An Unexpected New Lung Function Has Been Found – They Make Blood

Researchers have discovered that the lungs play a far more complex role in mammalian bodies than we thought, with new evidence revealing that they don’t just facilitate respiration – they also play a key role in blood production.

In experiments involving mice, the team found that they produce more than 10 million platelets (tiny blood cells) per hour, equating to the majority of platelets in the animals’ circulation. This goes against the decades-long assumption that bone marrow produces all of our blood components.

Researchers from the University of California, San Francisco also discovered a previously unknown pool of blood stem cells that makes this happen inside the lung tissue – cells that were incorrectly assumed to mainly reside in bone marrow.

“This finding definitely suggests a more sophisticated view of the lungs – that they’re not just for respiration, but also a key partner in formation of crucial aspects of the blood,” says one of the researchers, Mark R. Looney.

“What we’ve observed here in mice strongly suggests the lung may play a key role in blood formation in humans as well.”

While the lungs have been known to produce a limited amount of platelets – platelet-forming cells called megakaryocytes have been identified in the lungs before – scientists have long assumed that most of the cells responsible for blood production are kept inside the bone marrow.

Here, a process called haematopoiesis was thought to churn out oxygen-laden red blood cells, infection-fighting  white blood cells, and platelets – blood components required for the clotting that halts bleeding.

But scientists have now watched megakaryocytes functioning from within the lung tissue to produce not a few, but most of the body’s platelets. Source

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