Researchers at the University of San Francisco have stumbled upon a previously undiscovered function of lungs.

In their study published recently in Nature, they revealed that lungs play an important role in blood production. In fact, they produced more than half of the platelets in the circulation. Previously, blood production is only associated with bone marrow.

New Atlas notes that megakaryocytes -- cell producing platelets -- circulating through the lungs, have been spotted by scientists before, but they have always thought that they were all from the bone marrow.

"When we discovered this massive population of megakaryocytes that appeared to be living in the lung, we realized we had to follow this up," says one of the team researchers, Emma Lefrançais, in a statement.

The astonishing new discovery was made using video microscopy in the living mouse lung. The new sophisticated technique based on two-photon intravital imaging allowed them to examine interactions between the immune system and circulating platelets in the lungs of the mouse.

A substance known as green fluorescent protein (GFP) was injected into the mouse genome to monitor the path of the mouse platelets in real time.

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During the course of the observation, they have found that the megakaryocytes travel all the way from the bone marrow to the lungs to produce platelets. Amazingly, the lungs produce more than 10 million platelets per hour.

"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 Mark R. Looney, lead author of the paper.

Science Alert notes that the video microscopy also revealed that just outside the lung tissues are vast amounts of previously hidden blood stem cells and megakaryocyte progenitor cells.

"It's fascinating that megakaryocytes travel all the way from the bone marrow to the lungs to produce platelets," said Guadalupe Ortiz-Muñoz, PhD, co-author. "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."

The new study opens a door to discovery new ways to aid medical problems in the field of blood cell formation, lung biology and disease, and transplantation.

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