In vitro toxicity testing using human pluripotent stem cell derivatives

Abstract

Toxicity testing of chemicals, drug candidates, and food additives is in need of a change. The present methods, mainly consisting of animal models with their associated ethical concerns, are expensive, time-consuming, and importantly they are often poor predictors of the human in vivo toxicity. With the rapid biotechnology development, a paradigm shift for toxicity testing is emerging, focusing on bioinformatics, computational toxicity, systems biology, and cell-based in vitro models. The aim of this thesis was to investigate the utility of using cells, i.e. hepatocytes and cardiomyocytes, derived from human pluripotent stem cells (hPSC) as in vitro models for toxicity testing. The first part explored the feasibility of using hPSC-derived hepatocytes to study toxic drug exposure, and in addition investigated the relevancy of the cellular response. The second and major part of this thesis focused on hPSC-derived cardiomyocytes and the in-depth study of doxorubicin-induced toxicity. The studies revealed that the differentiation processes and culturing of hPSC-derivatives are stable and reproducible to form the basis for in vitro models for toxicity testing, even for longer studies over two weeks. The hepatocytes and the cardiomyocytes showed sensitivity towards the toxic compounds and both cell models dis-played a relevant cellular response to the toxic exposure. For example, the hepatocytes showed evidence of steatosis and phospholipidosis when incubated with hepatotoxic compounds over time. Besides an evident effect of doxorubicin on the cardiomyocyte function, the cells also proved to be useful for more in-depth mechanistic evaluations, as these studies gave insight, on multiple biological levels, in plausible mechanisms and identified potential biomarkers for doxorubicin-induced cardiotoxicity. In conclusion, this thesis presents findings that supports the vision and strategy of using in vitro models based on hPSC-derivatives together with advanced omics technologies for toxicity testing and risk assessment of drugs, food additives, and chemicals.