A FOUNTAIN of youthful cells reverses the damage found in diseases like multiple sclerosis, a study in mice reveals.

Nerve cells lose their electrically insulating myelin sheath as MS develops. New myelin-generating cells can be produced from stem cells, but the process loses efficiency with age.

Julia Ruckh at the University of Cambridge, and colleagues, have found a way to reverse the age-related efficiency loss. They linked the bloodstreams of young mice to old mice with myelin damage. Exposure to youthful blood reactivated stem cells in the old mice, boosting myelin generation.

White blood cells called macrophages from the young mice gathered at the sites of myelin damage. Macrophages engulf and destroy pathogens and debris, including destroyed myelin (Cell Stem Cell, DOI: 10.1016/j.stem.2011.11.019)