US scientists discovered a surprising hidden function of mammalian lungs – they help produce blood. Their study on mice showed that more than half of all platelets in mice are produced by the lungs, a process long attributed to bone marrow.

If science has thought us anything about the human body over the years, it´s that we’re not nearly close  to understanding all of its complexity, not even the seemingly trivial stuff. Just a few months ago we discovered a whole new organ dwelling within us, at a time where science is capable of producing synthetic life and genetically engineering embryos. A very recent finding about the lung doesn’t fall short in excitement as well.

A research group at the University of California, San Francisco (UCSF) used video microscopy to examine real-time cellular processes in mouse lungs, only to discover they facilitate another function besides respiration – they produce platelets, tiny blood cells responsible for blood clotting, and they produce lots. The team reported production of 10 million per hour, corresponding to the majority of all platelets in the animals’ blood stream. Their study was published just days ago in Nature.

“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.” said lead researcher Mark R. Looney.

Platelet production is carried out by special cells called megakaryocytes. While they have been previously found in lungs, they were mainly associated with bone marrow tissue to date. Apart from megakaryocytes, the group also identified a population of blood stem cells residing in the vicinity, further supporting the lung’s role in blood production, possibly even in humans.

“What we’ve observed here in mice strongly suggests the lung may play a key role in blood formation in humans as well” explained Looney, adding “this is the first description of blood progenitors resident in the lung, and it raises a lot of questions with clinical relevance for the millions of people who suffer from thrombocytopenia.

How exactly bone marrow cells ended up in the lungs remains unclear, but the group’s findings introduced an important new landscape for future hematopoiesis research.

“It’s possible that the lung is an ideal bioreactor for platelet production because of the mechanical force of the blood, or perhaps because of some molecular signaling we don’t yet know about.” concluded researcher Guadalupe Ortiz-Muñoz.

Learn more about the team’s fascinating discovery in the short video bellow:

By Luka Zupančič, MSc, University of Applied Sciences Technikum Vienna