Tsankov, A.M. et al. Nat. Biotechnol. 33, 1182–1192 (2015).

It is not easy to determine exactly how pluripotent stem cells, which can be derived from nearly any cell source or genetic background under a variety of conditions, compare in a given population with respect to their differentiation potential. Tsankov et al. provide an update of their ScoreCard assay for characterizing the potential of human pluripotent stem cells on the basis of gene expression signatures. The commercially available assay now relies on quantitative PCR rather than NanoString technology to measure gene expression, uses a revised set of 96 genes to better discriminate functional potential, and beefs up the statistical analysis to improve the power and accuracy of predictions of differentiation efficiency. The assay is a rapid and standardized way of assessing stem cells that may remove the need for the more involved and less quantitative teratoma-formation assay in mice.