It blows me away that in 2017, we’re still figuring out how the body works. This morning’s study shows that platelets and neutrophils work together a little like cattle dogs and a rancher. Let me explain.
Platelets are cell fragments that circulate in the blood. One purpose for platelets is to initiate clotting when a break in a blood vessel has occurred, such as due to a cut or a puncture wound. In addition, platelets are chockful of natural-healing growth factors, so not only do they help stop bleeding by clumping together and sealing up small wounds, they also get local cells on track to start repairing the wound or injury. Growth factors are specialized biochemicals that communicate with other cells, providing instructions and energy during the healing and rebuilding effort. I’ve used the analogy before that growth factors are little shots of espresso for the local cells that are working so hard to repair the damage.
Platelets have a short life, so our bodies are constantly replenishing our blood circulation with a fresh supply of new platelets. Platelets are produced from huge cells in our bone marrow called megokaryocytes. From the bone marrow, the platelets travel through blood vessels into our central circulation system where the heart pumps them throughout the body via the vascular system.
The platelets’ ability to stimulate local repair cells to get to work is why injections of platelet rich plasma (PRP) can be so beneficial to supercharging the healing process when the body is unable to heal the damage on its own. To create the PRP, whole blood is drawn from the patient. The blood is then centrifuged, separating the serum to concentrate the platelets. These concentrated platelets, the PRP, can then be reinjected in the precise location of the damage.
Now, in addition to clotting and stimulating healing, researchers seem to have found another big purpose for platelets: collecting bacteria into bundles so neutrophils can kill them. Let’s review a little on neutrophils before we look at the study.
Neutrophils are white blood cells that continuously circulate, along with red blood cells, platelets, and other cells, throughout our vascular system. They are are protective immune cells known as phagocytes, which means they ingest and release chemicals to destroy invading bacteria and other pathogens as well as dead cells and other debris.
Known best for their bacteria-hunting skills, when bacteria invade, neutrophils detect their presence, slip through the vessel walls, rush to the scene, and devour and destroy the bacteria. Neutrophils also have a short life, so, again, our bone marrow is constantly producing a fresh supply and, once mature, releasing them into active circulation.
The new study consisted of an extended focus on the activity of platelets at sites where inflammation (a response to damage or infection) has occurred. What they found was platelets and neutrophils, in effect, teaming up to destroy bacteria. How does this work?
After bacterial invasion, the researchers discovered that platelets migrate to the site of infection and patrol the area, gathering the bacteria, trapping them, and then bundling them into groups. Chemicals released from the bacteria during this process stimulate the phagocytic neutrophils to report to the location, where they are able to quickly capture and ingest the trapped bundles of bacteria and kill them, certainly a much more efficient process than chasing down and gobbling up one bacteria at a time.
The upshot? The body is pretty cool. It always amazes me that something we observe in life as a process, like a dog rounding up sheep or cattle so it’s easier for the rancher, is replicated inside us!
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About the Author
Christopher J. Centeno, M.D. is an international expert and specialist in regenerative medicine and the clinical use of mesenchymal stem cells in orthopedics. He is board certified in physical medicine as well as rehabilitation and in pain management through The American Board of Physical Medicine and Rehabilitation.…