Fig. 2

Major technical applications for culturing and analyzing brain organoids. Brain organogenesis could begin from embryoid bodies (EBs) generated from aggregates of iPSCs by centrifugation in U-bottomed wells. Brain organoids can be derived from EBs through undirected differentiation methods that lack inductive signals, or by patterning through directed methods to resemble specific brain regions (e.g., forebrain, midbrain, retina). These 3D cultures can be subsequently maintained by agitation culture, or spin bioreactor, or maintained in a multichannel microfluid chip. Brain organoids that resemble specific regions of the nervous system can be fused to generate brain assembloids. ALI-COs were maintained by organotypic slice culture at the air–liquid interface to improve oxygen supply, leading to improved neuronal survival and long-range projection formation. Transplanting brain organoids provides a strategy to establish a vascularized and functional in vivo model. The structure of functional neuronal networks and blood vessels in the grafts offers an unprecedented opportunity to model human brain development and disease