Retrovirus delivered neurotrophin-3 promotes survival, proliferation and neuronal differentiation of human fetal neural stem cells in vitro

Poor survival and insufficient neuronal differentiation are the main obstacles to neural stem cell (NSC) transplantation therapy. Genetic modification of NSCs with neurotrophins is considered a promising approach to overcome these difficulties. In this study, the effects on survival, proliferation and neuronal differentiation of human fetal NSCs (hfNSCs) were observed after infection by a neurotrophin-3 (NT-3) recombinant retrovirus. The hfNSCs, from 12-week human fetal brains formed neurospheres, expressed the stem cell marker nestin and differentiated into the three main cell types of the nervous system. NT-3 recombinant retrovirus (Retro-NT-3) infected hfNSCs efficiently expressed NT-3 gene for at least 8 weeks, presented an accelerated proliferation, and therefore produced an increased number of neurospheres and after differentiation in vitro, contained a higher percentage of neuronal cells. Eight weeks after infection, 37.9 ± 4.2% of hfNSCs in the Retro-NT-3 infection group expressed the neuronal marker, this was significantly higher than the control and mock infection groups. NT-3 transduced hfNSCs also displayed longer protruding neurites compared with other groups. Combined these results demonstrate that NT-3 modification promote the survival/proliferation, neuronal differentiation and growth of neurites of hfNSCs in vitro. This study proposes recombinant retrovirus mediated NT-3 modification may provide a promising means to resolve the poor survival and insufficient neuronal differentiation of NSCs.