Scientists discover new treatment that improves brain trauma recovery in mice

Researchers in the UK and Belgium have discovered a new treatment that more effectively restricts inflammatory reactions after brain trauma in mice, the Flemish Institute for Biotechnology (VIB) announced on Thursday. The groundbreaking aspect of the treatment is that the drug can be injected into the bloodstream and then travels through the blood-brain barrier into the brain. It is the first time that the blood-brain barrier could be breached in the specific case of brain trauma.

Traumatic brain injury, like that caused during a car accident or a fall, can lead to cognitive impairment or even dementia. What is important in such an injury is that it is an inflammatory response in the brain that often causes cognitive impairment.

The researchers already knew that T cells are able to sense and reduce inflammation. However, our brains have far fewer of these regulatory T cells than our blood. In order to limit the damage after a brain injury, it was therefore necessary to increase the number of T-cells in the brain. ​ 

The team discovered that the low number of T cells in the brain is due to the limited supply of the molecule interleukin 2, also known as IL2. The reason there is little IL2 in the brain compared to our blood is that the molecule cannot cross the blood-brain barrier. 

The scientists developed a 'gene delivery' system: the drug is injected into the bloodstream, crosses the blood-brain barrier and delivers the DNA that allows more IL2 molecules to be produced in the brain. The level of the IL2 molecule in the brain climbed to the same level as the blood, and the number of T cells could also build up in the brain, up to ten times higher than normal. 

The research has so far been carried out on mice. The tests showed that mice with more IL2 indeed had less damage after their brain injury. They also scored better on cognitive tests. "Not only have we found which drug works effectively to reduce brain damage, we have also managed to find a way to get the drug into the brain," says Professor Adrian Liston (Babraham Institute in the UK, which has collaborated with the VIB).

"This is a very big step for science. It was a real eureka moment when we saw the brains of the mice: then we knew the treatment worked."

The researchers have tested their system in no less than six different brain diseases or disorders, including multiple sclerosis and strokes. The team is also currently working on a publication on preventing cognitive decline in ageing mice. 

Clinical studies in humans have not yet been done. Professor Liston expects these to start within two years, after toxicology tests have been completed and if sufficient funding has been found. The clinical trials themselves would also take at least two years. 

The results of the study were published on Thursday in the scientific journal Nature Immunology. 

(KR)

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Scanning electron micrograph of a human T lymphocyte or T cell © AFP PHOTO /NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES