Micro- and nanoplastics can translocate across the placental barrier according to a systematic review published in early 2023, with nine out of eleven studies reporting such translocation (FPF reported). In an article published on June 7, 2023, in the journal Environment International, S. Chortarea from the Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, Switzerland, and co-authors were interested in the impact of nanoplastics on gene expression.
For their analysis, the researchers used an ex vivo human placenta perfusion model “that closely resembles the in vivo situation” and added polystyrene (PS) nanoplastics in concentrations of 25 µg/mL. They collected placental tissue samples before and after 6 h of perfusion, isolated the RNA, and applied them to whole genome microarray analysis to assess gene expression.
Chortarea and co-authors reported that PS nanoplastics changed the expression of inflammation- and iron homeostasis-related genes. Comparing these effects with those of engineered copper oxide nanoparticles showed that the two particle types induced different cellular responses in the placental tissue with the copper oxide nanoparticles rather affecting expression of genes related to angiogenesis, stress responses, and protein misfolding.
The authors concluded that the placenta as a signaling interface is susceptible to nanoparticle-induced changes which can already occur after single short-term exposure. “Therefore, future studies are warranted to understand if these changes persist and adversely affect embryo-fetal development.”
Five Horizon 2020 research projects are now working to better understand micro- and nanoplastic impacts on human health (FPF reported). One of the projects (AURORA) is specifically focusing on the assessment of microplastics’ effects on the placenta and the developing fetus, and it also uses placenta perfusion models.
Xuan Song and co-authors from the Chengdu BOE Hospital, Chengdu, China, evaluated the experimental evidence on micro- and nanoplastic effects on the reproductive system of mammals including the placenta and embryo development. In a review article published on June 5, 2023, in the journal Chemosphere, the authors described that they searched PubMed, Web of Science, CNKI, and Google Scholar and included literature related to mammals and focusing on the reproductive system and reproductive toxicity.
The review reported that humans can be exposed to small plastic particles via dietary intake, inhalation, and skin contact, as well as via plastics used in medical applications. Further, studies have shown that upon uptake, micro- and nanoplastics can enter the tissues and organs of the reproductive system. For instance, they were detected in human semen and testis (FPF reported) as well as the placenta (FPF reported).
The scientists further summarized evidence that once in the reproductive system the particles can induce cytotoxicity, oxidative stress, and inflammation all of which disturbs the immune and endocrine systems. Generally, the majority of studies have focused on the male reproductive system, e.g., demonstrating reproductive toxicity of microplastics in male mice (FPF reported and here), while neglecting research on the impacts on females. Plastic particles’ impact can also affect the offspring (FPF reported and here), and current evidence suggests that these effects “may be related to intergenerational inheritance.” However, Song and co-authors pointed out that further research on this is needed since it relates to the specific mechanism leading to reproductive toxicity. Moreover, they recommend that future studies should be designed in a multi-disciplinary way and extend to population studies.
References
Chortarea, S. et al. (2023). “Transcriptomic profiling reveals differential cellular response to copper oxide nanoparticles and polystyrene nanoplastics in perfused human placenta.” Environment International. DOI: 10.1016/j.envint.2023.108015
Song, X. et al. (2023). “Effects of micro(nano)plastics on the reproductive system: A review.” Chemosphere. DOI: 10.1016/j.chemosphere.2023.139138
