Can we cure ageing?
Professor of molecular biology at Harvard Medical School David Sinclair might have cracked the code, with mice in his lab growing younger.
Prof Sinclair and his team have reset aging cells in mice to earlier versions of themselves, to help old mice with poor eyesight suddenly see again.
"It's a permanent reset, as far as we can tell, and we think it may be a universal process that could be applied across the body to reset our age," Prof Sinclair told CNN.
He has spent the last 20 years studying ways to reverse the ravages of time, as most diseases are caused by aging itself.
"If we reverse aging, these diseases should not happen. We have the technology today to be able to go into your hundreds without worrying about getting cancer in your 70s, heart disease in your 80s and Alzheimer's in your 90s," Sinclair said at an event in partnership with CNN.
"This is the world that is coming. It's literally a question of when and for most of us, it's going to happen in our lifetimes."
He believes delaying and reversing aging is the best way to treat many diseases.
In his lab, sit two mice from the same litter, except one has been genetically altered to age faster. Prof Sinclair said if aging faster can be done, so can aging slower.
In 2007, Japanese biomedical researcher Dr Shinya Yamanaka won the Nobel Peace Prize for developing a revolutionary method for generating stem cells from existing cells of the body. However, the adult cells fully switched back to stem cells lost their identity.
Sinclair's team designed a way to deliver a virus with the same rejuvenating factors to damaged retinal ganglion cells at the back of an aged mouse's eye by injecting the virus into the eye and giving antibiotics to the moue which switch the pluripotent genes on.
"Somehow the cells know the body can reset itself, and they still know which genes should be on when they were young," Sinclair told CNN. "We think we're tapping into an ancient regeneration system that some animals use - when you cut the limb off a salamander, it regrows the limb. The tail of a fish will grow back; a finger of a mouse will grow back."
The aging cells forget how to function and what type of cell they are and Sinclair then tapes into that to reset the cell's ability to read the genome correctly again, as if it was young.
The changes lasted for months in mice and then the process is repeated - rewinding back the clock.
Making it a matter of time before humans can turn back time.