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Neural Stem Cells
An Overview
Rossella Galli, Angela Gritti, Luca Bonfanti,
Angelo Luigi Vescovi
From the Stem Cell Research Institute (R.G., A.G., A.L.V.),
DIBIT, Hospital San Raffaele, Milan, Italy; and the Department of Veterinary
Morphophysiology (L.B.), Rita Levi Montalcini Center for Brain Repair,
University of Turin, Grugliasco, Italy.
Correspondence to Angelo Luigi Vescovi, Stem Cell Research Institute, DIBIT,
Hospital San Raffaele, Via Olgettina 58, Milan, Italy, 20132. E-mail
vescovi.angelo@hsr.it.
This review focuses on the nature and functional properties of
stem cells of the adult mammalian central nervous system (CNS).
It
has recently been shown that cell turnover, including neurons, does
occur in the mature CNS, thanks to the persistence of precursor cells
that possess the functional characteristics of bona-fide neural stem
cells (NSCs) within restricted brain areas.
We discuss how the
subventricular zone of the forebrain (SVZ) is the most active
neurogenetic area and the richest source of NSCs.
These NSCs ensure a
life-long contribution of new neurons to the olfactory bulb and, when
placed in culture, can be grown and extensively expanded for months,
allowing the generation of stem cell lines, which maintain stable and
constant functional properties.
A survey of the differentiation
potential of these NSCs, both in vitro and in vivo, outlines their
extreme plasticity that seems to outstretch the brain boundaries, so
that these neuroectodermal stem cells may give rise to cells that
derive from developmentally distinct tissues.
A critical discussion
of the latest, controversial findings regarding this surprising phenomenon
is provided.
Key Words: stem cells, transdifferentiation, neurogenesis
© 2003 American Heart Association, Inc.
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