Blood Of Oldest Woman In The World Reveals Limits Of Human Longevity
Hundreds of genetic mutations were found in the blood of a 115-year-old woman.
Genetic mutations have been widely studied when linked with diseases such as cancer, but little research has been conducted on these mutations in healthy individuals., a Cold Spring Harbor Laboratory news release reported.
A research team discovered over 400 mutations in the blood of a healthy supercentenarian; the finding suggests lesions at the mutation sites are generally harmless.
The woman passed away in 2005; at the time of her death she was the oldest person in the world.
Human blood is continuously refreshed with hematopoietic stem cells from the bone marrow. This leads to the production of both white and red blood cells.
Errors often occur in cell division, and the more often the cells divide the more likely it is that these genetic mutations will accumulate. Many of these mutations have been linked to conditions such as leukemia, but little research has been done to determine whether or not healthy white blood cells also harbor these mutations.
The many mutations found in the supercentenarian's bloodssteam were not found in her brain, which experiences almost no cell division after birth.
The mutations are called "somatic mutations," they are not passed down to offspring and tend not to lead to health problems; they are usually found in "non-coding regions of the genome" that is rarely linked to disease, the news release reported.
The team found evidence that could provide insight into the limits of human longevity.
"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," lead author of the study, Dr. Henne Holstege said in the news release.
The researchers also looked at the length of the woman's telomeres, which are "repetitive sequences at the ends of chromosomes that protects them from degradation," the news release reported. When cell division occurs the telomeres shorten in length. The team found the telomeres in the woman's blood were significantly shorter than those in her brain.
"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," Holstege said.