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Gel holds promise for spinal cord healing

by Kelly Williams
April 08, 2008

Related Links

"Self-Assembling Nanofibers Inhibit Glial Scar Formation and Promote Axon Elongation after Spinal Cord Injury" - The Journal of Neuroscience The Mayo Clinic National Spinal Cord Injury Statistical Center (NSCISC) University of Alabama National Spinal Cord Injury Statistical Center

U.S. Statistics on Spinal Cord Injuries

• Approximately 11,000 new spinal cord injuries occur each year

• 52 percent of individuals with spinal cord injuries are considered paraplegic and 47 percent quadriplegic

• Average lifetime costs for paraplegics (age of injury 25): $428,000

• Average lifetime costs for quadriplegics (age of injury 25): $1.35 million

• Highest per capita rate of injury occurs between ages 16-30

• Average age at injury: 33.4

Sources: National Spinal Cord Injury Statistical Center, University of Alabama National Spinal Cord Injury Statistical Center

After his daughter became paralyzed from the waist down in a skiing accident, Dr. John Kessler decided to dedicate his life to finding a way for his daughter to walk again.

One of the main obstacles to recovery and potential prevention of paralysis from spinal cord injuries is scar tissue that forms and impedes the ability of the spine to heal itself.

But a gel Kessler developed with colleagues from Northwestern University and the University of Toronto significantly slows scar tissue formation when injected at the site of an injury and promotes spinal cord fiber regeneration in mice.

The scientists are now in the planning stages of redeveloping the gel for the FDA approval process and human testing, according to Kessler, chairman of the department of neurology and director of the Clinical Neuroscience Research Institute at Northwestern University’s Feinberg School of Medicine.

The results were published this month in the Journal of Neuroscience.

The study, completed at Northwestern University, was conducted approximately 10-15 times on rats and on two different strains of mice, according to Vicki M. Tysseling-Mattiace, one of Northwestern’s lead researchers on the study and a physical therapist. The mice were injected one time after the injury occurred at multiple sites around the injury.

In the real world, Kessler said that a patient needs time to get to the hospital, to stabilize, to consent to surgery and to prepare for major spinal cord surgery. As a result, in the study, the researchers waited 24 hours to inject the mice with the gel.

Once injected, the gel generates a semi-stable structure, much like scaffolding, that supports the spine while it repairs itself. “The whole idea is self-assembly,” said Kessler.

Then the gel dissolves at a point when, optimally, healing will have already occurred, according to Kessler.

Spinal cord injuries depend on two factors: the location of the injury and the severity of the injury. Kessler and his colleagues, to make the study completely standardized, gave each mouse the injury equivalent to the most severe possible spinal cord injury, “basically deliberately severing the spinal cord.”

The regeneration of spinal cord fibers occurred between 2 to 11 weeks after injury and injection. This would be equivalent to many months if the same growth rate was to be observed in human beings, according to Kessler. Also important to the success of the gel with humans is the rate at which the structure breaks down, meaning the gel being redeveloped for human use needs to last longer.

The researchers did not observe any negative side effects as a result of the injection, according to Kessler.

Because of the success of the study, the group is now in the process of planning to redevelop the gel so that it can be acceptable to the FDA and then be tested on human subjects. Kessler is not sure how long this process will take.

“The redeveloped gel needs to be tested to make sure it works as well as the original gel,” Tysseling-Mattiace said. “There may be several stages of experiments that the FDA will require before humans can be tested.”

Another factor doctors battle in spinal cord injury is the inflammation that follows, causing additional damage, Tysseling-Mattiace said.

Impeding doctors also, according to Tysseling-Mattiace, is the inability to pinpoint the precise location of injury. Current imaging technology doesn’t allow doctors to see past the combination of scar tissue, inflammation and spinal shock symptoms that often complicate diagnosis and treatment, she said.

Kessler and co-researcher Samuel Stupp have founded Nanotope, a company to eventually develop commercial applications of the self-assembling gel. Stupp, one of the authors of the article, is a professor of materials science, chemistry and medicine at Northwestern and director of the university’s Institute for BioNanotechnology in Medicine.

The success rate of translating successful studies on mice to human subjects is small, Kessler said. Experiments with the goal of creating treatments are wrong more times than they are right, he added. But he compared it to baseball: “The batting average is not exceptionally high. But I always say to my students, if you bat .320 you end up in the Hall of Fame.” Success every time is unrealistic, said Kessler.

The study results have the potential to be very promising for victims suffering from new injuries, but Kessler remains adamant about developing similar treatments to help victims, like his daughter, who suffer from chronic spinal injury.