Unveiling the hidden role of human lungs in blood cell production: A new frontier in medical science

For decades, medical science has attributed blood cell production solely to bone marrow, but a groundbreaking study by University of California, San Francisco (UCSF) researchers has challenged this long-held belief. Their latest findings reveal that human lungs harbor hematopoietic stem cells (HSCs)—the vital precursors responsible for generating red blood cells, platelets, and immune cells.

Published in Blood, this research not only enhances our understanding of blood production but also suggests lungs as a potential new source for life-saving stem cell transplants.

Lungs and Blood Cell Production: A Paradigm Shift

Traditionally, scientists believed bone marrow was the exclusive site for hematopoiesis—the formation of blood cells. However, this study builds on UCSF’s 2017 discovery in mice, where nearly 50% of platelet production was traced back to the lungs.

To confirm this in humans, researchers examined lung, bone marrow, and blood samples. The results were astonishing:

✅ Hematopoietic Stem Cells in the Lungs – HSCs were found in similar concentrations in both lung tissue and bone marrow.

✅ Lung HSCs Are Functional – When cultured in petri dishes, lung-derived HSCs produced red blood cells and megakaryocytes (which form platelets) at higher rates than their bone marrow counterparts.

✅ Stem Cells Can Restore Bone Marrow – Lung HSCs successfully repopulated bone marrow in HSC-deficient mice, proving their viability in blood production.

✅ Lung Stem Cells in Transplants – Analysis of routine bone marrow transplants revealed that nearly 20% of transplanted HSCs carried the signature of lung-derived stem cells—indicating that current transplants are not solely reliant on bone marrow.

What This Means for Medicine

This discovery could revolutionize stem cell transplantation, particularly for patients with leukemia and other blood disorders. If lung HSCs serve as an emergency reservoir for red blood cells, platelets, and immune cells, they could be harnessed for targeted therapies in regenerative medicine.

“This is a major step forward in understanding how blood cell production works,” said Dr. Mark Looney, senior author of the study and professor of medicine at UCSF. “It opens up new opportunities for therapeutic applications of hematopoietic stem cells, especially for patients requiring transplants.”

What’s Next?

Scientists still have many questions:

• Could lung-derived HSCs be superior for specific medical treatments?
• Do lungs produce blood for emergency replenishment, independent of bone marrow?
• How can these findings enhance stem cell transplant success rates?

As research progresses, the role of the lungs in hematopoiesis may become a cornerstone of future treatments, offering new hope for millions of patients worldwide.