Many of the genes involved in natural repair of the injured spinal cord of a fish called the lamprey are also active in the repair of the peripheral nervous system in mammals, according to a new study.
European river lampreys (Lampetra fluviatilis) in Pirita river, Estonia. Image credit: Tiit Hunt / CC BY-SA 3.0.
Lampreys are jawless, eel-like fish that shared a common ancestor with humans about 550 million years ago.
They can fully recover from a severed spinal cord without medication or other treatment, and go from paralysis to full swimming behaviors in 10 to 12 weeks.
“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 co-lead author Dr. Ona Bloom, of the Feinstein Institute and the Zucker School of Medicine at Hofstra/Northwell.
“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.”
Dr. Bloom and co-authors analyzed the lampreys’ healing process to determine which genes and signaling pathways were activated as compared to a non-injured lamprey.
The researchers 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.
“This reinforces the idea that the brain changes a lot after a spinal cord injury,” said co-lead author Dr. Jennifer Morgan, director of the MBL’s Eugene Bell Center for Regenerative Biology and Tissue Engineering.
“Most people are thinking, ‘What can you do to treat the spinal cord itself?’ but our data really support the idea that there’s also a lot going on in the brain.”
The scientists also saw that many of the genes associated with the response to spinal cord injury are part of the Wnt signaling pathway, which also plays a role in tissue development and in regeneration in several other animals, like salamanders and zebrafish.
These data suggest specific signaling pathways that may be different after spinal cord injury in mammals, like humans, which do not have the same natural regenerative responses.
“Furthermore, when we treated the animals with a drug that inhibits the Wnt signaling pathway, the animals never recovered their ability to swim,” Dr. Morgan said.
“Future research will explore why the Wnt pathway seems particularly important in the healing process.”
The study is published in the journal Scientific Reports.
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Paige E. Herman et al. 2018. Highly conserved molecular pathways, including Wnt signaling, promote functional recovery from spinal cord injury in lampreys. Scientific Reports 8, article number: 742; doi: 10.1038/s41598-017-18757-1
