Last week the San Diego Union-Tribune reported that scientists at the University of California San Diego successfully guided regenerating nerve axons to cell targets, where they re-established nerve connections. This research could potentially lead to a treatment for reversing paralysis in patients with spinal cord injuries.
Dr. Mark Tuxynski of UCSD said, “It was a breakthrough a few years ago to finally get axons to regenerate. “With this advance, we’ve shown it’s possible to direct an axon to find the correct target from among potentially millions of incorrect ones in the spine and brain and make the right connection.”
Axons are the components of nerve cells that conduct electrical impulses; these electrical impulses allow for communication between neurons. Spinal cord injuries often damage axons, cutting of neural communication. This can result in sensory loss or paralysis.
In the UCSD experiment, researchers restored severed neural connections in lab rats using a combination of therapies. One therapy involved injecting a virus carrying a growth factor into the target site. The growth factor, neurotrophin-3, attracts growing axons. Researchers also grafted cells across the injury site to support axon growth.
Naomi Kleitman of the National Institute of Neurological Disorders and Stroke said, “What this work dramatically sows is that it will take a combination of things to effectively repair spinal cord injuries. It’s one important step in a long process of many steps. There are still many things we don’t know. There are likely more elements that will be needed before it’s possible to translate this research to humans. The process, even now, sounds like a lot. But compared to being paralyzed for the rest of your life, maybe it’s not asking too much.”
The research has a long way to go. The UCSD research was with sensory neurons rather than the motor neurons that govern movement. Motor neurons may be tougher to manipulate. Also, the regenerated axons were not electrically active. In other words, while the reconnected in the right place, they did not work.
Tuszynski speculates that the regenerated axons may lack a myelin sheath, a fatty coating that acts like an insulator. The myelin sheath works much like the rubber coating on electrical wiring.
“Just as an electrical circuit needs insulation so it doesn’t short-circuit, it appears that these regenerating axons require restoration of the myelin sheath to ultimately restore function,” Tuszynski said.
Later this year, Geron, a biotech company, will begin trials for a stem cell procedure that could stimulate myelin production. There is hope.
Earlier this year, the Christopher and Dana Reeve Foundation conducted a survey which found that 1.275 million Americans suffer from a spinal cord injury, and more than 5.6 million Americans live with some degree of paralysis. Spinal cord injuries cause 23 percent of paralysis cases. (Stroke and multiple sclerosis may also cause paralysis.)
Spinal cord injuries can be devastating for victims and families. If you or a loved one have suffered a spinal cord injury and you feel that someone else is at fault, call MLN Law at 404-531-9700 to schedule your free consultation.