Stress-induced alteration of small extracellular vesicles drives amyloid-beta sequestration and exacerbates Alzheimer's disease pathogenesis.

While small extracellular vesicles (sEVs) are implicated in amyloid-β trafficking, the mechanisms governing their interaction with Aβ aggregates and plaque formation remain unresolved. Here, we report a sEVs undergo dynamic structural remodelling in response to stress, enabling selective binding to Aβ aggregates- a phenomenon absent under normal physiological conditions. Using multimodal stressors, including mechanical (ultrasonication/agitation), physical (hyperthermia), and biological (oxidative damage), we demonstrate that stress-modified sEVs exhibit high-affinity binding to small Aβ aggregates (SA) through scaffold reorganization, as validated by Lipidomic analyses, single-molecule fluorescence microscopy, and quantitative colocalization assays. Crucially, these remodelled sEVs act as potent carriers, enhancing SA internalization by neuronal cells in vitro. Strikingly, in post-mortem Alzheimer’s disease (AD) brains and APP-PS1 transgenic mice, sEVs were spatially enriched at amyloid plaque margins, suggesting a direct role in Aβ sequestration and plaque expansion. Consistent with clinical relevance, sEVs isolated from AD patients exhibited an intrinsic SA-binding capacity, recapitulating stress-induced interactions observed experimentally. Our findings reveal that stress-primed sEVs function as pathological chaperones, binding to and internalizing Aβ aggregates, thereby accelerating plaque nucleation and disease progression. This study provides the first evidence of stress-mediated sEV plasticity as a critical driver of Aβ pathology, redefining therapeutic strategies targeting extracellular vesicle biology in neurodegenerative disorders.