Testing potential developmental toxicants with a cytotoxicity assay based on human embryonic stem cells

Area of Science:

• Developmental toxicology
• Stem cell biology
• In vitro toxicology

Background:

• Embryonic stem cell differentiation models early development, offering potential for embryotoxicant detection.
• Existing murine embryonic stem cell assays lack human relevance; human-specific tests are crucial to avoid inter-species classification errors.
• Human-relevant toxicity testing is needed to accurately assess developmental risks.

Purpose of the Study:

• To develop and validate a novel in vitro assay using human cell types for developmental toxicity testing.
• To assess the embryotoxic potential of known developmental toxicants using human embryonic stem (hES) cells.
• To evaluate the utility of hES cells in predicting chemical-induced developmental toxicity.

Main Methods:

• Developed a multi-cell type assay using human foreskin fibroblasts, hES cell-derived progenitors, and pluripotent hES cells.
• Tested known embryotoxicants including all-trans retinoic acid (ATRA), 13-cis retinoic acid (13CRA), valproic acid (VPA), and 5-fluorouracil (5-FU).
• Assessed cell viability using intracellular ATP content and resazurin reduction assays; investigated basic fibroblast growth factor (bFGF) protective effects.

Main Results:

• The novel assay reliably detected the embryotoxic potential of 5-FU, ATRA, 13-CRA, and VPA.
• Differences in sensitivity among the three human cell types contributed to the reliable detection of toxicants.
• The assay demonstrated effectiveness in identifying substances with inter-species differences in toxicity, such as 13-CRA.

Conclusions:

• The developed assay system effectively identifies embryotoxicants using human cell types.
• Human embryonic stem cells are valuable tools for in vitro developmental toxicity testing.
• This approach offers a human-relevant alternative for assessing chemical safety during development.