Stem cells delay their death, helping in regeneration

American scientists have shown that stem cells are able to postpone their own death in order to respond to trauma that requires their participation.

The study, published on may 7 in the journal Current Biology, was conducted on planarians – tiny flatworms used as a model to study regeneration due to their unique ability to recover from any injury using stem cells.

“Planarian stem cells, even when challenged and under a lot of duress, will still respond to an injury by delaying death”, – said Divya Shiroor, first author and a graduate student in Dr. Carolyn Adler’s lab, in the Department of Molecular Medicine, Cornell University of Veterinary Medicine, USA.

The research team exposed the planarians to radiation, and then half of them were injured. Irradiated flatworms that were not injured demonstrated the expected levels of stem cell death (apoptosis). However, the stem cells of the wounded worms survived by grouping around the site of injury, delaying their death to repair the damage.

“We show that this inevitable radiation-induced cell death can be significantly delayed if animals are injured soon after radiation exposure”, – said Shiroor.

The discovery may be important for cancer research and therapy, especially in exploring chemotherapy and surgery options for patients.

“By understanding how injury prompts planarian stem cells to withstand radiation. We hope to identify genes that, if shared with mammals, could perhaps help hone existing therapies”, – Shiroor said.

Planarians are commonly used in basic research because they have much in common with people. Like humans, planarians have stem cells, similar organs, and similar genes, but they respond to injuries much more skillfully due to the greater number of stem cells and the lack of a developed immune system, which usually complicates the healing process in humans.

“This really simplifies the process of understanding the effects of both injury and radiation on stem cells, and allows us to study it directly without being hampered by parallel processes integral to wound healing, such as inflammation, that get simultaneously triggered in mammals”, – Shiroor said.

By discovering the mechanisms that control stem cells after being injured in a planarian model, researchers could use their knowledge to study a similar reaction in the human body.

Scientists are aware of the many ways that planarians can use stem cells for successful recovery and regeneration. However, the combination of trauma and radiation exposure, which was first studied at the Adler laboratory to identify a new stem cell response, is unique. Researchers plan on digging deeper to understand the mechanism for stem cell damage recognition, and what role other cells can play in this reaction.

“We have identified a key gene that is required for stem cell persistence after radiation and injury”, – Shiroor said. “And we plan on using this as a stepping stone for further exploration.”