lab mouse being held by hands wearing blue latex gloves
Sean Cate
Sean Cate
April 25, 2023 ·  2 min read

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

Scientists have long been fascinated by the potential for young blood to rejuvenate aging bodies. However, recent research on mice has shown that the reverse may also be true: old blood may have detrimental effects on young bodies1. In this article, we explore the strange effects of giving young mice the blood of old mice and what it could mean for future research.

The Experiment

In a study from just last year, researchers gave young mice the blood plasma of old mice. The young mice began to exhibit signs of aging, including liver aging and reduced physical ability2. The old blood seemed to affect via a released phenotype that was promoting aging through muscle strength and endurance.

The researchers also found that the old blood could affect additional cells around it, regardless of whether or not chronological aging had taken place yet. So older blood inside a body could – in theory – slowly age you from the inside.  

The Implications

This research has important implications for our understanding of aging and how it can be treated. It suggests that aging is not simply a matter of the accumulation of damage over time, but may also be influenced by abilities we lose inside the body2. It also raises questions about the potential side effects of blood transfusions and other medical procedures that involve the transfer of blood or plasma from older donors to younger recipients or vice versa.

There is growing interest in the potential of young blood to rejuvenate aging bodies, and the hope is to eventually start treating a geriatric demographic to “turn back the clock” so to speak2. However, the results of this study suggest that young blood may not be a panacea for aging and may even have negative effects on younger bodies if given in excessive amounts.

The research on the effects of old blood on young mice is a fascinating development in the field of aging research. While it may seem like a strange and unsettling experiment, it has provided valuable insights into the complex processes of aging and the potential risks of medical procedures involving blood transfusions. As researchers continue to explore the mysteries of aging, we may find new ways to prevent or even reverse the effects of aging on the human body.

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  1. “Scientists Gave Young Mice The Blood of Old Mice. Then Things Got Weird” Science Alert. Agust 15, 2022.
  2. “Young blood can rejuvenate old mice — and scientists are starting to understand why” CBC Radio. December 10, 2021.