Transcriptional Characterization of Glioma Neural Stem Cells Diva ...

2.2 Neural Stem Cells Introduction
proliferative defects. However, a subpopulation of cells was able to expand
continuously without Pax6, retaining the progenitor markers but displaying
an altered capacity to differentiate into astrocytes and oligodendrocytes, high-
lighting the role of Pax6 beyond neurogenic competence. The findings by this
study, therefore, suggest that Sox2 and Pax6 are both critical for self-renewal
of differentiation-competent radial glia [169].
Time-lapse videomicroscopy of the NS cells derived by Conti et al [107] also
demonstrated that cell nuclei of those NS cells undergo interkinetic nuclear
migration, a well-characterised feature of NEP and radial glia cells in vivo.
Importantly, the mouse fetal brain, human ES cell and human fetal cortex-
derived NS cells, expressed the same radial glia and neurogenic markers as the
mouse ES cell-derived NS cells, although the human cells exhibited moderate
levels of GFAP, consistently with the known activity of the human GFAP pro-
moter in radial glia and unlike the very feeble expression observed in mouse NS
cells [310,418]. Human ES cell and fetal cortex-derived NS cells also proliferate
more slowly than the mouse-derived ones, like in neurospheres, and after se-
quential withdrawal of EGF and FGF2, generate mixed populations of TuJ1 +
neuron-like cells and GFAP + cells, with pure populations of cells with typical
astrocyte morphology and intense GFAP immunoreactivity readily produced
after exposure to serum [107].
In a separate study, Sun et al [481] report the derivation and characterisa-
tion of human NS cell lines from human fetal cortex and spinal cord using
a continuous adherent procedure that is more efficient than allowing primary
cells to form neurospheres and subsequently isolating NS cells, as described
in the protocol by Conti et al. In the protocol developed by Sun et al, pri-
mary cells are seeded onto laminin coated dishes in growth medium containing
both EGF and FGF2. In these conditions cells readily attach and produce
a morphologically heterogeneous population containing both Nestin + neural
precursors and Tuj1 + neurons. In order to enrich for undifferentiated neural
precursors, the cells are temporarily transferred onto gelatin coated dishes, in
which conditions neurons and committed neuronal progenitors fail to survive.
Three weeks after initial plating, the primary human culture is homogeneously
Nestin + and Tuj1 - [481].
Once established, human NS cells can be expanded continuously in monolayer
culture where they homogeneously express immature neural precursor markers
Nestin and Sox2. The long-term expansion of these cells can also occur suc-
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