Out with the old, in with the new

Muraro et al., reporting on page 805, use stem cell transplants to suppress active multiple sclerosis (MS), and then show that the treatment increased the number of naive T cells at the expense of the memory T cells that are associated with disease.

Intense immunosuppression followed by stem cell transplantation has been shown to slow or stop the formation of new brain lesions in up to 95% of patients with aggressive MS. Yet it has been controversial and rarely used, mainly because immunosuppression is risky and because nothing was known about how transplantation induced remission. One proposed theory was that transplantation might change the composition of the T cell pool and bias it away from autoreactivity.

Muraro and colleagues now provide the first evidence that stem cell transplantation allows patients to regenerate...