Multiple sclerosis (MS) is characterized by widespread multifocal demyelination and axonal loss, causing paralysis, blindness, loss of sensation, and a lack of coordination. Current disease-modifying strategies are primarily aimed at preventing further autoimmune destruction, but little can be done to reverse symptoms once the demyelination is established. In the April 17 Nature, Stefano Pluchino and colleagues at San Raffaele Hospital, Milan, Italy, show that injection of adult neurospheres in mice can induce recovery of demyelination in a chronic model of MS (Nature, 422:688-694, April 17, 2003).

Pluchino et al. grew in vitro neural stem cells labelled with the expression of the Escherichia coli b-galactosidase (b-gal) gene (lacZ) and injected them (intravenously or intracerebroventricularly) into mice with experimental autoimmune encephalomyelitis (EAE). They observed that in both cases, significant numbers of donor cells entered into demyelinating areas of the central nervous system and differentiated into mature brain cells. Within...