We tested the effect of neural differentiation on the frequency of mar mosaicism. When we compared NPCs differentiated from p15 high and low mar hiPSCs as determined by karyotyping at p12 (DL5459 C5 [high mar], 55.0%; DL5459 C6 [low mar], 10.0%), there were no obvious differences with respect to NPC cellular morphology or detection of NPC markers such as FOXP2, NESTIN, and PAX6 (Figures 4A and 4B). Interestingly, the percentage of mosaicism in carrier high and low mar hiPSC NPCs, evaluated by GLDC FISH, was similar (35% ± 2.5%) but differed from source hiPSCs (high mar, 55.0%; low mar, 10.0%), suggesting that the level of mosaicism in NPCs did not reflect the source hiPSCs (Figures 4C and 4D; Table S2).
