Researchers at the Weizmann Institute of Science in Israel made the discovery while studying how fruit-fly larvae respond to radiation damage. Their findings were published in Nature Communications.
The study focused on a process called compensatory proliferation, in which surviving cells multiply to replace cells that have been destroyed by injury.
Researchers identified a population of cells that activated an enzyme involved in programmed cell death but did not die.
They named these cells DARE cells, meaning cells in which the initiator caspase had been activated but that survived.
After radiation exposure, the DARE cells multiplied rapidly and helped rebuild damaged tissue.
Researchers found that they replenished nearly half of the affected tissue within 48 hours.
The scientists also identified another group called NARE cells, which had not activated the same cell-death pathway.
Although NARE cells also participated in tissue regeneration, experiments showed that they could not drive the process on their own.
The researchers found that signals released by dying cells helped activate DARE cells, triggering them to contribute to tissue repair.
They then investigated how DARE cells managed to survive after activating the cell-death process.
Normally, activation of the initiator caspase is followed by activation of executioner caspases, which destroy the cell.
However, in DARE cells, the process stopped before reaching this final stage.
The researchers linked their survival to a molecular motor protein that keeps the initiator caspase attached to the cell membrane.
When the researchers blocked this protein, DARE cells died and tissue regeneration was reduced.
The discovery may also provide clues about cancer treatment. Researchers found that descendants of DARE cells that survived the first radiation exposure were seven times more resistant to cell death when exposed to radiation again.
This finding could help explain why some cancer cells survive radiation treatment and contribute to tumour recurrence.
However, the research was conducted in fruit flies, so it is not yet known whether the same mechanism operates in humans.
The study also found that DARE and NARE cells communicate with each other through growth signals, creating a feedback system that promotes tissue repair while limiting excessive growth.
Researchers say the findings provide a new perspective on how tissues balance cell death, survival and regeneration, while further studies will be needed to determine whether the mechanism could eventually have implications for human health and cancer research.
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