British scientists at the Imperial College in London have reported that respiratory diseases such as asthma and pulmonary fibrosis automatically trigger the release of the body’s own endogenous stem cells from the bone marrow, which is already recognized as an important site of stem cell activity. Not only are blood cells formed in the bone marrow through hematopoiesis, but mature granulocytes and stem cells such as hematopoietic stem cells, mesenchymal stem cells and fibroblasts are known to reside in the bone marrow.
Now the researchers have found that chemical mediators which are released by lung diseases into the blood stream can trigger the mobilization of these various cells from the bone marrow into the blood from which they are then recruited to the lungs, often with competing objectives, such as inflammation which is caused by the granulocytes, and tissue repair or remodelling which is promoted by the stem cells. Both processes, however, play a role in healing and recovery.
As the researchers explain, “Understanding the factors and molecular mechanisms that regulate the mobilization of granulocytes and stem cells from the bone marrow may lead to the identification of novel therapeutic targets for the treatment of a wide range of respiratory disorders.” Even before such mechanisms are fully understood, the administration of externally derived stem cells could also augment the body’s natural implementation of its own endogenous stem cells in the treatment of respiratory diseases.