Brains get stiffer with old age, scientists have discovered in breakthrough that could lead to new treatments for multiple sclerosis.
University of Cambridge researchers found the brain tissue of rats becomes less flexible over time.
This affects the cells that maintain normal brain function, and cause the fatty substance that surrounds and protects nerves, called myelin sheath, to regenerate.
Myelin damage is a key feature of MS. This prevents nerves sending messages around the body, leading to poor mobility, blurred vision and even incontinence.
When the researchers transplanted old, stiff brain cells from older rats to younger animals, the cells regenerated to become more ‘youthful’.
Experts hope the ‘fascinating’ study could one day lead to MS treatments that ‘regain lost function in the brain’.
Multiple sclerosis may be triggered by the brain become ‘stiffer’, research suggests (stock)
MS is a lifelong condition that affects the brain and spinal cord. Common symptoms include muscle spasms, slow thinking and sexual problems.
Around 100,000 people are thought to have MS in the UK, MS Society statistics show.
And in the US, nearly one million adults have the condition, according to the National Multiple Sclerosis Society.
There is no cure, with treatments focusing on reducing relapses and easing symptoms.
Muscles and joints become stiffer with age, which makes everyday movements more difficult, the researchers wrote in the journal Nature.
To uncover if the same is true for our brains, they analysed the brain cells of young and old rats.
The team specifically looked at oligodendrocyte progenitor cells (OPCs), which are a form of stem cell that maintain brain function and regenerate myelin.
Stem cells are basic cells with the ability to differentiate into more specialised cells.
The effect of ageing on OPCs is thought to play a role in MS’ onset but also affects healthy people, the researchers wrote.
WHAT IS MULTIPLE SCLEROSIS?
Multiple sclerosis (known as MS) is a condition in which the immune system attacks the body and causes nerve damage to the brain and spinal cord.
It is an incurable, lifelong condition. Symptoms can be mild in some, and in others more extreme causing severe disability.
MS affects 2.3 million people worldwide – including around 400,000 in the US, and 100,000 in the UK.
It is more than twice as common in women as it is in men. A person is usually diagnosed in their 20s and 30s.
The condition is more commonly diagnosed in people of European ancestry.
The cause isn’t clear. There may be genes associated with it, but it is not directly hereditary. Smoking and low vitamin D levels are also linked to MS.
Symptoms include fatigue, difficulty walking, vision problems, bladder problems, numbness or tingling, muscle stiffness and spasms, problems with balance and co-ordination, and problems with thinking, learning and planning.
The majority of sufferers will have episodes of symptoms which go away and come back, while some have ones which get gradually worse over time.
Symptoms can be managed with medication and therapy.
The condition shortens the average life expectancy by around five to 10 years.
To determine whether these effects are reversible, they transplanted OPCs from old rats into the soft, spongy brains of younger animals.
The team were surprised to find the older brain cells rejuvenated and began to behave like the younger, more vigorous cells.
In a second part of the experiment, the researchers developed materials in the laboratory with a similar softness to either young or old brains.
‘We were fascinated to see that when we grew young, functioning rat brain stem cells on the stiff material, the cells became dysfunctional and lost their ability to regenerate, and in fact began to function like aged cells,’ co-lead author Dr Kevin Chalut said.
‘What was especially interesting, however, was that when the old brain cells were grown on the soft material, they began to function like young cells. In other words, they were rejuvenated.’
The researchers then investigated the role of the protein Piezo1.
This is found on the surface of OPCs and informs the cell whether its surrounding environment is soft or stiff.
‘When we removed Piezo1 from the surface of aged brain stem cells, we were able to trick the cells into perceiving a soft surrounding environment, even when they were growing on the stiff material’, Dr Chalut said.
Co-lead author Professor Robin Franklin added: ‘What’s more, we were able to delete Piezo1 in the OPCs within the aged rat brains, which led to the cells becoming rejuvenated and once again able to assume their normal regenerative function’.
Dr Susan Kohlhaas, director of research at the MS Society, which part funded the research, said: ‘MS is relentless, painful, and disabling.
‘Treatments that can slow and prevent the accumulation of disability over time are desperately needed.
‘The Cambridge team’s discoveries on how brain stem cells age and how this process might be reversed have important implications for future treatment.
‘It gives us a new target to address issues associated with aging and MS, including how to potentially regain lost function in the brain.’