Self-healing salamander points to cure for paralysed
Amphibian’s ability to regenerate spinal cord could potentially be recreated in humans
AN ENDANGERED salamander may hold the key to helping paralysed people walk again, scientists believe.
The axolotl, or Mexican salamander, has the astonishing ability to regenerate limbs and even its spinal cord if it has been injured.
Now a study by the University of Minnesota has discovered how the amphibians achieve the feat, and how humans may be able to replicate the process.
When an axolotl suffers a spinal cord injury, nearby glial cells begin proliferating rapidly, positioning themselves to rebuild connections between nerves and reconnect the injured spinal cord.
By contrast, when a human suffers a spinal cord injury, the glial cells form scar tissue, which blocks nerves from ever reconnecting with each other.
The US team discovered that a particular protein called c-fos, which is carried by both salamanders and humans, is crucial for the regeneration process. However, in humans the protein is prevented from working by another family of proteins known as Juns, which trigger scar tissue formation.
Scientists are hopeful that if they can create a drug to switch off the Jun proteins, that will allow the glial cells to grow back the spinal cord.
“Humans have very limited capacity for regeneration, while other species like salamanders have the remarkable ability to functionally regenerate limbs, heart tissue and even the spinal cord after injury,” said Dr Karen Echeverri, the lead researcher and assistant professor in the department of genetics, cell biology and development at the University of Minnesota.
“We have discovered that despite this difference in response to injury, these animals share many of the same genes with humans. This knowledge could be used to design new therapeutic targets for treating spinal cord injury or neurodegenerative diseases.”
The spinal cord is a bundle of nerves and other tissue that extends from the brain’s base at the top of the neck down the length of the back. If it is damaged or injured, messages from the brain are disrupted, leading to partial or total loss of feeling or movement in limbs or internal organs below the injury.
There are around 40,000 people living with spinal cord damage in Britain, and every year 1,000 people suffer a life-changing injury.
The axolotl, which is also known as the Mexican walking fish, is native to lakes near Mexico City, and grows to around nine inches in length.
It can grow back lost limbs in just a few weeks, and even grow extra limbs. It can replace its lungs and parts of its brain if it suffers a head injury and it heals without any scarring.
In the new study, researchers compared gene expressions in humans and salamanders to try to pinpoint where they were differing.
“Our approach allows us to identify not just the mechanisms necessary to drive regeneration in salamanders but what is happening differently in humans in responses to injury,” said Miss Echeverri, who believes the breakthrough could help with a variety of injuries.
The research was presented at the 2018 Experimental Biology Meeting in San Diego.