‘Immortal’ Irish marine animal provides hope for research into ageing

A small, native-Irish marine animal with remarkable powers of regeneration has provided stem cell scientists studying congenital defects and cancer biology with significant new leads.

Hydractinia echinata has the power to regenerate any lost body part, can clone itself, does not age biologically, and, according to Dr Uri Frank, who is leading the research at NUI Galway's regenerative medicine institute, "in theory - lives forever".

The tiny creature, which is a relative of jellyfish and sea anemones, is "perfect for understanding the role of stem cells in development, ageing and disease," says Dr Frank.

"Hydractinia has some stem cells which remain at an embryonic-like stage throughout its life. It sounds gruesome, but if it has its head bitten off, it simply grows another one within a few days using its embryonic or 'pluripotent' stem cells", explains Frank. "So the potential for research is immense", he adds.

The Galway team has discovered an unknown link between 'heat-shock' proteins and a cell-signalling pathway, known as Wnt signalling, in Hydractinia stem cells. "These two cellular signalling mechanisms are known to play important roles in development and disease, so they have been widely, though separately, studied. We have shown that they talk to each other, providing a new perspective for all scientists in this field," says Dr Frank. "We found the link coincidentally - we weren't looking for it."

Both the heat-shock proteins and Wnt signalling are known to be associated with cancer and cell growth.

Hydractinia stem cells should be "very similar to their human counterparts and studying them may provide information on human stem cells".

“So why don’t humans keep their pluripotent cells as adults?”, asks Dr Frank. “It’s a good question. Keeping them in a complex body like ours is probably too dangerous, as they can easily form cancer. It’s not so much a problem in simple animals - they would probably cut a cancer off.

“The price to become complex is to lose the ability to be immortal.”