Generation of human region-specific brain organoids with medullary spinal trigeminal nuclei.

Brain organoids with nucleus-specific identities provide unique platforms for studying human brain development and diseases at a finer resolution. Despite its essential role in vital body functions, the medulla of the hindbrain has seen a lack of in vitro models, let alone models resembling specific medullary nuclei, including the crucial spinal trigeminal nucleus (SpV) that relays peripheral sensory signals to the thalamus. Here, we report a method to differentiate human pluripotent stem cells into region-specific brain organoids resembling the dorsal domain of the medullary hindbrain. Importantly, organoids specifically recapitulated the development of the SpV derived from the dorsal medulla. We also developed an organoid system to create the trigeminothalamic projections between the SpV and the thalamus by fusing these organoids, namely human medullary SpV-like organoids (hmSpVOs), with organoids representing the thalamus (hThOs). Our study provides a platform for understanding SpV development, nucleus-based circuit organization, and related disorders in the human brain.