We also investigated DHA permeability for analyzing the function of the nutrient transporter in our BBB model. An analysis of DHA kinetics with nanoLC-MS/MS showed that ciBECs significantly increased the permeability of DHA compared with ECs (Figure S5D). This result suggested that nutrient transporters such as MFSD2A in hiPSC-derived ciBECs are functional in the BBB model.