Weathered plastic particles negatively affect mouse primary neurons and glial cells.

The global increase in plastics production has raised significant concerns regarding plastic waste in marine and terrestrial ecosystems and potential human health risks. Environmental weathering processes such as physical abrasion and ultraviolet (UV) irradiation cause plastic waste to fragment into tiny particles termed weathered nano- and microplastics (W-NMPs). Despite their potential human health hazards, W-NMPs are underinvestigated in terms of their effects, particularly on the central nervous system. We comparatively evaluated the effects of W-NMPs and plain NMPs (P-NMPs) synthesized for specific purposes on brain-derived cells in vitro. W-NMPs triggered apoptosis more robustly than P-NMPs in both primary neural progenitors and isolated oligodendrocyte progenitors, and significantly reduced cell proliferation in primary neural progenitors. We found that W-NMPs induced a more potent inflammatory response in isolated primary microglia than P-NMPs. In the neuron-glia co-culture model, W-NMPs also caused morphological changes in astrocytes. Finally, P-NMPs induced microglial cytotoxicity, but W-NMPs triggered a more vigorous inflammatory response in microglia than P-NMPs in the co-culture model. Our findings provide novel insights into the hazards of W-NMPs exposure to brain health.