µEST- Developmental toxicity screen
The µEST test system utilises the ability of mouse embryonic stem cells (ES cells) to differentiate in vitro into various tissues of all three germ layers. Supposing that exposure of ES cells to embryotoxic and teratogenic compounds during this process interferes with correct differentiation, the resulting amount of a given tissue, e.g. cardiac tissue, will be a marker for developmental toxicity. To distinguish a specific embryotoxic effect from a plain cytotoxic effect, results of the µEST are compared to results from a standard cytotoxicity assay (XTT test).
The mechanistic principle of the test was described by Spielmann et al. in 1997. At its 17th Meeting in October 2001, the ECVAM Scientific Advisory Committee (ESAC) endorsed this assay for embryotoxicity testing as scientifically validated and ready for consideration for regulatory acceptance and application. The µEST test system was stated equivalent to the EST by ECVAM, and gained acceptance as "suitable for REACH" by ECVAM in 2008.
Predictivity of µEST (70 compounds tested)
- Specificity 87%
- Sensitivity 88%
- Negative predictive value 81%
- Positive predictive value 91%
- Accuracy 87%




