Fig. 1.

Engineered human choroid plexus (ChP)-on-a-chip to reconstitute ChP physiology under CSF flow. a Schematic description of the 3D microfluidic chip to recapitulate the human ChP in the brain and TME in the ChP by engineering in vivo-like cerebrospinal fluid (CSF) flow dynamics. b, c (b) Schematic and (c) photograph of the top and bottom of the human ChP-on-a-chip. d Sequential steps for the microfluidic patterning; (i) Fill the central channel with a hydrogel mixed with the cell suspension by capillary-guided fluid patterning and wait for polymerization. (ii) Fill and withdraw a blank hydrogel through an injection hole of the flow channel to make the hydrogel remain only underneath the sides of the central channel as a blank ECM zone to separate the flow channels and central channels. And wait for polymerization. (iii) Fill the flow channels and the side channels with cell suspension or media.