Immortal Jellyfish May Hold Clues to Human Healing

The tiny, translucent jellyfish Turritopsis dohrnii can reverse its life cycle and become young again. Scientists now want to learn whether the cellular processes behind that feat might one day help people heal.

Marine biologist Maria Miglietta of Texas A&M University at Galveston has tested the animal’s limits. She has cut, boiled and starved it, overloaded its tanks with salt, and put it in fresh water. Again and again, the jellyfish seems to evade death.

How the Transformation Works

Under stress, the jellyfish stops moving and sinks to the bottom of its tank. Then it becomes a ball of cells, nothing like the tentacled, umbrella-shaped adult known as the medusa. Within one to three days, a polyp, an early life stage, buds from the ball and grows into a colony. That colony eventually produces hundreds of new medusae.

“From one jellyfish that doesn’t die, then you get this colony that can form hundreds more,” Miglietta said. Each new jellyfish can, in principle, rejuvenate in the same way.

Scientists first reported the discovery in 1992, after an Italian scientist who kept the animals in a laboratory forgot to feed them over a weekend. He expected to find dead specimens. Instead, he found new polyps in the container, Miglietta said. Stefano Piraino, a biologist at Italy’s University of Salento, then studied how the process might work. He found that certain tissues in the medusa revert to a stem-cell-like state and then specialise into other cell types. “Adult cells become ‘undifferentiated’ and become something else that is needed to form the polyp,” Miglietta said.

The Human Question

Researchers aren’t pursuing a fountain of youth for wealthy patients. Their aim is more modest and practical: Miglietta and other scientists want to learn whether cells and tissues could be coaxed into more youthful states to heal wounds and treat age-related diseases.

Michael Koldobskiy, a pediatric oncologist and physician-scientist at Johns Hopkins, described the broader goal. “The holy grail of this kind of thing, I think, would be regenerative biology: trying to reverse ageing-related degeneration or degradation,” he said. “We’re a long way away from harnessing that for human benefit, but I think understanding these organisms that evolved these processes millions of years ago could potentially really pay off.”

Koldobskiy said the ultimate target would be a molecular switch that controls the process, and a check on whether humans carry the same one. If they do, researchers could explore ways to heal tissue damaged by strokes or heart attacks, or reverse damage linked to age-related vision loss or Alzheimer’s disease. “We’re not going to shrink down to an embryo again and restart,” he said. “But at the organ and tissue level, I think it’s very much a possibility.”

What the Genes Reveal

A 2022 study compared Turritopsis dohrnii’s genes with those of a related species not known to rejuvenate. Victor Quesada, a molecular biologist and bioinformatician at the University of Oviedo in Spain, urged caution. He noted that it’s difficult to know whether the related species lacks the ability, since many jellyfish remain understudied.

Still, the jellyfish showed notable differences. It had more copies of genes that produce proteins helping repair mutations and other DNA damage that builds up with age. It also had more copies of genes that help maintain telomeres, the caps at the ends of DNA strands that protect genetic material. Telomeres normally shorten with age, and Quesada said the jellyfish’s greater ability to maintain them could be one factor in its longevity.

“This is just the beginning of understanding the secrets of Turritopsis dohrnii’s rejuvenation strategy and whether any aspect of it could be applied to humans,” Quesada said. “We assume in many diseases, that there’s no way back. Perhaps there might be a way back, if we [learn] enough about... how those mechanisms work.”

Miglietta’s own research, published in 2019 and 2021 with colleagues, found increased activity in genes with unknown functions, alongside genes involved in DNA repair and telomere maintenance. A separate preliminary study by Miglietta found some overlap between genes activated during the cyst stage and genes linked to human longevity. That overlap hints at possible shared pathways between the species. Miglietta is now working with Koldobskiy to test whether researchers can induce such processes in human cells. Scientists have managed to trigger rejuvenation-like processes in mammalian cells, but applying them to human tissue has proved difficult.

Fragility in the Wild

The species ranges across oceans, from the Mediterranean to the Caribbean and Japan. Miglietta suspects its resilience explains that wide distribution. “It’s comforting to think that nature has found a solution to one of the main problems of humans: ageing and death,” she said.

The animal is fragile, too. Some jellyfish in Miglietta’s laboratory seem unable to rejuvenate, and those that can may eventually reach a limit and die of old age. The species is hard to keep in captivity and seems to need specific conditions. In the wild, shifting plankton supplies, predators and algae that smother colonies may kill it.

Maria Pascual-Torner of Spain’s Institute of Marine Sciences, who co-authored the 2022 study with Quesada, put it plainly. “Although it has the ability to rejuvenate and, theoretically, not die from ageing, it is at the same time an extremely vulnerable organism,” she said. “The immortal jellyfish also reminds us that life and death are inseparable parts of the same reality.”

Why This Matters: The research remains at an early stage, and the scientists involved are cautious about how far it can go. The jellyfish can’t yet serve as a template for human treatment, and Koldobskiy himself says the path is long. Still, the questions are concrete: wound healing, stroke and heart damage, and diseases that take a heavy toll on older people and their families. Turning those questions into therapies will require sustained public funding for basic biology, not just private interest in longevity. The gap between a curious laboratory finding from 1992 and a usable medical tool is wide. Closing it will depend on patient, collaborative research of the kind public institutions are best placed to support across borders.