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 Scientists
Reverse Paralysis in Dogs
by Rick Callahan, CNN News, December 2004
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Dogs with
paralyzed hind legs regained the ability to walk after getting a
shot of a chemical cousin of antifreeze that helped repair nerve
cells in their damaged spinal cords, scientists reported.
Purdue University researchers who led the project hope the
approach can soon be tried in people, but caution that there are
significant differences between human and canine spinal cords.
The treatment only worked on dogs given the injections within
about three days of their injury. Some dogs not given the
injections eventually walked again, but those getting the new
treatment had a dramatically higher recovery rate.
In one case, a dachshund named Oscar was initially sent home
with a wheel cart and little hope of recovery after a serious
injury.
Soon after the dog got the chemical treatment, he began walking,
although his back legs work in unison, giving him an unusual
gait.
"I used to make fun of him, saying he walks like a drunken
sailor," said Oscar's owner, Dan Paulin of Boonville, Ind. "I
don't think he'll ever be normal, but at least he's not confined
to the wheel cart."
In the study, 19 paraplegic dogs were injected with polyethylene
glycol, or PEG - a nontoxic liquid polymer composed of long
strings of the same type of molecules found in antifreeze.
Within eight weeks, 13 of the 19 canines, about 68 percent,
regained the use of their hind legs and were able to walk, some
almost as well as before their injury.
The dogs were injected twice with PEG, first soon after their
owners brought them to the researchers' labs and then after
standard surgery and steroids to reduce inflammation.
Among a group of 24 dogs that received just the standard surgery
and rehabilitation therapies, only about 25 percent regained the
same level of mobility, feeling and bodily functions, with about
62 percent remaining paraplegic.
The study's findings appear in the December issue of the Journal
of Neurotrauma.
Scientists at Purdue, Indiana University's Indianapolis campus
and Texas A&M University took part in the research on dogs ages
2 to 8 between 2001-03.
Richard Borgens, the Purdue professor of neuroscience who
oversaw the study, said his West Lafayette, Ind., lab had
previously used PEG to repair damaged spinal cords in guinea
pigs with about a 90 percent success rate.
His team has even fused severed guinea pig spinal cords using
PEG, although the dogs in the study had spinal disc ruptures
that crushed, but did not sever, their spinal cords.
Although exactly how PEG works remains unclear, Borgens said it
appears to act as a sort of "molecular Band-Aid" that forms a
temporary seal over breaches in nerve cells in the spinal cord,
aiding their healing process.
"This stuff is kind of like a radiator stop-leak for the nervous
system. The polymer spreads out and forms a seal over the
damaged areas in the nerve cells and allows the membrane below
to reconstruct itself," said Borgens, director of Purdue's
Center for Paralysis Research.
He said PEG also appears to prevent secondary tissue death that
often causes more damage than the original injury. Borgens said
the agent only covers damaged cells and tissues when injected
into the blood stream.
Purdue has enlisted a yet-to-be-announced corporate sponsor that
will make PEG in a form suitable for human clinical trials.
Pending federal approval, Borgens hopes those trials can begin
within about 18 months on people with hours-old or days-old
spinal injuries.
W. Dalton Dietrich, the scientific director of The Miami Project
To Cure Paralysis, said the rapid improvements in the dogs are
intriguing, but point to the need for follow-up work to learn
more about how PEG works and evaluate its safety. "Although the
results are very provocative, additional studies are required,"
he said.
Karen Kline, an associate professor of neurology and
neurosurgery at Iowa State University's College of Veterinary
Medicine in Ames, Iowa, called the findings promising. She said
PEG, which she plans to test on dogs at her lab, appears to
stabilize damaged tissue to allow more rapid healing than
typically occurs naturally.
"It has such promise, but I think we need to look at more
animals and make sure that we're getting a positive outcome,"
Kline said.
On the Net: Purdue Center for Paralysis Research:
http://www.vet.purdue.edu/cpr/
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