Investigation of potential toxic effects of nano- and microplastics on human endometrial stromal cells

Nanoplastics (NPs) and microplastics (MPs) have become a global concern in recent years. Most current research on the impact of plastics on obstetrics has focused on their accumulation in specific tissues in animal models and the disease-causing potential of MPs. However, there is a relative lack of research on the cellular changes caused by the accumulation of MPs. In this study, we aimed to establish a proper in vitro exposure protocol for polystyrene (PS)-NPs and MPs and to investigate possible cytotoxic effects of PS-NPs and MPs on human endometrial stromal cells (ESCs) using different plastic sizes and concentrations. The results showed that smaller plastics, specifically 100 nm PS-NPs and 1 μm PS-MPs, had a higher cellular uptake propensity than larger particles, such as 5 μm PS-MPs, with significant morphological changes and cell death observed at concentrations above 100 μg/mL a 24-h period. In addition, confocal microscopy and real-time imaging confirmed the accumulation of these particles in the nucleus and cytoplasm, with internalization rates correlating with particle size. Also, 100 nm PS-NPs reduced cell proliferation and induced apoptosis. In conclusion, this study demonstrates that exposure to 100 nm PS-NPs and 1 μm PS-MPs leads to dynamic accumulation in ESCs, resulting in cell death or decreased proliferation at specific concentrations, which highlights the potential cellular toxicity of NPs or MPs.