Platform and Assay Development
Human embryonic stem cells for use in drug discovery and toxicity testing
Early developmental toxicity assays for screening of various compounds for the potential risks for abnormal development in the growing embryo are traditionally based on animal cells. As species differences might affect the accuracy of the assessments, there is an increasing need for alternative cell sources. In vitro differentiation of hES cells bear a resemblance to the early stages of human embryonic development and offers unique possibilities for alternative toxicity testing.
Developmental toxicity evaluations, as used in safety assessment assays, are suffering from a lack of normal, reproducible and easily available human cell systems. Pluripotent hES cells and their derivatives will improve the quality of targets, hits, and leads, thus reducing late-stage attrition. The promise of hES cells for in vitro toxicology is the indefinite access to starting material of identical origin in combination with highly human relevant assays for e.g. developmental toxicity testing.
Cellartis has several years of experience of actively working with developmental- and cytotoxicity applications (Adler et al, 2008; Jensen et al, 2009). To meet the future needs for large amounts of hES cells and derivatives, we have developed quality controlled techniques for the expansion of undifferentiated human embryonic stem cells, and protocols for spontaneous differentiation in multi-well plate format for a medium/high throughput assay. Today, we can present cytotoxicity models based on human undifferentiated stem cells, partially differentiated cells or terminally differentiated cells. In addition, we have cellular models for developmental toxicity tests. Our toxicity models are reliable and reproducible, and allow the simultaneous screening of a large number of compounds with good reproducibility and high human relevance. This allows the recapitulation of early human development as a unique tool for the detection and in-depth study of substances which interfere with the complex processes involved in human embryonic development.
The flexibility of our toxicity assays gives the users a unique opportunity to design a model suitable for their specific needs.
The combination of genetic engineering with the use of hES cells or their derivatives to generate genetically modified hES cell lines would greatly further widen the current application range. For example, by introducing reporter genes such as green fluorescent protein (GFP) directly coupled to promoters of special interest, relevant effects can be studied in specific cell types. Cellartis has an ongoing project in collaboration with Life Technologies with the mutual aim to create e.g. reporter lines that can be employed in toxicity assays (Thyagarajan et al, 2008).
Adler S, Lindqvist J, Uddenberg K, Hyllner J & Strehl R (2008) "Testing potential developmental toxicants with a cytotoxicity assay based on human embryonic stem cells." Altern Lab Anim. 2008 May;36(2):129-40.
Thyagarajan B, Shin S, Liy Y, Lakshmiapathy U, Xue H, Ellerström C, Strehl R, Hyllner J, Rao M, Chesnut J (2008) “Creation of engineered human embryonic stem cell lines using phi C31 integrase” Stem Cells 26: 119-26.
Jensen J, Hyllner J, & Bjorquist P. (2009) "Human Embryonic Stem Cell Technologies and Drug Discovery" J. Cell. Physiol. 219: 513–519