"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."
"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."
"... 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 ..."
Journal reference: Genome Research, DOI: 10.1101/gr.162131.113