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Crimson blood cells carry oxygen from the lungs to each different organ, and blood-forming stem cells should make about 200 billion new purple blood cells every day to maintain the oxygen flowing.
For a few years, scientists assumed that blood manufacturing befell within the bone marrow. However now, researchers at UCSF are exhibiting it is also taking place within the lungs.
They discovered hematopoietic stem cells (HSCs) in human lung tissue that make purple blood cells, in addition to megakaryocytes, which produce the platelets that type blood clots. The findings seem Feb. 27 within the Blood Journal
The work suggests the lungs may very well be a potent supply for life-saving stem cell transplants.
“For decades, bone marrow transplants have been a lynchpin in the treatment of cancers like leukemia,” mentioned Mark Looney, MD, professor of medication and laboratory medication at UCSF and senior writer of the paper. “The lung HSCs could prove to be a second and significant reservoir of these precious stem cells.”
From mouse to human
In 2017, the UCSF workforce discovered cells within the mouse lung making 50% of the mouse’s platelets.
In addition they found lung stem cells in mice that made all of the constituents of blood, together with purple blood cells, megakaryocytes and a number of other kinds of immune cells.
Looney’s group needed to show this was additionally taking place in folks. So, they obtained donated samples of lung, bone marrow and blood, and in contrast what they present in every tissue.
Screening a golf-ball-sized quantity of lung tissue, the scientists discovered stem cells within the lung that strongly resembled the well-known HSCs of bone marrow. Surprisingly, the HSCs have been discovered at related charges in each lung and bone marrow.
“The lung HSCs weren’t one-offs—they were a reliable presence in the lungs,” mentioned Catharina Conrad, MD, Ph.D., postdoctoral scholar in Looney’s lab and first writer of the paper. “But we still needed to know that they were actually capable of making blood.”
So, the scientists coaxed lung and bone marrow HSCs to mature in petri dishes and located the lung HSCs have been productive identical to the bone marrow HSCs.
“Both types of HSCs thrived in our gold-standard stem cell experiment, but the lung HSC colonies made more red blood cells and megakaryocytes, while the bone marrow colonies tended to make more immune cells,” Looney mentioned.
The human lung HSCs might additionally restore bone marrow in HSC-deficient mice. The invention confirmed Looney’s earlier discovery that the mouse lung and bone marrow complemented each other in producing blood, even sending stem cells to revive each other.
“We think these HSCs could be a reservoir of hematopoiesis in a particular organ, in this case the lung, that gets activated whenever the body needs more of any part of the blood, whether it’s platelets, red blood cells or immune cells,” Looney mentioned.
Attending to know the brand new HSC on the town
To point out that the lung HSCs really resided within the lung, and weren’t simply escapees from the bone marrow, Conrad and Looney regarded for the HSCs in human lung tissue samples.
They discovered them between blood vessels in an association that was harking back to what’s seen in bone marrow.
“They really seem to live there and aren’t just passing through,” Conrad mentioned.
Lastly, the workforce analyzed the output of routine bone marrow transplants, which right this moment start with a blood draw from a donor adopted by a display screen for stem cells.
Remarkably, practically a fifth of the stem cells remoted for bone marrow transplant carried the signature of lung HSCs—suggesting that cells in “bone marrow transplants” aren’t solely from bone marrow.
There’s much more to study concerning the lung HSCs. Might the totally different swimming pools of HSCs serve totally different therapeutic roles in medication? Why do the lungs themselves must make blood?
“The lungs are critical to blood circulation, so it’s tantalizing to see the lung HSCs as an emergency reservoir for red blood cell and platelet production,” Looney mentioned. “Now that we know they exist, it opens up a lot of new opportunities for a therapy, hematopoietic stem cell transplantation, that is very commonly used for patients with the need.”
Extra info:
Catharina Conrad et al, Decoding useful hematopoietic progenitor cells within the grownup human lung, Blood Journal (2025). DOI: 10.1182/blood.2024027884
Journal info:
Blood
Supplied by
College of California, San Francisco
Quotation:
Discovery of lung-based blood stem cells might rework transplant therapies (2025, February 27)
retrieved 27 February 2025
from https://medicalxpress.com/information/2025-02-discovery-lung-based-blood-stem.html
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