Aging is a battle that humans have known they can't win since the beginning of history. We can hate it or (eventually) accept it but ultimately we can’t avoid growing old. However, over the years scientists have been trying to pinpoint the roots of this biological process and work out if there is any way to stop or reverse it. There have been some minor successes along the way and a new study adds to these.

The researchers were able to reverse the aging process of some old human cells by delivering a specific molecule to their mitochondria, the structures within cells where energy is produced. This approach stops the cells from becoming senescent, a point at which they can no longer duplicate. Some researchers believe that the accumulation of these cells in organs is key to the aging process.

“We still don’t fully understand why cells become senescent as we age, but damage to DNA, exposure to inflammation and damage to the protective molecules at the end of the chromosomes – the telomeres – have all been suggested,” the authors wrote in a post on The Conversation. “More recently, people have suggested that one driver of senescence may be loss of our ability to turn genes on and off at the right time and in the right place.”

The study is published in the journal Aging and describes how delivering hydrogen sulfide directly to mitochondria can allow old cells to regain the dividing abilities of younger cells. Hydrogen sulfide is the compound that makes rotten eggs smell. It is dangerous in high doses but has been shown to be beneficial at low levels. Delivering it directly where it is needed can reduce potential risks.

The team believes that the presence of the molecule in mitochondria can increase the abundance of certain splicing factors, proteins that essentially switch genes on and off in response to environmental changes. There are about 300 proteins in this group and their numbers tend to decline as we age. The hydrogen sulfide boosted the amount of two splicing factors connected to senescence, reducing this aging mechanism.

“We are hopeful that in using molecular tools such as this, we will be able to eventually remove senescent cells in living people, which may allow us to target multiple age-related diseases at once. This is some way in the future yet, but it’s an exciting start,” the researchers concluded.

The key to eternal youth is not at hand, but understanding aging might at least make growing old easier.