Proteomic profiling of brain organoids and extracellular vesicles identifies early Alzheimer's disease biomarkers and drug response heterogeneity

<h4>Introduction</h4>Alzheimer's disease (AD) exhibits high genetic and clinical heterogeneity that limits therapeutic success. Patient-derived brain organoids and their extracellular vesicles (EVs) provide physiologically relevant models to study disease mechanisms and individualized drug responses.<h4>Methods</h4>We generated the largest brain organoid cohort to date, derived from 30 independent induced pluripotent stem cell (iPSC) lines from AD and control individuals. Comparative proteomic profiling was performed on both organoids and their secreted EVs to capture molecular diversity and treatment effects.<h4>Results</h4>Organoids and EVs consistently recapitulated neuronal proteomic signatures and revealed early alterations in AD-related pathways, including synaptic and neurotransmitter dysfunction. Distinct proteomic responses mirrored individual variability in selective serotonin reuptake inhibitor sensitivity.<h4>Discussion</h4>Integrating organoid and EV data provides a systems-level view of AD pathophysiology and treatment response, positioning this dual-platform model as a cost-effective tool for precision medicine and drug discovery.