Why is the adult mammalian central nervous system unable to regenerate damaged axons? Scarring of glial tissue may be a factor, according to Jerry Silver and his colleagues at Case Western Reserve University School of Medicine. The researchers devised a way to inject minute quantities of neuronal tissue into the adult rat CNS with the minimum of trauma. The extent to which axons regenerated turned out to correlate with increased levels of proteoglycans within the extracellular matrix at the transplant site. Proteoglycans are associated with glial scarring. These results suggest that reactive glial extracellular matrix is directly associated with failure of axon regrowth in living animals and, more positively, that adult nerve tissue beyond the glial scar can support regeneration of axons. This work might help shed new light on a possible role for glial scarring in Alzheimer's disease.—June Kinoshita
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- Davies SJ, Fitch MT, Memberg SP, Hall AK, Raisman G, Silver J. Regeneration of adult axons in white matter tracts of the central nervous system. Nature. 1997 Dec 18-25;390(6661):680-3. PubMed.