In a study, published in the EMBO Journal researchers found that when mitochondria were eliminated from ageing cells they became much more similar to younger cells. This experiment was able for the first time to conclusively prove that mitochondria are major triggers of cell ageing.

The team carried out a series of genetic experiments involving human cells grown in the laboratory and succeeded in eliminating the majority, if not all, the mitochondria from ageing cells. Cells can normally eliminate mitochondria which are faulty by a process called mitophagy. The scientists were able to "trick" the cells into inducing this process in a grand scale, until all the mitochondria within the cells were physically removed.

To their surprise, they observed that the ageing cells, after losing their mitochondria, showed characteristics similar to younger cells, that is they became rejuvenated. The levels of inflammatory molecules, oxygen free radicals and expression of genes which are among the makers of cellular ageing dropped to the level that would be expected in younger cells.

"This is a very exciting and surprising discovery. We already had some clues that mitochondria played a role in the ageing of cells, but scientists around the world have struggled to understand exactly how and to what extent these were involved,” author said."These new findings highlight that mitochondria are actually essential to the ageing of cells."

The team also deciphered a new mechanism by which mitochondria contribute to ageing. They identified that as cells grow old, mitochondrial biogenesis, the complex process by which mitochondria replicate themselves, is a major driver of cellular ageing.

http://www.ncl.ac.uk/press/news/2016/02/mitochondriashowntotriggercellageing/#hp-banner