Transcriptional Characterization of Glioma Neural Stem Cells Diva ...

2.2 Neural Stem Cells Introduction
with immunochemical and electrophysiological properties of mature neurons.
Importantly, even after prolonged expansion, NS cells maintain their potential
to differentiate efficiently into neurons and astrocytes in vitro as well as upon
transplantation into the adult brain [107]. To promote oligodendroglial differ-
entiation cells were cultured on laminin coated dishes in medium containing
N2 supplement plus FGF2, PDGF and forskolin, a growth factor combination
known to enhance oligodendrocyte progenitor proliferation, which efficiently
differentiated NS cells into oligodendrocytes [165]. To summarise the charac-
terisation of the mouse NS cell lines derived by Conti et al:
· they express the astrocyte differentiation marker GFAP upon addition
of serum or BMP4 and differentiate into astrocytes;
· they express neuronal markers type III β-tubulin (TUBB3), Microtubule-
associated protein 2 (MAP2) and ERBB2 upon removal of EGF and
FGF2 (in this order) and differentiate into neurons. All NS cell lines
produced in the study by Conti et al were electrophysiologically active
and exhibited voltage-gated Na + and Ca 2+ conductance, typical of ma-
turing nerve cells;
· they show no significant decline after many passages and retain diploid
chromosome content throughout late passages, maintaining intact the
differentiation potential in both the neuronal and glial direction;
· they do not form teratomas 31 , an important step towards the confirma-
tion of the identity of NS cells. Unlike ES cells, in fact, the differentiation
potential of NS cells is incapable of teratoma formation and this obser-
vation was reproduced in an experiment by Conti et al [107] in which NS
cells were transplanted in mouse fetal and adult brain and grafted onto
mouse kidney, where they did not proliferate or give rise to teratomas.
The absence of any histological evidence of unregulated proliferation or
tumor formation was a clear confirmation of the identity of the NS cells.
Although the NS cell lines generated via the niche-independent NS cell protocol
are capable of differentiating into all three lineages of the CNS, i.e. astrocytes,
oligodendrocytes and neurons, the neuronal subtypes are limited to the gen-
eration of large amounts of GABAergic neurons 32 according to the results by
31 Encapsulated germ cell tumor derived from pluripotent cells with tissue or organ components
resembling normal derivatives of all three germ layers.
32 Neurons that release the main CNS inhibitory neurotransmitter GABA.
47