Within 30 days, hiPSC-astrocytes were immunopositive for the astrocyte markers ALDH1L1 (Cahoy et al., 2008) and Vimentin (VIM) (Schnitzer et al., 1981), as well as the glutamate transporters GLAST (EAAT1 and GLUT1) (Rothstein et al., 1994) (Figures 1C, S1L, and S1M). Compared with NPCs or excitatory neurons (hNGN2-induced neurons) (Brennand et al., 2015), hiPSC-astrocytes expressed GFAP (Ludwin et al., 1976), S100β (Ludwin et al., 1976), VIM (Schnitzer et al., 1981), AQU4 (Hubbard et al., 2015), ACSBG1 (Chaboub and Deneen, 2013), and APOE (Boyles et al., 1985) by qPCR (Figure 1D), although expression levels between individual hiPSC-astrocytes and primary astrocyte lines varied substantially. In addition, hiPSC-astrocytes expressed low levels of the neuronal markers TUJ1, MAP2AB, RELN, and CACNA1C (Figure 1E).
