[Developing and standardizing experimental protocols using human iPS-derived cells to predict adverse drug reactions in pre-clinical safety studies].

In this study, we have standardized experimental protocols to evaluate the possibility of using cells differentiated from human induced pluripotent stem cells (hiPSCs) in the pre-clinical studies for the drug approval processes. Cells differentiated from hiPSC, especially cardiomyocytes, neurons and hepatocytes, are expected to be used as new pharmacological and toxicological assay tools. Current preclinical test methods have limitations for predicting clinical adverse drug reactions. This is because of the so-called 'problem of species difference'. Drug-induced arrhythmia, cognitive impairment and hepatotoxicity which can't be predicted in pre-clinical studies are major causes of the high rate attrition of new-drug candidates in clinical studies and of withdrawal of products from the market. The development of new pre-clinical test methods using cells differentiated from hiPSCs would resolve these problems, in addition to solving the issue of "the replacement, refinement and reduction (3Rs)" of animal experiments. From 2010 to 2011, we surveyed companies belonging to the Japan Pharmaceutical Manufacturers Association (JPMA) and academic researchers about the usage of differentiated cells in their laboratories. We found that studies were performed using differentiated cells from different cell lines of hiPSC with laboratory-specific differentiation methods. The cells were cultured in various conditions and their activities were measured using different methods. This resulted in a variety of pharmacological responses of the cells. It is therefore impossible to compare reproducibility and ensure reliability of experiments using these cells. To utilize the cells in the drug approval processes, we need robust, standardized test methods to accurately reproduce these methods in all laboratories. We will then be able to compare and analyze the obtained results. Based on the survey, the Ministry of Health, Labor and Welfare funded our study. In our study, we standardize pharmacological methods among several laboratories, including our laboratory, to develop robust tests, using the same lot of cells, the same culture conditions, reference compounds, experimental protocols, and analysis methodology. In conclusion, to standardize robust test methods, we need a consistent supply of high-quality differentiated cells. Further, indexes to quantify the quality of the differentiated cells will be needed for their effective usage in the pre-clinical safety studies.