Patient-specific, human-based cellular models that integrate biomimetic BBB, immune, and myelinated neuron components are critically needed to enable translationally relevant and accelerated discovery of neurological disease mechanisms and interventions. By engineering a brain-mimicking 3D hydrogel and co-culturing all six major brain cell types derived from patient iPSCs, we have constructed, characterized, and utilized a multicellular integrated brain (miBrain) immuno-glial-neurovascular model with in vivo- like hallmarks. As proof of principle, here we utilized the miBrain to model Alzheimer's Disease pathologies associated with APOE4 genetic risk. APOE4 miBrains differentially exhibit amyloid aggregation, tau phosphorylation, and astrocytic GFAP. Unlike the co-emergent fate specification of glia and neurons in organoids, miBrains integrate independently differentiated cell types in a modular system with unique utility for elucidating cell-type specific contributions to pathogenesis. We here harness this feature to identify that risk factor APOE4 in astrocytes promotes tau pathogenesis and neuronal dysregulation through crosstalk with microglia.
One-sentence summary: A novel patient-specific brain model with BBB, neuronal, immune, and glial components was developed, characterized, and harnessed to model Alzheimer's Disease-associated pathologies and APOE4 genetic risk.