Key molecular signal that shapes regeneration in planarian stem cells discovered

Researchers at the Stowers Institute have identified a key molecule that directs stem cells in the planarian flatworm to make copies of themselves. The molecule, called EGFR-3, is part of a cascade of signals that seem to control the way these cells divide and differentiate in response to near-lethal levels of radiation. 

The finding, which appears online August 11, 2016, in the journal Developmental Cell, has important implications for advancing regenerative medicine and for developing more effective cancer therapies.

"All the genes in this signaling cascade are conserved, from planaria on up to humans. A similar process could also be taking place within our very own cells, we just don't know it," says Alejandro Sánchez Alvarado, Ph.D., an investigator at the Stowers Institute and Howard Hughes Medical Institute, who is the senior author of the study.

Planarians are world-renowned for their regenerative properties. Split one down the middle, and two identical organisms will appear in its place. Cut a fragment 1/279th the size of the original animal and it will regenerate a complete animal. This ability originates in a special group of adult stem cells called neoblasts that are spread throughout the bodies of these freshwater worms.

Several years ago, researchers tested the limits of these resilient creatures by subjecting them to near-lethal doses of radiation. They found that even if just a single neoblast remained, it was enough to replenish the entire population of planarian stem cells.