Bile Acid Stress Disrupts Homeostasis and Placental Functional Programs in Human First-Trimester Trophoblast Organoids

Intrahepatic cholestasis of pregnancy (ICP) is characterized by elevated maternal bile acids (BAs), yet their effects on human trophoblast organization and transcriptional responses remain incompletely understood. Here, we used human first-trimester trophoblast organoids (TOs) to characterize cellular and transcriptional responses to a defined six-component BA mixture (50–150 μM). BA exposure disrupted organoid architecture and intercellular organization, with attenuated proliferation-associated features and more prominent SDC1 staining. These changes were accompanied by increased DNA fragmentation and cleaved caspase-3 staining and by reduced ATP-dependent viability, supporting an apoptotic component of BA-associated trophoblast injury. Bulk RNA sequencing after exposure to 150 μM BA for 96 h identified 413 differentially expressed genes, of which 364 were downregulated and 49 were upregulated. Downregulated transcripts were primarily associated with placental endocrine and secretory processes, epithelial organization, cell adhesion, and transport, whereas a smaller subset of lipid-handling genes was upregulated. RT-qPCR confirmed concordant upregulation of PLIN2 and ABCG1 in two independent donor-derived TO lines. Collectively, these findings show that BA mixture exposure is associated with structural injury and altered transcriptional profiles in human TOs, thereby providing insight into trophoblast responses to BA stress.