Ellen Fritsche

Swiss Centre for Applied Human Toxicology | SCAHT

The vertebrate nervous system is vulnerable to chemical toxicity and the widespread release of chemicals into the environment outstrips the capacity to assess their safety. We devised a battery of automated behavior assays in larval zebrafish (Danio rerio), a 3R-compliant model amenable to higher-throughput chemical screens. The battery captures st...

Cockayne Syndrome B (CSB) is a hereditary multiorgan syndrome which—through largely unknown mechanisms—can affect the brain where it clinically presents with microcephaly, intellectual disability and demyelination. Using human induced pluripotent stem cell (hiPSC)-derived neural 3D models generated from CSB patient-derived and isogenic control line...

Exposure to nanoparticles (NPs) in pregnancy is increasingly linked to adverse effects on embryo‐fetal development and health later in life. However, the developmental toxicity mechanisms of NPs are largely unknown, in particular potential effects on the placental secretome, which orchestrates many developmental processes pivotal for pregnancy succ...

In the European regulatory context, rodent in vivo studies are the predominant source of neurotoxicity information. Although they form a cornerstone of neurotoxicological assessments, they are costly and the topic of ethical debate. While the public expects chemicals and products to be safe for the developing and mature nervous systems, considerabl...

Cockayne syndrome (CS) is a rare hereditary autosomal recessive disorder primarily caused by mutations in Cockayne syndrome protein A (CSA) or B (CSB). While many of the functions of CSB have been at least partially elucidated, little is known about the actual developmental dysregulation in this devasting disorder. Of particular interest is the reg...

Introduction: The Adverse Outcome Pathway (AOP) concept facilitates rapid hazard assessment for human health risks. AOPs are constantly evolving, their number is growing, and they are referenced in the AOP-Wiki database, which is supported by the OECD. Here, we present a study that aims at identifying well-defined biological areas, as well as gaps...

The first Stakeholder Network Meeting of the EU Horizon 2020-funded ONTOX project was held on 13-14 March 2023, in Brussels, Belgium. The discussion centred around identifying specific challenges, barriers and drivers in relation to the implementation of non-animal new approach methodologies (NAMs) and probabilistic risk assessment (PRA), in order...

Both because of the shortcomings of existing risk assessment methodologies, as well as newly available tools to predict hazard and risk with machine learning approaches, there has been an emerging emphasis on probabilistic risk assessment. Increasingly sophisticated AI models can be applied to a plethora of exposure and hazard data to obtain not on...

Cockayne syndrome is a rare hereditary autosomal recessive disorder characterized by diverse neurological afflictions. However, little is known about the cerebral development in CS patients. We generated neurospheres and cerebral organoids utilizing Cockayne Syndrome B Protein (CSB) deficient induced pluripotent stem cells derived from two patients...

Chinese herbal medicine (CHM) is used among pregnant women. However, the question of its safety during pregnancy remains unclear. The use of these products relies on history of use data but there are specific toxicities like developmental neurotoxicity that are clearly understudied. Here we use the zebfrafish embryo developmental toxicity assay (ZE...

New approach methodologies (NAMs) have the potential to become a major component of regulatory risk assessment, however, their actual implementation is challenging. The European Partnership for the Assessment of Risks from Chemicals (PARC) was designed to address many of the challenges that exist for the development and implementation of NAMs in mo...

In chemical safety assessment, benchmark concentrations (BMC) and their associated uncertainty are needed for the toxicological evaluation of in vitro data sets. A BMC estimation is derived from concentration-response modelling and results from various statistical decisions, which depend on factors such as experimental design and assay endpoint fea...

Proper brain development is based on the orchestration of key neurodevelopmental processes (KNDP), including the formation and function of neural networks. If at least one KNDP is affected by a chemical, an adverse outcome is expected. To enable a higher testing throughput than the guideline animal experiments, a developmental neurotoxicity (DNT) i...

The currently accepted methods for neurotoxicity (NT) testing rely on animal studies. However, high costs and low testing throughput hinder their application for large numbers of chemicals. To overcome these limitations, in vitro methods are currently being developed based on human-induced pluripotent stem cells (hiPSC) that allow higher testing th...

The currently accepted methods for neurotoxicity (NT) testing rely on animal studies. However, high costs and low testing throughput hinder their application for large numbers of chemicals. To overcome these limitations, in vitro methods are currently developed which are based on human induced pluripotent stem cells (hiPSC) that allow higher testin...

Proper brain development is based on the orchestration of key neurodevelopmental processes, including the formation and function of neural networks. If at least one key neurodevelopmental process is affected by a chemical, an adverse outcome is expected. To allow a higher testing throughput than the guideline animal experiments, a developmental neu...

For 3D neural cultures durable hydrogels are required, which persist over a long differentiation period and thus enable the maturation of neuronal networks (NN). Here, 3D models based on human induced pluripotent stem cell‐derived neural progenitor cells that are embedded in hydrogels of either pure alginate or alginate functionalized with the extr...

Following a multi-disciplinary approach integrating information from several experimental models we have collected new evidence supporting, expanding and redesigning the AOP “Disrupted laminin/int-β1 interaction leading to decreased cognitive function”. Investigations in vitro in rabbit and rat neurospheres and in vivo in mice exposed to EGCG (epig...

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. AT...

Severe oxygen and iron deficiencies have evolutionarily conserved detrimental effects, leading to pathologies in mammals and developmental arrest as well as neuromuscular degeneration in the nematode Caenorhabditis elegans. Yet, similar to the beneficial effects of mild hypoxia, non-toxic levels of iron depletion, achieved with the iron chelator bi...

In the field of hazard assessment, Benchmark concentrations (BMC) and their associated uncertainty are of particular interest for regulatory decision making. The BMC estimation consists of various statistical decisions to be made, which depend largely on factors such as experimental design and assay endpoint features. In current data practice, the...

Developmental neurotoxicity (DNT) is a major safety concern for all chemicals of the human exposome. However, DNT data from animal studies are available for only a small percentage of manufactured compounds. Test methods with a higher throughput than current regulatory guideline methods, and with improved human relevance are urgently needed. We the...

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are formed as a result of natural cellular processes, intracellular signaling, or as adverse responses associated with diseases or exposure to oxidizing chemical and non-chemical stressors. The action of ROS and RNS, collectively referred to as reactive oxygen and nitrogen species (R...

Adverse outcome pathways (AOPs) are organized sequences of key events (KEs) that are triggered by a xenobiotic-induced molecular initiating event (MIE) and summit in an adverse outcome (AO) relevant to human or ecological health. The AOP framework causally connects toxicological mechanistic information with apical endpoints for application in regul...

Public awareness and discussion about animal experiments and replacement methods has greatly increased in recent years. The term 'the Three Rs', which stands for the Replacement, Reduction and Refinement of animal experiments, is inseparably linked in this context. A common goal within the Three Rs scientific community is to develop predictive non-...

The evaluation of substances for their potency to induce embryotoxicity is controlled by safety regulations. Test guidelines for reproductive and developmental toxicity rely mainly on animal studies, which make up the majority of animal usage in regulatory toxicology. Therefore, there is an urgent need for alternative in vitro methods to follow the...

There is a call for a paradigm shift in developmental neurotoxicity (DNT) evaluation, which demands the implementation of faster, more cost-efficient, and human-relevant test systems than current in vivo guideline studies. Under the umbrella of the Organisation for Economic Co-operation and Development (OECD), a guidance document is currently being...

Neurotoxicology is the study of adverse effects on the structure or function of the developing or mature adult nervous system following exposure to chemical, biological, or physical agents. The development of more informative alternative methods to assess developmental (DNT) and adult (NT) neurotoxicity induced by xenobiotics is critically needed....

Limitations in genetic stability and recapitulating accurate physiological disease properties challenge the utility of patient‐derived (PD) cancer models for reproducible and translational research. We have genetically engineered a portfolio of isogenic human induced pluripotent stem cells (hiPSCs) with different pan‐cancer relevant oncoprotein sig...

The utility of patient-derived tumor cell lines as experimental models for glioblastoma has been challenged by limited representation of the in vivo tumor biology and low clinical translatability. Here, we report on longitudinal epigenetic and transcriptional profiling of seven glioblastoma spheroid cell line models cultured over an extended period...

Neurosphere cultures consisting of primary human neural stem / progenitor cells (hNPC) are used for studying the effects of substances on early neurodevelopmental processes in vitro. Differentiating hNPCs migrate and differentiate into radial glia, neurons, astrocytes and oligodendrocytes upon plating on a suitable extracellular matrix and thus mod...

Exposure to environmental pollutants like chemicals or air pollution is major health concern for the human population. Especially the nervous system is a sensitive target for environmental toxins with exposures leading to life stage-dependent neurotoxicity. Developmental and adult neurotoxicity are characterized by specific adverse outcomes ranging...

Neurotoxicity is caused by a large variety of compound classes and affects all life stages from the developing child to the elderly. Studying for neurotoxicity often involves animal models, which are very resource-intensive and bear the problem of species-differences. Thus, alternative human-based models are needed to overcome these issues. Over th...

Stable and predictive neural cell culture models are a necessary premise for many research fields. However, conventional 2D models lack 3D cell‐material/‐cell interactions and hence do not reflect the complexity of the in vivo situation properly. Here two alginate/gellan gum/laminin (ALG/GG/LAM) hydrogel blends are presented for the fabrication of...

The 3Rs concept, calling for replacement, reduction and refinement of animal experimentation, is receiving increasing attention around the world, and has found its way to legislation, in particular in the European Union. This is aligned by continuing high-level efforts of the European Commission to support development and implementation of 3Rs meth...

Due to their neurodevelopmental toxicity, flame retardants (FRs) like polybrominated diphenyl ethers are banned from the market and replaced by alternative FRs, like organophosphorus FRs, that have mostly unknown toxicological profiles. To study their neurodevelopmental toxicity, we evaluated the hazard of several FRs including phased-out polybromi...

Due to its high abundance and alarming toxic potential, arsenic is one of the most concerning environmental toxicants and still a global health concern. Consequences of chronic arsenic exposure for human health are diverse and range from skin lesions to neurotoxicity. The developing brain has been identified as particularly vulnerable to arsenic-me...

Biodegradable hydrogels that promote stem cell differentiation into neurons in three dimensions (3D) are highly desired in biomedical research to study drug neurotoxicity or to yield cell-containing biomaterials for neuronal tissue repair. Here, we demonstrate that oxidized alginate-gelatin-laminin (ADA-GEL-LAM) hydrogels facilitate neuronal differ...

The call for a paradigm change in toxicology from the United States National Research Council in 2007 initiates awareness for the invention and use of human‐relevant alternative methods for toxicological hazard assessment. Simple 2D in vitro systems may serve as first screening tools, however, recent developments infer the need for more complex, mu...

Glioblastoma (GBM) is a lethal disease with limited clinical treatment options available. Recently, a new inhibitor targeting the prominent cancer signaling pathway mTOR was discovered (Rapalink-1), but its therapeutic potential on stem cell populations of GBM is unknown. We applied a collection of physiological relevant organoid-like stem cell mod...

In cancer pharmacology, a drug candidate’s therapeutic potential is typically expressed as its ability to suppress cell growth. Different methods in assessing the cell phenotype and calculating the drug effect have been established. However, inconsistencies in drug response outcomes have been reported, and it is still unclear whether and to what ex...

Objective The lack of effective treatments against diabetic sensorimotor polyneuropathy demands the search for new strategies to combat or prevent the condition. Because reduced magnesium and increased methylglyoxal levels have been implicated in the development of both type 2 diabetes and neuropathic pain, we aimed to assess the putative interplay...

In this project we set up a human cell‐based DNTin vitro testing strategy that is based on test methods with high readiness and data generated therefrom. The methods underwent afit‐for‐purpose evaluation that considered four key elements: 1. The test system, 2. the exposure scheme, 3. the assay and analytical endpoint(s) and 4. the classification m...

Myelinating oligodendrocytes (OLs) establish saltatory nerve conduction during white matter development. Thus, interference with oligodendrogenesis leads to an adverse outcome on brain performance in the child due to aberrant myelination. An intertwined network of hormonal, transcriptional and biosynthetic processes regulates OLs development, there...

The aim of this study was to develop a rabbit neurosphere culture to characterize differences in basic processes of neurogenesis induced by intrauterine growth restriction (IUGR). A novel in vitro neurosphere culture has been established using fresh or frozen neural progenitor cells from newborn (PND0) rabbit brains. After surgical IUGR induction i...