Thomas Hartung

• MD PhD
• Chair at Johns Hopkins University

Microphysiological systems (MPS), including organ-on-chip platforms and complex organoid models, represent a transformative approach to human-relevant in vitro modeling. These technol­ogies bioengineer aspects of organ architecture and functionality, revolutionizing drug development, reducing animal testing, and enabling personalized medicine appro...

Risk assessors, managers, and decision-makers are responsible for evaluating diverse human, environmental, and animal health risks. Although the critical elements of risk assessment and management are well-described in national and international documents, the ethical issues involved in risk decision-making have received comparatively little attent...

Improving models to investigate neurodegenerative disease, neurodevelopmental disease, neurotoxicology and neuropharmacology is critical to improve our basic understanding of the human nervous system, as well as to accelerate discovery of interventions and drugs. Improved models of the human central nervous system could enable critical discoveries...

Chemical safety assessment still heavily relies on animal testing, presenting ethical dilemmas and limited human predictive value. New approach methodologies (NAMs), including in vitro and in silico techniques, offer alternative solutions. In silico toxicology has made progress in predicting chemical effects but frequently lacks biological mechanis...

The regular t4 workshops on biology-inspired microphysiological systems (MPS) have become a reliable benchmark for assessing fundamental scientific, industrial, and regulatory trends in the MPS field. The 2023 workshop participants concluded that MPS technology as used in academia has matured significantly, as evidenced by the steadily increasing n...

Toxicological test methods generate raw data and provide instructions on how to use these to determine a final outcome such as a classification of test compounds as hits or non-hits. The data processing pipeline provided in the test method description is often highly complex. Usually, multiple layers of data, ranging from a machine-generated output...

On occasion of the DNT5 meeting in Konstanz, Germany (April-2024), participants brainstormed on future challenges concerning a regulatory implementation of the developmental neurotoxicity (DNT) in vitro test battery (DNT-IVB). The five discussion topics below outline some of the key issues, opportunities and research directions for the next several...

The 5th International Conference on Developmental Neurotoxicity (DNT) Testing (DNT5) took place in April 2024 in Konstanz, Germany, organized by CAAT-Europe, the University of Konstanz, and scientists from the US EPA, SCAHT, and CAAT at Johns Hopkins University Bloomberg School of Public Health. The conference convened experts from regulatory agenc...

Chemical safety assessment still heavily relies on animal testing, presenting ethical dilemmas and limited human predictive value. New approach methodologies (NAMs), including in vitro and in silico techniques, offer alternative solutions. In silico toxicology has made progress in predicting chemical effects but frequently lacks biological mechanis...

In response to the increasing significance of artificial intelligence (AI) in healthcare, there has been increased attention – including a Presidential executive order to create an AI Safety Institute – to the potential threats posed by AI. While much attention has been given to the conventional risks AI poses to cybersecurity, and critical infrast...

The workshop titled State of the Science on Assessing Developmental Neurotoxicity Using New Approach Methods was co-organized by University of Maryland's Joint Institute for Food Safety and Applied Nutrition (JIFSAN) and the U.S. Food and Drug Administration's (FDA) Center for Food Safety and Applied Nutrition (CFSAN; now called the Human Foods Pro...

Validation establishes the reproducibility and relevance of regulatory test methods, particularly for new approach methods (NAMs) as alternatives to animal testing. While validation concepts provide a framework to assess method suitability, they rarely undergo method-critical assessment. This paper explores the philosophical and ethical foundations...

The validation of new approach methods (NAMs) in toxicology faces significant challenges, including the integration of diverse data, selection of appropriate reference chemicals, and lengthy, resource-intensive consensus processes. This article proposes an artificial intelligence (AI)-based approach, termed e-validation, to optimize and accelerate...

The increasing prevalence of neurodevelopmental disorders has highlighted the need for improved testing methods to determine developmental neurotoxicity (DNT) hazard for thousands of chemicals. This paper proposes the integration of organoid intelligence (OI); leveraging brain organoids to study neuroplasticity in vitro, into the DNT testing paradi...

Brain Microphysiological Systems including neural organoids derived from human induced pluripotent stem cells offer a unique lens to study the intricate workings of the human brain. This paper investigates the foundational elements of learning and memory in neural organoids, also known as Organoid Intelligence by quantifying immediate early gene ex...

Researchers in biomedical research, public health, and the life sciences often spend weeks or months discovering, accessing, curating, and integrating data from disparate sources, significantly delaying the onset of actual analysis and innovation. Instead of countless developers creating redundant and inconsistent data pipelines, BioBricks.ai offer...

Researchers in biomedical research, public health, and the life sciences often spend weeks or months discovering, accessing, curating, and integrating data from disparate sources, significantly delaying the onset of actual analysis and innovation. Instead of countless developers creating redundant and inconsistent data pipelines, BioBricks.ai offer...

Disagreements about language use are common both between and within fields. Where interests require multidisciplinary collaboration or the field of research has the potential to impact society at large, it becomes critical to minimize these disagreements where possible. The development of diverse intelligent systems, regardless of the substrate (e....

When The Principles of Humane Experimental Technique was published in 1959, authors William Russell and Rex Burch had a modest goal: to make researchers think about what they were doing in the laboratory - and to do it more humanely. Sixty years later, their groundbreaking book was celebrated for inspiring a revolution in science and launching a ne...

Developmental neurotoxicity (DNT) testing has seen enormous progress over the last two decades. Preceding even the publication of the animal-based OECD test guideline for DNT testing in 2007, a series of non-animal technology workshops and conferences (starting in 2005) shaped a community that has delivered a comprehensive battery of in vitro test...

Cell culture technology has evolved, moving from single-cell and monolayer methods to 3D models like reaggregates, spheroids, and organoids, improved with bioengineering like microfabrication and bioprinting. These advancements, termed microphysiological systems (MPSs), closely replicate tissue environments and human physiology, enhancing research...

Brain organoids are 3D in vitro culture systems derived from human pluripotent stem cells that self‐organize to model features of the (developing) human brain. This review examines the techniques behind organoid generation, their current and potential applications, and future directions for the field. Brain organoids possess complex architecture co...

Metabolomics is emerging as a powerful systems biology approach for improving preclinical drug safety assessment. This review discusses current applications and future trends of metabolomics in toxicology and drug development. Metabolomics can elucidate adverse outcome pathways by detecting endogenous biochemical alterations underlying toxicity mec...

The rapid progress of AI impacts diverse scientific disciplines, including toxicology, and has the potential to transform chemical safety evaluation. Toxicology has evolved from an empirical science focused on observing apical outcomes of chemical exposure, to a data-rich field ripe for AI integration. The volume, variety and velocity of toxicologi...

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...

Green toxicology is marching chemistry into the 21st century. This emerging framework will transform how chemical safety is evaluated by incorporating evaluation of the hazards, exposures, and risks associated with chemicals into early product development in a way that minimizes adverse impacts on human and environmental health. The goal is to mini...

Human brain organoids, aka cerebral organoids or earlier “mini-brains”, are 3D cellular models that recapitulate aspects of the developing human brain. They show tremendous promise for advancing our understanding of neurodevelopment and neurological disorders. However, the unprecedented ability to model human brain development and function in vitro...

The Human Exposome Project aims to revolutionize our understanding of how environmental exposures affect human health by systematically cataloging and analyzing the myriad exposures individuals encounter throughout their lives. This initiative draws a parallel with the Human Genome Project, expanding the focus from genetic factors to the dynamic an...

Historical data from control groups in animal toxicity studies is currently mainly used for comparative purposes to assess validity and robustness of study results. Due to the highly controlled environment in which the studies are performed and the homogeneity of the animal collectives it has been proposed to use the historical data for building so...

The rapid progress of AI impacts various areas of life, including toxicology, and promises a major role for AI in future risk assessments. Toxicology has shifted from a purely empirical science focused on observing chemical exposure outcomes to a data-rich field ripe for AI integration. AI methods are well-suited to handling and integrating large,...

Toxicology has undergone a transformation from an observational science to a data-rich discipline ripe for artificial intelligence (AI) integration. The exponential growth in computing power coupled with accumulation of large toxicological datasets has created new opportunities to apply techniques like machine learning and especially deep learning...

Introduction: The positive identification of xenobiotics and their metabolites in human biosamples is an integral aspect of exposomics research, yet challenges in compound annotation and identification continue to limit the feasibility of comprehensive identification of total chemical exposure. Nonetheless, the adoption of in silico tools such as m...

This protocol describes the design and development of a tool for evaluation of the internal validity of in vitro studies, which is needed to include the data as evidence in systematic reviews and chemical risk assessments. The tool will be designed specifically to be applied to cell culture studies, including, but not restricted to, studies meeting...

Human health is determined both by genetics (G) and environment (E). This is clearly illustrated in groups of individuals who are exposed to the same environmental factor showing differential responses. A quantitative measure of the gene-environment interactions (GxE) effects has not been developed and in some instances, a clear consensus on the co...

KEYWORDS predictive toxicology, new approach methodologies (NAMs), micro-physiological systems (MPS), PBPK modelling, data science Editorial on the Research Topic Advances in and applications of predictive toxicology: 2022 While the first use of the term "Predictive Toxicology" was mainly focusing on in silico approaches and applied almost synonymo...

367 Policy impact analysis is needed for evidence-based policy-making. Numbers are not always fun. "Statistics are the triumph of the quantitative method, and the quantitative method is the victory of sterility and death" is a quote from the Franco-English writer Hilaire Belloc (1870-1953). Bad policies are even less fun. There is a tremendous diff...

The EU's chemicals regulation, REACH, requires that most chemicals in the EU be evaluated for human health and ecosystem risks, with a mandate to minimize use of animal tests for these evaluations. The REACH process has been ongoing since about 2008, but a calculation of the resulting animal use is not publicly available. For this reason, we have u...

The predominantly animal-centric approach of chemical safety assessment has increasingly come under pressure. Society is questioning overall performance, sustainability, continued relevance for human health risk assessment and ethics of this system, demanding a change of paradigm. At the same time, the scientific toolbox used for risk assessment is...

To transfer toxicological findings from model systems, e.g. animals, to humans, standardized safety factors are applied to account for intra-species and inter-species variabilities. An alternative approach would be to measure and model the actual compound-specific uncertainties. This biological concept assumes that all observed toxicities depend no...

In our earlier work (Golden et al., 2021), we showed 70-80% accuracies for several skin sensitization computational tools using human data. Here, we expanded the data set using the NICEATM human skin sensitization database to create a final data set of 1355 discrete chemicals (largely negative, ∼70%). Using this expanded data set, we analyzed model...

Microphysiological systems (MPS) are 2D or 3D multicellular constructs able to mimic tissue microenvironments. The latest models encompass a range of techniques, including co-culturing of various cell types, utilization of scaffolds and extracellular matrix materials, perfusion systems, 3D culture methods, 3D bioprinting, organ-on-a-chip technology...

Progress in developing new tools, assays, and approaches to assess human hazard and health risk provides an opportunity to re-evaluate the necessity of dog studies for the safety evaluation of agrochemicals. A workshop was held where participants discussed the strengths and limitations of past use of dogs for pesticide evaluations and registrations...

The brain is arguably the most powerful computation system known. It is extremely efficient in processing large amounts of information and can discern signals from noise, adapt, and filter faulty information all while running on only 20 watts of power. The human brain's processing efficiency, progressive learning, and plasticity are unmatched by an...

Recent advances in human stem cell-derived brain organoids promise to replicate critical molecular and cellular aspects of learning and memory and possibly aspects of cognition in vitro. Coining the term “organoid intelligence” (OI) to encompass these developments, we present a collaborative program to implement the vision of a multidisciplinary fi...

Recently, the field of bioengineering, which uses biomedical knowledge to solve problems and create products, has made great progress creating tiny, functioning models of human organs, called organoids. The brain is the most complex organ of the human body. Although brain organoids have been created, they still cannot perform calculations, learn, m...

Environmental contaminants, naturally occurring toxicants, pesticide residues, and food additives are the four chemical-associated categories of six for food safety established by the Food and Drug Administration. The direct food additives, which are intentionally added to food, are the main focus of this case study, and the indirect food additives...

Understanding brain function remains challenging as work with human and animal models is complicated by compensatory mechanisms, while in vitro models have been too simple until now. With the advent of human stem cells and the bioengineering of brain microphysiological systems (MPS), understanding how both cognition and long-term memory arise is no...

In this issue of Neuron, Kagan et al.¹ implement learning-in-a-dish as an important step toward organoid intelligence. These systems may complement the study of molecular and cellular mechanisms of cognition and allow innovations in pharmacological and toxicological studies of neurodevelopmental or neurodegenerative disorders as well as advances in...

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...

An important discussion in today’s society is whether we should make animals suffer for the sake of science and product development. In this article, I present four examples of animal tests that were introduced in the past to protect patients and consumers, and I discuss attempts to replace those animal tests with other methods. When we started usi...

Brain organoids are important models for mimicking some three-dimensional (3D) cytoarchitectural and functional aspects of the brain. Multielectrode arrays (MEAs) that enable recording and stimulation of activity from electrogenic cells offer notable potential for interrogating brain organoids. However, conventional MEAs, initially designed for mon...

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-...

Alternative methods to animal use in toxicology are evolving with new advanced tools and multilevel approaches, to answer from one side to 3Rs requirements, and on the other side offering relevant and valid tests for drugs and chemicals, considering also their combination in test strategies, for a proper risk assessment. While stand-alone methods,...

Brain organoids are important models for mimicking some three-dimensional (3D) cytoarchitectural and functional aspects of the brain. Multielectrode arrays (MEAs) that enable recording and stimulation of activity from electrogenic cells are widely utilized in biomedical engineering. However, conventional MEAs, initially designed for monolayer cultu...

Introduction The metabolomics quality assurance and quality control consortium (mQACC) is enabling the identification, development, prioritization, and promotion of suitable reference materials (RMs) to be used in quality assurance (QA) and quality control (QC) for untargeted metabolomics research. Objectives This review aims to highlight current...

Oxidative stress is caused by an imbalance between the generation and detoxification of reactive oxygen and nitrogen species (ROS/RNS). This imbalance plays an important role in brain aging and age-related neurodegenerative diseases. In the context of Parkinson's disease (PD), the sensitivity of dopaminergic neurons in the substantia nigra pars com...

Progressive multifocal leukoencephalopathy (PML) is a frequent neurological complication in immunosuppressed patients. PML is caused by the JC virus (JCV), a neurotropic DNA polyomavirus that infects oligodendrocytes and astrocytes, causing inflammation and demyelination which lead to neurological dysfunction. The pathogenesis of PML is poorly unde...

Four decades of the Human Genome Project and its consequences have shown how the entrepreneurial state, through significant investment into science, can drive scientific progress and advance biomedicine. A certain fraction of diseases can now be explained as caused by genetics, and a more significant fraction as impacted by genetics. Besides anothe...

The development of therapies for and preventions against infectious diseases depends on the availability of disease models. Bioengineering of human organoids and organs-on-chips is one extremely promising avenue of research. These miniature, laboratory-grown organ systems have been broadly used during the ongoing, unprecedented coronavirus 2019 (CO...

This study assessed the hypothalamic-pituitary-adrenocortical (HPA) axis and lymphoid organs (thymus, spleen, and bone marrow) of Wistar rats treated with a mixture of chromium and benzene. Animals were assessed at three time-points (45, 90 and 135 days) following oral mixture exposure. The hypothalamus-pituitary system was examined in light and el...