Similar treatment could help people who are paralyzed
A combination therapy using transplanted cells and two experimental drugs has significantly improved function in paralyzed rats.
A treatment similar to the combo, tested by researchers at the University of Miami School of Medicine in Florida, could be useful in humans with spinal cord injury.
“The behavioral improvements in the rats receiving the triple therapy are dramatically better than those reported previously,” says US National Institute of Neurological Disorders and Stroke researcher Naomi Kleitman.
About 10,000 people in the US suffer from spinal cord injuries each year. These injuries occur when traumatic events damage cells in the spinal cord or sever nerves that relay signals to the brain.
Previous studies have shown that Schwann Cells—protective cells that wrap around axons in the Peripheral nervous system, forming the Myelin sheath—can be used to make a growth-stimulating “bridge” across a damaged spinal cord area. Myelin is a fatty substance that insulates nerve fibers and improves signal transmission.
Other research has suggested that a substance called cyclic adenosine monophosphate (cAMP) can activate growth factor genes in nerve cells, which work to regenerate damaged areas.
The current study is the first to try a combination of the two approaches in an animal model of spinal cord injury.
Kleitman and colleagues found that spinal cord injury triggers a loss of cAMP in the spinal cord and in some parts of the brain.
To compensate for cAMP loss, the researchers gave the rats a form of cAMP and a drug called Rolipram that prevents cAMP from being broken down.
They then transplanted Schwann cells into the rat spinal cords to bridge the damaged area.
Treatment with the triple-combination therapy preserved and increased cAMP levels in nerve cells after injury and preserved many of the myelinated nerve fibers in the animals.
The treated rats also grew back many more nerve fibers than untreated rats or rats that received just one or two of the therapies.
Rats that received the triple therapy had much better locomotion and coordination eight weeks after treatment than the control rats.
Feasible for humans
Of note for people suffering paralysis, the therapies tested in the study were selected for their likely feasibility in humans, says Kleitman.
Rolipram has already been tested in clinical trials for other disorders, and Schwann cells can be grown from a person’s own peripheral nerves.
The researchers are now planning follow-up studies to confirm their results and to further investigate the triple therapy.
By Gabe Romain