New light shone on nerve regeneration after spinal injury

Experts in the US claim that fish may provide the basis for research into how people can better recover from spinal injury.

The new claims have been made by University of Missouri researchers, who worked on the basis that fish, unlike humans, are capable of regenerating nerve connections and recovering mobility following an injury to their spinal cord.

When examined more closely, the study authors found that the sea lamprey, an eel-like fish, regrows neurons comprising the long nerve connections that link the brain to the spinal cord.

The specialists say that the study could influence future efforts to promote recovery in people who have suffered spinal cord injuries.

Andrew McClellan, professor of biological sciences in the College of Arts and Science and director of the MU Spinal Cord Injury Programme, commented: "There is a lot of attention to why, following a spinal cord injury, neurons regenerate in lower vertebrates, such as the sea lamprey, and why they don’t in higher vertebrates, such as humans."

During the research, Professor McClellan and his colleagues isolated and removed injured reticulospinal neurons from sea lamprey and grew them in cultures, then applied chemicals that activated a group of molecules known as second messengers to see what effects they had on these neurons’ growth.

They found that the activation of cyclic AMP - a molecule that relays chemical signals inside cells - acted as a form of 'on' switch, which converted neurons from a non-growing state to a growing one, though it had no effect on neurons that had already begun to grow.

The experts hope that the information may now influence studies of neural regeneration in mammals, including humans.

Professor McClellan concluded: "Cyclic AMP seems to be able to overcome some of these inhibitory factors and promotes at least some regeneration. Hopefully our studies with the lamprey can provide a list of conditions that are important for neural regeneration to help guide therapies in higher vertebrates, and possibly in humans."