The tiny freshwater polyp Hydra is a remarkable creature. It does not show any signs of aging and appears to be immortal. Researchers from Kiel University have examined this phenomenon and uncovered an important link to the aging process in humans that could lead to the development of advanced rejuvenation therapies.

How does the polyp Hydra do this? It accomplishes the feat of apparent immortality by reproducing through budding rather than mating. Each polyp contains stem cells capable of continuous proliferation. Without this endless supply of regenerating stem cells, the animals could not reproduce.

Geneticists at Kiel University, together with the University Medical Center Schleswig-Holstein, discovered that the same longevity gene that makes the hydra immortal may also explain why humans get older, and more infirm.

"Surprisingly, our search for the gene that causes Hydra to be immortal led us to the so-called FoxO gene," says Anna-Marei Böhm, PhD student and first author of the study.

All animals and humans have a FoxO gene. Until now, no one has been able to work out if FoxO plays a role in aging and why human stem cells become fewer and inactive with increasing age. The growing inactivity of stem cells as we age is critical. Because our stem cells lose the ability to proliferate and form new cells, aging tissue cannot regenerate any more. As a result, our muscles decline.

The Kiel researchers examined FoxO in several genetically modified polyps: Hydra with normal FoxO, with inactive FoxO and with enhanced FoxO. The scientists found that animals without FoxO possess significantly fewer stem cells.

“Our research group demonstrated for the first time that there is a direct link between the FoxO gene and aging“, says Thomas Bosch from the Zoological Institute of Kiel University, who led the Hydra study. “FoxO has been found to be particularly active in centenarians – people older than one hundred years – which is why we believe that FoxO plays a key role in aging – not only in Hydra but also in humans.”

The study has produced two conclusions. First, the FoxO gene plays a key role in the maintenance of stem cells and thus determines the life span of all animals. Secondly, the aging and longevity of organisms depends on two factors: the maintenance of stem cells and the maintenance of a functioning immune system.

The hypothesis can’t be verified yet on human beings as that would require genetic manipulation. Nonetheless, the research is a big step forward and more studies on the Hydra and the FoxO gene are planned which could lay the foundations for the development of advanced rejuvenation therapy for humans in the future.

Source: Kiel University