NPCs were plated as described above. After 24hr in expansion medium, NPCs were cultured for 26 div in Neurobasal medium containing B27, BDNF (10nM) and NT3 (10nM). 2/3 of the total volume of medium was replenished every 5–6 days. In particular, after 10 days from plating, differentiating NPCs were plated over mouse glia at a density of 50000/cm2 and cultured for an additional 3 weeks.