Microglia-containing cerebral organoids derived from induced pluripotent stem cells for the study of neurological diseases

Microglia play an important role in neuroinflammation and neurodegeneration. Here, we report an approach for generating microglia-containing cerebral orga-noids derived from human pluripotent stem cells involving the supplementation of growth factors (FGF, EGF, heparin) and 10% CO2 culture conditions. Using this platform, Western Pacific Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS-PDC) cerebral organoids were generated from patient-derived induced pluripotent stem cells (iPSCs). These ALS-PDC-affected organoids had more reactive astrocytes and M1 microglia, and had fewer M2 microglia than their unaffected counterparts, leading to impaired microglia-mediated phagocytosis. RNA-seq analysis of ALS-PDC and control organoids indicated that the most significant changes were microglia- and astrocyte-related genes (IFITM1/2, TGF-beta, and GFAP). The most significantly downregulated pathway was type I interferon signaling. Interferongamma supplementation increased IFITM expression, enhanced microglia-mediated phagocytosis, and reduced beta-amyloid accumulation in ALS-PDC-affected network. The results demonstrated the feasibility of using microglia-containing organoids for the study of neurodegenerative diseases.