The brain becomes stiff with age, like muscles and joints, scientists have said.
New research indicates that increasing brain stiffness with age leads to dysfunction of the brainstem.
However, scientists have identified ways to bring older stem cells into a younger, healthier state, potentially impacting future treatments for multiple sclerosis (MS).
The Cambridge Stem Cell Institute (Cambridge University) team studied old and young rat brains to understand the effects of age-related strangulation on oligodendrocyte precursor cells (OPCs).
These cells are important for maintaining normal brain function and for the regeneration of myelin – the fatty sheath surrounding the nerves, which is damaged in multiple sclerosis (MS).
The effects of age on these cells contribute to MS, but their function also decreases with age in healthy people.
Dr. Kevin Chalut, who led the research, said, "We were intrigued to see that when we grew up young, functioning stem cells of the rat brain on the stiff material, the cells became dysfunctional and lost their ability to regenerate, actually starting like aged cells function.
"What was particularly interesting was that the old brain cells, when grown on the soft material, began to function like young cells – in other words, they were rejuvenated."
In the study published in the Nature Journal, researchers transplanted older OPCs from old rats into the soft, spongy brain of younger animals.
They found that the older brain cells were rejuvenated and began to behave like the younger, stronger cells.
The researchers then developed new materials with different degrees of stiffness in the laboratory and used them to grow and study rat brain stem cells in a controlled environment.
The materials have been engineered to be as soft as young or old brains.
To understand how the softness and stiffness of the brain affects cell behavior, the researchers studied Piezo1 – a protein on the cell surface that informs the cell whether the environment is soft or stiff.
"When we removed Piezo1 from the surface of aged brain stem cells, we were able to induce the cells to sense a soft environment even when growing on the stiff material," said Professor Robin Franklin, who led the research.
Dr. Susan Kohlhaas, research director of the MS Society, which co-funded the research, said, "MS is relentless, painful, and disabling, and treatments that can slow down and prevent the accumulation of disability over time are urgently needed.
"The Cambridge team's discoveries about how stem cells age in the brain and how this process could be reversed will have important implications for future treatment as it gives us a new goal to address aging and MS related issues, including the issue How Lost Functions Can Be Recovered in the Brain Brain. "