UK & World News
Blood Of World's Oldest Woman Shows Life Limit
Scientists who examined the body of one of the world's oldest women say dying stem cells may be the "limit" on our lifespans.
They say two-thirds of Hendrikje van Andel-Schipper's blood at the time of her death originated from just two stem cells - humans are born with around 20,000.
The findings imply that most or all of the blood stem cells she started life with had already burned out and died.
Ms Andel-Schipper was born in Holland in 1890, and at one point was the oldest woman in the world.
When she died in 2005 she gave her body to science, and asked for the analysis to be made public.
Henne Holstege, from the VU University Medical Center in Amsterdam, said: "Is there a limit to the number of stem cell divisions, and does that imply that there's a limit to human life?
"It's estimated that we're born with around 20,000 blood stem cells, and at any one time, around 1,000 are simultaneously active to replenish blood."
The researchers also found that her blood cells had worn-down telomeres - the protective tips on chromosomes that burn down like candle wicks each time a cell divides.
On average, the telomeres on her white blood cells were 17 times shorter than those on brain cells, which hardly replicate at all throughout life.
Ms Holstege added the study could raise the possibility of extending life by reinjecting stem cells saved from birth or early life.
She told New Scientist: "If I took a sample now and gave it back to myself when I'm older, I would have long telomeres again - although it might only be possible with blood, not other tissues."