NG2-Expressing cells in the central nervous system: Are they oligodendroglial progenitors?

Antibodies against the chondroitin sulphate proteoglycan, NG2, are increasi ngly being used to identify the widespread population of oligodendrocyte pr ogenitor cells in the adult mammalian CNS. However, the specificity of this marker and the role of NG2-expressing cells in CNS function ave still open to question. In this review we consider the evidence that NG2(+) cells in the CNS are part of the oligodendrocyte lineage and whether they can give r ise to new oligodendrocytes following demyelination. in both the developing and mature rodent CNS, NG2(+) cells express the established oligodendrocyt e lineage marker PDGF-alpha R and from P7, the late progenitor antigen O4, which persists in immature oligodendrocytes. They do not express markers of other CNS populations, such as OX42 or GFAP, at any developmental age. NG2 (+) cells represent the major cycling cell population in the normal adult r at CNS, suggesting they have stem cell-like properties. NG2 immunoreactivit y is upregulated as a result of physical, viral, excitotoxic and inflammato ry insults to the CNS. Following demyelination NG2(+) cell number increases in the immediate vicinity of the lesion and rapid remyelination ensues. NG 2 expression has also been investigated in human tissue. Multiprocess beari ng cells, which morphologically resemble those identified with antibodies a gainst O4, persist in chronically demyelinated multiple sclerosis lesions. (C) 2000 Wiley-Liss, Inc.