US scientists have repaired the nerve damage caused by multiple sclerosis in lab experiments on mice.
Protective myelin is stripped away by MS
The team, from the Mayo Clinic in Rochester, hope their work will eventually lead to new treatments.
MS is caused by a defect in the body's immune system, which turns in on itself, and attacks the fatty myelin sheath which coats the nerves.
The researchers used a human antibody to re-grow myelin in mice with the progressive form of MS.
They told a meeting of the American Neurological Association they hope to begin patient trials after perfecting the technique further in animal tests.
MS affects around 85,000 people in the UK. Damage to the myelin coating undermines the ability of the nerves to work properly, leading to symptoms including blurred vision, loss of balance and, in some cases paralysis.
Although the symptoms can be managed to some degree, there is currently no way to restore damaged myelin.
Researcher Dr Moses Rodriguez said: "The concept of using natural human antibodies to treat disease of this kind has not yet been tested in humans, but these research findings are very promising".
His colleague Dr Arthur Warrington said: "The findings could eventually lead to new treatments that could limit permanent disability".
Myelin repair normally occurs in the body spontaneously, but MS appears to sabotage this mechanism.
The scientists found that a single low dose of the antibody - which was genetically engineered from a single cell - was enough to kick start it into action.
However, they found that the remyelination process reached a plateau after five weeks.
Tests also showed that the antibody worked even when combined with the steroid treatment which is often taken by people with MS.
Helen Yates, of the MS Resource Centre, said the findings were "very good news".
She said much emphasis in the research community had been placed on the search for a cure for the disease, but myelin repair could potentially help people regain previously lost function.
Dr Laura Bell, of the MS Society, said: "Myelin repair is an exciting avenue of research that holds a lot of promise as an MS treatment.
"This is an exciting study but it is early days - we'll be keen to see how it works in people with MS."
Chris Jones, of the MS Trust, also stressed that the work was at a very early stage.