Scientists Discover New Clues to Regeneration: How Flatworms Regrow Heads

Regeneration is one of the most useful skills that an organism can possess. Lizards can regrow their tails and starfish can regrow and entire part of themselves if they're cut to pieces. Yet scientists have long wondered why some creatures possess this ability while others don't. That's why they decided to examine the process of regeneration, looking at the masters of this particular adaptation: flatworms.

Flatworms--more specifically, Schmidtea mediterranea--possess the amazing ability to regenerate. Even if the worm is cut into 200 pieces, 200 new worms will regenerate from each and every piece. Unsurprisingly, scientists often use these creatures to study regeneration. In this case, though, the researchers decided to bring another species of flatworm into the mix--Dendrocoelum lacteum. Although a close cousin of S. mediterranea, this flatworm is supposedly incapable of regenerating a head from its posterior body half.

In order to find out exactly why D. lacteum doesn't possess the same abilities as its regenerative relative, the researchers examined the genes of the two species. More specifically, they focused on the Wnt-signaling pathway. Signaling pathways transmit information between cells, which means that they can "tell" cells how to function. In this case, the scientists inhibited the signal transducer of the Wnt pathway with RNAi. This made the worm cells believe that the signaling pathway had been switched "off."

So what happened? When the pathway was switched "off," D. lacteum was able to regrow a fully functional head--even when cut at its tail. This showed that regeneration may just be a matter of signals--at least when it comes to flatworms.

"We thought we would have to manipulate hundreds of different switches to repair a regeneration defect; now we learned that sometimes only a few nodes may do," said Jochen Rink, one of the researchers, in a news release. "We showed that by comparisons amongst related species we can obtain insights into why some animals regenerate while others don't--that's an important first step."

While these findings are interesting, they don't guarantee that scientists will be able to induce regeneration in more complicated organisms. That said, the research does show that the signals for regeneration may be simpler than we first expected and could pave the way for future studies.

The findings are published in the journal Nature.