Radical new drug can reverse effects of MS in just weeks

The breakthrough raises the prospect of new drugs for the debilitating condition which affects 2.5million around the world including 85,000 Britons.

The symptoms of MS, which range from clumsiness to paralysis, are caused by "friendly fire" from the body's immune system.

This destroys myelin, the fatty protective sheath around nerve fibres in the brain and spinal cord.

Over time, the nerves become scarred and the transmission of signals is disrupted.

Existing drugs can ease symptoms, but they are not suitable for all and there is no cure for the condition. They involve calming down the immune system and reducing damaging inflammation.

Finding a way to repair damaged myelin is the 'holy grail' of MS research.

Now, American scientists have succeeded in using a human antibody to re-grow myelin in mice with multiple sclerosis.

Myelin repair normally occurs in the body spontaneously. But in MS and other disorders of the central nervous system the process is very slow or fails altogether.

The scientists found that a single low dose of the antibody was enough to kickstart the repair mechanism in mice.

The antibody drug was also effective when given in combination with the MS drug methylprednisolone.

The mice had the progressive form of the disease, in which the illness gradually worsens without any periods of remission.

Yesterday, the scientists who genetically engineered the healing antibody described their results as "very promising".

Dr Arthur Warrington, one of the team from the Mayo Clinic in Rochester, Minnesota, said: "The findings could eventually lead to new treatments that could limit permanent disability."

Trials on humans are expected to allow further animal experiments.

British experts cautioned that the drug is still many years from the doctor's surgery.

Dr Laura Bell, of the MS Society, said: "Myelin repair is an exciting avenue of research that holds a lot of promise, which is why we have invested more than £3million in it at our research centres in Cambridge and Edinburgh.

"This is an exciting study but it is early days - we'll be keen to see how it works in people with MS."

Some MS patients suffer mild, intermittent symptoms for decades, while others steadily worsen, becoming blind or paralysed.

The discovery this year of two genes that increase the risk of MS was hailed as one of the biggest breakthroughs in fighting the condition in 30 years.