The Role of the 3Rs for Understanding and Modeling the Human Placenta

Modeling the physiology of the human placenta is still a challenge, despite the great number of scientific advancements made in the field. Animal models cannot fully replicate the structure and function of the human placenta and pose ethical and financial hurdles. In addition, increasingly stricter animal welfare legislation worldwide is incentivizing the use of 3R (reduction, refinement, replacement) practices. What efforts have been made to develop alternative models for the placenta so far? How effective are they? How can we improve them to make them more predictive of human pathophysiology? To address these questions, this review aims at presenting and discussing the current models used to study phenomena at the placenta level: in vivo, ex vivo, in vitro and in silico. We describe the main achievements and opportunities for improvement of each type of model and critically assess their individual and collective impact on the pursuit of predictive studies of the placenta in line with the 3Rs and European legislation.

Involvement of the Endocrine-Disrupting Chemical Bisphenol A (BPA) in Human Placentation

Background: Endocrine-disrupting chemicals (EDCs) are environmental chemicals/toxicants that humans are exposed to, interfering with the action of multiple hormones. Bisphenol A (BPA) is classified as an EDC with xenoestrogenic activity with potentially adverse effects in reproduction. Currently, a significant knowledge gap remains regarding the complete spectrum of BPA-induced effects on the human placenta. As such, the present study examined the effects of physiologically relevant doses of BPA in vitro. Methods: qRT-PCR, Western blotting, immunofluorescence, ELISA, microarray analyses, and bioinformatics have been employed to study the effects of BPA using nonsyncytialised (non-ST) and syncytialised (ST) BeWo cells. Results: Treatment with 3 nM BPA led to an increase in cell number and altered the phosphorylation status of p38, an effect mediated primarily via the membrane-bound estrogen receptor (GPR30). Nonbiased microarray analysis identified 1195 and 477 genes that were differentially regulated in non-ST BeWo cells, whereas in ST BeWo cells, 309 and 158 genes had altered expression when treated with 3 and 10 nM, respectively. Enriched pathway analyses in non-ST BeWo identified a leptin and insulin overlap (3 nM), methylation pathways (10 nM), and differentiation of white and brown adipocytes (common). In the ST model, most significantly enriched were the nuclear factor erythroid 2-related factor 2 (NRF2) pathway (3 nM) and mir-124 predicted interactions with cell cycle and differentiation (10 nM). Conclusion: Collectively, our data offer a new insight regarding BPA effects at the placental level, and provide a potential link with metabolic changes that can have an impact on the developing fetus.