Roman Kolar

Reconsidering pluripotency tests: Do we still need teratoma assays?

The induction of teratoma in mice by the transplantation of stem cells into extra-uterine sites has been used as a read-out for cellular pluripotency since the initial description of this phenomenon in 1954. Since then, the teratoma assay has remained the assay of choice to demonstrate pluripotency, gaining prominence during the recent hype surrounding human stem cell research. However, the scientific significance of the teratoma assay has been debated due to the fact that transplanted cells are exposed to a non-physiological environment. Since many mice are used for a result that is heavily questioned, it is time to reconsider the teratoma assay from an ethical point of view. Candidate alternatives to the teratoma assay comprise the directed differentiation of pluripotent stem cells into organotypic cells, differentiation of cells in embryoid bodies, the analysis of pluripotency-associated biomarkers with high correlation to the teratoma forming potential of stem cells, predictive epigenetic footprints, or a combination of these technologies. Each of these assays is capable of addressing one or more aspects of pluripotency, however it is essential that these assays are validated to provide an accepted robust, reproducible alternative. In particular, the rapidly expanding number of human induced pluripotent stem cell lines, requires the development of simple, affordable standardized in vitro and in silico assays to reduce the number of animal experiments performed.

Inconsistencies in data requirements of EU legislation involving tests on animals.

European Union (EU) legislation on the protection of animals used for scientific purposes requires that alternative methods must be used instead of animal tests wherever they are available. Unfortunately, this provision is not implemented to its full extent when it comes to risk assessment of chemicals and new products prior to their authorization and placing on the market in the EU. In this study, we screened data requirements of relevant EU law regarding chemicals (REACH), biocides, pesticides, and food safety (Novel Food) and found that data requirements as part of the risk assessment do not always reflect state-of-the-art science and technology. Most of the data requirements we investigated still include testing on animals for many toxicological endpoints, even though more than 40 alternative testing methods accepted at the level of the EU or the OECD are available. This may be due to a multitude of reasons, including a shortage of both manpower to implement existing knowledge and expertise in the field of alternative methods, as well as unclear and misleading statements on the applicability and state of validation of alternative methods. In conclusion, we strongly suggest a homogeneous EU-wide approach for all areas involving risk assessment of substances with the goal of better implementing the 3Rs and complying with Directive 2010/63/EU. This also would streamline data requirements, save costs on various levels, and enhance product safety for consumers.