At D54, a majority of cells were GAD67+ (77.2 ± 4.5%, Figure 1D, G, dark blue bar). We did not observe any PVALB+, CHAT+ or VGLUT1+ cells in these cultures. However, SST+ GAD67+ were present (Figure 1D, E). By D100 the percentage of GAD67+ cells was reduced (47.2 ± 7.5%, Figure 1G, light blue bar). A similar reduction in SST cell percentages was observed between D54 (46.3 ± 6.1%, dark blue bar) and D100 (24.9 ± 4.5%, light blue bar). We quantified the expression of SST subtype markers CALB2, NR2F2 and TH (Figure 1H, S1)(DeFelipe et al., 2013; Tasic et al., 2016). CALB2+ and NR2F2+ cell percentages decreased over time. At D54, 21.0 ± 4.7% (dark orange bar) of SST cells expressed CALB2, but only 10.3 ± 2.5% (light orange bar) by D100. SST and NR2F2 double-positive cell numbers were reduced between day 54 (35.6 ± 9.9%) and D100 (29.9 ± 4.9%). Only few SST+ cells were also TH+ at both D54 (5.8 ± 2.1%) and D100 (8.2 ± 3.4%).
