The alluring idea of an easy way to reverse ageing may soon become reality, thanks to remarkable new findings by neuroscientists.
Three interventions are known to slow down, and even reverse, the biological ageing clock. These are: transfusions of young blood, a hormone found in our bodies called klotho, and physical exercise.
But one important thing connects all of these, and that’s platelets.
Platelets are blood cells which sound your immune system’s alarm when your body is wounded, and form clots to help you heal.
Scientists from across the world have discovered that a group of molecules released by platelets known as platelet factor 4 (or PF4) are the crucial last step in delivering the benefits of these three activities to the brain. What’s more, PF4 can even help the brain reverse its age.
PF4 is released following injections of blood plasma (blood without the red blood cells) or klotho, or by exercising.
When 22-month-old mice – the equivalent to 70-year-old humans – were injected with young blood plasma, PF4 reversed their cognitive age. In fact, PF4 brought this age down to the equivalent of someone in their late 30s or early 40s. Young mice given PF4, meanwhile, became smarter.
The discoveries were made independently by three teams. But when they realised they had all identified PF4 as the key ingredient behind these benefits, these teams joined forces to publish their papers at the same time.
The studies on young blood and klotho injections were led by two different teams at the University of California San Francisco (UCSF). Scientists at the University of Queensland in Australia led the study on exercise.
The three papers have been published in the journals Nature, Nature Aging and Nature Communications.
“When we realised we had independently and serendipitously found the same thing, our jaws dropped,” said Dr Dena Dubal, the UCSF professor who led the study on klotho.
“The fact that three separate interventions converged on platelet factors truly highlights the validity and reproducibility of this biology. The time has come to pursue platelet factors in brain health and cognitive enhancement.”
Washed afresh with young blood
In ageing studies, scientists often transfuse blood from a young mouse into an old mouse via a procedure known as parabiosis. That’s because young blood is known to make animals more youthful, with more resilient muscles and a more flexible brain.
However, the team at the UCSF Bakar Aging Research Institute found that plasma on its own could mimic these benefits and reverse ageing.
They injected old mice with young blood plasma – which contains more PF4 than old blood. The old mice were rejuvenated, performing better in memory and learning tests than their counterparts.
They then injected the PF4 platelets on their own, and found that they were just as effective at reducing inflammation in the old mice’s ageing bodies and brains.
A protein-driven brain boost
The other UCSF team, led by Dr Dubal, found that an injection of klotho released PF4 in animals’ bodies.
A decade ago, Dubal showed that the klotho protein helps us stay healthy as we grow older by making our brains resistant to degeneration. But whenever she injected klotho into the body, it never reached the brain. She knew that there must be something else facilitating its benefits to brain health.
When the team injected klotho into the animals, they saw its huge impact on the brain. They observed the PF4 enhancing the formation of new neural connections to improve memory-making.
The team found that both young and old animals got a brain-boost from this. As a result, they’re now looking into use of klotho injections therapeutically.
Unlocking the benefits of exercise to the brain
The team from the University of Queensland discovered that PF4 was released into the bloodstream after exercise – and, as with the other teams, that this release improved brain performance.
Though injection-free, this option, the study suggests, may be better for young people as a preventative measure. For older people with mobility issues, the plasma or klotho injections would likely prove better interventions against cognitive decline.
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