Human CNS barrier-forming organoids with cerebrospinal fluid production

Cerebrospinal fluid (CSF) is a vital liquid, providing nutrients, signaling molecules, and clearing out toxic byproducts from the brain. The CSF is produced by the choroid plexus (ChP), a protective epithelial barrier that also prevents free entry from the blood. Here, we establish human ChP organoids with a selective barrier and CSF-like fluid secretion in self-contained compartments. We show that this in vitro barrier exhibits the same selectivity to small molecules as in vivo, and that ChP-CSF organoids can predict CNS permeability of novel compounds. The transcriptomic and proteomic signature of ChP-CSF organoids reveal a high degree of similarity to in vivo. Finally, the intersection of single cell transcriptomics and proteomic analysis uncovers key human CSF components produced by previously unidentified specialized epithelial subtypes.