Human neural stem cells transplanted into the brain can improve the functioning of nerve cells by supplying myelin — which sheathes neurons and aids electrical signalling — according to two independent groups.

David Rowitch at the University of California, San Francisco, and his colleagues transplanted the stem cells into four young boys with a genetic disease in which support cells known as oligodendrocytes fail to wrap neurons in myelin. A year after injection, magnetic resonance imaging (MRI) indicated that the transplanted cells had engrafted and had successfully myelinated brain cells.

Researchers led by Stephen Back at Oregon Health and Science University in Portland and Nobuko Uchida at StemCells Inc. in Newark, California, showed that the same type of stem cell matured into oligodendrocytes when transplanted into the brains of mice that lack myelin. The cells produced a myelin sheath that boosted the speed of neural signalling. The team also confirmed that MRI can track cell engraftment and myelination. Together, the studies indicate the potential for cell-based therapy in myelin disorders.

Sci. Transl. Med. 4, 155ra137; 155ra136 (2012);