Longevity Briefs: Could A Component Of Mouse Blood Slow Ageing In Humans?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Extracellular vesicles are microscopic packages containing genetic material and signalling molecules. They are released from our cells and travel via the blood before being absorbed by other cells elsewhere within the body, making them a form of ‘long-distance communication’. 

It seems that these extracellular vesicles, or EVs for short, might be one of our tickets to reversing the ageing process. Scientists have known for decades that old mice given transfusions of blood from young mice are rejuvenated, becoming healthier and living longer than they otherwise would. More recent research suggests that extracellular vesicles present within ‘young blood’ may be responsible for these beneficial effects, but these are still early days and much remains unknown. This study published in Nature Aging looked to further investigate the potential of EVs.

The discovery:

Researchers gave 20 month old male mice weekly injections with EVs isolated from young mice, and found that they lived significantly longer than control mice given saline injections. The median lifespan (meaning the age by which half of the mice were dead) was 30.6 months for the controls and 34.4 months for the treated mice, with 9 and 8 mice in each group respectively. The oldest mouse in the treatment group lived about 7 months longer than the oldest mouse in the control group. The treated mice also benefited from improved physical, cognitive and reproductive function. For example, treated mice had higher bone mass, higher sperm counts and more cortical and hippocampal tissue than their counterparts in the control group.

These benefits required EVs isolated from young mice – when injected with EVs from other old mice, no significant changes occurred. When young mice were given EVs from old mice, they instead showed signs of accelerated ageing. To get a better idea of how EVs might be exerting their beneficial effects, researchers then analysed protein production in various aged tissues from treated and control mice, and also studied the effects of EVs on cultured mouse cells. These experiments suggested that the beneficial changes linked to EVs were mostly related to improved function of the mitochondria (the ‘power plants’ of the cell) and the preservation of genetic and epigenetic information. These are all thought to be of central importance to the ageing process.

Finally, the researchers tried injecting old mice with EVs isolated from the blood of young humans, and found that many of the above benefits were reproduced.

The implications:

This study supports previous findings that young EVs can delay some aspects of the ageing process in mice. It also suggests that EVs do not need to be given when the animal is young for them to be beneficial, which is an important quality for a treatment designed to slow ageing. Perhaps most importantly, the study suggests that the benefits of EVs aren’t necessarily species specific. If human EVs work in mice, then animal EVs might work in humans, which would certainly help overcome supply challenges. The natural synthesis of EVs is a complex and intricate process that produces vesicles of varying sizes and contents. Synthesising them in the lab will be a significant challenge, and we aren’t even sure at this point what types of EV we should be trying to synthesise.