Breakthrough Discovery: Blood Stem Cells Found in Human Lungs

Recent research from the University of California, San Francisco (UCSF) has unveiled a groundbreaking finding in the field of hematology, suggesting that human lungs may play a crucial role in blood production. Traditionally, it has been believed that blood stem cells, responsible for generating red blood cells and other blood components, primarily reside in the bone marrow. However, this new study indicates that hematopoietic stem cells (HSCs) are also present in lung tissue.

The research, published in the Blood Journal, highlights the potential of lung-derived HSCs as a significant resource for stem cell transplants, which are vital in treating various blood disorders, including leukemia. Dr. Mark Looney, a notable figure in the study, emphasized that these lung-derived cells could serve as an alternative reservoir for stem cells, complementing the established bone marrow sources.

In previous studies conducted in 2017, the UCSF team discovered that lung cells in mice were responsible for producing a substantial portion of the organism's platelets. This prompted researchers to investigate whether similar processes occur in humans. By analyzing donated human lung, bone marrow, and blood samples, the team found that HSCs in lung tissue closely resembled those found in bone marrow, being present at comparable rates.

To further validate their findings, the researchers conducted experiments that involved coaxing both lung and bone marrow HSCs to mature in controlled laboratory settings. The results indicated that the lung-derived HSCs were just as productive as their bone marrow counterparts, producing a higher yield of red blood cells and megakaryocytes, which are essential for blood clotting.

Additionally, the study demonstrated that lung HSCs could effectively restore bone marrow in mice that lacked sufficient HSCs, reinforcing the notion that the lungs might provide a complementary source of blood production. Looney suggested that these lung-based stem cells might act as an emergency reservoir, activated when the body requires an increase in blood components such as red blood cells or platelets.

Further examination of human lung tissue confirmed the presence of HSCs, which were found organized in a manner similar to that seen in bone marrow, indicating they are not merely transient cells migrating from the bone marrow. Interestingly, a substantial portion of stem cells currently utilized in bone marrow transplants exhibited characteristics of lung-derived HSCs, indicating that these cells may contribute to the transplant process.

Despite the promising nature of these findings, researchers acknowledge that there is still much to learn about the functional roles of lung HSCs and their potential applications in medical therapies. Questions remain regarding the specific reasons for the presence of these stem cells in the lungs and whether different populations of HSCs could serve unique therapeutic purposes.

As the understanding of lung-based blood stem cells expands, it opens up new avenues for therapeutic strategies in hematopoietic stem cell transplantation, a procedure commonly employed to treat patients with various blood-related conditions.