5-Azacytidine and BDNF enhance the maturation of neurons derived from EGF-generated neural stem cells

EGF-generated neural stem cells can form astrocytes, neurons, and oligodendrocytes upon differentiation; however, the proportion of cells that actually form neurons is very small. In the present study, we have studied the effect that 5-azacytidine (5AzaC), a demethylation agent, and brain-derived growth factor (BDNF) have on the differentiation and maturation of neurons originating from EGF-generated neural stem cells. Stem cells were maintained under a variety of culture conditions using combinations of 5AzaC and BDNF either alone or together. More neurons, as determined by the number of beta-tubulin III-immunoreactive somata, were present in cultures maintained in BDNF medium (a nearly fourfold increase compared to control cultures). 5AzaC did not significantly affect neuronal number, regardless of the presence of BDNF. In addition to neuronal number, the effect of 5AzaC and BDNF on the distribution of the microtubule proteins MAP2 and Tau was analyzed. In most cultures, MAP2 and Tau were colocalized throughout the neuron. In contrast, neurons cotreated with 5AzaC and BDNF contained neurons that began to exhibit cytoskeletal segregation of MAP2 into the somatodendritic compartments. Tau remained dispersed within the somata and the axon. This effect was not produced when 5AzaC or BDNF was used individually. These results demonstrate that 5AzaC and BDNF cooperate to produce more mature neurons from EGF-generated neural stem cells then either molecule can alone.