How Biodegradable Nanoplastics Cross the Placenta and Affect Fetal Growth in Mice
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Biodegradable plastics, often hailed as eco-friendly alternatives to traditional plastics, are becoming increasingly common in packaging, medical devices, and textiles. But could these seemingly safer plastics pose hidden risks to unborn babies? Recent research in mice suggests that tiny nanoparticles derived from polylactic acid (PLA) plastics can cross the placenta and interfere with fetal development, raising important questions about the safety of biodegradable plastics during pregnancy.
TL;DR
- Oligomeric lactic acid (OLA) nanoplastics, breakdown products of biodegradable PLA plastics, can cross the placental barrier and accumulate in fetal organs in mice.
- Exposure to environmentally relevant doses of OLA during pregnancy disrupts placental blood vessel development by blocking a key molecular pathway involving the transcription factor GATA2, leading to restricted fetal growth.
Microplastics and nanoplastics have become pervasive environmental contaminants, found in soil, water, air, and even inside living organisms. While conventional plastics persist in the environment for decades, biodegradable plastics like PLA are designed to break down more quickly. However, this breakdown process generates tiny oligomeric lactic acid nanoplastics (OLA), whose biological effects are not well understood. Given the critical role of the placenta in protecting and nourishing the developing fetus, understanding whether OLA can cross this barrier and affect fetal development is essential. This study addresses that gap using a mouse model to explore how gestational exposure to OLA impacts placental function and fetal growth.
Researchers administered environmentally relevant doses of OLA to pregnant mice by oral gavage throughout gestation. To track OLA distribution, they used fluorescently labeled OLA and measured accumulation in maternal and fetal tissues using live imaging and mass spectrometry. Placental and fetal growth parameters were recorded, and detailed analyses of placental blood vessel development were conducted using histology and gene expression profiling. RNA sequencing and single-cell RNA sequencing of placental tissue helped identify molecular pathways disrupted by OLA exposure. Structural modeling was used to explore how OLA might interfere with the transcription factor GATA2, a key regulator of placental vascular development.
The study found that OLA nanoplastics readily cross the placental barrier and accumulate in various fetal organs, including the brain, liver, and kidneys. Pregnant mice exposed to OLA gave birth to pups with significantly reduced body size and placental weight, indicating intrauterine growth restriction. Examination of placental tissue revealed disrupted blood vessel formation, with reduced vascular areas and abnormal vessel structure. Molecular analyses showed that OLA exposure blocked the vascular endothelial growth factor (VEGF) signaling pathway by preventing the transcription factor GATA2 from entering the nucleus, impairing its ability to regulate genes essential for vascular development. These disruptions collectively contributed to impaired placental function and fetal growth restriction.
This research provides the first mechanistic evidence that biodegradable plastic-derived nanoplastics can cross the placenta and adversely affect fetal development by targeting specific molecular pathways. Given the widespread use of PLA plastics and the increasing human exposure to their breakdown products, these findings raise important considerations about the potential developmental risks associated with biodegradable plastics. While this study was conducted in mice and direct implications for human pregnancy require further investigation, it highlights the need for careful evaluation of emerging environmental contaminants and their impact on reproductive health.
Although the mouse model provides valuable insights, differences between species mean that the effects observed may not directly translate to humans. The doses used, while environmentally relevant, may differ from typical human exposures, and long-term consequences beyond birth were not assessed. Additionally, the study focused on one type of biodegradable plastic and its specific breakdown products; other plastics and environmental factors may have different effects. Further research is needed to confirm these findings in human tissues and to explore the broader implications for public health and plastic use policies.
Figures
Pregnant mice exposed to lactic acid oligomers show these compounds crossing the placenta and accumulating in both mother and fetus organs.
Exposure to lactic acid during pregnancy shrinks offspring size and placentas compared to controls, showing growth restriction effects.
Exposure to lactic acid during pregnancy alters placental blood vessel structure and reduces key vascular areas in mice at day 18.
Exposure to lactic acid disrupts placental blood vessel development, shown by gene and cell analyses in mouse placentas.