MON-140 Molecular Mechanisms of DEHP-Induced Fetal Growth Restriction (FGR) Through P53 Signaling Pathway Mediated Disruption of Trophoblast Cell Differentiation in the Placenta

Abstract Disclosure: L. Ouyang: None. Y. Yu: None. C. Wang: None. F. Yang: None. BackgroundEndocrine-disrupting chemicals (EDCs) are unavoidable environmental exposures during pregnancy and may affect the development of various fetal systems, including fetal growth restriction (FGR). However, the underlying mechanisms between EDCs and FGR remain unclear. One of the most common EDCs is DEHP [di (2-ethylhexyl) phthalate], which can enter the human body through multiple ways. The aim of this study is to explore the relationship between DEHP and FGR, and to explore underlying mechanisms. Method: DEHP was administered to C57BL/6 mice (6-8 weeks old), and samples were collected on E15.5 to observe fetal weight and crown-rump length. HE staining was used to assess the area of placental layers, CD34 immunohistochemistry was used to evaluate the changes of vascular indexes after DEHP intervention and immunofluorescence staining was performed to examine the remodeling of the uterine spiral arteries. Placental tissues underwent bulk RNA-sequencing, single-cell sequencing, and spatial transcriptome sequencing. MEHP (Main metabolic product of DEHP in the body) was used to intervene in the mouse trophoblast stem cells (mTSCs) differentiation process, and an in vitro differentiation model was established and also applied bulk RNA-sequencing. Flow cytometry was used to assess the differentiation process of mTSCs, while qPCR and Western blot were employed to examine changes in P53 and related markers.ResultsPregnant mice exposed to DEHP exhibited decreased fetal weight and reduced crown-rump length. Spatial transcriptomics sequencing and HE staining results revealed a significant reduction in the area of the placental spongiotrophoblast layer. CD34 immunohistochemical staining indicated a notable decrease in the vascular area and length. Immunofluorescence staining showed increased expression of α-SMA and decreased expression of CK7. Single-cell sequencing suggested a significant reduction in the Spiral atery-associated trophoblast giant cells (SpA-TGCs) cell subpopulation after DEHP intervention. MEHP was used to intervene in the in vitro differentiation process of mTSCs. Flow cytometry results indicated a significant reduction in polyploidy cells in the MEHP-treated group compared to the control group (P<0.05), qPCR results showed a marked decrease in the SpA-TGC related markers Prl3b1 and Prl8a9 (P<0.05), suggesting differentiation blockade. Both single-cell sequencing and bulk RNA-sequencing results focused on the cell cycle and P53 signaling pathways, qPCR and Western blot results indicated a significant upregulation of P53 expression following MEHP intervention. ConclusionsDEHP exposure induces upregulation of P53 expression, which disrupts the cell cycle and impairs the differentiation of SpA-TGCs. This alteration contributes to abnormal remodeling of the uterine spiral arteries, ultimately leading to the development of FGR Presentation: Monday, July 14, 2025