Why do so many previously healthy people become much frailer overnight when they hit their seventies? Scientists at the Wellcome Sanger Institute in Cambridge, UK, may have found an answer.
According to their study, as published in Nature, while the production of blood cells in adults under 65 came from as many as 20,000 to 200,000 stem cells, in those aged over 70, blood cells were produced by only 10 to 20 stem cell clones that had accumulated “driver mutations” over the course of a person’s life.
The Sanger Institute’s Dr Peter Campbell, senior researcher on the study, says these “selfish” cells dramatically reduce blood cell diversity in older people, leading to increased frailty.
“We’ve shown, for the first time, how steadily accumulating mutations throughout life lead to a catastrophic and inevitable change in blood cell populations after the age of 70.
“What is super exciting about this model is that it may well apply in other organ systems too. We see these selfish clones with driver mutations expanding with age in many other tissues of the body – we know this can increase cancer risk, but it could also be contributing to other functional changes associated with ageing,” he said.
Dr Elisa Laurenti, joint senior researcher, added that earlier growth of clones with cancer-causing mutations can be set off by factors such as chronic inflammation, smoking, infection and chemotherapy.
“We predict that these factors also bring forward the decline in blood stem cell diversity associated with ageing. It is possible that there are factors that might slow this process down, too.
“We now have the exciting task of figuring out how these newly discovered mutations affect blood function in the elderly, so we can learn how to minimise disease risk and promote healthy ageing,” she said.
So perhaps living a healthier lifestyle can persuade these selfish cells to share after all.
