*2.2. Cell Culture*

Human fetal NSCs were purchased from Clontech (human neural cortex; catalog number Y40050). Maintenance of hNSCs was performed in Neurobasal medium without phenol red (Thermo Fisher, Waltham, MA, USA) and in the presence of B-27 supplement (1:100; catalog number 12587010; Thermo Fisher), N-2 supplement (1:200; catalog number 17502-048; Invitrogen, San Diego, CA, USA), 20 ng/mL fibroblast growth factor (catalog number 4114-TC-01M; R&D Systems, Minneapolis, MN, USA, 20 ng/mL epidermal growth factor (catalog number 236-EG-01M; R&D Systems), GlutaMAX

(catalog number 35050061; Thermo Fisher), and sodium pyruvate. Cells were prepared in 6-well plates precoated with laminin (10 mg/mL; catalog number L2020; Sigma-Aldrich, St. Louis, MO, USA) and were grown to near confluence (80 to 90%) prior to passage. For passaging, cells were rinsed gently with phosphate-buffered saline (PBS) (without calcium and magnesium) and then treated with TryPLE for 5 min at 37 ◦C for cell detachment (catalog number 12563029; Thermo Fisher). The GSC 387 cell line was prepared and maintained similarly to what has been previously described using the media and detachment conditions used for hNSCs described above [29]. Vero cells (ATCC CCL-81) were purchased from ATCC and cultured in Dulbecco's Modified Eagle Medium (DMEM) (Gibco, Waltham, MA, USA) with high glucose (4.5 g/L), 10% fetal calf serum (FCS) (Sigma), and 1% Penicillin-Streptomycin (PS) (Sigma-Aldrich, St. Louis, MO, USA) at 37 ◦C and 5% CO2.
