Animals
1:21 pm
Wed September 26, 2012

Mammalian Surprise: African Mouse Can Regrow Skin

Originally published on Wed September 26, 2012 5:54 pm

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.

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Transcript

MELISSA BLOCK, HOST:

And finally this hour, more science about some astonishing things animals can do. Some creatures can regenerate lost body parts. If a predator grabs a lizard by the tail, it can abandon its tail and run and later, grow a new one. Some salamanders can replace entire legs and fish entire fins. Mammals, including humans, can't grow new limbs, of course, but scientists recently discovered a mouse with an unusual ability to repair itself. NPR's Nell Greenfieldboyce explains.

NELL GREENFIELDBOYCE, BYLINE: Ashley Seifert first heard about this mouse when he was at a get-together with some other scientists. He mentioned to an ecologist that he was interested in how animals regrow lost body parts. And the guy immediately said, hey, you should study these rodents we see at our research site in Kenya.

ASHLEY SEIFERT: He told me there were these animals that, when captured by mammalogists, would shed their skin and go taking off into the wild. And, you know, when I heard that I thought he was sort of joking and that it couldn't have been a behavior like that.

GREENFIELDBOYCE: A mouse that can shed its skin like a lizard sheds its tail? It seemed unlikely. Seifert is a researcher at the University of Florida who studies regeneration. He says, mammals can do some routine maintenance work like making new blood cells, but when it comes to replacing injured tissue...

SEIFERT: Mammals are really bad at that in general, at least the mammals that have been studied.

GREENFIELDBOYCE: 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.

SEIFERT: 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. And it was at that point I realized this is definitely worth trekking over to Kenya to at least investigate.

GREENFIELDBOYCE: He flew to Kenya, put traps on some rocky outcroppings and waited. Eventually, he caught some of these brownish-gray mice, called African spiny mice.

SEIFERT: 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. And, you know, I'm like, OK, this is really happening, these animals have incredibly weak skin.

GREENFIELDBOYCE: It's probably weak on purpose so they can escape the clutches of a predator. And, unlike other mammals, these mice don't get big scars. Instead, they generate a near-perfect replacement of the original skin, complete with new hair. That's really unusual. In the journal Nature, Seifert and his colleagues say the cellular processes seen in these mice are similar to what's seen in body repair experts like salamanders.

SEIFERT: You know, 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. And at some level, the sort of long term goal, right, would be to be able to extrapolate these and sort of give us an insight into developing new human therapies to allow humans to regenerate, where normally they're incapable of doing so.

GREENFIELDBOYCE: The new discovery has impressed other scientists who study regeneration like Voot Yin at the Mount Desert Island Biological Lab in Maine. He says it should make scientists rethink what adult mammals are capable of.

VOOT YIN: 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.

GREENFIELDBOYCE: He says by studying these mice and other animals, scientists could potentially find new ways to heal wounds without scarring. Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.