CE34 - Contaminants, écosystèmes et santé

Impact of co-exposure to nanoceria and benzo-(a)-pyrene on human placental barrier – PregNanoBaP

Impact of human placenta exposure to benzo-a-pyrene coated nanoceria

Pollutants are everywhere in the environment and many of these contaminants can reach placenta after exposure during the pregnancy. The overall aim of this project is to address the effects at cellular and molecular levels of pollutants like nanoceria and benzo-(a)-pyrene, and of their mixture, on human placental development and functions. The long-term aim is to characterize the consequences of pregnant women exposure to these pollutants on pregnancy outcome to reveal biomarkers of exposure.

Main issues and objectives

This project aims to set up the placenta toxicology bases in response to two highly relevant contaminants from environmental pollution when they are encountered together in mixture: BaP and nanoceria. These two pollutants are contaminants to which pregnant woman and the unborn child are daily exposed to, and for which there are few documentations available for estimating their toxicity directly by using human placental models. The overall aim of this project is to determine the biological consequences of an exposure to CeO2 NP stably coated by BaP by using ex vivo and in vitro placental models. <br />Our main objectives are: <br />1) to quantify the background levels of CeO2 in human placenta trough pregnancy <br />2) to evaluate the placenta uptake of these pollutants (e.g. by using ex vivo placental perfusion); <br />3) to determine the toxicity of these pollutants and explore the induced-detoxification pathway by using primary cultures of human trophoblasts; <br />4) to determine how these pollutants in combination alter the integrity and the hormonal function of the human placental barrier such as the formation of a functional syncytiotrophoblast (in vitro trophoblasts cultures); <br />5) to characterize the impact on mitochondria homeostasis, a major organelle involved in trophoblasts differentiation and placental fonctioning. <br />These results could provide some insights of the effects of the interaction of nanoparticles with other pollutants, such as the hydrophobic BaP. As major expected results, we hypothesize that coating nanoceria with lipophilic BaP could modify NP’s surface properties and increase their cellular uptake, modify BaP biopersistence and toxicity, impair the differentioation of trophoblasts, mitochondria homeostasis and hormonal function of the placenta. These pollutants together may synergistically affect de proper functioning of the placenta in comparison to their individual exposures.

Placenta models:
Human placentas will be collected at Cochin-Port Royal maternity from first trimester (voluntarily and legally termination of pregnancies) and term pregnancies (cesarians). Placentas will be collected from non-smoking and healthy women after obtaining patients written consents (CPP: 2015-May-13909).
The ex vivo cotyledon perfusion model: cotyledons from term placentas will be directly used to estimate the passage of these pollutants from maternal to foetal compartment.
Primary trophoblasts and chorionic villi explants: will be isolated after placental dissection and cultured as tissue-explants to reproduce contact between placental villi and contaminants in the maternal blood. Human primary trophoblasts will be purified from placental villi and cultured in a classical culture model and are able to differentiate after 72h of culture, or in a bi-chamber system to mimic the placental barrier.
Reference standardized CeO2 NP (NM212, JRC, IHCP) will be provided from our current collaborators (Dr Boland and Dr Devineau, Univ. of Paris). The CeO2 NP will be used either alone, in a mixture with BaP (parallel addition), or as BaP-coated NP (at a ratio that mimics the airborne levels). In this project, CeO2 NP will be used at concentration range from 0.005 - 10 µg/cm2.
The BaP (Sigma) will be used at concentrations between 0.01 - 4 µM. For the combined exposures, the level of BaP will not exceed 1µM.
The stably BaP-coating of CeO2 NP are already done and confirmed and by our collaborator Dr Boland (Univ. of Paris) to a ratio that mimics the airborne levels of BaP found on the atmospheric ultrafine PM at Paris (1µM BaP per 40 µg/cm2 CeO2).
Exposure times: trophoblasts or explants will be incubated from 4h to 72h and perfusion of placenta for 6h.


to be expected

to be expected

The exposure of women to environmental contaminants during the pregnancy can lead to harmful effects on the pregnancy outcome. Pollutants are likely to act not only directly on the fetus but also indirectly with an impact on placenta, whose multiple functions plays a crucial role in foetal development and in the success of pregnancy. A growing body of epidemiological evidence have established a causal relationship between the mother’s exposure to air pollution and the increased risk of adverse pregnancy outcomes (e.g. intra-uterine growth retardation, preterm birth and fetal mortality). Emerging pollutants such as nanoparticles (NP) of cerium dioxide (CeO2) are recently being added to diesel fuels and cigarettes, and thus are found in ambient pollution with a major risk of exposure for pregnant women. Today, the Organization of Economic Cooperation and Development (OECD) has included CeO2 NP (or nanoceria) in the priority list for the evaluation of their toxicity. Polycyclic aromatic hydrocarbons (PAH) are the main group of carcinogenic and genotoxic substances found in air pollution. The benzo-a-pyrene (BaP), the most studied as PAH prototype, is generated during incomplete combustion of organic sources and is also an endocrine disruptor. When these pollutants are found at high levels in the maternal bloodstream, they are associated to pregnancy complications leading to low birthweight (for BaP) and fetal neural defects (for the cerium). NP can carry other molecules, such as lipophilic BaP issued from common combustion sources, forming a corona that may facilitate the entry of NP in the body. The consequences of placental exposure to such environmental pollutants, especially in cocktail, which is more representative to the reality of the environmental exposure, are still poorly documented. The proposal presented here aims to establish the molecular basis of placental toxicology by evaluating the effects of NP of CeO2 in combination with BaP on the integrity and functions of human placental barrier. We will investigate here the effects of these pollutants on the placenta function as well as the molecular and cellular mechanisms involved, particularly in terms of detoxification process (Aryl hydrocarbon Receptor pathway, AhR), the induction of oxidative stress and dysfunction of mitochondria, a key organelle for both trophoblast differentiation and steroidogenesis. The group has internationally recognized expertise in human placenta physiopathology, especially as regard to use of human placental models’ representative of the different pregnancy periods, on mitochondrial functions (expertise of the coordinator) and of AhR activity during placental ontogeny (published manuscript). Moreover, by bringing together methodological approaches from several pluridisciplinary fields at junction of human placental physiology, toxicology, biochemistry and in parallel with physico-chemistry of NP, this original study will open the field of investigations of the effects of these pollutants (in combination) on the foeto-placental unit. The human placenta, indispensable for human development and target of circulating xenobiotics, could become a reference for the evaluation of airborne pollutant’s toxicity during the pregnancy. Moreover, this project could become an important step up to providing a scientifically guided recommendations for the regulation of the environment of the pregnant women. The feasibility of this project is assured by the PremUp network that will provide access to biological placenta samples at different pregnancy stages, by the technological platforms available within the University of Paris and Gif-CNRS Campus and by the FHU prematurity label of the group. This project is in coherence with several program challenges of ANR 2020 “Eco Health”.

Project coordinator


The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.



Help of the ANR 326,211 euros
Beginning and duration of the scientific project: February 2021 - 48 Months

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