Once damaged, nerves in the spinal cord normally cannot grow back, so, as we all know, the patient becomes paralyzed below the area of injury and long-term morbidity results.
Word on Health was therefore cautiously optimistic after reading a new study published last week in the Early Edition of the Proceedings of the National Academy of Sciences. The pre-clinical data showed that treating injured rat spinal cords with the enzyme – sialidase, improved nerve regrowth, motor recovery and nervous system function.
Sialidase is a bacterial enzyme that removes specific chemical groups found on the surface of nerve cells. The chemical groups normally function to stabilize the cells, but also act to prevent nerve regeneration.
The research team from Johns Hopkins treated rats with lower-back impact injury — severe enough to lose hind-limb function. The rats were injected with sialidase directly over the spinal cord immediately following injury. The researchers then implanted a small intrathecal pump that delivered a steady stream of sialidase directly to the injury over the course of two weeks. Their hope was that bathing the injured nerves in the enzyme would help their recovery and promote regrowth. They then let the rats recover for another three weeks before assessing the degree of recovery.
Using a well-established, 21-point scale where zero represents paralysis and 21 is normal function, the team of researchers assessed both treated and untreated rats for a range of functions including whether they could lift their feet off the ground and whether they had coordinated leg movements.
The initial injury rendered all rats to score below four, and all rats, treated or not, recovered somewhat by the end of two weeks. By the end of five weeks after injury most untreated rats scored 12 or less, while most treated rats scored better than 15. According to Ronald Schnaar a professor of pharmacology and molecular sciences at Johns Hopkins, “The difference in coordination control was most remarkable.”
In addition to motor control, spinal cord injury can cause other nervous system problems, including losing the ability to control blood pressure and heart rate. Researchers found that treated animals improved blood pressure control, something they interpreted as improved communication in the spinal cord. Finally, the team looked at the nerve ends under a microscope and found that treated nerves showed an increased number of “sprouted” nerve ends.
While the data appears promising, as always, we caution that efficacy in animals also doesn’t necessarily translate to humans. Furthermore, it will be a long road to using this as a drug in people. Nevertheless it is a step in the right direction.