A few small steps for mice may lead to one giant leap for research into spinal cord injuries.
Severe spinal cord injuries often leave patients paralyzed from the injury site down, even if only some nerves were damaged. Researchers at Boston Children’s Hospital wanted to know why undamaged nerve pathways stop functioning — and their experiment resulted in paralyzed mice regaining their ability to walk.
The study, led by research associate Dr. Zhigang He, provides insight into why unharmed parts of the spinal cord stop working and how they can be revitalized. Researchers reported that 80 percent of paralyzed mice that were treated with a particular compound regained their ability to walk.
Neurons, or nerve cells, transmit messages from the brain to various parts of the body to trigger functions such as motion. For most spinal cord injury patients, not all of the nerve connections to the brain are severed. Despite these pathways remaining intact, at least half of patients still experience complete paralysis and loss of sensation. These out-of-commission neurons are called inhibitory, meaning they fail to foster communication between brain and spine. “We think that if we can understand why those connections are not functional, that might help develop more efficient strategy for functional recovery,” He said. “We don’t have to make a new connection, we can rely on pre-existing connections.”
All the mice had injuries that left them unable to walk despite part of the spinal cord remaining intact. Researchers ran tests to determine which inhibitory neuron to target for treatment and tested 10 compounds that affect a neuron’s excitability, or its ability to send a message. The team searched for a compound that would excite the quiet nerves and restore function when injected into the circulatory system.
The most promising compound, developed by Canadian researchers to treat patients experiencing chronic pain due to nerve dysfunction, can cross the blood-brain barrier that blocks certain substances from traveling between the brain and the spinal cord. He hopes this means the treatment can one day be administered to humans through IV injection.
He said the team was inspired by the only treatment known to be effective on spinal cord injuries: epidural stimulation, the application of a continuous electric current to the lower spinal cord. Despite its proven efficiency, function recovery disappears when the stimulation ceases. The researchers set out to find a method that could produce a longer effect, which led them to administer the compound through injection.
Allison Hagan can be reached at firstname.lastname@example.org.