SUMMARY Cerebral organoids, three-dimensional cultures that model organogenesis, provide a new platform to investigate human brain development. High cost, variability and tissue heterogeneity limit their broad applications. Here we developed a miniaturized spinning bioreactor (SpinΩ) to generate forebrain-specific organoids from human iPSCs. These organoids recapitulate key features of human cortical development, including progenitor zone organization, neurogenesis, gene expression, and notably, a distinct human-specific outer radial glia cell layer. We also developed protocols for midbrain and hypothalamic organoids. Finally, we employed the forebrain organoid platform to model Zika virus (ZIKV) exposure. Quantitative analyses revealed preferential, productive infection of neural progenitors with either African or Asian ZIKV strains. ZIKV infection leads to increased cell death and reduced proliferation, resulting in decreased neuronal cell layer volume resembling microcephaly. Together, our brain region-specific organoids and SpinΩ provide an accessible and versatile platform for modeling human brain development and disease, and for compound testing including potential ZIKV antiviral drugs.

SUMMARY Studies of Parkinson’s disease (PD) have been greatly hindered by lack of access to affected human dopaminergic (DA) neurons. Here, we report generation of induced pluripotent stem cells that carry the p.G2019S mutation (G2019S-iPSCs) in the Leucine-Rich Repeat Kinase-2 (LRRK2) gene, the most common PD-related mutation. We demonstrate that these G2019S-iPSCs were able to differentiate into DA neurons and showed increased expression of key oxidative stress response genes and α-synuclein protein. Moreover, G2019S-mutant DA neurons were more sensitive to caspase-3 activation, caused by exposure to hydrogen peroxide, MG-132, and 6-hydroxydopamine, compared to unaffected DA neurons. These findings suggest that G2019S-iPSC-derived DA neurons exhibit early phenotypes linked to PD. Due to high penetrance of the LRRK2 mutation and its clinical resemblance to sporadic PD, these neurons may provide a valuable platform for identification of novel pharmacological agents and diagnostics for modeling and alleviation of a subset of disease phenotypes.

Dysregulated neurodevelopment with altered structural and functional connectivity is believed to underlie many neuropsychiatric disorders1, and ‘a disease of synapses’ is the major hypothesis for the biological basis of schizophrenia2. Although this hypothesis has gained indirect support from human post-mortem brain analyses2–4 and genetic studies5–10, little is known about the pathophysiology of synapses in patient neurons and how susceptibility genes for mental disorders could lead to synaptic deficits in humans. Genetics of most psychiatric disorders are extremely complex due to multiple susceptibility variants with low penetrance and variable phenotypes11. Rare, multiply affected, large families in which a single genetic locus is probably responsible for conferring susceptibility have proven invaluable for the study of complex disorders. Here we generated induced pluripotent stem (iPS) cells from four members of a family in which a frameshift mutation of disrupted in schizophrenia 1 (DISC1) co-segregated with major psychiatric disorders12 and we further produced different isogenic iPS cell lines via gene editing. We showed that mutant DISC1 causes synaptic vesicle release deficits in iPS-cell-derived forebrain neurons. Mutant DISC1 depletes wild-type DISC1 protein and, furthermore, dysregulates expression of many genes related to synapses and psychiatric disorders in human forebrain neurons. Our study reveals that a psychiatric disorder relevant mutation causes synapse deficits and transcriptional dysregulation in human neurons and our findings provide new insight into the molecular and synaptic etiopathology of psychiatric disorders.