Why do we get older? When do we die and why? Is there a life without ageing? For centuries, science has been fascinated by these questions. Now researchers from Kiel (Germany) have examined why the polyp Hydra is immortal – and unexpectedly discovered a link to ageing in humans. The study carried out by Kiel University together with the University Medical Center Schleswig-Holstein (UKSH) will be published this week in the Proceedings of the National Academy of Sciences (PNAS).
Hydra – mysteriously immortal The tiny freshwater polyp Hydra does not show any signs of ageing and is potentially immortal. There is a rather simple biological explanation for this: these animals exclusively reproduce by budding rather than by mating. A prerequisite for such vegetative-only reproduction is that each polyp contains stem cells capable of continuous proliferation. Without these stem cells, the animals could not reproduce any more. Due to its immortality, Hydra has been the subject of many studies regarding ageing processes for several years. Ageing in humans When people get older, more and more of their stem cells lose the ability to proliferate and thus to form new cells. Ageing tissue cannot regenerate any more, which is why for example muscles decline. Elderly people tend to feel weaker because their heart muscles are affected by this ageing process as well. If it were possible to influence these ageing processes, humans could feel physically better for much longer. Studying animal tissue such as those of Hydra – an animal full of active stem cells during all its life – may deliver valuable insight into stem cell ageing as such.