Part 7: The 9 causes of aging - Cell senescence

It is now time to address the seventh identified cause of aging: cellular senescence. Do not hesitate to consult the other causes presented previously right here !

Senescence: Definition

A senescent cell is an aging cell whose function deteriorates. It then stops dividing and changes activity. These are the “zombie cells” of our body, not dead but nevertheless incapable of reproducing.

During this change, normal cells will begin to change their metabolism and may begin to secrete pro-inflammatory molecules, which in turn will signal surrounding cells that there is a problem. By this mechanism, the first senescent cell reduces the health of the other cells, and that's where everything starts to go wrong.

As a result, senescent cells accumulate with age in certain tissues, causing them to lose their homogeneity and possibly promoting their degeneration more quickly.

However, senescence may have been selected as a mechanism to prevent cancer cell proliferation. Indeed, we have noticed that cancer cells do not have senescence mechanisms and are almost immortal.

Senescence and immunity

Fortunately, the immune system can eliminate senescent cells. Obviously, however, this requires an effective immune system. Unfortunately, as we age, the immune system becomes less effective, at the same time as more and more cells become senescent. Inevitably, this leads to the accumulation of senescent cells in some of our tissues.

Therefore, this mechanism, which is initially a defense mechanism, is beneficial in young people. It protects the body from the proliferation of cancer cells, but requires an effective immune system to eliminate them and strong stem cells to replace them.

Conclusion

As the body ages, senescent cells accumulate due to a lack of stem cell turnover and a less effective immune system. And the accumulation of these further weakens the surrounding tissues... Another vicious circle.

Some researchers, however, made an interesting discovery - when they induced the self-destruction of senescent cells in aged mice, they observed that the mice regained their vitality. It will be interesting to see how research on senescence evolves in the future!

SOURCES:

Guilhem Velvé Casquillas on http://www.longlonglife.org/