We first screened 11 different media conditions on forebrain-patterned NPCs (Brennand et al., 2015, Brennand and Gage, 2011) derived from hiPSCs (Table 1). The screening conditions, based on recently published hiPSC-astrocyte differentiation protocols (Chen et al., 2015, Haidet-Phillips et al., 2014, Jiang et al., 2013, Krencik et al., 2011, McGivern et al., 2013, Serio et al., 2013, Shaltouki et al., 2013), included different combinations of fibroblast growth factor 2 (FGF2) (Haidet-Phillips et al., 2014), ciliary neurotrophic factor (CNTF), (Krencik et al., 2011, Shaltouki et al., 2013), bone morphogenetic protein 4 (BMP4) (Han et al., 2013, Jiang et al., 2013, Shaltouki et al., 2013), fibroblast bovine serum (FBS) (Han et al., 2013, Shaltouki et al., 2013), neuregulin (Pinkas-Kramarski et al., 1994, Shaltouki et al., 2013), insulin (Heni et al., 2011), and ascorbic acid (AA) (Palm et al., 2015), as well as three commercial astrocyte media (ScienCell, Gibco, and Lonza) for the culture of primary human fetal astrocytes (Table 1). Screening criteria included immunoreactivity for two classical markers of astrocyte identity, S100β and glial fibrillary acidic protein (GFAP) (Ludwin et al., 1976),
