Can humans regenerate body parts?

Written by Monica Villavicencio

Starfish can do it. So can spiders and salamanders. They can regrow their arms, legs, and tails.

James Sikes, assistant professor, biology: Researches the evolution and development of regeneration in invertebrates, particularly marine and freshwater flatworms. His paper on regeneration in the Procotyla fluviatilis was published in Nature, one of the world’s most prominent scientific journals, in July.

Humans can too—to a small extent and only for a very short while. A baby can regrow an entire fingertip until the age of 2 or 3. But then the ability disappears.

What if humans could recover that ability to regenerate? The idea’s not as crazy as you might think, says USF Assistant Professor of Biology James Sikes.

He studies flatworms because flatworms regenerate like no other creature. Cut one into 275 pieces and, within a week, you’ll have 275 completely formed, brand new worms.

To discover their regenerative secret, Sikes focused on a type of flatworm that has lost virtually all of its ability to regenerate, the Procotyla fluviatilis. He sequenced its genes and compared them to those in flatworms that can regenerate. By doing that, he discovered the gene responsible for inhibiting regeneration. He decided to investigate what would happen if he turned off the gene’s signaling pathway.

“I couldn’t believe it,” Sikes recalls. “I looked at these animals, and said, ‘I think they’re regenerating heads.’”

It was the first time a scientist anywhere had reawakened a creature’s ability to regrow a body part.

Of course, humans are infinitely more complex than flatworms. Still, Sikes believes the discovery could have tremendous implications for humans.

“The idea that there is an underlying ability to regenerate, that maybe you’re still holding onto it, and that maybe you can turn that ability back on gives a boost to research on regenerative medicine,” Sikes says.

Medical researchers are already training adult stem cells to regenerate damaged tissue.

“The biggest effects would be in neural diseases, if we can reverse brain damage or heart damage after a heart attack,” says Sikes. “If we can replace a damaged nerve cell and get circuitry back perfectly, paralysis would not happen.”

And as for regenerating fingertips?

“Can we do it today? No. Tomorrow? Probably not,” he says. “But we probably have more underlying abilities in our bodies than we realize.”

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