Environmental nano- and microplastics (N/MPs) are increasingly detected in human tissues, raising growing concerns about their potential impact on human health. Despite their pervasive presence, their biological effects at the cellular level remain poorly understood. A new multidisciplinary study provides important insights into how polyethylene (PE) N/MPs interact with human vaginal epithelial cells, revealing the induction of oxidative stress, metabolic disruption, and modulation of immune responses.
In this work, researchers exposed VK2 E6/E7 vaginal keratinocytes to a range of environmentally relevant PE N/MPs, spanning from 200 nm to 9 µm. Fluorescently labeled nanoparticles were also employed to enable precise tracking of particle uptake and intracellular localization. By combining advanced transcriptomic profiling with high-resolution imaging, the study offers a comprehensive view of how these particles affect cellular physiology.
Gene expression analysis revealed a significant dysregulation of lipid metabolism and cholesterol biosynthesis pathways, alongside the activation of oxidative stress responses. At the same time, modulation of immune-related genes suggested the onset of an adaptive, potentially tolerogenic response, indicating that cells may attempt to mitigate or adapt to the presence of nanoplastics rather than mounting a purely pro-inflammatory reaction. These findings highlight the complex and multifaceted nature of cellular responses to environmental contaminants.
Crucially, the study employed synchrotron-based soft X-ray imaging at the TwinMic beamline of Elettra Sincrotrone Trieste. Through Scanning Transmission X-ray Microscopy (STXM), researchers were able to directly visualize the internalization and intracellular distribution of nanoplastics at subcellular resolution, providing spatial information that is not accessible with conventional optical or electron microscopy alone, see Figure 1. Complementary Low-Energy X-ray Fluorescence (LEXRF) analysis enabled the mapping of elemental composition within exposed cells, revealing significant alterations in key elements such as carbon, oxygen, sodium, and magnesium. These elemental shifts point to metabolic stress, possible membrane perturbations, and broader changes in cellular homeostasis.
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