Stimulus-Based ApoE Alzheimer's Disease Induction Model Using Microglia-Containing Brain Organoids for Drug Discovery.

Alzheimer's Disease (AD) is a multifaceted progressive neurodegenerative disease characterized by memory deficits and cognitive impairment. The disease is clinically diagnosed by the presence of β-amyloid (Aβ), hyperphosphorylated tau, and neurodegeneration. Animal models serve as an indispensable tool to understanding AD pathogenesis and evaluating potential therapeutic approaches. However, despite the development of more than 200 rodent models, species-specific differences limit the translational relevance. Brain organoids generated from induced pluripotent stem cells (iPSCs) have the potential to bridge the gap between transgenic mouse models and clinical trials in human patients. Herein, we describe a robust stimulus-based neuroimmune organoid model that demonstrates neuroinflammation, neurodegeneration, and lipid dysregulation with AD-relevant pathological markers. Using planar organoids containing neurons, astrocytes, microglia, and vascular cells, we performed in-depth characterization of the induced AD-like phenotype using supernatant proteomic analysis, immunofluorescence staining, NfL and GFAP release, scRNAseq, bulk RNAseq, and pathway analysis both acutely (24 h) and chronically (7 days). Furthermore, we show that the induced neuroinflammation, lipid dysregulation, and neurodegeneration can be ameliorated using small molecules. This defined inducible model system presents an opportunity for drug discovery and development using a complex multicellular brain microenvironment derived from human iPSCs.