Animal-free computational modelling for prevention of human chemical-induced neural tube defects
Animal-free methods for human chemical safety assessment are promising tools for the reduction of animal testing. However, these methods only measure a small aspect of biology compared to an in vivo test. The reductionist nature of these methods thus limits their individual application in the regulatory arena of chemical risk assessment. Ontologies can be used to describe human biology, and delineate the basis of adverse outcome pathway networks that describe how chemical exposures may lead to adverse health effects. This pathway description can then help to select animal-free in vitro and in silico methods, comprehensively covering the network. The comprehensiveness of this approach, firmly rooted in human biology, is expected to facilitate regulatory acceptance of animal-free methods. As an example, this video zooms in on the development of a computational model for neural tube development, an aspect of human development that is especially vulnerable to chemical disruption. This research is part of the ONTOX project (https://www.ontox-project.eu). For more information on the concept of the Virtual Human, click here (https://doi.org/10.1016/j.cotox.2019.03.009.).
Developmental neurotoxicity testing using stem cells
Children should grow up in a safe and healthy environment. Disruption of brain development may have enormous impact on future life and might result in disorders such as ADHD or cognitive decline. The effect of compound exposure on the developing brain is largely unknown, since in the current regulatory test procedures in experimental animals effects on the brain are rarely investigated and human relevance of these animal models is under debate. Researchers at RIVM are developing a cell model based on human stem cells that mimics a small part of the developing brain. This method is human-relevant, animal-free, and based on mechanistic knowledge of human biology and physiology of brain development. The model can be an important component in a testing strategy to test the safety of chemicals and pharmaceuticals on the developing brain.
Projects and initiatives
Transition Project towards Animal-free Innovations
Animal-free innovations are emerging at a fast pace. TPI Chair Daniela Salvatori, and TPI ambassadors Jeffrey Beekman and Elly Hol, explain why animal-free innovations are important and how TPI supports researchers in finding or developing animal-free methods for their research. They call for collaboration.
Understanding implant safety in vitro
Each year, millions of people receive an implant. The function of damaged tissues or organs is successfully restored in most people, however, some do develop complications. The safety of medical devices is indicated for legislation using international regulations. In the relevant standards, tests mainly focus on the chemical nature of the implants using classical toxicological end-points. However, more recently we have learned that the mechanical forces from an implant on the host-tissue can have significant effects on the host-response as well. At RIVM we want to develop an animal-free model that better resembles the interface between the implant and the host-tissue, and by updating the testing strategies contribute to implant safety on the long term.
Projects and initiatives
Preclinicaltrials.eu is a registration platform dedicated to animal studies protocols, and which aims to provide a comprehensive overview of all animal studies, including those that might otherwise remain unpublished. Preregistration promotes transparency, reduces biases and misconduct, (e.g., selective outcome reporting, publication bias, HARKing) and stimulates the reduction of involuntary duplication. This approach benefits researchers individually, as proof of good planning, and their peers by increasing data sharing. By promoting openness and transparency, Preclinicaltrials.eu encourages robust and responsible research, in alignment with the 3Rs.
Projects and initiatives
RE-Place: a database centralising the available expertise on NAMs in Belgium
RE-Place is a scientific project funded by the Flemish and Brussels government which aims to collect all available expertise on the use of alternative methods to animal testing, also known as ‘New Approach Methodologies (NAMs)’ in one central database. As the development of NAMs is continuously evolving, it can be challenging for (young) scientists to find relevant information on the use thereof. In order to facilitate access to this type of information, the ‘RE-Place’ project was launched. The RE-Place database not only provides a reliable overview of the different NAMs, but also the names of experts and research centres where these techniques can be learned in Belgium. If you are interested to participate in this project, don’t hesitate to contact info@RE-Place.be! The RE-Place project is coordinated by Sciensano and the Vrije Universiteit Brussel.
Scientific solutions for the gap in translational medicine: skin model platform with melanoma (3D melanoma)
The developing process of a new drug, from first testing to regulatory approval and ultimately to market is a long, costly, and risky path. Noteworthy is the fact that almost 95% of the drugs that go into human trials fail. According to the National Institutes of Health (NIH), 80 to 90% of drug research projects fail before they ever get tested in humans. The value of preclinical research, mainly conducted in animal model experiments for predicting the effectiveness of therapies and treatment strategies in human trials, has remained controversial. Only 6% of the animal studies are successfully translated into the human response. Breaking down failure rates by therapeutic area, oncology disorders account for 30% of all failures. The absence of human-relevant models with receptors, proteins, and drug interactions in the in situ microenvironment leaves a gap in the scientific discovery process of new therapies. In this context, the present work presents the development of a sophisticated in vitro skin model platform focus on boosting melanoma treatment. The results showed a physiological microenvironment of human skin with epidermal differentiation and development of stratified layers (basement membrane, stratum spinosum, stratum granulosum, and stratum corneum). Furthermore, it was observed the pathophysiological microenvironment of the melanoma with invasion or migration through the basement membrane into the dermis and no epidermal differentiation. Vemurafenib treatment, the gold standard which targets BRAF mutations, showed a decrease in proliferation and invasion of melanoma tumors, with an increase in epidermis keratinization. Melanoma incidence continues to increase year-on-year and is currently responsible for >80% of skin cancer deaths. It is the most common cutaneous form and is known to have the highest mutational load of all cancers. Nowadays, patients with advanced melanoma BRAFV600E mutation can benefit from monotherapies or targeted therapies. Although the initial response rate is effective, disease progression and tumor chemoresistance rapidly occur in the majority of patients. Therefore, the treatment of melanoma remains a challenge, and despite the advances, there is still an urgent need to identify new therapeutic strategies. 3D Model Melanoma is considered one important tool for studying the evolution of the pathology, as well as evaluating the effectiveness of new therapeutic approaches.
Optimizing CAR-T-cell therapy using 3D tumor models and real-time cell imaging
Chimeric antigen receptor (CAR) T-cell therapy accounts for one of the most promising therapeutic advances in cancer immunotherapy. In this form of adoptive cell transfer, T-cells of a patient are engineered to express so-called ‘CARs’, in which the antigen-recognition capacity of antibodies is combined with T-cell activating domains. So far, CAR-T-cell therapy obtained its most impressive results in hematological malignancies resulting in the approval of five CAR-T cell products by the FDA for hematologic indications. However, CAR-T-cell therapy has not mirrored its success in solid tumors. The poor efficacy of CAR-T-cell therapy in solid tumors has, in part, been attributed to the lack of understanding in how CAR-T-cells function in a solid tumor microenvironment. Classical validation methods rely on the use of specificity and functionality assays in 2D models against adherent target cells or target cells in suspension. Yet, by using these models, observations made in vitro may differ greatly to an in vivo situation where tumors are engrafted in 3D structures. We developed a more relevant and translational 3D tumor model using eGFP+ target cells. This allows us to couple 3D tumor cell killing by CAR-T-cells to live-cell imaging, providing an efficient quantification of target cell death. As proof- of-concept, we used a 3D model of eGFP+ glioblastoma cells and CAR-T-cells targeting a pan-cancer antigen. This 3D glioblastoma model allowed us to show that classical scFv-based CAR-T-cell therapy of glioblastoma cells can be improved by nanoCAR-T-cells. Furthermore, combining nanoCAR-T-cell therapy with a genetic approach of nanobody-based anti-PD-L1 immune checkpoint blockade further increased the cytotoxicity of the nanoCAR-T-cell therapy.
Biotransformation of two proteratogenic anti-epileptics in the zebrafish (Danio rerio) embryo
The zebrafish (Danio rerio) embryo has gained interest as an alternative model for developmental toxicity testing, which still mainly relies on in vivo mammalian models (e.g., rat, rabbit). However, cytochrome P450 (CYP)-mediated drug metabolism, which is critical for the bioactivation of several proteratogens, is still under debate for this model. Therefore, we investigated the potential capacity of zebrafish embryos/larvae to bioactivate two known mammalian proteratogens, carbamazepine (CBZ) and phenytoin (PHE) into their mammalian active metabolites, carbamazepine-10,11-epoxide (E-CBZ) and 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH), respectively. Zebrafish embryos were exposed to three concentrations (31.25, 85, and 250 μM) of CBZ and PHE from 51⁄4 to 120 hours post fertilization (hpf) at 28.5°C under a 14/10 hour light/dark cycle. For species comparison, also adult zebrafish, rat, rabbit and human liver microsomes (200 μg/ml) were exposed to 100 μM of CBZ or PHE for 240 minutes at 28.5°C. Potential formation of the mammalian metabolites was assessed in the embryo medium (48, 96, and 120 hpf); pooled (n=20) whole embryos/larvae extracts (24 and 120 hpf); and in the microsomal reaction mixtures (at 5 and 240 minutes) by targeted investigation using a UPLC–Triple Quadrupole MS system with lamotrigine (0.39 μM) as internal standard. Our study showed that zebrafish embryos metabolize CBZ to E-CBZ, but only at the end of organogenesis (from 96 hpf onwards), and no biotransformation of PHE to HPPH occurred. In contrast, our in vitro drug metabolism assay showed that adult zebrafish metabolize both compounds into their active mammalian metabolites. However, significant differences in metabolic rate were observed among the investigated species. These results highlight the importance of including the zebrafish in the in vitro drug metabolism testing battery for accurate species selection in toxicity studies.
Lung tumor spheroids for onco-immunological research
Lung cancer thrives in a complex multicellular tumor microenvironment that impacts tumor growth, metastasis, response, and resistance to therapy. While orthotopic murine lung cancer models can partly recapitulate this complexity, they do not resonate with high-throughput immunotherapeutic drug screening assays. To address the current need for relevant and easy-to-use lung tumor models, we established a protocol for fully histo-compatible murine and human lung tumor spheroids, generated by co-culturing lung fibroblasts with tumor cells in ultra-low adherence 96-well plates. Moreover, we describe their application potential to study tumor-stroma organization, T-cell motility, and infiltration as well as distinct macrophage subsets’ behavior using confocal microscopy. Finally, we report on a 3D target specific T-cell killing assay that allows spatio-temporal assessment using live cell imaging and flow cytometry. This lung tumor spheroid platform can serve as a blueprint for other solid cancer types to comply with the need for straightforward onco-immunology assays.
Respiratory toxicity using in vitro methods
The airways form a barrier for inhaled compounds, however, such compounds may cause local effects in the airways or may lead to lung diseases, such as fibrosis or COPD. Cell models of the respiratory tract, cultured at the air-liquid-interface (ALI) are a relevant model to assess the effects of inhaled compounds on the airways. Such models allow human relevant exposure, which is via the air, and assessment of effects on the epithelial cell layer. At RIVM we use air-liquid-interface cultured cell models and expose these to airborne compounds to assess the effects of agents such as nanomaterials, air pollutants or compounds from cigarette smoke. By using a mechanism-based approach to assess the effects of these compounds we invest in animal-free alternatives that better predict adverse effects in humans.
Setting up a PDXO platform of pancreatic cancer with spatial -omics characterization
Pancreatic ductal adenocarcinoma (PDAC) is known for its aggressive biology and lethality. Due to a low success rate of current diagnostic and therapeutic approaches in clinic, there is an urgent need for preclinical research studies to investigate the underlying biology of this malignancy. This knowledge is indispensable to facilitate the development and validation of potential new therapeutic compounds. Superior to conventional biomedical research models, the focus of this study is on the development and use of a well-established patient-derived 3D in vivo model, mimicking the tumor as it is present in a human body. The development and characterization of pancreatic cancer derived organoids. This model is extensively analysed using advanced histological methods omics technology to perform tumor subtyping. 15 established PDAC organoid lines and their corresponding parental tumors are validated using immunostainings and DNA hotspot sequencing. This study is the first to show in situ detection of important driver mutations of pancreatic cancer, like KrasG12D, both in parental tumor and organoids. Additionally, specific culture conditions are defined to develop subtype-specific organoids which are validated using multiplex RNA in situ hybridization and transcriptomics. We are proud to collaborate in a fruitful international project, aiming to set-up a pre-clinical screening platform for pancreatic cancer based on patient-derived organoids -and xenografts. Altogether, spatial-omics in depth analysis of both models will demonstrate (1) high resemblance to parental tissue and (2) subtype-specific signatures associated with type of model. Ultimately, the screening platform can be used by pharmaceutical companies to facilitate oncological drug testing in a subtype specific way. Publications Ilse Rooman's lab: https://pubmed.ncbi.nlm.nih.gov/34330784/ https://pubmed.ncbi.nlm.nih.gov/31161208/