OEG suspensions were prepared as Ruitenberg et al. described. Purified OEGs were seeded onto poly-L-lysine-coated dishes at a density of 1×106 cells in DF-10S. The next day, the medium was replaced with fresh medium containing pcDNA3.1(+)-NT3 or pcDNA3.1(+), and cells were left for 72 h. After that, the OEG cultures were washed with L-15 medium, detached by trypsinization and washed twice in serum-free DMEM/F-12 medium. Next, cells were pelleted bylow-speed centrifugation,carefully resuspended, and diluted in appropriate volume of DMEM/F-12 to obtain the OEG suspension at 50 000 /μL. The viability of OEG suspensions, which was assessed by counting the percentage of dead cells using Trypan blue staining, was >95%.