Brain fluid from young mice can be injected into the brains of older mice to restore memory damaged by aging. The effect is attributed to a protein, Fgf17, which is emerging as a possible brain rejuvenation factor.
Researchers at Stanford University in California have found that injecting cerebrospinal fluid taken from young mice into the brains of adult mice improves their age-affected cognitive function.
Aging affects brain capacities, especially memory, so the fact that symptoms of aging in brain function can be reversed may lead to treatments for age-associated neurodegenerative diseases in the future.
Cerebrospinal fluid (CSF) bathes the brain tissue and spinal cord of all vertebrate animals, providing it with nutritional compounds. It is essential for normal brain development.
However, as mammals age, the CSF loses some of its efficiency, and these changes could affect cells related to memory.
That is why Tal Iram, a neuroscientist at the aforementioned University, and his colleagues investigated whether young cerebrospinal fluid, injected into older people, could improve degraded brain functions, including memory. They publish the results of their study in the journal Nature.
a little further
It was already known that plasma from young mice can restore memory function in older rodents, but the new researchers set out to go a little further: extracting CSF and then reinjecting it into another brain, which represents a greater technical challenge, due to its complexity.
To test their hypothesis, the first thing these researchers did was provide the mice with an experience that they could easily remember: for 20 months, they gave them small electrical shocks on their paws, associated with flashes of light and sound, so that they learned to relate them with downloads.
They then reinjected the brains of older mice with cerebrospinal fluid from the young mice who had experienced the experience, and subjected them to an eye-opening experience.
Those mice with cerebrospinal fluid from young mice were exposed to flashes of light and sound, but without giving them electric shocks.
The researchers found that 40% of these mice reacted with fear to flashes of light and sound, as if they had experienced the electric shocks suffered by young mice.
The brain is malleable
These results suggest that young CSF can restore, to some extent, brain capacities degraded with agingindicating that the brain is malleable and that its functioning can be improved.
The researchers also delved into the mechanisms involved in this improvement in brain function and analyzed the changes that the young cerebrospinal fluid caused in the hippocampus, the region of the brain that manages memory.
They discovered that the rejuvenation of is due to a protein, fgf17, involved in cell growth, that it is outlined as a possible factor of brain rejuvenation, as well as that certain genes (different in CSF from young and old) could be used to obtain the same response, without the need to extract brain fluid from younger mice.
Hopes for human treatments
The results obtained in this work are surprising and promising, but there is still time before they can contribute to recovering memory in humans.
John LermaDirector of the Cajal International Center for Neurosciences (CINC-CSIC), points out that this work not only describes that the CSF constitutes a biochemical environment determined by age, which influences cognitive processes and cell survival, but also determines which genes they are turned on or off when the mice are treated with liquid as youngsters.
He adds that the research opens up hope for relatively easy-to-administer treatments that can alleviate memory loss in Alzheimer’s and other dementias, but also physiological joint decline.
Naturally, more needs to be learned, on one side (basic mechanistic aspects) and on the other (to what extent is this likely to work in humans as a therapy), concludes Lerma.
Young CSF restores oligodendrogenesis and memory in aged mice via Fgf17. Tal Iram et al. Nature (2022). DOI:https://doi.org/10.1038/s41586-022-04722-0