MS Nerve Cell Damage Explained Through New Evidence

Woman in WheelchairA study recently conducted has uncovered a probable reason why damage to nerve cells done by multiple sclerosis seems to accumulate over time. Researchers from the University of California, San Francisco and University of Cambridge have conducted a study that suggests the body’s own mechanism to repair damaged myelin seems to slow down in people with MS.

The study, which was conducted analyzing both mice and human tissue, showed that the repair of nerve fibers is hampered by certain biochemical signals that inhibit the development of oligodendrocytes, cells that function to repair other cells in the brain. They are also used by the body to form myelin, a protective sheath that forms around the fibrous strands radiating from nerve cells and act as effective insulators. Damage to this protective sheath can lead to electrical signal disruptions among the nerve cells.

In people with multiple sclerosis, the body’s immune system starts attacking the oligodendrocytes until it does considerable damage to the myelin sheath, leading to various symptoms associated with MS. When this occurs, the brain may still be able to recruit and call upon fresh and immature oligodendrocytes to the myelin sheath in order to repair the damage. This might be a possible explanation why the most common form of the said disease, the relapsing remitting MS, undergoes a certain period where symptoms may disappear or may be greatly reduced for months or years at a time. This might only happen until the repair process fails and the disease progresses further.

In order to find out whey the repair process ultimately fails in people with MS, the researchers went on to find out more about the key stages involved in how the body tries to repair damaged myelin as well as the genes that play a significant role during the repair. Eventually, the researchers focused on the gene called Tcf4 primarily because it is usually seen strongly in areas of damage and where repair attempts are underway. This gene is seen to be involved in a series of biochemical events known as the Wnt pathway which play a significant role in the development of tissues including the brain. It is only now that researchers believe the pathway to also have a role in the progress of MS.

In order to further study the role of the Wnt pathway in MS, researchers tried hyper activating it in the oligodendrocytes in mice which led to a considerable delay in the repair process in mice. Although the animals showed evidence of repair, the process was delayed as compared to those in normal mice. The presence of the gene Tcf4 was also tested in human tissue and researchers found the said protein were found in areas damaged by Ms and not on normal and healthy tissue. Other previous studies were also examined and the researchers found that many of the signaling molecules of the Wnt pathway become overactive in lesions found on patients with MS.

Source:  University of California – San Francisco. "Why Repair Of Brain’s Wiring Fails." ScienceDaily 24 August 2009. 1 September 2009

 
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