Effects of Organophosphate Flame Retardant EHDPP on Human Trophectoderm Differentiation Using a Human Extended Pluripotent Stem Cell Model

Abstract Early placental development represents a critical window for environmental disruption. The placenta originates from the trophectoderm, the earliest extraembryonic lineage, yet environmental chemicals that disrupt trophectoderm differentiation remain poorly characterized. In this study, we used human extended pluripotent stem cells (hEPS) to evaluate the effects of 2-ethylhexyl diphenyl phosphate (EHDPP), a widely detected organophosphate flame retardant associated, on trophectoderm differentiation. EHDPP exposure reduced the expression of the trophectoderm markers GATA2 and NR2F2 at 1,000 nM (nominal concentration, measured concentration at 124.18 ± 13.75 ng/mL), suggesting the disruption of trophectoderm differentiation potential. Mechanistically, EHDPP exposure disrupted cellular metabolic homeostasis, characterized by impaired mitochondrial respiration at 1,000 nM (nominal concentration), markers of mitochondrial integrity including HSP60 and cytochrome C at 1 nM, and depletion of key tricarboxylic acid (TCA) cycle metabolites, such as α-ketoglutarate at 100 nM (nominal concentration, measured concentration at 10.46 ± 0.42 ng/mL). These findings provide human-relevant evidence that EHDPP disrupts trophectoderm differentiation and highlight metabolic dysfunction as a key feature of chemical-induced developmental hazards.