Daily exposure to per- and polyfluoroalkyl substances (PFAS) can disrupt placental function in the early stages of pregnancy. These are crucial findings from a recent study published in Environmental Research, underscoring the need to implement solutions and policies to curb their presence in the environment and in everyday use.
The Study
To demonstrate how everyday chemical exposure to PFAS can subtly alter the release of placental hormones, the invasion and the genetic pathways essential for the early stages of pregnancy, researchers designed a placenta-relevant PFAS mixture to evaluate its impact on trophoblast function, using a three-dimensional spheroid model of trophoblasts. Defining PFAS concentrations in the first trimester is important because organogenesis, cellular differentiation, and placental development occur during this life stage.
For example, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are two common PFAS that reduce proliferation, viability and cell migration in bidimensional trophoblast cell lines.
These same chemicals have also been linked to the upregulation of inflammatory pathways in previous studies. Therefore, researchers believe that more than merely asking whether and to what extent a single PFAS can impact fetal development, it is more important to define how a mixed PFAS accumulation could influence placental function and bidimensional trophoblasts. On this basis, they collected a total of 31 first-trimester placental samples from elective pregnancy terminations. All evaluated samples were between seven and eleven weeks of gestation to determine PFAS levels.
Although all were positive for PFAS, the quantified levels varied considerably: of 56 PFAS targets, 16 were detected and quantified above the limit of quantification (LOQ) in more than one sample, though all originated from a single geographic region in Germany, which may limit the generalizability of the measured PFAS concentrations. For instance, despite PFOS use having been markedly curtailed in industry since 2000, relatively high concentrations (0.13–0.46 ng/g) were detected in placental samples obtained from 2023 onward. Moreover, relatively high levels of perfluorononanoic acid (PFNA) emerged as the unexpectedly primary contributor to the PFAS mixture, with concentrations ranging from LOQ to 9.45 ng/g, followed by concentrations of PFOA and perfluorobutanoic acid (PFBA).
Design of the PFAS Mixture
The concentrations of PFAS measured in the placenta (ng/g) were converted into cellular exposure concentrations (nM). To generate experimental treatments, a placenta-based PFAS mixture reflecting the measured ratios was prepared and then diluted across a broad concentration range. Cells and spheroids were exposed to PFAS concentrations spanning 0.01 μM to 300 μM, while lower concentrations (0.01–1 μM) were chosen to reflect environmentally relevant exposure, with higher concentrations used to explore potential threshold or nonlinear effects.
PFNA, PFOS, perfluorobutanoic acid (PFBA), PFOA, perfluorohexanesulfonic acid (PFHxS) and perfluorodecanoic acid (PFDA) were used to assemble the mixture in the following placental ratio of 80:7:5:4:2:2 and to determine whether the PFAS mixture would influence the viability of trophoblastic cells. The JEG-3 and HTR-8/SVneo cell lines were treated with varying PFAS concentrations (0.01–300 μM), and cell viability was measured with an MTT assay, a fundamental colorimetric test in cellular biology used to assess viability, proliferation and cytotoxicity.
Cell viability was significantly reduced in both cell lines at 150–300 μM, demonstrating a clear concentration-dependent effect. Because cells grown in two dimensions respond differently to chemicals, the effects of the PFAS mixture were also evaluated on 3D trophoblast spheroids, yielding the following results: after 48 hours of PFAS exposure, the JEG-3 spheroids showed an increase in necrotic cell fluorescence only at 300 μM, while live-cell fluorescence remained unchanged. The HTR-8/SVneo spheroids did not show differences in live or necrotic cell fluorescence across the different concentrations.
The activity of caspases 3 and 7 increased only in the HTR-8/SVneo spheroids at 300 μM. These findings indicate that trophoblast spheroids exhibit distinct and more resilient viability responses to PFAS compared with 2D cultures. While trophoblast spheroids exposed to PFAS mixtures remained viable, their invasive function was altered: for example, the JEG-3 spheroids displayed a complete loss of invasion at the highest PFAS concentration and morphological signs of damage, compared with lower concentrations where invasion increased at later time points. By contrast, the PFAS mixtures inhibited invasion of the HTR-8/SVneo spheroids at low and mid concentrations, though high concentrations did not yield a statistically significant inhibition.
The Findings
These results suggest that PFAS mixtures differently influence the invasiveness of trophoblast spheroids depending on the cell type and concentration, and to assess transcriptional changes, mRNA levels of genes related to apoptosis, invasion, migration, and proliferation were measured. PFAS exposure downregulated several apoptosis-related genes in JEG-3 spheroids, while increased CASP3 and decreased LGALS3 in HTR-8/SVneo spheroids. Genes associated with proliferation, invasion and migration also showed cell-type-specific responses, including downregulation of EGFR, NOTCH3 and PGF in JEG-3 spheroids and a reduction of MIF but with an increase of IGF2 in HTR-8/SVneo spheroids.
These data would suggest that PFAS mixtures alter gene expression in trophoblast spheroids, aligning with disruption of pathways that support placental development and function. However, to fully understand the implications of exposure to PFAS mixtures on pregnancy and fetal development, further in vivo longitudinal research and mechanistic investigations will be required. Overall, the study’s findings emphasize the need for a more rigorous risk assessment of chemical mixtures that incorporates endpoints relevant to pregnancy.
Source
Xia Y, Fu Q, Voss H et al. Real-life per- and polyfluoroalkyl substances mixture impairs placental function: Insights from a trophoblast spheroid model. Environmental Research, 2025, 287, 123037. Doi: https://www.sciencedirect.com/science/article/pii/S001393512502290X
Abbonati a Karla Miller
