Microglia integrated neural spheroids enable neuroinflammatory responses and correct network dysfunction induced by alpha-synuclein mutation

Microglia are the primary resident immune cells of the brain, playing both protective and deleterious roles in neurological diseases, which makes them an enticing therapeutic target. Here we developed a Neural Microglia Integrated Multicellular iPSC-derived Cultured Spheroids (NeuroMIMICS) system that enables measurements of both neural network activity and immune responses using human iPSC-derived microglia, astrocytes, and neurons. We validated microglia functionalities in these neural tri-cultures including phagocytic activity, directed motility, and inflammatory responses. RNAseq analysis revealed a phenotypical acquisition of immune functionality via microglia incorporation, supported by increased cytokine production in spheroids challenged with pathogen-like insults. We then demonstrated that the incorporation of healthy microglia corrected alpha-synuclein A53T-mediated dysfunctional phenotypes in the neural spheroids. This work demonstrates a unique immunocompetent functional neural model that is robust and suited for high-throughput screening, laying the groundwork for its application to accelerate the discovery of new therapeutics for neurological diseases.