Cellular and Molecular Landscape of 3D Human Organoid Models

In vitro models of corticogenesis using mouse and human embryonic stem cells (ESC) have revolutionized and improved our understanding of human brain development and disease. Among these, 3D organoid systems were able to recapitulate features of the in vivo developing cortex.Here we tested several models for cell identity, organoid heterogeneity, cell polarity, and neuronal maturation following either default differentiation or directed differentiation conditions. Our findings support that 3D cortical organoid models based on default “intrinsic” conditions generate a broad spectrum of brain cell identities. Conversely, directed differentiation methods without Wnt activation gave rise to the highest degree of cortical cell identity. All protocols generated organoids that showed a time-dependent expression in genes involved in the establishment of synapses and neuronal function. Interestingly, cortical organoids after 3 months in culture showed patterns of expression of genes such as Huntingtin and Tau that resemble embryonic cortex rather than the adult brain.