Pluripotent Stem Cells in Developmental Toxicity Testing: A Review of Methodological Advances

Abstract

Millions of children are born each year with a birth defect. Many of these defects are caused by environmental factors, although the underlying etiology is often unknown. In vivo mammalian models are frequently used to determine if a chemical poses a risk to the developing fetus. However, there are over 80 000 chemicals registered for use in the United States, many of which have undergone little safety testing, necessitating the need for higher-throughput methods to assess developmental toxicity. Pluripotent stem cells (PSCs) are an ideal in vitro model to investigate developmental toxicity as they possess the capacity to differentiate into nearly any cell type in the human body. Indeed, a burst of research has occurred in the field of stem cell toxicology over the past decade, which has resulted in numerous methodological advances that utilize both mouse and human PSCs, as well as cutting-edge technology in the fields of metabolomics, transcriptomics, transgenics, and high-throughput imaging. Here, we review the wide array of approaches used to detect developmental toxicants, suggest areas for further research, and highlight critical aspects of stem cell biology that should be considered when utilizing PSCs in developmental toxicity testing.

Figure 1.

The mESCs test. A, Viability of pluripotent murine D3 ESCs and differentiated 3T3 fibroblasts is compared across an 8-point dose-response following 10 days of toxicant exposure. B, EBs are generated via the hanging drop method, and allowed to differentiate into contracting cardiomyocytes while being exposed for 10 days across an 8-point dose-response. C, EB formation via the hanging drop method. Compound concentrations that reduce cell viability (IC₅₀) and cardiomyocyte differentiation (ID₅₀) by 50% are calculated and input into the EST prediction model to determine the embryotoxic potential of the test compound. D, Hypothetical example of concentration-response curves for an embryotoxic compound that inhibits cardiomyocyte differentiation at non-cytotoxic concentrations. E, Hypothetical example of concentration response curves for a nonembryotoxic compound that only inhibits cardiomyocyte differentiation at cytotoxic concentrations.