For cell preparation, cells were rinsed once with 1XPBS (Invitrogen), and treated with TrypLE (Invitrogen) for 5 min at 37 °C. TrypLE was neutralized with DMEM/F12 (Invitrogen)+10% FBS. Cells were centrifuged at 1000, r.p.m. for 5 min, and resuspended in PBS (2 × 105 μl−1 or 500 μl−1 for 5 × 105 and 500 transplanted cells, respectively). Cells were kept on a bed of ice before transplantation. For cell transplantation, anaesthetized NSG mice were inserted in a stereotactic frame, the skull surface was exposed and a hole was drilled at the appropriate site to allow single/unilateral (right hemisphere) injection of the cell preparations. Antero-posterior (AP), lateral (L) and vertical (V) coordinates (in mm) for cell transplantations were taken relative to the bregma: AP+0.5, L+2, V −1.5. For cell injections, a 10 μl Hamilton syringe was used and the flow rate set at ∼0.5 μl min−1 (2.5 μl or 0.5 μl animal for 5 × 105 and 500 transplanted cells, respectively). For each condition, five animals were injected. Randomization was unnecessary and no blinding was done.
