Most of our bones contain spongy tissue, bone marrow, responsible for the production of red blood cells and immune system cells. What we have known so far is that immune cells, formed in the core of the long leg and leg bone, passed through the blood through different parts of the body, including the brain, to fight infections or treat injuries,
The skull tunnel, recently discovered by a group of scientists led by Dr. Matthias Nahrendorf, Harvard Medical School and the Massachusetts General Hospital (Boston), a tiny blood vessel network that accelerates the cell trajectory. on lesions located in the brain.
"The body needs to have a faster treatment, use a shortcut to bring the first spas to an inflammation site," says Nahrendorf. And in this search, they find the tunnels for the first time, the direct route of arrival and quick access to injuries caused by inflammatory brain diseases.
The research was focused on neutrophils, certain types of white blood cells, which were among the first to reach the damaged area. Scientists have labeled these cells with specific colors to follow their path and found that during the stroke of a brain that supplies neutrophils to injured tissue rather than tibia, the leg's legs away from the site of injury. Likewise, after a heart attack, skull and thighs give a similar number of neutrophils in the heart, which is far from both areas.
The fact that the bone marrow of the whole body does not contribute equally to the immune cells to help inflammed or infected tissues suggests that injured brain and bone marrow skull must "communicate" in some way resulting in a reaction almost directly from the nearest neutrophils. The pieces of cells that cells use to "talk" are small proteins that play an essential role in organizing cellular work.
What is a gear starting after a cardiovascular accident? The factor derived from stromal cells (SDF-1) is the protein responsible for the retention of neutrophils in the bone marrow. Several hours after the injury, SDF-1 is reduced to the spinal cord, but not in the tibia, and in response to the damage, only neutrophils are released from the cranial spine, which is the closest inflammation site.
Arriving in the brain
Curious about the path of neutrophils, researchers used powerful microscopes. "We began to look closely at the skull, looking at it from all corners, trying to find out how neutrophils are coming to the brain," recalls Nahrendorf. "So we discovered small channels that linked the core directly to the outer brain cover," he adds.
Blood flows normally from the inside of the skull to the bone marrow, but after a stroke, the neutrophils moved through the channels in the opposite direction to easily reach the lesion.
Did they know the same in skull and tibia? Nahrendorf explains that in mice they have similar characteristics, and those human skulls have five times the diameter: "At this time we do not understand the channel architecture, but at least we know its place is unique," says Nahrendorf,
For explorers it is likely that the tunnels were also used by other cells. In addition, they have an important therapeutic goal. "We believe that close to meninga, a membrane that connects the brain, makes them attractive for drug delivery if the drug can be introduced into the cavity cavities. Our hope is to use them to stop inflammatory processes caused by hypertension, acute cerebrovascular accident and even chronic conditions such as Alzheimer's disease, "he says.
Pablo Iribarren, associate professor of the Department of Clinical Biochemistry at the UNC Faculty of Chemistry and chief scientist Conicet (Cibici), an expert on inflammatory brain processes, affirms: "The finding not only adds a new white blood cell entrance door, but changes the idea of how they come to the injured tissue. "
"This shows that white blood cells can, if necessary, migrate against blood flow, something that differs from what is already known. Additionally, the production of these cells can be adapted to urgent needs and so regionally. Study opens the possibility of better understanding of an inflammatory response during a stroke, "he says.
Iribarren agrees with Nahrendorf that this new route can be used for the use of immunomodulatory molecules for the treatment of various cerebral localization diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, infections and cancer.
It also suggests that this route may be used to direct the activity of the vaccine to the brain and to help remove amyloid proteins deposited during Alzheimer's disease and other neurodegenerative diseases.
Apart from the therapeutic projection of findings, the work of these scientists is a fascinating example of how an intelligent observer can extract such a useful concept from such a complex system.