Polyvinyl Chloride and Polypropylene Model Nanoplastics Exhibit Distinct Interaction Patterns and Cellular Responses in Human Umbilical Vein Endothelial (HUVECs) Cells

Micro- and nanoplastics (MNPs) are increasingly detected in human tissues, yet their polymer-specific effects on endothelial cells remain poorly understood, particularly at the placental and fetal level. We compared cadmium selenide quantum dot-labelled polypropylene (PP) and polyvinyl chloride (PVC) model nanoplastics (NPs) in human umbilical vein endothelial cells (HUVECs) using particle characterization, MTT assays, flow cytometry, confocal microscopy, apoptosis analysis, and synchrotron nano-X-ray fluorescence imaging. PP nanoplastics caused an early reduction in metabolic activity, showed the strongest cell-associated fluorescence, and produced the greatest increase in membrane permeability and late apoptotic/necrotic populations. PVC nanoplastics displayed a more punctate distribution with greater overlap with membrane-associated regions and induced a stronger increase in LC3B-positive vesicular structures. Nano-XRF detected Cd-enriched signals associated with the labelled particles and a polymer-specific Cd–Cl spatial association in PVC-exposed cells. Sulfur mapping further revealed localized sulfur-poor regions along the cell periphery in exposed cells, suggesting localized remodeling of peripheral membranes. These findings indicate that PP and PVC NPs interact differently with endothelial cells and elicit distinct structural and functional responses. Polymer composition should therefore be considered when assessing the vascular and prenatal effects of MNP exposure.