Hidden ‘tunnels’ that carry immune cells to brain found in human skulls

HIDDEN tunnels which link the human skull to the brain have been discovered by scientists, leading to hopes the breakthrough may help in stroke and Alzheimer’s research.

Researchers believe that the passages provide a quick channel for immune cells to reach the brain from the bone marrow in the skull. Previously it was thought that immune cells formed in the bone marrow of the limbs was transported up to the brain to clear out infection.

But the study suggests the body has a quicker way of healing itself, which could open the door to a better understanding of neurodegenerative diseases like Alzheimer’s.

“We always thought that immune cells from our arms and legs travelled via blood to damaged brain tissue,” said Dr Francesca Bosetti, programme director at the NIH’s National Institute of Neurological Disorders and Stroke in the UK.

“These findings suggest that immune cells may instead be taking a short-cut to rapidly arrive at areas of inflammation.

“Inflammation plays a critical role in many brain disorders and it is possible that the newly described channels may be important in a number of conditions. The discovery of these channels opens up many new avenues of research.”

The discovery was made after injecting dye into the bone marrow of mice with brain injuries and watching how the immune cells made their way to the injury. Researchers found that immune cells, called neutraphils, showed up first and appeared to be coming from the skull.

Matthias Nahrendorf, Professor of Radiology at Harvard Medical School, added: “We started examining the skull very carefully, looking at it from all angles, trying to figure out how neutrophils are getting to the brain.

“Unexpectedly, we discovered tiny channels that connected the marrow directly with the outer lining of the brain.”

The team then looked at scans of human skulls from people who had undergone brain surgery and found that the same tunnels are also present.

“Now we want to investigate the relevance of these channels – which we also observed in skull sections removed from human patients – to inflammatory central nervous system diseases, including acute stroke, hypertension and even chronic conditions like Alzheimer’s disease,” added Prof Nahrendorf.

The research was published in the journal ‘Nature Neuroscience’. (© Daily Telegraph, London)