For differentiation into neural precursor cells (NPCs) an adapted version of the protocol from Shi and colleagues25 was used. Briefly, confluent hiPSCs were Accutase passaged and plated at 500,000 cells/cm2 on Matrigel™ coated MW6 plates in mTeSR™1 complete medium supplemented with 10 μM ROCK inhibitor for 1 day (days in vitro (DIV) -2). The day after medium was changed completely with mTeSR™1 complete medium (DIV -1). At DIV0, neural induction was started by changing the medium into N2B27 (Neurobasal medium and DMEM:F12 Glutamax medium in a ratio 1:1, 1% B27 supplement, 1 mM Glutamax, 0.5x Pen/Strep, 0.5% N2 supplement, 2.5 μg/ml insulin (Sigma), 50 μM 2-mercaptoethanol, 0.5x MEM NEAA, 500 μM sodium pyruvate (all Thermo Fisher Scientific, unless stated otherwise) supplemented with 10 μM SB431542 (Sigma), and 1 μM dorsomorphin (Tocris Bioscience) for a total of 12 days. At DIV 12, the neuroepithelial sheet was mechanically broken into large aggregates and replated onto laminin (Sigma) coated MW6 plates. At DIV 13 and 15 medium was replaced with N2B27 medium supplemented with 20 ng/ml FGF2 (Stem Cell Technologies) for neural precursor
