Scientists Uncover Reasons on Failure of Myelin Repair

Scientists have uncovered further evidence how damage to the nerve cells in people with multiple sclerosis accumulates due to the body’s failure to effectively repair the myelin sheath. The new evidence suggests that the body’s own natural mechanism may somehow stall in its ability to repair damaged myelin in the nerve fibers over time. This can result in a more rapid progression of the disease which brings about several symptoms to worsen in people with MS.

Myelin is the substance found surrounding the nerve fibers in the central nervous system. It acts as an insulating material that protects the nerve cells, allowing them to send and receive signals from the brain and to the other parts of the body. In multiple sclerosis, the body’s immune system may suddenly mount an attack on the myelin sheath, doing great damage to it. Damage to myelin can greatly hamper the effective functions of the nerve cells that may lead to the symptoms associated with diseases such as multiple sclerosis.

The study, conducted by researchers from the University of California in San Francisco and the University of Cambridge, uncovered clues as to how the body’s own ability to repair cells such as myelin may stall and lead to the myelin unable to function more effectively. The study that was conducted on both mice and human tissue showed that the repair to the nerve fibers may be hampered by certain biochemical signals that inhibit the development of cells called oligodendrocytes. These cells function as the body’s repair workers.

It is the oligodendrocytes that help form the myelin sheath in the fibrous cables known as axons in the nerve cells. In multiple sclerosis, the body’s immune system’s T cells and the B cells attack the oligodendrocytes. Eventually, the myelin sheath thins out until such a time where it no longer is able to provide insulation to the nerve fibers and brings about certain disruptions on nerve signals which lead to the symptoms associated with MS.

At some point, point the brain might still be able to get fresh and immature oligodendrocytes to try and repair the damage on the myelin sheath. But this might only occur up to a certain time. This might help explain why one common form of multiple sclerosis, relapsing-remitting MS, may have symptoms that can suddenly disappear or become greatly reduced for months and even years, only to appear again.

The study helped the scientists uncover certain genes which contribute to the different stages of the body’s cell repair process. The scientists also uncovered that a cascade of biochemical events called the Wnt pathway may play a role in the delay of the repair process undertaken by the oligodendrocytes. The scientists hyper-activated the Wnt pathway in mice which caused quite a substantial delay in cell repair activity usually made by the oligodendrocytes. The Wnt pathway may be causing a roadblock that may delay the oligodendrocytes from repairing the damaged myelin sheath.


University of California – San Francisco. "Why Repair Of Brain’s Wiring Fails." ScienceDaily 1 July 2009. 7 July 2009

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