Expandable human neuronal progenitor cells (hNPCs) from one unaffected male (GM08330, Coriell Institute for Medical Research) and one BD male (GM05224, Coriell Institute for Medical Research) were generated from iPSCs31 (Madison et al., manuscript under revision in Molecular Psychiatry) and cultured on poly-ornithine/laminin-coated six-well plates (BD Biosciences, San Jose, CA, USA) with neural expansion medium [70% Dulbecco’s Modified Eagle Medium (DMEM) (Invitrogen, Carlsbad, CA, USA), 30% Ham's F-12 (Mediatech, Manassas, VA, USA) supplemented with B-27 (Invitrogen), 20 ng/ml each EGF (Sigma Sigma-Aldrich, St Louis, MO, USA) and bFGF (R&D Systems, Minneapolis, MN, USA)]. Terminal neural differentiation was achieved by plating NPCs at a seeding density of 4×104 cells per cm2 on poly-ornithine/laminin-coated plates and culturing them for up to 8 weeks in differentiation medium [DMEM/F12 (Invitrogen), Glutamax (Invitrogen) supplemented with B-27 and N2 (Invitrogen), 200 µM L-ascorbic acid (Sigma) and 100 µM dibutryl-cAMP (Sigma)]. Culture medium was replaced every 3–4 days during neural differentiation. Cell samples were collected by manual scraping, pelleted by centrifugation to remove culture medium, quickly frozen on dry ice, and finally stored at −80°C.
