Effects of all trans-retinoic acid or combined with neurotrophic factors on the differentiation of EGF-responsive neural stem cells

Abstract

This experiment aimed at exploring the effects of all trans-retinoic acid (ATRA) or combined with neurotrophic factors on the differentiation of epidermic growth factor (EGF)-responsive neural stem cells (NSCs). The forebrain SVZ region from neonatal SD rats (P1-P2) was dispersed and cultivated in the serum-free media (DMEM/F12 1:1, 2% B27 supplement) with EGF (20 ng/ml). The neurospheres of second passage were used to observe the effects of ATRA 1 μM alone, ATRA 1 μM + BDNF(brain-derived neurotrophic factor) 10 ng/ml or ATRA 1 μM + GDNF(glial cell line-derived neurotrophic factor) 10 ng/ml on differentiation in experimental groups. Blank control and vehicle control (DMSO 1:1000 v/v) were set in parallel. Immunocytochemistry was used to identify the expression of cell markers after 6-7 days of differentiation. The majority of cells in each group were still Nestin-positive. MAP-2-positive cells were significantly increased in all experimental groups, while no difference in the number of MAP-2-positive cells was observed either among 3 experimental groups or between 2 control groups. GFAP expressions were similar in all the groups. MBP-positive cells were seldom observed in each group. It indicated that ATRA could enhance the differentiation of EGF-responsive NSCs into cell phenotype of neurons. At the concentration of 10 ng/ml, neither BDNF nor GDNF had significant synergistic effect with ATRA in promoting the differentiation of NSCs. [J Physiol Sci. 2007;57 Suppl:S176]