Scientists have discovered that a mouse found in Africa can lose large patches of skin and then grow it back without scarring, perhaps as a way of escaping the clutches of a predator.
The finding challenges the conventional view that mammals have an extremely limited ability to replace injured body parts. There are lizards that can regrow lost tails, salamanders that can replace amputated legs, and fish that can generate new fins, but humans and other mammals generally patch up wounds with scar tissue.
That's why Ashley Seifert, a biologist who studies regeneration at the University of Florida, was skeptical when he was at a social get-together and an ecologist told him about some rodents at a research site in Kenya.
"He told me there were these animals, that, when captured by mammalogists, would shed their skin and go taking off into the wild," says Seifert. "You know, when I heard that, I thought he was sort of joking and that it couldn't have been a behavior like that."
Then, a few months later, someone who worked at the Kenya research site sent him a picture of a mouse he had caught in a trap.
"He was holding it in one hand. And there was the piece of skin which had just sort of come off its back, sitting on his leg, and he took a picture of that too," recalls Seifert.
So Seifert flew to Kenya, put traps on some rocky outcroppings and eventually caught some of these brownish-gray mice, called African spiny mice.
"Probably one of the first one or two that I handled, he didn't like being held and sort of moved his body backwards, pushed off with one of his limbs, and that caused a huge tear in his back," recalls Seifert, who realized that the mice really did have incredibly weak skin that tore easily.
And what's more, their skin had an incredible ability to heal. Instead of big scars, Seifert says these mice generate a near-perfect replacement of the original skin, complete with new hair. What's more, when holes are punched into their ears, these mice can re-create the missing hair, skin and cartilage.
In a report in the journal Nature, he and his colleagues describe the cellular process that these mice use to repair wounds. Seifert says that it's similar in some ways to the process that occurs when salamanders regrow limbs.
"My goal, really, is to build on this research and begin to look at some of the underlying mechanisms which are permitting this to occur," says Seifert, who hopes the work could lead to new therapies to allow humans to regenerate tissue in new ways.
Other researchers say that what these African spiny mice can do is just amazing. Voot Yin, a biologist who studies organ regeneration in zebra fish at the Mount Desert Island Biological Lab in Maine, says that traditionally, the field has assumed that adult mammals are lousy at regeneration.
"And obviously, this work showing that you can lose up to 50, 60 percent of your skin and yet heal properly and regenerate all of the missing structures is a remarkable observation," says Yin.
Yin says by studying these mice and other animals to find the common genetic circuits that allow regeneration to occur, scientists could potentially find new ways to heal wounds without scarring.