Influence of nerve growth factor on proliferation, differentiation and apoptosis of neural stem cells

Objective To evaluate the influence of different doses of nerve growth factor (NGF) on the proliferation, differentiation and apoptosis of embryonic rat neural stem cells. Methods The neural stem cells were isolated from subventricular zone of rat embryonic brains and cultured in serum-free medium DMEM/F12 with B27. NGF with different doses of 10, 20, 50 μg/L were added into the different experimental groups. The proliferation ability of the cells was measured by methyl thiazol tetrazolium (MTT) assay at 10th day. All cells were collected in plates at 7th day. Streptvidin-peroxidase immunocytochemistry was used to detect the expression of neuron specific enolase (NSE) and glial fibrillary acidic protein (GFAP) , and the number of NSE( + ) and GFAP( + ) cells was counted. The apoptosis rat at 5th day after culture was assessed. Results There was no significant difference in the the number of neurospheres between 10 μg/L NGF group (0. 150 ±0. 025) and positive control group (0. 158 ±0. 017), but there was significant difference between 10 μg/L NGF group and blank control group (0. 128 ±0. 015). In 10, 20,50 μg/L N GF groups, the rate of NSE ( + ) cells was ( 15. 21 ± 1.27) %, (20. 64 ± 2. 61 )%, (24. 20 ± 3. 10) %, and that of GFAP( + ) cells was (27.98 ± 2. 35 ) %, ( 28.94 ± 2. 84 ) %, ( 30. 79 ± 3.23 ) % respectively. The rate of cells differentiation was increased with the dose of NGF added[( FNsE (+ ) = 3.47,FGFAp( + ) = 3. 47 ,PGFAP( + ) ＜ 0. 05)]. Flow cytometry revealed that in 20, 50 μg/L NGF groups the apoptosis rate was significantly increased as compared with other groups. The proliferation index (PI) in 10 μg/L NGF group was higher than other groups. Conclusion NGF at a rational dose can promote the proliferation and differentiation of human NSC. Low dose of NGF mainly facilitates the proliferation of NSCs, and high dose of NGF shows obvious influence on proliferation of NSC. Key words: Neural growth factor;  Neural stem cells;  Proliferation;  Differentiation