Society-funded Study Shows Evidence of Nerve Regeneration within MS Lesions

A study of brain tissue obtained from nine people with MS shows that, while many areas of damage show expected loss of myelin and nerve cells, a few older lesions showed a 72% increase in nerve cells when compared with neighboring brain regions. Authors Bruce Trapp, PhD, Ansi Chang, MD, and colleagues (Cleveland Clinic Foundation) believe their findings support the possibility that nerve cells in the white matter of the brain can be replaced after they are destroyed by MS. The report appears in an early online issue of Brain (July 23, 2008). The study was funded by the National MS Society and the National Institutes of Health.

Background:

MS occurs when the immune system attacks the brain and spinal cord. Although damage to nerve fiber-insulating myelin is a hallmark of this attack, increasing evidence indicates that it is actually the damage to nerve fibers themselves that leads to the progression of disease and the disability experienced by many people with MS. Researchers are looking for ways to stop this progression, in some cases, by tapping into the body’s capacity for self-repair.

The Study/Results:

Dr. Trapp’s team obtained brain tissue samples from nine people with MS and four people without MS via autopsy. In the MS brains they identified seven acute, or newly active, lesions (areas of myelin damage or inflammatory disease activity) and 59 chronic or long-standing lesions. In all seven acute lesions and 44 of the chronic lesions, the density of nerve cells was markedly reduced, documenting the destruction of nerve cells along with myelin. However, in 15 of the chronic lesions, nerve cells were increased by 72% compared with neighboring brain regions. The nerve cells showed signs of being fully mature, and these lesions also had increased densities of immature nerve cells. They also noted an increase in activated microglia, brain cells that – paradoxically – spur on the immune attack in MS but have recently been shown to promote nerve cell development.

In exploring a possible source for the regenerating nerve cells found in the lesions, the team found evidence that they originated in part from bordering “subventricular zones” of the brain, areas where cells originate during brain development.

This is a groundbreaking, basic research finding that adds to growing information on the ability of the brain to rebuild itself. Much further research is necessary to determine how well these identified nerve cells function, and how they might be harnessed in future therapeutic strategies aimed at restoring function in people with MS.