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Gene therapy helps repair myelin in brain tissue

Scientists at the California Institute of Technology demonstrated the ability to repair damage done to myelin of cells in the brain using an investigational gene therapy. This development suggests a possible treatment for certain diseases like multiple sclerosis that target myelin. This study was published in the February issue of The Jour­nal of Neuroscience.

Multiple sclerosis is a debilitating neu­rological disease that is characterized by destruction of myelin found around parts of cells (neurons) in the nervous system. This incapacitating ailment can be attributed to a rogue immune system, mistakenly attacking the person’s own myelin. Without myelin, the nerves are less capable of sending sig­nals throughout the body and become prone to damage.

Currently, most treatment options for multiple sclerosis are centered on pre­venting further damage from the immune system, typically by suppressing its activity. Since symptoms of the disease are caused by myelin damage, additional medications are usually used.

Leukemia inhibitory factor (LIF), a key protein found in the brain, is capable of increasing the number of cells that can repair myelin in the body. Since natural amounts aren’t enough to stop the disease from progressing, the scientists believe that LIF could potentially reverse damage done if given in high enough amounts.

In order to test this, the researchers used a “gene therapy” to cause certain cells to release more LIF. Gene therapies are a relatively new advancement that changes how cells in the body produce certain proteins and divide. This is usually done by changing the DNA, allowing researchers to regulate the body externally.

However, changes to the DNA of cells are a difficult maneuver, requiring some way to deliver and place new DNA into the cell. In this case, the scientists used a virus incapable of causing disease to allow higher amounts of LIF to be produced. Mice that display traits of multiple sclerosis were infected with the virus to test its effects. Currently there are no similar therapies used in conventional medicine.

The scientists found that by causing temporary increases in LIF, the amount of cells capable of regenerating myelin were brought levels up close to where they are in a normal individual. By using high amounts of LIF over a short time, it appeared that the myelin damage was successfully reversed without affecting brain tissue.

When given over a prolonged time, it appeared LIF showed some negative effects on certain cells in the brain. Therefore, it appears that scientists have to fall within a certain time frame for the therapy to be effective.

Despite the encouraging result, the re­searchers only considered how much myelin was present rather than evaluating whether the therapy works to reverse symptoms of multiple sclerosis. The scientists hope that further studies will push the therapy into hu­man clinical trials.

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