An Antibody treatment that neutralizes a nerve growth inhibitor has repaired damaged spinal cords in rats and could do the same in humans.
Researcher Lisa Schnell and colleagues at the Brain Research Institute in Zurich, Switzerland have found that Nogo, a potent Central Nervous System growth inhibitor, can be neutralized by antibodies in animal models of spinal cord damage, and have now used this knowledge to develop a treatment method that could be applied in people.
“We first managed to successfully regenerate fibers in the spinal cord of an adult animal’s central nervous system as long ago as 1990, but this involved implanting cells directly into the brain to secrete antibodies, which is not something you want to do as a routine treatment for people,” says Schnell. “Since then we have purified the antibodies and developed ways to produce enough of them to use as a medicine.”
Nogo (for “neurite outgrowth inhibitor”) is a protein that inhibits the Regeneration of axons after central nervous system injury. Axons are the telephone lines of the nervous system, carrying nerve impulses along the brain and spinal cord.
It is thought that Myelin is responsible for the inability of axons to regenerate following injury. Myelin is an electrically insulating fat that forms a sheath around axons and speeds the transmission of impulses along nerve cells.
Researchers have theorized that myelin locks an adult’s fully formed neural network in place, preventing the development of new and potentially harmful circuits. This protective mechanism, however, prevents nerve cells from repairing themselves when damaged.
“The problem with repair systems is that they can overshoot, which could leave you with the wrong connection so that you want to move your arm but your leg moves instead, or you might get terrible constant pains,” says Schnell. “The Nogo protein system may be there to protect us from any of these mistakes. But of course that gives us a problem if we get injured.”
Antibodies, used by the immune system to identify and neutralize foreign objects, can also be used in medicine to target specific objects such as cancer cells.
By inserting very fine tubes under the membrane that surrounds the brain and spinal cord, Schnell and colleagues have now been able to deliver concentrated Nogo antibodies directly to damaged areas in the spinal cords of rats.
After treatment, the rats performed well on a series of Motor tests. In addition, anatomical analysis of the Nogo-neutralized rats showed increased sprouting and long distance regeneration of axons.
Once the anti-Nogo system is shown to be safe in other animal models, the first human patients with spinal cord injuries will be considered for treatment.
“The first patients we would try this technique on would probably be recently injured young men and women with severe injuries who have no hope of spontaneous recovery,” says Schnell.
The research was reported in Lisbon, Portugal at a meeting of the Federation of European Neuroscience Societies (read abstract).
By Gabe Romain