And that may be a very good thing indeed! Lampreys are jawless, eel-like fish that, about 550 million years ago, shared a common ancestor with humans. The observation that a lamprey can fully recover from a severed spinal cord without medication or other treatment is what spurred this study. They can go from paralysis to full swimming behaviour in 10 to 12 weeks.
Associate Professor Ona E. Bloom, PhD, of the Feinstein Institute for Medical Research along with colleagues at the Marine Biological Laboratory (MBL), published today that many of the genes that repair an injured spinal cord in a lamprey are also active in the repair of the peripheral nervous system in mammals. This discovery is significant because it shows the possibility that the same or similar genes may be used to improve spinal cord repair in other animals and perhaps eventually lead to therapeutic developments for humans.
“Scientists have known for many years that the lamprey achieves spontaneous recovery from spinal cord injury, but we have not known the molecular recipe that accompanies and supports this remarkable capacity,” said Dr. Bloom, “In this study, we have determined all the genes that change during the course of recovery in the lamprey. Now that we have that information, we can use it to test if specific pathways are actually essential to the process.”
The researchers analysed the lampreys’ healing process to determine which genes and signalling pathways were activated as compared to a non-injured lamprey. They found the expression of many genes in the spinal cord change over time with recovery and that a number of genes also change in the brain. They also saw that many of the genes associated with the response to spinal cord injury are part of the Wnt signalling pathway, which also plays a role in tissue development and in regeneration in several other animals, like salamanders and zebrafish. These data suggest specific signalling pathways that may be different after spinal cord injury in mammals, like humans, which do not have the same natural regenerative responses.
This discovery is likely a long way from being used for treatments, however. Now that researchers know what genetic changes occur during the recovery process, they will be able to test out turning genes and pathways on and off in order to hone in on the exact sequence required for healing. Once this sequence is defined, it could be tested in other animals.