An immortal animal hints at how cells avoid aging

Every time a cell divides, the ends of its chromosomes become slightly shorter. These ends are called telomeres (protective structures at chromosome tips). When they become too short, the cell stops dividing and eventually dies or enters a dormant state. This mechanism functions as a biological clock. Stem cells avoid this fate by using the enzyme telomerase, which replenishes telomeres.

Hydra are essentially mobile bundles of stem cells. They can regenerate any part of their body. The study shows that hydra use telomerase not only in stem cells, but also in ordinary body cells (somatic cells). That is remarkable: in most animals, including humans, this enzyme is nearly inactive in somatic cells.

Not directly transferable to humans

The question is whether we can learn from hydra biochemistry. The researchers are cautious: hydra are evolutionarily distant from humans. They are built almost entirely from stem cells, making them comparable to a mobile embryo. That is fundamentally different from the architecture of human organs.

Furthermore, activating telomerase in human somatic cells carries risks. Cancer cells use exactly the same trick to become immortal. Higher telomerase activity in normal cells could promote tumor growth. That tension makes direct application complex.

What comparative biology reveals

Comparative biology, studying different species to understand aging patterns, offers valuable insights into the evolution of aging. The fact that some species broadly deploy telomerase and do not age, while others do not, suggests that aging is not a biological inevitability but an evolutionary choice. For longevity research, that is a relevant idea: if aging is facultative, it is in theory also adjustable. How exactly remains unknown for now.

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