This study utilized adult DRG-derived neural stem cells (NSCs) that were previously established in our laboratory (Singh et al., 2009). The line of DRG-NSC, among others, have been screened for sustained longevity and stability using non-passaged method (Zhou & Chiang, 1998). The multipotency and stability has been tested in these screened neural stem cells (Zhou et al., 2000; Singh et al., 2009a), and the epigenetic profile has been characterized (Singh et al., 2009b). We have raised both adult and embryonic DRG NSCs. After characterization, we found they are extremely similar in multipotency, renewability, capability of migration, and phenotype expression (Singh et al., 2009a). The adult DRG-NSCs were maintained in Dulbecco's Modified Eagle Medium / F-12 Nutrient Mix (D-MEM/F-12) media containing N2 supplement (12μL/mL, Invitrogen, Carlsbad, CA), and penicillin-streptomycin (12μL/mL, Sigma, St. Louis, MO) and grown in a humidified incubator at 37°C and 5% CO2. Media was supplemented with 10ng/mL epidermal growth factor (EGF, Harlan Bioproducts for Science, Indianapolis, IN) and basic fibroblast growth factor twice per week (bFGF, PeproTech, Rocky Hill, NJ) for maintenance of NSCs in neurosphere form. During
