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Your liver is no more than three years old no matter your actual age

Everyone’s liver is a little under three years old, scientists have found, answering a long-standing question about how fast the organ regenerates. 

Liver

Unlike other organs, livers are able to repair themselves, an essential feature which allows them to flush out dangerous toxins without enduring permanent damage to cells.

But it was unclear how long the process took, or whether it slowed down with age. 

Many scientists speculated that because the body’s ability to heal itself diminishes as people grow older, the liver’s capacity to renew should also decrease.

To find out, researchers at Dresden University of Technology (TU Dresden) in Germany analysed the livers of multiple individuals who died at ages between 20 and 84 years old. 

Surprisingly, they found the liver cells of all subjects were more or less the same age.

“No matter if you are 20 or 84, your liver stays on average just under three years old,” said Dr Olaf Bergmann, research group leader at the Centre for Regenerative Therapies at TU Dresden. 

“Some studies pointed to the possibility that liver cells are long-lived while others showed a constant turnover.  

“It was clear to us that if we want to know what happens in humans, we need to find a way to directly assess the age of human liver cells.”

Retrospective radiocarbon birth dating used

To determine the biological age of the cells, the team used a technique called retrospective radiocarbon birth dating.

Nuclear tests carried out in the 1950s introduced massive amounts of radiocarbon into the atmosphere, and as a result, cells formed in this period have higher amounts of radiocarbon in their DNA.

Following the official ban of aboveground nuclear testing in 1963, the amounts of atmospheric radiocarbon started to drop and so did the amounts of radiocarbon incorporated into the animal DNA, creating a clock that can be used to date cells.

The less radiocarbon in cells, the younger they were.  

“Even though these are negligible amounts that are not harmful, we can detect and measure them in tissue samples,” added Dr Bergmann. 

The team has previously used the technique to show that the formation of new brain and heart cells is not limited to embryonic development, but continues throughout life. 

Currently, the group is investigating whether new human heart muscle cells can still be generated in people with chronic heart disease.

The liver can regenerate through life but if cells are badly damaged through conditions such as cirrhosis, they can no longer renew. In such cases, transplants are required. 

The research was published in the journal Cell Systems.  

Reference: The Telegraph: Sarah Knapton