In an unusual experiment, researchers from the United States and Russia connected the blood systems of young and old mice for 12 weeks, which slowed cell aging in the older animals and increased their lifespan by 10 percent.
This study extends previous research showing that there are components in the blood of young mammals that are worth studying to discover beneficial properties for slowing aging.
While the results are impressive, they do not support holistic blood transfusion in the human body. Putting aside the huge biological gap between mice and humans, there are many known and serious risks associated with such procedures for the recipient, not to mention the questionable ethics of donation.
“What’s important is what’s driving this process, and that’s still unknown,” explains James White, a cell biologist at Duke University.
“Could it be proteins or metabolites? Is the young mouse coming in with new cells, or is it just compensating for the old, aging-inducing blood?”
To find out, geneticist Bohan Zhang and his colleagues at Harvard University combined the blood systems of pairs of young mice (3 months old), pairs of old mice (two years old), and pairs consisting of an old mouse and a young mouse, and compared the results.
The study found that the old mice that received young blood had more regulatory compounds such as tricarboxylic acid, which indicates chemical processes normally interrupted by aging, increased production of mitochondria – the “energy centers” of cells, reduced inflammation and higher expression of genes associated with longevity.
“This effect correlates with longer lifespan, improved physiological performance and globally rejuvenated” genetic regulators and cellular proteins, the researchers explain in their paper, confirming that 12-week blood pooling was much more effective than the previously studied short-term blood pooling (five weeks).
While Zhang and colleagues’ study was going through the peer-review process, another study using similar methods was published, which unfortunately brought bad news for young donor mice. They lost part of their lifespan due to the procedure.
This means that the researchers can’t rule out the possibility that whole cell exchange is causing these changes, for example by replacing and diluting the number of damaged old cells that the donor body then has to cope with.
However, Zhang and his team could not find any evidence that young cell types linger anywhere, such as in the bone marrow, although the positive results remain.
The researchers are keen to find out the cardiovascular components behind these incredible benefits.
The study was published in the journal Nature Aging.
