PARIS (AFP) - Stem cells transplanted into early-phase multiple sclerosis patients stabilised, and in some cases reversed, the debilitating neurological disorder, according to a study published Friday. Multiple sclerosis (MS) is an autoimmune disease that impairs movement and coordination, while causing muscle weakness, cognitive impairment, slurred speech and vision problems. Certain drugs can retard or roll back symptoms during in the initial phase of the disease's spread. But in the decade or more after onset, MS is characterised by gradual but irreversible neurological impairment. There is no known cure. In clinical trials, a team of scientists led by Richard Burt of Northwestern University in Chicago essentially rebuilt the immune system of 21 adults " 11 women and 10 men " who had failed to respond to standard drug treatments. First they removed defective white blood cells that, rather than protecting the body, attacks the fatty sheath, called myelin, that protects the nervous system. The immune systems were then replenished with so-called haemopoeitic stem cells " extracted from the patient's bone marrow " capable of giving rise to any form of mature blood cell. The technique is not new. But this was the first time it had been applied to young and relatively health individuals in the early, so-called "relapsing-remitting" phase of the disease. Participants had had MS for roughly five years. After an average follow-up period of three years, 17 of the 21 patients improved by at least one point on a standard disability scale, and none had a final score lower than before the stem cell transplant. The procedure "not only seems to prevent neurological progression, but also appears to reverse neurological disability," concluded the study, published in the British medical journal The Lancet. Cognitive functions and quality of life were improved, and the treatment had a low level of toxicity compared to other drug therapies. Five of the patients did relapse, but achieved remission after receiving other immunosuppressive therapy, the study noted. Further trials are needed using control groups to determine how effective the new approach may be, noted Gianluigi Mancardi of the University of Genoa in Italy. But "the results imply that this is a valuable alternative to the transplant conditioning therapies used so far," he wrote in a commentary, also in The Lancet. MS affects millions of people worldwide, including almost 100,000 in Britain and 400,000 in the United States.