postnatal fibroblasts (HPFs) were established from dissociated foreskin tissue derived from 1–3 day-old newborns. Before being used for experiments, primary fibroblast cells were passaged for at least 3 times. Primary mouse cortical cultures and glial monolayer cultures were established as previously described13. To maintain the iN cell culture, cells were either cultured in N3 media media (DMEM/F2 (Invitrogen), apotransferrin (100 µg/ml), insulin (5 µg/ml), sodium selenite (30 nM), progesterone (20 nM), putrescine (100 nM), penicillin/streptomycin) supplemented with neurotrophic factors including brain derived neurotrophic factor, glial cell-derived neurotrophic factor, neurotrophin-3 and ciliary neurotrophic factor (R&D systems) or dissociated using papain and replated onto previously established monolayer culture of primary mouse glia or primary neurons from mouse cortex in neuronal growth media (MEM (Gibco) supplemented with B27 (Gibco), glucose (5mg/ml), transferring (10 µg/ml), 5% fetal bovine serum and Ara-C (2µM, Sigma)13,25.
