Things Got Really Weird When Scientists Gave Young Mice the Blood of Old Mice

Even though the elixir of life continues to be the subject of legend, the concept may not be as far-fetched as it always was.

When young mice were given the blood of elderly mice as part of a new experiment, the rodents’ bodies momentarily took on the characteristics of older mice. 

The results of the study were published in the peer-reviewed academic journal Nature Metabolism on July 28, 2022.

Curiously, when human cells were soaked in older people’s plasma, the impact that occurred on aging was similar.

All of the three-month-old mice were male, and they all got blood from a 22- to 24-month-old mouse. The muscle strength of the younger mice was then tested to see if the old blood caused the tissues to age.

Compared to a control group of young mice that got blood from another young mouse, the researchers found that the young mice that got blood from an old mouse had “decreased maximal twitch force and significantly shorter rates of force development and relaxation during contractions.”

The mice were put on a treadmill before and seven days after the blood infusion to see how long they could run. When mice didn’t want to move, a puff of air got them moving, and they ran until they were too tired.

Mice that received old blood got tired faster and ran less distance on the treadmill than the control group.

In addition to that, these mice exhibited indicators for kidney impairment and signs of age-related liver deterioration.

In this experiment, older mice were fed the blood of younger mice, which resulted in a decrease in lipids as well as fibrosis and weariness, and an increase in muscle endurance.

This most recent finding was consistent with the findings of an earlier research project carried out in 2005 by the University of California, which demonstrated that reversing the signs of aging in older mice can be accomplished by creating conjoined twins comprised of young and older mice and allowing them to share blood and organs.

“Using heterochronic blood exchange, we report a transfer of physiologic senescence from old to young mice,” the scientists explained. “This response is unrelated … to chronological age.”

The researchers had a hypothesis that cells from older mice were releasing a “senescence-associated secretory phenotype” (SASP) that accelerated aging and its accompanying symptoms, such as muscle weakness, loss of endurance, and tissue damage.

Even though chronological aging has not yet taken place, the presence of these senescent cells, which are old cells that have ceased reproducing but have not yet been eliminated from the body, has the potential to have an effect on neighboring cells found within a younger human.

Within the first six days of the experiment, the scientists detected many signs of aging after placing human kidney cells in plasma collected from persons between the ages of 60 and 70.

However, when the experiment was performed using plasma obtained from adults aged 20 to 30, these indicators were not discovered in any of the samples.

The researchers draw the conclusion that both experiments provide evidence that altering and manipulating a variety of parameters, including SASP, could result in the development of new therapeutic procedures leading to humans living for a longer period of time.