Mainland research on stem cells could point the way to an effective treatment for Huntington's disease, an inherited incurable degenerative brain disorder. According to research published in the international journal Cell Stem Cell, a team of scientists, mostly from Shanghai and Beijing, were able to restore nerve circuits in the damaged brains of mice by injecting them with neurons cultivated from human embryonic stem cells. The lead author of the study, neuroscientist Dr Su-Chun Zhang from the University of Wisconsin-Madison, said the research was promising, but it would take much time and effort to work up from the mouse model to treatment for human Huntington's patients. Huntington's is a genetic disorder that affects movement and cognitive abilities. Patients degenerate gradually over an average of 15 years until they die. The disease is triggered when special cells known as Gaba projection neurons degenerate, destroying key nerve circuits in the brain. The scientists used human embryonic stem cells to produce large batches of these neurons and injected them into the brains of mice whose Gaba projection neurons had been destroyed. To their surprise, the new neurons not only meshed well with the mice brains, they also restored the nerve circuitry, improving their movement and co-ordination. Zhang said neuroscientists used to think that once the nerve circuits in the brain were damaged, it was impossible to re-establish them with transplanted cells. 'The implications of this study are important not only because they suggest it may one day be possible to use cell therapy to treat Huntington's, but also because it suggests the adult brain may be more malleable than previously believed,' he said. Dr Ma Lixiang, from Shanghai Medical College's department of anatomy, histology and embryology, said the team spent five years trying to find a reliable way to turn a high proportion of the stem cells into the Gaba neurons. 'Our target is a high proportion of this type of special Gaba neurons. We need to transplant them into brains. If there are few Gaba neurons, transplantation is pointless,' Ma said. The researchers injected about 80,000 neurons into each brain of 15 mice, noticing big improvements in the mice over the next few months. 'For example, just two months after the injections, mice with the Gaba neurons could run in a wheel for 40 seconds, up from 10 seconds before the injections,' she said. Ma said the team had already made stem cells from the skin cells of Huntington's patients and the next step was to alter the stem cells' genetic make-up. After that they would turn the stem cells into neurons to transplant them into animal and human brains. Huntington's affects about one person in every 10,000 in the West, but there are no statistics on its prevalence on the mainland, according to Ma. She said she had followed two families in Inner Mongolia who together had dozens of family members with the disease, and many stopped going to the doctor once they knew their condition could not be cured. 'The disease interferes with their ability to work because of the uncontrollable writhing movements and many have lost their jobs,' Ma said. 'At the last stage of their disease, all they can do is lie in bed and rely on relatives to take care of them every minute of the day.' The research appeared in the online version of the journal on March 16 and will be available in the paper version on April 6.