A multi-organoid-on-a-chip platform for interrogating human brain (dys)connectivity

SUMMARY Brain imaging approaches are a promising method for unveiling network abnormalities in living brains of patients with psychiatric disorders; however, understanding these pathologies will only be possible when human specific abnormalities in cell connectivity, network circuit activity and transcriptomes can be directly interrogated and correlated in an experimental system amenable to high-throughput manipulation and phenotyping. Despite the excitement surrounding human brain organoids derived from pluripotent stem cells, scientists are frustrated with the limited physiologically relevant anatomy and maturation of brain organoids. We propose to pioneer a multi-organoid-on-chip (MoC) platform, combining tissue engineering technologies and newer organoid analysis readouts, to address this challenge. As a first proof of concept study, we propose to recapitulate the human visual system, a commonly affected network in multiple neuropsychiatric disorders, by co-developing three (retinal, thalamic, cortical) organoids on a microfluidic device designed to foster functional connectivity, thereby allowing: i) co-development of distinct central nervous system (CNS) structures with distinct anatomical organizations; ii) establishment and mapping of reproducible and functional long-range connectivity between defined CNS structures; iii) activity-dependent maturation of synaptic connections by spontaneous, optogenetically-regulated, and sensory-evoked stimulation of neuronal activity. The synthetic platform will also facilitate high-throughput multimodal analysis with direct correlation between specific circuit connectivity and molecular dynamics at single cell resolution, in healthy and diseased organoids. In addition to improving the understanding and screening of drugs for complex brain disorders, our platform provides a valuable resource for the broader research community interested in modeling circuit-level dysfunctions in other types of neurological disorders, including retinal diseases and optic neuropathy. Finally, we expect that the method and modular technologies developed within this proposal will be foundational and easily adapted to recapitulate connectivity between other brain regions, thereby broadening its future impact and applications.