Cell death enzyme-linked immunosorbent assay, a photometric enzyme immunoassay for cytoplasmic histone-associated DNA fragments associated with apoptosis, detected increased DNA fragmentation consistent with apoptosis in SZ NPCs (1.446±0.003) relative to controls (1.18±0.05; P<0.001) (Supplementary Figure 3E). A cytotoxicity assay that indirectly measures the lactate dehydrogenase activity present in the cytoplasm of the intact cells did not detect differences between control (19.6±2.1) and SZ (17.1±0.7) NPCs (P>0.19) (Supplementary Figure 3F). By most, but not all measures, increased oxidative stress did not appear to meaningfully affect survival (Supplementary Figures 3E and F) and/or replication (Supplementary Figure 3B, C and D) of SZ hiPSC NPCs under routine culture conditions.
