From the just plain cool files

I'm thrilled to have a legitimate reason to blog about the lowly planeria. This little flat worm is renowned amongst high school and freshman biology students for it's ability to regrow copies of itself when cut in half. In theory, slicing right between the planeria's eyes can even produce a two-headed worm, though that's one of the many experiments that never actually worked for me.

It turns out that what allows planeria to regenerate could also teach scientists about our own regenerative stem cells. Two papers in last week's Science investigated the planeria's regenerative stem cells, called neoblasts. They found that at least some of the neoblasts have the ability to form all tissues in the worm's body, much like embryonic stem cells or reprogrammed iPS cells.

A press release from the Whitehead Institute quotes one of the co-first authors Dan Wagner:

“This is an animal that, through evolution, has already solved the regeneration problem,” says Wagner. “We’re studying planarians to see how their regeneration process works. And, one day, we’ll examine what are the key differences between what’s possible in this animal and what’s possible in a mouse or a person.”

The team also identified some of the signals that tell the neoblast whether it should form a head or a tail. This polarity issue is a big deal. A stem cell that can become anything needs clues to tell it what to and not to become. That's as true in a human as it is in a worm.

A. A.