Studying how geckos grow new tails for clues to spinal cord injuries

Geckos grow new tails. Could the science behind spinal cord injuries someday encourage similar cell regeneration and repair in humans?

Researchers at the University of Guelph have for the first time identified the stem cells in a leopard gecko’s spinal cord that allow it to drop its tail when in danger and grow a new one. The discovery advances the science behind spinal cord injuries with the hope of someday encouraging similar cell regeneration and repair in humans.

Mammals are a pretty advanced group of creatures, but one thing we can’t do is regenerate body parts like some of our fish, reptile and amphibian cousins.

Zebrafish have hearts not too distant from human ones, yet they’re able to close wounds in the heart and grow whole new sections of the muscle. Starfish can regrow their limbs, so can some lizards, including the leopard gecko, which is able to lose its tail and regrow it within a month.

The surprising thing is that the gecko seems to be able to decide where along its vertebrae the break will occur, meaning that when a predator has it by the tail, it can choose how much it will leave behind as an added distraction (the tail keeps wiggling after detached) while it scampers off. That’s right, geckos grow new tails of varying lengths, depending on the situation.

Gecko regeneration is the focus of study in the biomedical sciences lab of Professor Matt Vickaryous, whose team recently published a paper in the Journal of Comparative Neurology showing that a particular group of stem cells called radial glia cells along with a specific type of cerebrospinal fluid-containing cells are activated whenever the animal drops its tail.

“We knew the gecko’s spinal cord could regenerate, but we didn’t know which cells were playing a key role,” said Vickaryous, in a press release. “Humans are notoriously bad at dealing with spinal cord injuries so I’m hoping we can use what we learn from geckos to coax human spinal cord injuries into repairing themselves.”

While we don’t drop body parts when predators come by, humans do respond to structural damage, only in a different way: by forming scar tissue. That process allows for the quick closing and healing of wounds but at the same time closes the door on regeneration.

And while geckos and humans are quite different in many respects, humans also produce radial glia stem cells, most prominently in our brains and spinal cords at a time when we’re doing the most structural growth, as fetuses. By adulthood, these stem cells are much less abundant.

“This may play a role in why we have a limited ability to repair our spinal cords,” says Vickaryous. “We are missing the key cells types required.”

The issue, then is whether radial glia cells can be injected into an injured area of the spinal cord so as to prevent scar tissue from forming and, the theory goes, allow for nerve and spinal cord regeneration.

To that end, Vickaryous and his team are now continuing their work with the leopard gecko to investigate the role that radial glia cells play in cell and tissue regeneration on other parts of its body, including brain tissue.

Geckos are able to regenerate many tissues throughout their bodies, making them ideal models for studying wound healing and tissue re-development. We can learn a lot from them,” says Vickaryous.

Below: Regeneration, University of Guelph