Q. A colleague recently mentioned he’d heard something about “channels in the human skull.” Do you know anything about this? Frankly, it sounds a bit weird to me.

A. It certainly is amazing, I’ll say that. You may recall my blog mentioning the discovery by Jonathan Kipnis MD and his colleagues, that the brain actually contains an immune system (e.g., immune vessels run through the meninges, the three layers tissue that cover and protect the brain). Now there is more immune research.

As you probably know, spongy bone-marrow tissue inside most of the bones in the body produce cells. In addition to red blood cells, bone marrow produces immune cells—including bone marrow of the skull. A recent study funded in part by the National Institutes of Health and published in Nature Neuroscience, found tiny tunnels that link skull bone marrow to the lining of the brain. It appears these “channels” may provide a direct link for immune cells to follow when they are responding to injuries caused by strokes and other brain disorders.

Using detailed imaging of human skull samples obtained from surgery, Matthias Nahrendorf, M.D., Ph.D., professor at Harvard Medical School and Massachusetts General Hospital in Boston, and his colleagues uncovered the presence of these channels in both the inner and outer layers of bone.

Francesca Bosetti, Ph.D., program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), was quoted as saying: “We always thought that immune cells from our arms and legs traveled via blood to damaged brain tissue. These findings suggest that immune cells may instead be taking a shortcut 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.”