December 1, 2006
A study by an international team of collaborators funded in part by the National MS Society suggests that a substantial amount of natural repair can occur to the myelin coating that insulates and protects nerve fibers in the brain and which is damaged by immune forces in people with MS. While previous studies had shown that natural myelin repair occurs in people with MS, this study found evidence of myelin repair, or “remyelination,” in a proportion of patients’ tissues across most types and stages of multiple sclerosis.
The study, published early online in the journal Brain (doi: 10.1093/brain/awl217; slated for December 2006 publication), was conducted by Drs. Peter Patrikios and Hans Lassmann (Medical University of Vienna) and was financed by the National Institutes of Health and the European Union, with additional support from the National MS Society’s “MS Lesion Project” led by Dr. Claudia Lucchinetti (Mayo Clinic).
The investigators examined autopsied brain tissues from 51 people who’d had MS in their lifetimes, including individuals with relapsing-remitting MS, secondary-progressive MS, primary-progressive MS and some with an unknown clinical course. Regions showing past or current disease activity, or lesions, were analyzed for signs of myelin damage (“plaques”) and repair (“shadow plaques”) using a variety of microscopic, staining and labeling techniques.
In about 20 percent of patients’ brains studied, remyelination was extensive, not only in those with the more common relapsing course, but also in those with progressive disease. The investigators found that the amount of remyelination ranged from sparse to nearly complete repair. Longer disease duration and older age at death were associated with more extensive remyelination. No link was found between the extent of repair and the age at onset, gender or type of MS.
When myelin is damaged, messages being sent along the underlying nerve fibers can misfire or be lost. Remyelination of nerve fibers is thought to restore function and also protect them from damage. Further research is required to uncover factors that determine why some individuals show highly efficient myelin repair while others do not. The investigators emphasize that their findings of variable rates of remyelination should be factored into the design of future clinical trials aimed at stimulating myelin repair.
-- Research and Clinical Programs Department
