Safety sciences and the identification of chemical hazards have been seen as one of the most immediate practical applications of human pluripotent stem cell technology. Protocols for the generation of many desirable human cell types have been developed, but optimization of neuronal models for toxicological use has been astonishingly slow, and the wide, clinically important field of peripheral neurotoxicity is still largely unexplored. A two-step protocol to generate large lots of identical peripheral human neuronal precursors was characterized and adapted to the measurement of peripheral neurotoxicity. High content imaging allowed an unbiased assessment of cell morphology and viability. The computational quantification of neurite growth as a functional parameter highly sensitive to disturbances by toxicants was used as an endpoint reflecting specific neurotoxicity. The differentiation of cells toward dorsal root ganglia neurons was tracked in relation to a large background data set based on gene expression microarrays. On this basis, a peripheral neurotoxicity (PeriTox) test was developed as a first toxicological assay that harnesses the potential of human pluripotent stem cells to generate cell types/tissues that are not otherwise available for the prediction of human systemic organ toxicity. Testing of more than 30 chemicals showed that human neurotoxicants and neurite growth enhancers were correctly identified. Various classes of chemotherapeutic agents causing human peripheral neuropathies were identified, and they were missed when tested on human central neurons. The PeriTox test we established shows the potential of human stem cells for clinically relevant safety testing of drugs in use and of new emerging candidates.
Significance: The generation of human cells from pluripotent stem cells has aroused great hopes in biomedical research and safety sciences. Neurotoxicity testing is a particularly important application for stem cell-derived somatic cells, as human neurons are hardly available otherwise. Also, peripheral neurotoxicity has become of major concern in drug development for chemotherapy. The first neurotoxicity test method was established based on human pluripotent stem cell-derived peripheral neurons. The strategies exemplified in the present study of reproducible cell generation, cell function-based test system establishment, and assay validation provide the basis for a drug safety assessment on cells not available otherwise.
Keywords: Human pluripotent stem cells; In vitro drug and toxicity testing; Neural differentiation; Peripheral neuropathies.