Studying Worm DNA Could Teach Humans How to Regrow Limbs

Life would be much easier if you were able to regrow your own hand, head or you’re your heart. Thanks to the acorn worm, humans may be one step closer to regenerating important parts of the body, a study suggests.

Researchers at the University of Washington studied the acorn worm, a worm with a genetic makeup similar to humans. Normally found in sand around coral reefs, acorn worms are able to regrow every major body part, including the head, nervous system and internal organs, after being cut in half.

“We share thousands of genes with these animals, and we have many, if not all, of the same genes they are using to regenerate their body structures,” said lead author Shawn Luttrell, a UW biology doctoral student, in a press release. “This could have implications for central nervous system regeneration in humans if we can figure out the mechanism the worms use to regenerate.”

By studying the gene expression patterns of acorn worms as they regrew body parts, researchers determined that a certain set of genes could be responsible for activating a pattern of genetic activity that promotes growth. Three or four days after being cut in half, the regeneration process began as the worms started to regrow a mouth.

After five to 10 days, the worms regrew a new neural tube, the worm equivalent to the human spinal cord and brain. If the researchers are able to identify the genes responsible for the regeneration of the acorn worms, they could activate the same kind of regrowth in tissue cells from a person with an amputation.

“Regeneration gives animals or populations immortality,” said senior author Billie Swalla, a UW biology professor. “Not only are the tissues regrown, but they are regrown exactly the same way and with the same proportions so that at the end of the process, you can’t tell a regenerated animal from one that has never been cut.”

Scientists are trying to decipher which types of cells the worms use to regenerate. They also hope to activate genes to stimulate complete regeneration in animals that currently aren’t able to regrow all tissues.

“I really think we as humans have the potential to regenerate, but something isn’t allowing that to happen,” Swalla said. “I believe humans have these same genes, and if we can figure out how to turn on these genes, we can regenerate.”

It is believed that humans aren’t able to regenerate due to an overactive immune system as it frenzies in an attempt to stop bleeding and prevent infection. Another theory is that our size could prevent any kind of energy-extensive regeneration, such as regrowing a limb.

Swalla is the director of Friday Harbor Laboratories at UW. Co-authors include Kirsten Gotting of Stowers Institute for Medical Research along with Eric Ross and Alejandro Sànches Alvarado of the Stowers Institute and the Howard Hughes Medical Institute.

The study was published in the December issue of Developmental Dynamics. The research was funded by the National Institutes of Health, Howard Hughes Medical Institute, the Seeley Fund for Ocean Research on Tetiaroa and a National Science Foundation graduate fellowship.