A study at the Marine Biological Laboratory brings science a step closer to understanding how spinal cord regeneration could work in people.
Research by Jennifer R. Morgan, the director of MBL’s Eugene Bell Center For Regenerative Biology and Tissue Engineering, showed that genes that direct spinal cord repair in the lamprey, a jawless eel-like fish, are also found in humans.
Both humans and lampreys are vertebrates, animals that have spinal columns, and they shared a common ancestor 550 million years ago. However, only the lampreys can recover nerve function after severe damage to the spinal cord.
This group of lamprey repair genes are also activated in humans but in the peripheral nervous system, which are nerves outside of the spinal cord and brain. It is a gene program that has been conserved over time in the two different species but is not used in mammals for spinal cord repair.
“For some reason it is not being turned on,” Dr. Morgan said.
The lamprey has been a powerful model for neurological studies for decades, Dr. Morgan said. Its large neurons and spinal cord allow scientists to track the electrical signals that lead to motion and behavior in the animal, as well as nerve regeneration.
“If you completely sever the spinal cord, they are able to regenerate the gap,” Dr. Morgan said. “They go from paralysis to fully swimming in 10 to 12 weeks.”
Scientists have been delving into this ability of the lampreys by looking at the genes involved. A group of scientists that have gathered at MBL in the summer over the years—which includes Dr. Morgan, Ona E. Bloom from the Feinstein Institute for Medical Research in New York, Jeramiah J. Smith at the University of Kentucky and Joseph D. Buxbaum at the Icahn School of Medicine at Mount Sinai in New York City—was able to determine the molecular recipe of how lampreys can recover, Dr. Morgan said.
“These days it’s easy to collaborate across the phone and the internet, but nothing takes the place of those interactions, being in the room together and discussing research and experimental design,” Dr. Morgan said.
She said that the scientists looked at the genes expressed before and after a spinal cord injury in a group of lampreys by taking multiple samples from the brains and spinal cords from within hours after injury to three months later after they healed.
The scientists also found that gene expression in the lamprey brain with a spinal cord injury was more widespread than expected. A high number of genes in the brain were activated rather than just a small number linked to the injury site, which suggests the brain’s involvement in healing may be more complex.
“We have to think about what’s happening in the brain,” Dr. Morgan said. “Not a lot of data is out there.”
Now that the researchers have identified the genes active in regeneration, the next step is to see which neural pathways they control. She said that this research could potentially give insight into possible strategies for clinical interventions to repair spinal cord injuries in humans.