How cells become younger again

Researchers discover fountain of youth for cells

06/12/2013

Ulm scientists have come to a fountain of youth for cells on the track. As in the trade magazine „research“ of the German Research Foundation (DFG) is the protein „RhoGTPase Cdc42“ responsible for the aging process of stem cells. As stem cells age, they are no longer able to properly make blood, weakening the body's immune defenses and producing fewer red blood cells. This leads to age-related anemia, which results in a weakening of the body. In experiments with genetically engineered mice, scientists have recently reversed this process by inhibiting protein activity and rejuvenating cells.

Aging of the blood stem cells leads to the weakening of the body
Hartmut Geiger, Professor of Dermatology and Allergology at the University Hospital Ulm, and his team studied the aging process of blood stem cells in mice. Hematopoietic stem cells are found mainly in the bone marrow, where they form countless new blood cells every day. They produce red blood cells responsible for oxygen transport and white blood cells, which play an important role in the immune system. In addition, they form platelets, which are responsible for the coagulation of the blood. While blood cells have a limited lifespan and share little, blood stem cells are almost indefinitely divisible. Only the aging process means that the stem cells can no longer properly form blood.

Geiger and his colleagues succeeded in reversing this phenomenon in mice after they first demonstrated that blood stem cells age faster due to increased RhoGTPase Cdc42 protein activity. The researchers observed that inhibition of the protein in the mice led to a reorganization of the stem cells, which rejuvenated them sustainably. „The aging process could therefore be reversed at this point. This approach could initially help in the mouse that their immune system still works well in old age and the age-related anemia is slowed down, "writes Geiger in the journal. „Whether these results can be transferred to humans and thus provide new therapeutic approaches, research must find out in the coming years. Nevertheless, it becomes clear that aging at the molecular and cellular level does not have to be a one-way street.“

Can the aging of the cells be stopped in the future??
In the future, it may therefore be possible not only to stop the aging process, but even to reverse it. But until then it is still a long way. Because not only the blood stem cells but also all other cells of the body age. Thus, the function of the organs diminishes with age. If the research succeeds in deciphering this process, the lungs, heart, kidneys and liver could also work longer and better. This could be an important contribution to health in old age, which would ultimately allow a longer, healthier life. At present, however, the researcher of aging is not concerned with concrete measures, but rather with the decoding of the molecular mechanisms of cell aging.

„Above all, it is model organisms such as yeast, roundworm, fruit fly or mouse that help scientists fundamentally unravel the aging process“ so violinist. Their advantage, above all, is that they aged very quickly compared to humans. For a yeast cell, these are only a few days, for a mouse three years. Meanwhile, it is also known that some mechanisms of aging in yeast, worm and mouse worked very similar, explains the scientist. This could argue that the results can be at least partially transferred to the human organism.

Telomeres have an influence on the aging of the cells
Regardless of these mechanisms, each organism also ages individually, because each cell contains individual DNA, genetic material, which inter alia encodes the blueprints for the cell proteins. These proteins and protein assemblies provide the cell with everything it needs. As cell aging is associated with diminished cell function, researchers suggest that both damaged DNA and damaged proteins are responsible for the aging process.

In this context, the research also focuses on so-called telomeres, which were discovered by the US cell biologists Elizabeth Blackburn, Carol Greider and Jack Szostak. The researchers received the Nobel Prize for Medicine. Telomore are the culmination of chromosomes, the carriers of the genome of cells. They sit like protective caps on the end of the chromosomes and make sure that they do not fray. In this way, the telomeres prevent the ends from being recognized as a damaged genome and being fought by the immune system. „However, the telomeres shorten with each cell division. If they fall below a critical length, the cell stops dividing or dies. The older a human, the shorter the telomeres of its chromosomes are“, reports Geiger. „The protein telomerase is a kind of antagonist that slows down the aging process by making sure that these protective caps are not too short. But not all cells have enough of this life-prolonging enzyme. One theory assumes that telomere length is an indicator of cell life expectancy.“ Nevertheless, therapy with telomerase drugs would not be a solution since not only stem cells but also cancer cells contain telomerase. Thus, although telomerase drugs would slow down the aging process, at the same time they also promote cancer. (Ag)