Wednesday August 30 03:01 AM EDT
By Adam Marcus
TUESDAY, Aug. 29 (HealthSCOUT) -- It's not the conventional Park Avenue nose job, but Connecticut scientists say they've used modified snout cells from swine to regenerate protective spinal tissue in rats.
The technique, which combines gene therapy and putting animal tissue into humans, could lead to treatments for paralysis, Parkinson's disease and other nerve conditions like multiple sclerosis.
However, rats in the study had only mild spinal cord injuries, so the experiment didn't prove that the treatment can reverse crippling damage. A report on the work appears in the September issue of Nature Biotechnology.
Led by Jeffery Kocsis, a Yale University neuroscientist, the researchers grafted nerve cells from pig snouts into rats whose spinal cords had been partially severed.
The animals had weakened immune systems. But to further prevent rejecton, the transplant tissue -- which consisted of olfactory ensheathing cells and Schwann cells shield nerve fibers -- was packing a human gene for a protein that blocks massive immune responses.
That approach was developed by Alexion Pharmaceuticals, a New Haven, Conn., biotech firm., which took part in the study.
About a month after the transplant, seven of 10 animals that received the pig tissue had sprouted nerves that spread across the site of the injury. What's more, the new nerves carried electrical signals faster, and their protein sheaths, or myelin, were more robust, than normal.
Stephen Squinto, a co-founder of Alexion, says that while the new myelin isn't identical to the original, "it certainly functions as well as the normal myelin that had been there." Electrical tests of the regrown nerves "show that the potential is there to completely reverse the damage that had been done."
Squinto says his company is planning to work with scientists in Florida who will perform "crush" tests with the altered pig tissue. These experiments will see if the therapy can work in animals that have had severe spinal cord damage such as that a paraplegic might endure.
The approach, this time using pig brain cells, has also been tried successfully in both rodent and primate models of Parkinson's disease, Squinto says. "We have been able to restore function in both of those settings," he says.
Arlene Chiu, who oversees spinal cord injury research at the National Institute of Neurological Disorders and Stroke, calls the Nature Biotechnology study "an important contribution." However, Chiu says, it's not the first time that scientists have demonstrated a successful graft of "support" cells to help damaged nerves regenerate.
In fact, Spanish researchers reported earlier this year that grafts from rats into rats of olfactory ensheathing cells restored mobility and function to the animals despite clean breaks in their spinal cords -- something the Connecticut scientists didn't attempt.
Chiu also says there's no direct evidence in the latest effort that the grafts themselves made the myelin coating the nerves.
Untreated animals in the study also sprouted myelinated nerves, though far fewer of them. "An alternate explanation could be that the therapy might be stimulating native tissue to form myelin," she says.
The prospect of having pigs as a source of nerve grafts is exciting because sheath cells are difficult to collect from humans, she says. "Anything you could harvest from these transgenic pigs that you could use for humans would obviously be very important" for therapeutic purposes.
What To Do
The new treatment is years and big ifs away from being ready for the estimated 250,000 to 400,000 Americans with spinal cord injuries.
This National Institutes of Health Web site has information on other experimental and more mature therapies for spinal cord damage.
You can also try the National Spinal Cord Injury Association for information,
support and much more.