Can myelin be re-grown?

A Mayo Clinic research team led by Dr. Moses Rodriguez reported success promoting regrowth of myelin in laboratory mice with TMEV, a viral disease that causes damage in the spinal cord similar to MS. The mice were given injections of immune-system proteins called antibodies. Some of these were "pooled" antibodies or immunoglobulins--which are found in the bloodstream and are part of the normal human immune system. Others were monoclonal antibodies, meaning they were clones (or exact copies) of unique antibodies created through biotechnology. Mice treated with pooled antibodies and with certain monoclonal antibodies showed signs of increased myelin repair in their spinal cords.

This is another small but important step toward developing a therapy that might restore the functions MS steals away

Remyelination

MS symptoms are caused by damage to myelin, a substance that insulates nerve fibers in the brain and spinal cord. When myelin is damaged, the affected nerves can't conduct efficiently. Although the body can repair myelin, in MS the repair is insufficient, and nerve fibers tend to acquire scarring. The underlying nerve may be injured as well.

If myelin could be regrown or more completely repaired before the underlying nerve is permanently harmed, the nerve might work normally--and the person might recover lost functions. Thus, research on remyelination is the logical partner to research on treatments to stop MS damage from occurring in the first place.

Lab animals only

The Mayo results are in lab animals only; the treatments have not been tried in MS. Nevertheless, the report, published in the June issue of Proceedings of the National Academy of Sciences, has drawn a great deal of attention. The development of specific monoclonal antibodies that target the oligodendrocytes, the cells that make and maintain myelin, raises the possibility of an effective remyelination therapy Scientists had previously observed that a variety of diseases, including MS, respond to treatment with immunoglobulin-G, which regulates the immune system and seems to play a part in spurring regrowth of myelin. (That therapy is called IVIg.)

The Mayo team received support from the Society and from Acorda Therapeutics, a biotechnology company Acorda is now planning all the work that must be done before the first pilot safety trials in people with MS can start. The company must first complete studies on potential toxicity and drug activity in the body (or pharmacokinetics). They also need to devise ways to manufacture a large enough supply of the antibodies to conduct human trials.

For more information about the Mayo research, visit their Web site <www.mayohealth.org> or Acorda Therapeutics at <www.acorda.com>.