Speaker 1: Prof. dr. Paul Jennings
Human induced Pluripotent Stem Cells a giant step towards replacement
Toxicology has undergone a dramatic transition over the last decade, focusing much more to mechanistic effects at a cell and tissue level. This has been aided by technological advances such as whole genome transcriptomics, proteomics and metabolomics. We are now witnessing a new potential sea-change in drug development and toxicology, that of human induced Pluripotent Stem Cells (iPSC) and gene editing. This technology for the first time allows us to investigate chemical interactions in defined population targets and to alter these genomes to test hypothesis and to create gene reporters. Since iPSC can be differentiated into an increasing types of tissues, it will soon be possible to determine both tissue-specific and donor-specific effects of applied chemicals, biologicals and nanoparticles. Coupled with maturing technologies including RNAseq, metabolomics, mitochondrial respiration (Seahorse bioanalyser), high content imaging, 3D spheroid culture and organ-on-a-chip technology, create exciting new avenues for the development of new drugs and therapies with unparalleled safety profiles.
Speaker 2: Dr. Nynke Kramer
The Role of In Vitro Kinetics in Chemical Potency Ranking and Quantitative In Vitro-In Vivo Extrapolation
The role of in vitro bioassays in toxicological risk assessment is changing from a hazard identification screening tool towards a hazard characterisation tool replacing animal tests. In this new role, concentration-effect relationships that perturb a biological pathway in an in vitro cell assay is translated to human or animal toxicological equivalent doses, a procedure referred to as quantitative in vitro-in vivo extrapolation (QIVIVE). Kinetics in vivo (i.e. absorption, distribution, metabolism and excretion, ADME) play a central role in such QIVIVE studies as these processes determine the concentration of the chemical at the target organ where the toxic effect is initiated. The draft OECD guidance document on Good In Vitro Method Practices (GIVIMP) emphasises that similar kinetic processes determine the target concentration and thus the level of bioactivity of chemicals in in vitro assays. Despite chemicals or assays eliciting similar effects at similar nominal concentrations, the bioavailable concentration may vary greatly between chemicals and assays, thus hampering QIVIVE analysis when only the traditional nominal concentration is used. Depending on the physicochemical properties of the chemical (e.g. logP, H, pKa and membrane-water partition coefficients) and the assay setup (e.g. serum level, well plate dimension etc.), test chemicals may evaporate, degrade, metabolise, and bind to serum constituents, cell attachment matrices, well plate plastic, and non-specifically to cells. Here, measurement and modelling tools to assess bioavailable concentrations of test chemicals in in vitro clearance and toxicity assays are presented.
Speaker 3: Prof. dr. Ronette Gehring
What can we learn from the in silico cow?
How physiologically-based pharmaco-/toxicokinetic modeling can contribute to the 3R’s in toxicological and pharmaceutical research
The effects of most xenobiotics on living animals are related to their concentrations at receptor sites in various tissues of the body. Kinetics is therefore an important sub-discipline of pharmacology and toxicology, driving our understanding of exposure-effect relationships and guiding decisions about risk management and dose optimization. Although it is possible to approach the study of compound kinetics empirically, this requires data generation through in vivo experiments, which are expensive, not always practical, and unethical when they require exposing experimental animals to toxic doses of chemicals. Physiologically-based pharmaco- and toxicokinetic (PBP/TK) modeling is an alternative approach that predicts a compound’s kinetics and tissue-specific dosimetry based on our understanding of how they interact with living organisms and tissues to drive the processes of absorption, distribution, metabolism and excretion. Although PBP/TK models require a lot of data for their initial development, once established and validated, they minimize the need for further in vitro experiments. This approach is becoming increasingly popular as the software and computing power are no longer a limiting factor. Sharing models and the data needed for their development will be important factors contributing towards the goal of minimizing the use of animals in toxicological and pharmaceutical research in the future
Speaker 4: Dr. Anne Kienhuis
Transition to animal-free innovations in regulatory safety assessment
In 2018, RIVM published the Roadmap for animal-free innovations in regulatory safety assessment, commissioned by the Ministry of Agriculture, Nature and Food Quality following their ambition “The Netherlands as a frontrunner in animal-free innovation in 2025”. The aim of this Roadmap is to describe the steps required to facilitate the transition to animal-free safety assessment. This transition requires: a paradigm shift embracing a different approach to safety assessment. To achieve this paradigm shift, a social dialogue needs to be initiated unifying various interests, various perceptions of safety and various degrees of acceptance. At the same time we need continued development of animal-free new approach methodologies, including focus on other or additional endpoints, in which the sequence or ‘workflow’ of these tests in the new system needs to be considered, as well as how the tests comply with the needs for safety assessment and how they can be implemented in the regulatory context. Attention is needed for the consequences: what measures will result from the outcomes of these tests? The activities set out in this Roadmap have been defined in collaboration with Dutch representatives of industry, NGOs, regulatory bodies, government organisations, and knowledge institutes involved in the regulatory framework. The activities need to be undertaken on an international level, with due consideration of the 6 Cs: Commitment, Coordination, Continuity, Communication, Cooperation and Cost.
Prof. dr. Paul Jennings
Paul Jennings was appointed Professor at the Division of Molecular and Computational Toxicology, VU, Amsterdam, in July 2017. Paul hails from Dublin Ireland. He conducted his BSc and PhD in University College Dublin under Prof. Michael Ryan. He then moved to Innsbruck, Austria working with Prof. Walter Pfaller. In 2009 Paul habilitated in Epithelial Physiology. His background is in epithelial and renal biology, in vitro cell culture system development and mechanistic toxicology. Current scientific interests include the utilisation of human induced pluripotent stem cells for toxicological investigations and chemical safety assessment.
Nynke Kramer is assistant professor in Toxicology at the Institute for Risk Assessment Sciences (IRAS) of Utrecht University. Nynke heads its ‘In Vitro Toxicology’ research group and is responsible for pharmacokinetic modeling, ecotoxicology, and quantitative in vitro-in vivo extrapolation at graduate and postgraduate level. Her research focuses on developing analytical techniques and models to improve the extrapolation of effect concentrations obtained from in vitro cell assays to toxic doses relevant to humans and animals. Her current research follows up on her PhD thesis, completed at the same institute in 2010. Her research has led to a number of publications uncovering parameters determining the free concentration of test chemicals in in vitro cell assays. The issue of freely available concentrations in in vitro assays has slowly picked up momentum. Illustratively, Nynke’s research has been awarded the SETAC Procter and Gamble 2007 Fellowship for Doctoral Research in Environmental Sciences. She used the prize money to do part of her research at the Swiss Federal Institute for Aquatic Science and Technology, Eawag, Dübendorf, Switzerland. Before starting her PhD, Nynke obtained her BSc degree in Life Sciences at University College Utrecht in 2003 and her MSc degree in Environmental Change and Management at the University of Oxford in 2004. In her free time, which she does not have, she sits on the board of the Dutch-Belgian society of in vitro methods, INVITROM, and helps organise INESPO, the yearly international sustainability olympiad for high school students to pursue innovative solutions to environmental issues.
Ronette Gehring graduated as a veterinarian in 1996 from the Faculty of Veterinary Science at Onderstepoort, and was awarded the MMedVet specialist degree in Veterinary Pharmacology from the University of Pretoria in 2000. She became a Diplomate of the American College of Veterinary Clinical Pharmacology in 2006 and joined the faculty of the Kansas State, College of Veterinary Medicine the same year. During her tenure at Kansas State University, Ronette served as the regional director (Mid-West) of the Food Animal Residue Avoidance Databank. She is Past-President of the American Academy of Veterinary Pharmacology and Therapeutics and serves as Secretary-Treasurer of the American College of Veterinary Clinical Pharmacology. Ronette joined the Faculty of Veterinary Medicine at Utrecht University in October 2017. She leads the Veterinary Pharmacology and Pharmacy group within the Faculty of Veterinary Medicine. Her research aims to build bridges between the basic, applied and clinical sciences, focussing on questions that are relevant to veterinary clinical practice and One Health. She uses mathematical modeling and simulation as a tool to answer a wide range of research questions, including the optimisation of drug dosage regimens for veterinary species, characterisation of population variability, and extrapolation research findings from in vitro to in vivo and between species. This approach contributes towards Utrecht University's mission of reducing, refining and replacing animal models in biomedical research. In addition to her research, Ronette is passionate about teaching and is constantly seeking ways to prepare veterinary students for exciting career opportunities in the 21st century.
Dr. Anne Kienhuis is a scientist affiliated to the Department of Innovative Testing Strategies at the Centre for Health Protection Research of the National Institute of Public Health and the Environment (RIVM). She studied molecular health sciences at Maastricht University and holds a PhD on toxicogenomics and hepatic in vitro models. At RIVM she is project coordinator 3R’s for het Ministry of Agriculture, Nature and Food Quality and is involved in several research projects and international networks in this area.