Part 7: The 9 causes of ageing - Cell senescence

It is now time to discuss the seventh identified cause of ageing: cellular senescence. Feel free to check out the other causes previously presented right here!

Senescence: Definition

A senescent cell is an ageing cell whose function deteriorates. It then stops dividing and changes its activity. These are the "zombie cells" of our body, not dead but unable to reproduce.

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

As a result, senescent cells accumulate with age in certain tissues, causing them to lose their homogeneity and eventually degenerate more rapidly.

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. Of course, this requires an effective immune system. Unfortunately, as we age, the immune system becomes less efficient, 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 defence 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 renewal and a less effective immune system. And the accumulation of these further weakens the surrounding tissues... Another vicious circle.

However, some researchers have 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 the research on senescence develops in the future!

SOURCES:

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