Researchers can take 1/279th of a worm, called a planarian, and have the creature regenerate the rest of its quarter-inch body. The key to this feat lies in an army of stem cells ready to leap into action to grow heads, tails and organs, said Alejandro Sànchez Alvarado, a University of Utah School of Medicine researcher.
"We humans aren't particularly good at doing this," Sànchez Alvarado said of growing replacement limbs.
Understanding how stem cells work in worms could offer new knowledge about how the cells work in other creatures, such as humans, said Peter Reddien, a former U. researcher who is now with the Whitehead Institute for Biomedical Research, in Cambridge, Mass. Learning how stem cells are maintained and deployed holds promise for the field of regenerative medicine, which would direct stem cells to repair damaged or dead human tissue.
A U. team discovered that knocking out a certain gene disrupts the regeneration process in worms. The gene, called smedwi-2, apparently plays a key role in how stem cells get ready to direct other cells to rebuild the missing part.
"When we shut the gene down, planarians can't regenerate at all," said Reddien, an author on a study in today's edition of the journal Science.
Versions of the gene appear in other forms of life, ranging from plants to mammals, said Sànchez Alvarado, who is a professor of neurobiology and anatomy and is another author on the study. This is the first planarian gene found to disrupt regeneration.
For planarians, when a body part is removed, stem cells kick into gear. Each activated stem cell splits into two daughter cells - one is a new stem cell while the other moves to the damaged area and turns into whatever tissue is needed, such as brain, muscle or skin.
This gene finding is part of broader work looking at the molecular basis for how worms regenerate. Scientists have been knocking out individual genes of interest to learn about their functions, Reddien said.
He called the research the tip of the iceberg for understanding which genes are involved with regeneration in the worms. The next step for the smedwi-2 gene will be to learn how it influences stem cells in the regeneration process.
glavine@sltrib.com
