In a new study into advancing the longevity of humans it was found that in the healthy white blood cells of a 115-year-old woman, there were over 400 mutations.
Of course genetic mutations have been linked to diseases such as cancer, but these new findings by researchers suggest that mutations in white blood cells are largely harmless over a lifetime. And may have beneficial effects on ageing. Blood is continually replenished by hematopoietic (meaning “to make blood”) stem cells that are inside our bone marrow and divide to produce different types of blood cells. Cell division can lead to genetic mutations and hundreds of mutations have been found in patients with blood cancers. However, until recently little was known about white blood cells and mutations. Because they weren’t harmful, they weren’t studied.
The woman in the study was the oldest person in the world when she died in 2005 at 115 years old. She is also thought to be the oldest person ever to donate her body to science. The hundreds of mutations identified in her white blood cells appeared to be tolerated by the body and did not cause any disease.
The researchers also found possible new insight into the limits of human longevity, according to the authors of the study published on-line April 23 in the journal Genome Research.
Lead author Dr. Henne Holstege (pictured below) said in a journal news release:
“To our great surprise we found that, at the time of her death, the peripheral blood was derived from only two active hematopoietic stem cells (in contrast to an estimated 1,300 simultaneously active stem cells), which were related to each other. Because these blood cells had extremely short telomeres, we speculate that most hematopoietic stem cells may have died from ‘stem cell exhaustion,’ reaching the upper limit of stem cell divisions.”
The researchers also found that the woman’s white blood cells’ telomeres were extremely short. Telomeres, which are at the ends of chromosomes and protect them from damage, get a bit shorter each time a cell divides. Further research is needed to learn whether such stem cell exhaustion is a cause of death in extremely old people.
The next step will be to see if the white blood cell mutations can be artificially produced, and their effect on longevity, and whether avoiding stem cell exhaustion is feasible, thus prolonging life.