Researchers reveal why people suddenly become more frail at age 70. They discovered a “catastrophic change” in the composition of blood cells, paving the way for new therapies to slow the aging process.
Cambridge researchers have discovered a process that leads to a ‘catastrophic’ change in blood composition in old age, increasing the risk of blood cancers and anemia, and reducing the effectiveness of white blood cells in fighting infection.
Scientists believe similar changes occur in all organs of the body, from skin to brain, which might explain why people often age in good health for decades before experiencing a more rapid decline in their 70s or 80s.
“What’s exciting regarding this work is that there might be a common set of processes at work,” exclaims Dr. Peter Campbell, the study’s lead author and head of the “Cancer, aging and somatic mutation” at the Sanger Institute in Cambridge. “Ultimately the goal would be to slow down or intervene in the aging process, but at least we see a possibility of using it to measure biological age. »
A set of processes at work
Aging is a complex process, but many scientists have suspected that the gradual accumulation of mutations in cells gradually degrades the body’s ability to function properly. The latest research suggests that this reasoning is flawed, or at best incomplete, and instead blames the “selfish” cells that become dominant in old age.
Working with scientists from the Wellcome-MRC Cambridge Stem Cell Institute, Dr. Campbell and his colleagues studied blood cells from people of all ages, from newborns to septuagenarians and octogenarians. They found that adults under 65 had a wide array of red and white blood cells produced by a diverse population of 20,000 to 200,000 different types of stem cells in their bone marrow.
Sudden collapse of the stock of stem cells
Among those over 65, the picture was radically different. About half of their blood cells came from just 10 or 20 separate stem cells, which greatly reduced the person’s blood cell diversity, with consequences for their health.
In their article published in the journal Nature, the researchers explain that while the stem cells involved in making blood mutate over time, most of these changes are harmless. But problems arise when rare “pilot” mutations accelerate stem cell growth, often producing lower quality blood cells in return. When a person is in their 30s or 40s, the growth advantage of aberrant stem cells makes little difference, but by age 70 and older, these rapidly growing cells come to dominate blood cell production.
“Exponential growth explains why there’s such a sudden change in frailty following age 70, why aging hits at that age,” Campbell said. Faster-growing blood stem cells are linked to blood cancers and anemia, but they also make people less resistant to infections and medical treatments such as chemotherapy.
“What we know from other organ systems is that many of the same observations apply,” Campbell added. The researchers now plan to look for the same process in the skin to understand why aging leads to wrinkles and slower healing.
Dr Elisa Laurenti, assistant professor at the Wellcome-MRC Cambridge Stem Cell Institute and co-principal investigator of the study, said chronic inflammation, smoking, infection and chemotherapy can all produce stem cells with carcinogenic mutations .
“We predict that these factors also promote the decline in blood stem cell diversity associated with aging,” she said. “It is possible that certain factors can also slow down this process. We now have the exciting task of understanding how these newly discovered mutations affect blood function in the elderly, so that we can learn how to minimize disease risk and promote healthy aging. »
With The Guardian