Astrocytes are the most abundant cell type in the adult central nervous
system (CNS), and their functional diversity in response to injury is
now being appreciated. Astrocytes have long been considered the main
player in the inhibition of CNS repair via the formation of the gliotic
scar, but now it is accepted that astrocyte can play an important role
in CNS repair and remyelination. Interest in the relationship between
astrocytes and myelination focused initially on attempts to understand
how the development of plaques of astroglial scar tissue in multiple sclerosis
was related to the failure of these lesions to remyelinate. It is now
considered that this is an end stage pathological response to injury,
and that normally astrocytes play important roles in supporting the
development and maintenance of CNS myelin.
Astrocytes are therefore not considered a barrier to myelination as they once were, but remyelinating a lesion with astrocytic scars is still a grand challenge.