Synchrotron imaging uncovers nano- and microplastic effects in vaginal epithelial cells
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.
Figure 1: (left) Confocal microscopy showed QD fluorescence within vesicles, indicating internalization of PE nanoparticles (red dots), while green autofluorescence outlined cell morphology. Cells marked with yellow boxes were selected for further imaging (scale bar = 50 μm). (center) STXM absorption (Abs) and differential phase contrast (PhC) images are shown for control cells and cells exposed to 25 and 50 μg/mL PE QD/NPs, revealing changes in morphology. (right) LEXRF elemental distribution maps highlight elemental localization. Scale bars = 5 μm.
The integration of STXM and LEXRF provided a unique, correlative imaging approach, linking structural, chemical, and biological information within the same cellular context, offering a unique level of detail in the study of pollutant-cell interactions.
Overall, this in vitro work demonstrates that environmental nanoplastics can penetrate human epithelial cells, of the reproductive system, accumulate intracellularly, and trigger a cascade of responses affecting oxidative balance, metabolism, and immune regulation. These findings contribute to a growing body of evidence that N/MPs are not biologically inert, but can actively interfere with cellular function.
Beyond its specific biological insights, the study highlights the critical role of advanced synchrotron-based imaging in environmental health research. The methodologies developed here open new avenues for investigating how nanoscale pollutants interact with biological systems, paving the way for future studies in more complex tissue models and organ-level systems. Ultimately, this research represents an important step toward a deeper understanding of the potential risks posed by N/MPs to human health, particularly female reproductive health, and the environment.
This research was conducted by the following research team:
Paola Pontecorvi1,*, Matteo Cassandri2,*, Alessandra Gianoncelli3, Lorella Pascolo4, Fabrizio Cece2, Elena Niccolai5, Simona Camero2,6, Valentina Bonanni3, Sara Bozzer4, Enrico Romano7, Simona Ceccarelli2, Claudia Bearzi8, Roberto Rizzi9, Amedeo Amedei5, Antonio Angeloni9, Cinzia Marchese2 and Francesca Megiorni9
1 Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Rome, Italy
2 Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
3 Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, Italy
4 Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
5 Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
6 Department of Life Sciences, Health and Health Professions, Link Campus University, Rome, Italy.
7 Department of Sense Organs, Sapienza University of Rome, Rome, Italy
8 Institute for Biomedical Technologies, National Research Council, Segrate, Milan, Italy
9 Department of Well-being, Health and Environmental Sustainability, Sapienza University of Rome, Rieti, Italy
* These authors contributed equally
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Reference
P. Pontecorvi, M. Cassandri, A. Gianoncelli, et al. “Polyethylene nano- and microplastics trigger metabolic stress responses in human vaginal epithelial cells”, Cell Death Discov. 12, 173 (2026); DOI: 10.1038/s41420-026-03038-6.
