The elixir of life remains legendary, but aging the youth before their time may not be so far-fetched.
In a new experiment, young mice briefly experienced signs of aging when scientists infused them with the blood of older mice. A similar aging effect occurred when human cells were immersed in the plasma of older individuals.
The young mice – three months old and all males – received a blood transfusion from an older mouse aged 22-24 months. The younger mice were then tested for muscle strength to see if the old blood was triggering the effect of tissue aging.
Compared to a control group (young mice that received a blood transfusion from another young mouse), the mice that received blood from an old mouse had “reduced maximal muscle strength and significantly shorter rates of strength development and relaxation during contractions,” the researchers reported. .
The mice were tested for their physical endurance on a treadmill at baseline and seven days after the blood infusion. (Mice that refused to run were stimulated by a blast of air that kept them running until exhausted.)
Mice that received old blood fatigued faster and ran a shorter distance on the treadmill than the control group.
These mice also had biomarkers for kidney damage and signs of liver aging.
When older mice in this experiment were fed younger blood, lipids and fibrosis and fatigue decreased, and muscle endurance increased.
This latter result mirrors an earlier study conducted by the University of California in 2005, which found that creating conjoined twins from young and old mice (and thus sharing blood and organs) can reduce the signs of aging in the old mice. turning back.
“Using heterochronic blood exchange, we report a transfer of physiological aging from old to young mice,” the researchers say. “This response is independent of chronological age.”
The researchers hypothesized that cells from older mice release a senescence-associated secretory phenotype (SASP) that promotes aging, such as muscle weakness, loss of stamina and tissue damage.
These senescent cells — old cells that have stopped reproducing but have not been removed from the body — can potentially affect nearby cells in a younger individual, even without chronological aging first.
The researchers also placed human kidney cells in plasma from people between the ages of 60 and 70 and found multiple biomarkers of aging within six days of the experiment. These biomarkers were not found when the experiment was repeated with plasma from people aged 20 to 30 years.
Both experiments indicate that adjusting and modulating various factors, including SASP, could lead to new therapeutic strategies when it comes to longer life, the researchers conclude.
The research was published in Nature Metabolism.