Blood of World's Oldest Woman Hints at Limits of Life
Written by Editor   
Tuesday, April 29, 2014 09:18 PM

Death is the one certainty in life – a pioneering analysis of blood from one of the world's oldest and healthiest women has given clues to why it happens.

Born in 1890, Hendrikje van Andel-Schipper was at one point the oldest woman in the world. She was also remarkable for her health, with crystal-clear cognition until she was close to death, and a blood circulatory system free of disease. When she died in 2005, she bequeathed her body to science, with the full support of her living relatives that any outcomes of scientific analysis – as well as her name – be made public.

Researchers have now examined her blood and other tissues to see how they were affected by age.

What they found suggests, as we could perhaps expect, that our lifespan might ultimately be limited by the capacity for stem cells to keep replenishing tissues day in day out. Once the stem cells reach a state of exhaustion that imposes a limit on their own lifespan, they themselves gradually die out and steadily diminish the body's capacity to keep regenerating vital tissues and cells, such as blood.

In van Andel-Schipper's case, it seemed that in the twilight of her life, about two-thirds of the white blood cells remaining in her body at death originated from just two stem cells, implying that most or all of the blood stem cells she started life with had already burned out and died.

The other evidence for the stem cell fatigue came from observations that van Andel-Schipper's white blood cells had drastically worn-down telomeres – the protective tips on chromosomes that burn down like wicks each time a cell divides. On average, the telomeres on the white blood cells were 17 times shorter than those on brain cells, which hardly replicate at all throughout life.

"It's estimated that we're born with around 20,000 blood stem cells, and at any one time, around 1000 are simultaneously active to replenish blood," says Holstege. During life, the number of active stem cells shrinks, she says, and their telomeres shorten to the point at which they die – a point called stem-cell exhaustion.

Tantalisingly, Holstege says the results raise the possibility of rejuvenating ageing bodies with injections of stem cells saved from birth or early life. These stem cells would be substantially free of mutations and have full-length telomeres. "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," she says.

Source:  http://www.newscientist.com/article/dn25458-blood-of-worlds-oldest-woman-hints-at-limits-of-life.html#.U2BdxMfgRjM