Nonetheless, when we tested the ability of hNGN2 overexpression to robustly induce neurons from these same six individuals (three controls and three schizophrenia patients), we initially failed to produce suitable populations for comparisons (Fig. 7). While we did not attempt to discern whether this variation arose from altered levels of replication, cell death or induction efficiencies in transduced NPCs, it was adequately addressed by varying the initial seeding density of individual NPC lines (Fig. 7). Once optimal plating densities are empirically established, these values appear to be relatively robust from experiment-to-experiment. Therefore, if achieving a consistent neuronal density at the end-point is required, we recommend that the protocol be specifically tailored with respect to starting cell density for each NPC line used.
