The main cause of multiple sclerosis is that components of the body’s own immune system (chiefly T cells foreign to the CNS) attack and damage the myelin of neurons. Although axon loss is a later symptom of the disease, it is secondary to the demyelination process. This suggests that in order to find a cure, scientists need only reverse the degeneration of myelin, a challenge to be sure but one that does not compare to the Herculean task of re-establishing axonal connectivity in functional circuits.
Yang et al recently reviewed the current research into cellular therapy for remyelinating the damaged tissue. One of their suggestions is that since some amount of remyelination in already occurs (with inter-patient variability), it is likely that scientists will be able to catalyze or otherwise enhance the natural system, which may be easier than designing a new, artificial repair system.
There is preliminary evidence that oligodendrocyte lineages, Schwann cells, olfactory ensheathing cells, and/or various stems cells may be able to restore nervous system function in rodent models. However, there are at least three major challenges: 1) If stem cells are used, their differentiation will have to be controlled so that tumor formation is mitigated, 2) The existing scarring at lesions will make the repair process more difficult for the transplanted cells, and 3) The route of administration of the cells will take time to perfect, since multiple sclerosis takes affect in disparate parts of the brain.
Overall, this research is an example of the tremendous potential of neural engineering, and the amount of work that will need to be put into it in order to reach that potential.
Yang, J, et al. 2009 Cellular remyelinating therapy in multiple sclerosis. Journal of the Neurological Sciences 276: 1-5. doi:10.1016/j.jns.2008.08.020.