse or the rabbit insulin blood glucose drop assay.

Identifying sublethal endpoints for evaluating neurotoxic compounds utilizing the fish embryo toxicity test

Fish embryos are increasingly being utilized in aquatic toxicity testing, as evidenced by the Organisation for Economic Co-operation and Development's approval of the fish embryo acute toxicity (FET) test. However, the FET test only allows for the estimation of acute toxicity, whereas other test methods such as the larval growth and survival (LGS) test allow for the estimation of both acute and chronic toxicity. Additionally, it has been demonstrated that the FET test is less sensitive than other test methods for some neurotoxic compounds. To address these limitations, efforts to identify sublethal endpoints that increase FET test sensitivity and allow for the prediction of sublethal adverse effects have begun. As such, the objectives of the current study were 1) to compare estimated LC50 values from the FET and LGS test for three known neurotoxicants: fluoride (F), nickel (Ni), and cadmium (Cd) and 2) to evaluate the responsiveness of potential sublethal endpoints for the FET test related to growth (i.e., wet weight and snout-vent length), neurological development (i.e., spontaneous contraction frequency and eye size), and cardiovascular function (i.e., heart rate and pericardial area). The calculated LC50 values from the F and Cd FET test were significantly higher than those from the LGS test, demonstrating that the FET test is less sensitive than the LGS test for neurotoxic compounds. Only Cd exposure resulted in alterations in any of the sublethal endpoints investigated. Embryos/eleutheroembryos exposed to Cd displayed alterations in length, eye size, and pericardial area at concentrations five-fold less than the estimated LC50 value, suggesting that for Cd the inclusion of these sublethal endpoints would improve the sensitivity of the FET test. Overall, these results provide evidence that for some neurotoxicants, the inclusion of sublehtal endpoints may improve the utility of the FET test; however, further research utilizing a broader range of neurotoxicants with differing mechanisms of action, is needed to fully establish such endpoints in the context of routine FET test.

Opportunities for Reduction in Acute Toxicity Testing via Improved Design

The conventional method for assessing acute oral toxicity (OECD Test Guideline 401) was designed to identify the median lethal dose (LD50), using the death of animals as an endpoint. Introduced as an alternative method (OECD Test Guideline 420), the Fixed Dose Procedure (FDP) relies on the observation of clear signs of toxicity, uses fewer animals and causes less suffering. More recently, the Acute Toxic Class method and the Up-and-Down Procedure have also been adopted as OECD test guidelines. Both of these methods also use fewer animals than the conventional method, although they still use death as an endpoint. Each of the three new methods incorporates a sequential dosing procedure, which results in increased efficiency. In 1999, with a view to replacing OECD Test Guideline 401, the OECD requested that the three new test guidelines be updated. This was to bring them in line with the regulatory needs of all OECD Member Countries, provide further reductions in the number of animals used, and introduce refinements to reduce the pain and distress experienced by the animals. This paper describes a statistical modelling approach for the evaluation of acute oral toxicity tests, by using the revised FDP for illustration. Opportunities for further design improvements are discussed.

Reduction of Numbers of Animals Used in the Quality Control of Biologicals

Laboratory animals are used for the quality control of vaccines. In particular, the potency testing of batches of inactivated vaccine requires large numbers of animals. The possibilities for reduction have been evaluated, and the results are summarised in this paper. Several approaches were studied, including the retrospective analysis of test data, with the objectives of determining the minimum number of animals required per vaccine dilution group, and evaluating the feasibility of a single-dose potency test. Other studies focused on the development of serology-based models and the use of genetically uniform animals. Based on the outcome of these studies, a substantial reduction in the number of animals used for the potency testing of toxoid vaccines has been achieved or will be achieved in the near future. As reduction alternatives can generally be explored in a relatively simpler and less time-consuming way than replacement alternatives, more emphasis should be placed on reduction strategies than at present.

A Statistical Evaluation of the Fixed Dose Procedure

The Fixed Dose Procedure (FDP) was first proposed in 1984 by the British Toxicology Society, as an alternative to the conventional LD50 test (OECD Test Guideline 401), for determining acute oral toxicity. The FDP used fewer animals and caused less suffering than the LD50 test, and provided information on acute toxicity which allowed substances to be classified according to the European Union hazard classification system. In 1992, the FDP was introduced as OECD Test Guideline 420. In 1999, as part of an initiative to phase out Test Guideline 401, a review of the FDP was undertaken. The aim of the review was to provide further reductions and refinements, and classification according to the criteria of the Globally Harmonised Hazard Classification and Labelling Scheme. The revised FDP was adopted by the OECD in 2001. This article concerns the development and revision of the FDP. It illustrates how statistical modelling and simulation can be used to increase the efficiency of a test procedure and reduce the number of animals needed for an in vivo validation of the procedure.

Training for Reduction in Laboratory Animal Use

Reduction, refinement and replacement of laboratory animals wherever possible, are the guiding principles of the Federation of European Laboratory Animal Science Associations (FELASA) education guidelines. Of these, reduction is probably the least understood. Reduction and refinement are dependent upon each other. In the reduction “axis”, there is a window of appropriate numbers of animals; too few and the experiment will lack power — too many and animals will be wasted. Reduction must be understood as the appropriate number of animals required for each experiment. The refinement “axis” is more straightforward. Better welfare is always desirable. Any factor can interfere with a study in two ways. If it changes the mean, this may not be serious, because it should do so in all groups. If it causes a change in variation, then this is far more troublesome, because this is bound to alter the appropriate number of animals for an experiment. Scientists are definitely concerned about the variation of the characters that they are working with. It is obvious that changes in variation may be study-specific, which makes the formulation of overall guidelines difficult. Indeed, instead of trying to assess the impact of housing and procedures on every possible character, it could be more productive to look at the effects of welfare indicators on variation, with the understanding that low variation here is likely to be reflected by low variation in most other characters, while aiming to achieve the most uniform welfare of the animals in the study.

Environmental Enrichment: Room for Reduction?

Environmental enrichment strategies are usually regarded as refinement. However, when the welfare of animals is enhanced through successful enrichment programmes, a reduction in the number of animals needed can be expected, because fewer animals might be lost during the course of experiments. Several examples of studies where enrichment can lead to reduction will be presented. They include the beneficial effects of nesting material for laboratory mice, the effects of husbandry procedures on controlling aggressive behaviour in male laboratory mice, and the effects of enrichment on variation in the results of experiments.

The Choice of Animal Model and Reduction

Careful choice of the animal model is essential, if research is to be conducted efficiently, by using the minimum number of animals in order to provide the maximum amount of information. Inbred strains of rodents provide an excellent way of controlling and investigating genetic variation in characters of interest and in response to experimental treatments. Outbred stocks, in which genetic and non-genetic factors are inextricably mixed, are much less suitable, because random and uncontrolled genetic variation tends to obscure any treatment responses. In some cases, the use of inbred strains has led to major advances in scientific understanding. The specific example given here is in the understanding of host–parasite relationships but, more generally, inbred strains have been of critical importance in research which has resulted in the award of at least 17 Nobel prizes. And yet, despite the extensive literature on the properties and scientific value of inbred strains, many scientists continue to use outbred stocks in the mistaken belief that the use of such animals will, in some mysterious way, make their research more applicable to humans. There is really no evidence that this is so, and there is much evidence that the use of inbred strains has been highly successful in many disciplines.

Lobar evenness of deposition/retention in rat lungs of inhaled silver nanoparticles: an approach for reducing animal use while maximizing endpoints

BACKGROUND

Information on particle deposition, retention and clearance are important for the evaluation of the risk of inhaled nanomaterials to human health. Recent revised OECD inhalation toxicity test guidelines require to evaluate the lung burden of nanomaterials after rodent subacute and subchronic inhalation exposure (OECD 412, OECD 413). These revised test guidelines require additional post-exposure observation (PEO) periods that include lung burden measurements that can inform on lung clearance behavior and translocation. The latter being particularly relevant when the testing chemical is a solid poorly soluble nanomaterial. Therefore, in the spirit of 3 R's, we investigated whether measurement of retained lung burden of inhaled nanoparticles (NPs) in individual lung lobes is sufficient to determine retained lung burden in the total lung. If it is possible to use only one lobe, it will reduce animal use and maximize the number of endpoints evaluated.

RESULTS

To achieve these goals, rats were exposed nose-only for 1 or 5 days (6 h/day) to an aerosol of 20 nm well-dispersed silver nanoparticles (AgNPs), which is the desired particle diameter resulting in maximum deposition in the pulmonary region when inhaled as singlets. After exposure, the five lung lobes were separated and silver concentration was measured using inductively coupled plasma-mass spectrophotometer (ICP-MS). The results showed that the retention of deposited silver nanoparticle in the different lung lobes did not show any statistically significant difference among lung lobes in terms of silver mass per gram lung lobe. This novel finding of evenness of retention/deposition of inhaled 20 nm NPs in rats for all five lobes in terms of mass per unit tissue weight contrasts with earlier studies reporting greater apical lobe deposition of inhaled micro-particles in rodents. The difference is most likely due to preferred and efficient deposition of inhaled NPs by diffusion vs. additional deposition by sedimentation and impaction for micron-sized particles.

CONCLUSION

AgNPs following acute inhalation by rats are evenly retained in each lung lobe in terms of mass per unit lung tissue weight. Accordingly, we suggest sampling any of the rat lung lobes for lung burden analysis can be used to determine deposited or retained total lung burden after short-term inhalation of NPs and using the other lobes for collecting and analyzing bronchoalveolar lavage fluid (BALF) and for histopathological analysis. Therefore, by combining lung burden measurement, histopathological tissue preparation, and BALF assay in the same rat will reduce the number of animals used and maximize the number of endpoints measured.

Predicting the in vivo pulmonary toxicity induced by acute exposure to poorly soluble nanomaterials by using advanced in vitro methods

BACKGROUND

Animal models remain at that time a reference tool to predict potential pulmonary adverse effects of nanomaterials in humans. However, in a context of reduction of the number of animals used in experimentation, there is a need for reliable alternatives. In vitro models using lung cells represent relevant alternatives to assess potential nanomaterial acute toxicity by inhalation, particularly since advanced in vitro methods and models have been developed. Nevertheless, the ability of in vitro experiments to replace animal experimentation for predicting potential acute pulmonary toxicity in human still needs to be carefully assessed. The aim of the study was to evaluate the differences existing between the in vivo and the in vitro approaches for the prediction of nanomaterial toxicity and to find advanced methods to enhance in vitro predictivity. For this purpose, rats or pneumocytes in co-culture with macrophages were exposed to the same poorly soluble and poorly toxic TiO2 and CeO2 nanomaterials, by the respiratory route in vivo or using more or less advanced methodologies in vitro. After 24 h of exposure, biological responses were assessed focusing on pro-inflammatory effects and quantitative comparisons were performed between the in vivo and in vitro methods, using compatible dose metrics.

RESULTS

For each dose metric used (mass/alveolar surface or mass/macrophage), we observed that the most realistic in vitro exposure method, the air-liquid interface method, was the most predictive of in vivo effects regarding biological activation levels. We also noted less differences between in vivo and in vitro results when doses were normalized by the number of macrophages rather than by the alveolar surface. Lastly, although we observed similarities in the nanomaterial ranking using in vivo and in vitro approaches, the quality of the data-set was insufficient to provide clear ranking comparisons.

CONCLUSIONS

We showed that advanced methods could be used to enhance in vitro experiments ability to predict potential acute pulmonary toxicity in vivo. Moreover, we showed that the timing of the dose delivery could be controlled to enhance the predictivity. Further studies should be necessary to assess if air-liquid interface provide more reliable ranking of nanomaterials than submerged methods.

Enhancing the fathead minnow fish embryo toxicity test: Optimizing embryo production and assessing the utility of additional test endpoints

The fathead minnow fish embryo toxicity (FET) test has been identified as a potential alternative to toxicity test methods that utilize older fish. However, several challenges have been identified with the fathead minnow FET test, including: 1) difficulties in obtaining appropriately-staged embryos for FET test initiation, 2) a paucity of data comparing fathead minnow FET test performance to the fathead minnow larval growth and survival (LGS) test and 3) a lack of sublethal endpoints that could be used to estimate chronic toxicity and/or predict adverse effects. These challenges were addressed through three study objectives. The first objective was to optimize embryo production by assessing the effect of breeding group composition (number of males and females) on egg production. Results showed that groups containing one male and four females produced the largest clutches, enhancing the likelihood of procuring sufficient numbers of embryos for FET test initiation. The second study objective was to compare the performance of the FET test to that of the fathead minnow LGS test using three reference toxicants. The FET and LGS tests were similar in their ability to predict the acute toxicity of sodium chloride and ethanol, but the FET test was found to be more sensitive than the LGS test for sodium dodecyl sulfate. The last objective of the study was to evaluate the utility and practicality of several sublethal metrics (i.e., growth, developmental abnormalities and growth- and stress-related gene expression) as FET test endpoints. Developmental abnormalities, including pericardial edema and hatch success, were found to offer the most promise as additional FET test endpoints, given their responsiveness, potential for predicting adverse effects, ease of assessment and low cost of measurement.

The Identification of Pivotal Transcriptional Factors Mediating Cell Responses to Drugs With Drug-Induced Liver Injury Liabilities

Drug-induced liver injury (DILI) is a leading cause of drug attrition during drug development and a common reason for drug withdrawal from the market. The poor predictability of conventional animal-based approaches necessitates the development of alternative testing approaches. A body of evidence associates DILI with the induction of stress-response genes in liver cells. Here, we set out to identify signal transduction pathways predominantly involved in the regulation of gene transcription by DILI drugs. To this end, we employed ATTAGENE's cell-based multiplexed reporter assay, the FACTORIAL transcription factor (TF), that enables quantitative assessment of the activity of multiple stress-responsive TFs in a single well of cells. Homogeneous reporter system enables quantitative functional assessment of multiple transcription factors. Nat. Methods 5, 253-260). Using this assay, we assessed TF responses of the human hepatoma cell line HepG2 to a panel of 64 drug candidates, including 23 preclinical DILI and 11 clinical DILI compounds and 30 nonhepatotoxic compounds from a diverse physicochemical property space. We have identified 16 TF families that specifically responded to DILI drugs, including nuclear factor (erythroid-derived 2)-like 2 antioxidant response element, octamer, hypoxia inducible factor 1 alpha, farnesoid-X receptor, TCF/beta-catenin, aryl hydrocarbon receptor, activator protein-1, E2F, early growth response-1, metal-response transcription factor 1, sterol regulatory element-binding protein, paired box protein, peroxisome proliferator-activated receptor, liver X receptor, interferone regulating factor, and P53, and 2 promoters that responded to multiple TFs (cytomegalovirus and direct repeat 3/vitamin D receptor). Some of TFs identified here also have previously defined role in pathogenesis of liver diseases. These data demonstrate the utility of cost-effective, animal-free, TF profiling assay for detecting DILI potential of drug candidates at early stages of drug development.

Application of Recombinant Factor C Reagent for the Detection of Bacterial Endotoxins in Pharmaceutical Products

Recombinant Factor C (rFC) is non-animal-derived reagent used to detect bacterial endotoxins in pharmaceutical products. Despite the fact that the reagent was first commercially available nearly 15 years ago, the broad use of rFC in pharmaceutical industry has long been lagging, presumably due to historical single-source supplier concerns and the lack of inclusion in worldwide pharmacopeias. Commercial rFC reagents are now available from multiple manufacturers, thus single sourcing is no longer an issue. We report here the successful validation of several pharmaceutical products by an end-point florescence-based endotoxin method using the rFC reagent. The method is equivalent or superior to the compendia bacterial endotoxins test method. Based on the comparability data and extenuating circumstances, the incorporation of the end point fluorescence technique and rFC reagent in global compendia bacterial endotoxins test chapters is desired and warranted.LAY ABSTRACT: Public health has been protected for over 30 years with the use of a purified blood product of the horseshoe crab, limulus amebocyte lysate. More recently, this blood product can be produced in biotech manufacturing processes, which reduces potential impacts to the horseshoe crab and related species dependent upon the crab, for example, migrating shorebirds. The pharmaceutical industry has been slow to adopt the use of this reagent, Recombinant Factor C (rFC), for various reasons. We evaluated the use of rFC across many pharmaceutical products, and in other feasibility demonstration experiments, and found rFC to be a suitable alternative to the animal-derived limulus amebocyte lysate. Incorporation of rFC and its analytical method into national testing standards would provide an equivalent or better test while continuing to maintain patient safety for those who depend on medicines and while securing pharmaceutical supply chains. In addition, widespread use of this method would benefit existing animal conservation efforts.

Primary hepatocytes from Arctic char (Salvelinus alpinus) as a relevant Arctic in vitro model for screening contaminants and environmental extracts

Contaminants find their way to the Arctic through long-range atmospheric transport, transport via ocean currents, and through increased anthropogenic activity. Some of the typical pollutants reaching the Arctic (PAHs, PCBs) are known to induce cytochrome P450 1a (CYP1A) protein expression and ethoxyresorufin-O-deethylase (EROD) activity through the aryl hydrocarbon receptor (AhR). In addition, some endocrine disrupting chemicals (EDCs) such as estrogen mimics (xenoestrogens) have been documented in Arctic areas and they may interfere with natural sexual development and reproduction. In vitro assays that are capable of detecting effects of such pollutants, covering multiple endpoints, are generally based on mammalian or temperate species and there are currently no well-characterized cell-based in vitro assays for effect assessment from Arctic fish species. The present study aimed to develop a high-throughput and multi-endpoint in vitro assay from Arctic char (Salvelinus alpinus) to provide a non-animal (alternative) testing method for an ecologically relevant Arctic species. A method for isolation and exposure of primary hepatocytes from Arctic char for studying the toxic effects and mode of action (MoA) of pollutants was applied and validated. The multi-versatility of the bioassay was assessed by classical biomarker responses such as cell viability (membrane integrity and metabolic activity), phase I detoxification (CYP1A protein expression, EROD activity) and estrogen receptor (ER) mediated vitellogenin (Vtg) protein expression using a selection of model compounds, environmental pollutants and an environmental extract containing a complex mixture of pollutants. Primary hepatocytes from Arctic char were successfully isolated and culture conditions optimized to identify the most optimal assay conditions for covering multiple endpoints. The hepatocytes responded with concentration-dependent responses to all of the model compounds, most of the environmental pollutants and the environmental sample tested. The bioassay response and sensitivity of the hepatocytes from Arctic char differed slightly from closely related salmonid species, thus highlighting the need for developing in vitro assays relevant for Arctic species. The present multi-endpoint in vitro assay offer a highly versatile tool to screen potential effects of pollutants and complex samples relevant for Arctic exposure scenarios.

The C. elegans model in toxicity testing

Caenorhabditis elegans is a small nematode that can be maintained at low cost and handled using standard in vitro techniques. Unlike toxicity testing using cell cultures, C. elegans toxicity assays provide data from a whole animal with intact and metabolically active digestive, reproductive, endocrine, sensory and neuromuscular systems. Toxicity ranking screens in C. elegans have repeatedly been shown to be as predictive of rat LD50 ranking as mouse LD50 ranking. Additionally, many instances of conservation of mode of toxic action have been noted between C. elegans and mammals. These consistent correlations make the case for inclusion of C. elegans assays in early safety testing and as one component in tiered or integrated toxicity testing strategies, but do not indicate that nematodes alone can replace data from mammals for hazard evaluation. As with cell cultures, good C. elegans culture practice (GCeCP) is essential for reliable results. This article reviews C. elegans use in various toxicity assays, the C. elegans model's strengths and limitations for use in predictive toxicology, and GCeCP. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Journal of Applied Toxicology published by John Wiley & Sons Ltd.

In Vivo Pig-a gene mutation assay: Guidance for 3Rs-friendly implementation

The rodent Pig-a assay is an in vivo method for the detection of gene mutation, where lack of glycosylphosphatidylinositol-anchored proteins on the surface of circulating red blood cells (RBCs) serves as a reporter for Pig-a gene mutation. In the case of rats, the frequency of mutant phenotype RBCs is measured via fluorescent anti-CD59 antibodies and flow cytometry. The Pig-a assay meets the growing expectations for novel approaches in animal experimentation not only focusing on the scientific value of the assay but also on animal welfare aspects (3Rs principles), for example, amenable to integration into pivotal rodent 28-day general toxicology studies. However, as recommended in the Organisation for Economic Co-operation and Development Test Guidelines for genotoxicity testing, laboratories are expected to demonstrate their proficiency. While this has historically involved the extensive use of animals, here we describe an alternative approach based on a series of blood dilutions covering a range of mutant frequencies. The experiments described herein utilized either non-fluorescent anti-CD59 antibodies to provide elevated numbers of mutant-like cells, or a low volume blood sample from a single N-ethyl-N-nitrosourea treated animal. Results from these so-called reconstruction experiments from four independent laboratories showed good overall precision (correlation coefficients: 0.9979-0.9999) and accuracy (estimated slope: 0.71-1.09) of mutant cell scoring, which was further confirmed by Bland-Altman analysis. These data strongly support the use of reconstruction experiments for training purposes and demonstrating laboratory proficiency with very few animals, an ideal situation given the typically conflicting goals of demonstrating laboratory proficiency and reducing the use of animals. Environ. Mol. Mutagen. 57:678-686, 2016. © 2016 Wiley Periodicals, Inc.

3-D nasal cultures: Systems toxicological assessment of a candidate modified-risk tobacco product

In vitro toxicology approaches have evolved from a focus on molecular changes within a cell to understanding of toxicity-related mechanisms in systems that can mimic the in vivo environment. The recent development of three dimensional (3-D) organotypic nasal epithelial culture models offers a physiologically robust system for studying the effects of exposure through inhalation. Exposure to cigarette smoke (CS) is associated with nasal inflammation; thus, the nasal epithelium is relevant for evaluating the pathophysiological impact of CS exposure. The present study investigated further the application of in vitro human 3-D nasal epithelial culture models for toxicological assessment of inhalation exposure. Aligned with 3Rs strategy, this study aimed to explore the relevance of a human 3-D nasal culture model to assess the toxicological impact of aerosols generated from a candidate modified risk tobacco product (cMRTP), the Tobacco Heating System (THS) 2.2, as compared with smoke generated from reference cigarette 3R4F. A series of experimental repetitions, where multiple concentrations of THS2.2 aerosol and 3R4F smoke were applied, were conducted to obtain reproducible measurements to understand the cellular/molecular changes that occur following exposure. In agreement with "Toxicity Testing in the 21st Century - a Vision and a Strategy", this study implemented a systems toxicology approach and found that for all tested concentrations the impact of 3R4F smoke was substantially greater than that of THS2.2 aerosol in terms of cytotoxicity levels, alterations in tissue morphology, secretion of pro-inflammatory mediators, impaired ciliary function, and increased perturbed transcriptomes and miRNA expression profiles.

Arabian killifish (Aphanius dispar) embryos: A model organism for the risk assessment of the Arabian Gulf coastal waters

Fish embryos are excellent models for studies aimed at understanding toxic mechanisms and indications of possible acute and chronic effects. For the past 3 yr, an Arabian killifish (Aphanius dispar) fish embryo test has been developed in the authors' laboratory as a routine ecotoxicological test that can be used to support risk assessment of potential contaminants in Arabian Gulf coastal waters. Tests were conducted with 3 reference toxicants (3,4-dichloroaniline [DCA], sodium dodecyl sulfate, and zinc sulfate [Zn]) and chlorine, a disinfectant used widely in industrial cooling systems around the Arabian Gulf region. The 50% effect concentration (EC50) for DCA was 0.47 mg/L and 1.89 mg/L for embryos exposed before 6 hpf and after 168 hpf, respectively. Sublethal effects were mainly observed at concentrations above 2.5 mg/L, the effects included severe pericardial edema and tail shortage. The sodium dodecyl sulfate ionic surfactant caused mortality at both early and late stages of embryo development; it caused coagulation, severe deformity, and hemolysis. Both the EC50 and the 50% lethal concentration (LC50) for sodium dodecyl sulfate were 9.37 mg/L. Salinity influenced the toxicity of Zn to killifish embryos: at 40 psu Zn was found not to be toxic, whereas at 20 psu toxicity had increased significantly (p < 0.05). Values of EC50 and LC50 were 2.5 mg/L and 4 mg/L, respectively. Concentrations above 15 mg/L in embryos were often accompanied by upper abdominal edema and inhibition of growth, especially evident in the tail. Chlorine caused mortality at a lower concentration; for example, at 0.05 mg/L 33% of embryos were found dead at the end of the experiment. The LC50 for chlorine was determined to be 0.08 mg/L. Examination of the existing literature showed similar results to the present study's findings. The results suggest a more comparable sensitivity of killifish embryos to that of other fish embryo test recommended species. The present study's findings support the ability of killifish to be an indicator organism for environmental risk assessments of Arabian Gulf waters. Benefits include sensitivity to a wide range of substances and conditions, animal alternative, ease of fish breeding, and clarity of the embryos.

Cardiomyocyte H9c2 cells present a valuable alternative to fish lethal testing for azoxystrobin

The present study aims at identifying, among six mammalian and fish cell lines, a sensitive cell line whose in vitro median inhibitory concentration (IC50) better matches the in vivo short-term Sparus aurata median lethal concentration (LC50). IC50s and LC50 were assessed after exposure to the widely used fungicide azoxystrobin (AZX). Statistical results were relevant for most cell lines after 48 h of AZX exposure, being H9c2 the most sensitive cells, as well as the ones which provided the best prediction of fish toxicity, with a LC50,96h/IC50,48h = 0.581. H9c2 cell proliferation upon 72 h of AZX exposure revealed a LC50,96h/IC50,72h = 0.998. Therefore, identical absolute sensitivities were attained for both in vitro and in vivo assays. To conclude, the H9c2 cell-based assay is reliable and represents a suitable ethical alternative to conventional fish assays for AZX, and could be used to get valuable insights into the toxic effects of other pesticides.

[The characterization of the use of animals in teaching from the perception of students of biological and health sciences]

Animals are used for various purposes in the scientific realm and their use in teaching is highlighted in this research. Seeking to understand this use better, a questionnaire was administered to 427 students of medicine, pharmacy and biological sciences of Santa Catarina and Rio Grande do Sul federal universities. Data was gathered revealing high rates of feelings of discomfort, and the predominant interest in supporting the substitution of animals in the teaching environment. The conclusion reached is that the use of animals for teaching purposes has the ability to generate strong conflict, especially when the perception of animal suffering is identified by the students. Finally, three types of use of animals in the context of teaching are proposed.

Testing Chemical Safety: What Is Needed to Ensure the Widespread Application of Non-animal Approaches?

Scientists face growing pressure to move away from using traditional animal toxicity tests to determine whether manufactured chemicals are safe. Numerous ethical, scientific, business, and legislative incentives will help to drive this shift. However, a number of hurdles must be overcome in the coming years before non-animal methods are adopted into widespread practice, particularly from regulatory, scientific, and global perspectives. Several initiatives are nevertheless underway that promise to increase the confidence in newer alternative methods, which will support the move towards a future in which less data from animal tests is required in the assessment of chemical safety.

Scientists face growing pressures to move away from using traditional animal toxicity tests to determine whether manufactured chemicals are safe. This essay explores the incentives, hurdles, and ongoing initiatives towards a reduced reliance on such tests.

The utility of animal models in developing immunosuppressive agents

The immune system comprises an integrated network of cellular interactions. Some responses are predictable, while others are more stochastic. While in vitro the outcome of stimulating a single type of cell may be stereotyped and reproducible, in vivo this is often not the case. This phenomenon often merits the use of animal models in predicting the impact of immunosuppressant drugs. A heavy burden of responsibility lies on the shoulders of the investigator when using animal models to study immunosuppressive agents. The principles of the three R׳s: refine (less suffering,), reduce (lower animal numbers) and replace (alternative in vitro assays) must be applied, as described elsewhere in this issue. Well designed animal model experiments have allowed us to develop all the immunosuppressive agents currently available for treating autoimmune disease and transplant recipients. In this review, we examine the common animal models used in developing immunosuppressive agents, focusing on drugs used in transplant surgery. Autoimmune diseases, such as multiple sclerosis, are covered elsewhere in this issue. We look at the utility and limitations of small and large animal models in measuring potency and toxicity of immunosuppressive therapies.

Historical data analyses and scientific knowledge suggest complete removal of the abnormal toxicity test as a quality control test

In the early 1900s, the abnormal toxicity test (ATT) was developed as an auxiliary means to ensure safe and consistent antiserum production. Today, the ATT is utilized as a quality control (QC) release test according to pharmacopoeial or other regulatory requirements. The study design has not been changed since around 1940. The evidence of abnormal toxicity testing as a prediction for harmful batches is highly questionable and lacks a scientific rationale. Numerous reviews of historical ATT results have revealed that no reliable conclusions can be drawn from this QC measure. Modern pharmaceutical manufacturers have thorough control of the manufacturing process and comply with good manufacturing practice rules. Contaminants are appropriately controlled by complying with the validated manufacturing processes and strict QC batch release confirming batch-to-batch consistency. Recognizing that product safety, efficacy, and stability can be ensured with strict QC measures, nowadays most regulatory authorities do not require the ATT for most product classes. In line with the replacement, reduction, and refinement (3Rs) initiative, the test requirement has been deleted from approximately 80 monographs of the European Pharmacopoeia and for the majority of product classes in the United States. For these reasons, it is recommended that the ATT should be consistently omitted world-wide and be removed from pharmacopoeias and other regulatory requirements.

[Animal experiments and the major achievements in the history of biomedicine]

It is shown that major achievements in the history of biomedicine, obtained in experiments on animals: the discovery of blood circulation, the achievements of microbiology and development of the concept of immunity, the discovery of reflex and the doctrine of higher nervous activity, achievements of genetics, formation of modeling methods on animals and drug testing. It is stressed that the benefits for science and medicine, obtained through experimentation on animals, does not relieve scientists from responsibility.

The development of response surface pathway design to reduce animal numbers in toxicity studies

BACKGROUND

This study describes the development of Response Surface Pathway (RSP) design, assesses its performance and effectiveness in estimating LD50, and compares RSP with Up and Down Procedures (UDPs) and Random Walk (RW) design.

METHODS

A basic 4-level RSP design was used on 36 male ICR mice given intraperitoneal doses of Yessotoxin. Simulations were performed to optimise the design. A k-adjustment factor was introduced to ensure coverage of the dose window and calculate the dose steps. Instead of using equal numbers of mice on all levels, the number of mice was increased at each design level. Additionally, the binomial outcome variable was changed to multinomial. The performance of the RSP designs and a comparison of UDPs and RW were assessed by simulations. The optimised 4-level RSP design was used on 24 female NMRI mice given Azaspiracid-1 intraperitoneally.

RESULTS

The in vivo experiment with basic 4-level RSP design estimated the LD50 of Yessotoxin to be 463 μg/kgBW (95% CI: 383-535). By inclusion of the k-adjustment factor with equal or increasing numbers of mice on increasing dose levels, the estimate changed to 481 μg/kgBW (95% CI: 362-566) and 447 μg/kgBW (95% CI: 378-504 μg/kgBW), respectively. The optimised 4-level RSP estimated the LD50 to be 473 μg/kgBW (95% CI: 442-517). A similar increase in power was demonstrated using the optimised RSP design on real Azaspiracid-1 data. The simulations showed that the inclusion of the k-adjustment factor, reduction in sample size by increasing the number of mice on higher design levels and incorporation of a multinomial outcome gave estimates of the LD50 that were as good as those with the basic RSP design. Furthermore, optimised RSP design performed on just three levels reduced the number of animals from 36 to 15 without loss of information, when compared with the 4-level designs. Simulated comparison of the RSP design with UDPs and RW design demonstrated the superiority of RSP.

CONCLUSION

Optimised RSP design reduces the number of animals needed. The design converges rapidly on the area of interest and is at least as efficient as both the UDPs and RW design.

Combining in vitro embryotoxicity data with physiologically based kinetic (PBK) modelling to define in vivo dose-response curves for developmental toxicity of phenol in rat and human

In vitro assays are often used for the hazard characterisation of compounds, but their application for quantitative risk assessment purposes is limited. This is because in vitro assays cannot provide a complete in vivo dose-response curve from which a point of departure (PoD) for risk assessment can be derived, like the no observed adverse effect level (NOAEL) or the 95 % lower confidence limit of the benchmark dose (BMDL). To overcome this constraint, the present study combined in vitro data with a physiologically based kinetic (PBK) model applying reverse dosimetry. To this end, embryotoxicity of phenol was evaluated in vitro using the embryonic stem cell test (EST), revealing a concentration-dependent inhibition of differentiation into beating cardiomyocytes. In addition, a PBK model was developed on the basis of in vitro and in silico data and data available from the literature only. After evaluating the PBK model performance, effective concentrations (ECx) obtained with the EST served as an input for in vivo plasma concentrations in the PBK model. Applying PBK-based reverse dosimetry provided in vivo external effective dose levels (EDx) from which an in vivo dose-response curve and a PoD for risk assessment were derived. The predicted PoD lies within the variation of the NOAELs obtained from in vivo developmental toxicity data from the literature. In conclusion, the present study showed that it was possible to accurately predict a PoD for the risk assessment of phenol using in vitro toxicity data combined with reverse PBK modelling.

Ethical considerations in hibernation research

Ethical research practices are a key component of scientific integrity and of public support for research. Hibernation research presents specific ethical issues in regard to animal welfare. In this article, the authors apply the '3Rs' principles of humane experimental technique (replacement, reduction and refinement) to hibernation research. They provide recommendations for hibernation researchers and suggest future directions for addressing issues specific to hibernation research. They discuss the use of appropriate behavioral and physiological monitoring procedures, the development of species-specific brain atlases for placement of brain probes, the provision of environmental enrichment and the management of studies involving pharmacological induction of torpor. Addressing these issues in hibernation research will lead to improvements in research outcomes and in welfare of hibernating species.

The use of fish-derived cell lines for investigation of environmental contaminants

This unit describes protocols for growing salmonid cell lines and using them in in vitro toxicology studies. Cell viability of cultures is assessed with three indicator dyes: alamar blue for metabolic activity, CFDA-AM for membrane integrity, and neutral red for lysosomal activity. These protocols are essential tools for investigating environmental toxicity at the cellular level.

A policy at the University of Adelaide for student objections to the use of animals in teaching

In veterinary medical education, the use of animals or cadaveric tissue as a component of teaching practice is common. Teachers are required, during the process of ethical review, to apply the 3 Rs principle (replacement, refinement, reduction) whenever they consider using animals during a teaching exercise. This often involves use of replacement strategies, such as utilization of video footage or simulation-based training. However, aside from legislative or ethical requirements imposed by a country's regulatory framework on the institution, students are often the key advocates for using alternative teaching practices that do not make use of animals. This has prompted many institutions with veterinary and other life sciences teaching programs to develop student-conscientious objection policies to the use of animals in teaching. In this article, we discuss the procedures implemented to make provision for student-conscientious objectors at a new Australian Veterinary School, at the University of Adelaide. We also describe the processes to provide information to students and faculty on this issue and to facilitate information gathering on alternatives.

[Cypridopsis vidua as a test-model for the assessment of the toxicity of chemical substances, their mixtures and objects of the environment]

The results of experimental studies on development a new test-model for the evaluation of toxicity, based on the application as a test-object aquatic crustaceans Cypridopsis vidua (Ostracoda), typical for ecosystems of Belarus and compares favorably with standardized test models (ease of maintenance in laboratory cultures, high reproducibility and sensitivity) are presented. The sensitivity of the test model to common environmental pollutants has been shown. The opportunity of using it to assess the acute toxicity of chemical substances and their mixtures, integral toxicity of water in Natural Bodies & Sewage. Systems, industrial waste, extracts of products has been proved. The recommendations for use in testing specific groups of substances have been proposed.

Evaluating the phylogenetic position of Chinese tree shrew (Tupaia belangeri chinensis) based on complete mitochondrial genome: implication for using tree shrew as an alternative experimental animal to primates in biomedical research

Tree shrew (Tupaia belangeri) is currently placed in Order Scandentia and has a wide distribution in Southeast Asia and Southwest China. Due to its unique characteristics, such as small body size, high brain-to-body mass ratio, short reproductive cycle and life span, and low-cost of maintenance, tree shrew has been proposed to be an alternative experimental animal to primates in biomedical research. However, there are some debates regarding the exact phylogenetic affinity of tree shrew to primates. In this study, we determined the mtDNA entire genomes of three Chinese tree shrews (T. belangeri chinensis) and one Malayan flying lemur (Galeopterus variegatus). Combined with the published data for species in Euarchonta, we intended to discern the phylogenetic relationship among representative species of Dermoptera, Scandentia and Primates. The mtDNA genomes of Chinese tree shrews and Malayan flying lemur shared similar gene organization and structure with those of other mammals. Phylogenetic analysis based on 12 concatenated mitochondrial protein-encoding genes revealed a closer relationship between species of Scandentia and Glires, whereas species of Dermoptera were clustered with Primates. This pattern was consistent with previously reported phylogeny based on mtDNA data, but differed from the one reconstructed on the basis of nuclear genes. Our result suggested that the matrilineal affinity of tree shrew to primates may not be as close as we had thought. The ongoing project for sequencing the entire genome of Chinese tree shrew will provide more information to clarify this important issue.

Chlorpyrifos induces apoptosis and DNA damage in Drosophila through generation of reactive oxygen species

The present study investigated the apoptosis and DNA damage inducing potential of chlorpyrifos (CP) in Drosophila melanogaster. Third instar larvae of Drosophila were treated with different concentrations of CP (0.015-15.0 microg/L) for 2-48 h. Reactive oxygen species (ROS) generation, oxidative stress markers, DNA damage and apoptotic cell death end points were measured in them. A significant increase in DNA damage was concomitant with apoptotic mode of cell death in 15.0 microg/L CP-treated organisms for 24 and 48 h. Depolarization in mitochondrial membrane potential and increased casapase-3 and caspase-9 activities in these organisms indicated both as potential targets of CP. A significant positive correlation was observed among ROS generation, apoptosis and DNA damage. The study suggests that (i) ROS may be involved in inducing apoptosis and DNA damage in the CP-exposed larvae of Drosophila and (ii) D. melanogaster may be used as an alternative in vivo animal model for xenobiotics hazard assessment.