An experimental drug being tested in dogs with spinal cord injuries could one day help humans, too.
In a study funded by the U.S. Department of Defense, researchers are testing the drug called GM6001 in dachshunds and other long-bodied dogs with spinal cord injuries. They hope it will help the dogs walk again and lead to desperately needed human treatments.
"It's an opportunity to improve the outcome for these dogs and, at the same time, show that this is a good drug," said study co-investigator Linda Noble-Haeusslein, co-director of the UCSF Brain and Spinal Cord Injury Center.
In 2006, Noble-Haeusslein found that GM6001 helped mice recover from spinal cord injuries. The drug works by blocking an enzyme that infiltrates the spinal cord after the injury and propagates the damage.
"After you have a spinal cord injury, the deficits you see are not just a consequence of the initial injury, but rather events that occur after the injury," said Noble-Haeusslein. "These events are a little more delayed in onset, so we have the possibility of preventing them."
A spinal cord injury causes paralysis as well as respiratory, urinary and gastrointestinal complications by cutting the wires of the nervous system. As many as 200,000 Americans have a spinal cord injury, according to the U.S. Centers for Disease Control and Prevention. And no drug has been found to improve the prognosis.
To test the effects of GM6001 in a natural model of spinal cord injury, Noble-Haeusslein teamed up with Jonathan Levine, a veterinarian and assistant professor of neurology at Texas A&M College of Veterinary Medicine and Biomedical Sciences, for a canine clinical trial.
"At Texas A&M, we see almost 200 dogs with spinal cord injuries every a year," said Levine, adding that in dogs, as in humans, the injuries vary in severity. "The kinds of processes we see in these dogs are probably very similar to those in people with traumatic spinal cord injury."
The researchers plan to enroll 80 dogs over three years. Half will receive an injection of GM6001 under their skin as soon as their owners bring them in; the other half will receive a placebo. Levine suspects about half the dogs will be dachshunds -- better known as wiener dogs -- which are particularly prone to spinal cord injuries because of their long bodies and short legs.
A pilot trial of GM6001 in dogs found the drug was safe. But the new study, funded by a $750,000 Department of Defense grant, aims to show it works, too. If it does, it could lead to similar treatments for the 20,000 Americans who suffer spinal cord injuries each year, many of whom are soldiers. But timing is everything.
"You want to do this as quickly as possible," said Noble-Haeusslein, adding that 24 hours after a spinal cord injury might be too late for the drug to work. The drug will not ease the symptoms in people with established spinal cord damage.
For the dogs and their owners, the study is a shot at a better life. The drug won't reverse the spinal cord injury, but it might help a dog maintain the ability to bear weight or even walk. Levine said physiotherapy is also important for these pet patients.
"Physical rehabilitation is amazingly helpful in the recovery process. It gets these dogs up and moving and prevents them from losing muscle mass," he said.
Like humans, dogs can get assistive devices like wheelchairs and slings.
"The goal is to prevent dogs from dragging themselves around and to allow better mobility at home," Levine said.
If the study offers clues for treating human spinal cord injuries, it will add weight to the moniker, "man's best friend."
"The wonderful thing about this program is it's another example of the close relationship between dogs and people. We share an emotional bond and some biological similarity," said Levine. "It's a way humans can help dogs and dogs can help humans."