Human iPSCs-derived microglia-containing 3D brain-region specific neural spheroids for disease modeling and therapeutic development

Authors

• J Zhang
• Y Lim
• A Medina
• M Carrasco Carvajal
• E Lee
• M Ferrer

Abstract

Microglia, the immune cells in the brain, regulate neuroinflammation which contribute to the progression of neurodegenerative diseases such as Parkinson’s (PD). Despite accumulating evidence showing the involvement of microglia in PD, there is a critical need for physiologically relevant human neural models that recapitulate microglial contributions to neuroinflammation and neurodegenerative disease states to enable therapeutics discovery and development. To address this, we have developed a protocol to generate high throughput screening (HTS)-compatible 3D tri-culture model involving a scaffold-free aggregation of differentiated hiPSCs-derived neurons, astrocytes, and microglia. These tri-culture spheroids mimic brain-region-specific cell-type composition and display distinct calcium oscillation patterns that respond to compound dosing making them uniquely suitable as functional assays for drug screening. In this study, we first validated that the microglia in tri-culture spheroids exhibit a range of functional activity including phagocytic activity, P2Y12 receptor-mediated motility, inflammatory responses towards a variety of pathogen-associated molecules, and predictable pharmacological responses to known compounds. Next, we demonstrated that incorporation of microglia alters spontaneous calcium oscillations in healthy spheroids, implicating microglia-neuron interactions in vitro. We showed that healthy microglia incorporation into PD-like spheroids reverses the disease phenotype observed in the PD model. Finally, we found that incorporation of microglia containing a disease-associated TREM2 R47H variant into the tri-culture spheroids results in a distinct calcium oscillation profile compared to wildtype, which may highlight the unique sensitivity of the tri-culture model. Together, this study demonstrates a novel physiologically relevant HTS platform for studying microglia in healthy and disease conditions which could facilitate therapeutic development.

Scientific Focus Area: Neuroscience

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