Recent developments in 3D cultures exploiting the self-organization ability of pluripotent
stem cells have enabled the generation of powerful in vitro systems termed brain organoids.
These 3D tissues recapitulate many aspects of human brain development and disorders
occurring in vivo. When combined with improved differentiation methods, these in vitro
systems allow the generation of more complex "assembloids," which are able to reveal
cell diversities, microcircuits, and cell-cell interactions within their 3D organization.
Here, the ways in which human brain organoids have contributed to demystifying the
complexities of brain development and modeling of developmental disorders is reviewed
and discussed. Furthermore, challenging questions that are yet to be addressed by
emerging brain organoid research are discussed.