Recent evidence suggests that micro- and nanoplastics (MNPs) reach the placenta via maternal blood. Cytotrophoblasts and syncytiotrophoblasts are the first placental cells in direct contact with maternal blood, and the key mediators of placental exchange, endocrine, and immune function. Nevertheless, the transport and toxicity of MNPs in these important cell types are still largely unexplored.
In a study published on September 21, 2022, in the peer-reviewed scientific journal Environmental Health Perspectives, Hanna Dusza from Utrecht University and colleagues investigated the uptake, transport, and toxicity of diverse MNPs in an in vitro cell model of human cytotrophoblasts and syncytiotrophoblasts using nondifferentiated and differentiated BeWo b30 choriocarcinoma cells, respectively. The researchers investigated pristine (freshly manufactured) and experimentally weathered polystyrene (PS, 0.05-10 μm) and high-density polyethylene (HDPE; 0-80 μm) MNPs. Experimentally weathered particles were of specific interest as they better mimic real-life environmental exposures.
The team found that all pristine and weathered particles up to 10 μm in size, were taken up by both placental cell types, and observed a size-dependent, limited translocation through the cellular barrier, which was not affected by coating the particles with human plasma. None of the doses investigated (concentration range from 0.1 to 100 µg/ml) affected cell viability after 24 hours of exposure, and only the smallest 50 nm particles at the highest concentration, affected cell plasma membrane integrity in cytotrophoblast cells. Furthermore, the authors investigated the effects of MNPs on the expression of genes involved in steroidogenesis and found modest down-regulation of hsd17b1 exposed to pristine but not weathered MNPs. The researchers analyzed the difference in chemical composition between the pristine and weathered particles using nontargeted mass spectrometry techniques and found that the pristine particles were much more chemically complex than the weathered ones, and included compounds such as catalysts, colorants, antioxidants, and plasticizers.
According to the authors, these results demonstrate that diverse MNPs and compounds associated with them are internalized and translocated in placental cells where they can induce subtle biological effects. They note that environmental weathering processes are important and should be investigated as they might change the chemical composition of particles possibly affecting their toxic potential.
The study was carried out with support from the Netherlands Organization for Health Research and Development (ZonMw), and three of the study’s authors, including Dusza, are also partners within AURORA.
Dusza, H. et al. (September 21, 2022). “Uptake, Transport, and Toxicity of Pristine and Weathered Micro- and Nanoplastics in Human Placenta Cells.” Environmental Health Perspectives