Seeking a cure for ALS

February 23, 2006, vol. 35, no. 4
By Barry Shell

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When Charles Krieger is doing neurological testing at the G.F. Strong Rehab Centre's amyotrophic lateral sclerosis (ALS) clinic in Vancouver, his patients often ask, “Have you found a treatment yet? Is there a cure for my condition?”

Unfortunately there isn't. But Krieger, an associate professor of kinesiology, is working on it with his research team. The most common cause of neurological death in Canada, ALS is a progressive, fatal degeneration of motor neurons, killing the nerve cells that send messages to muscles.

Unable to function, the muscles gradually weaken, waste away, twitch and cramp. Paralysis begins with arms and legs, and becomes life threatening when it extends to muscles for breathing and eating. Half of ALS sufferers die within three years but a few may live for 30 years or more. The cause of ALS is unknown, but about 10 per cent of cases are of genetic origin involving a number of different genes.

One gene gets the most attention. Researchers around the world are trying to find out what goes wrong when the SOD1 gene suffers a mutation. Because of this, special transgenic mice containing mutated versions of the human SOD1 gene are available for research.

“Mutant SOD mice develop ALS-like symptoms similar to the human disease so they are a good model for studying ALS,” says Coral Lewis, a master of science graduate student working in Krieger's lab.

Lewis is studying how the blood-brain barrier, which protects the brain and spinal cord from foreign material, prevents the many disease-fighting cells of the human immune system from getting in, leaving the brain without the usual army of specialized cells to combat disease. To compensate, the brain and spinal cord have their own immune cells called microglia, which are capable of mounting an inflammatory response to foreign bodies or disease.

Scientists don't understand whether the microglia also promote nerve degeneration or whether they are involved in cleaning up the mess left when ALS causes nerve cells to die. Because of this duality, Krieger's research team is focused on determining the number and distribution of microglia cells in diseased mice.

Jennifer Solomon, a doctoral student in molecular biology and biochemistry, is another member of Krieger's research team. “I was initially interested in spinal cord injury and why nerves, once dead, can never re-grow,” says Solomon. Since peripheral nerves do have the ability to regenerate, she wondered why nerves inside the brain or spinal cord don't grow back. Her PhD thesis involves experiments to transport various growth factor genes across the blood brain barrier by embedding them in microglia. If Krieger and his team are successful, it could lead to a treatment of neurological disorders like ALS involving bone marrow transplants to deliver specialized disease-fighting cells to the brain.

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