Lung diseases are a common result of birth defects and premature birth. Cystic fibrosis is one of the most common inherited disorders with childhood onset in the United States. Premature babies commonly experience respiratory problems after birth, and these infants are at an increased risk for bronchopulmonary dysplasia (BPD). Improvements in treatment have made it possible for many infants to survive lung defects. However, survival of impaired lung function at birth likely contributes to an expanding spectrum of chronic lung disease in children and adults.
Stem cells, the self-duplicating cells that maintain specialized cells within a tissue, are likely to be critical target cells in lung disease. In 2005, future Children’s Hospital Boston stem cell researcher Carla Kim, PhD, was the first person to discover a group of stem cells from the adult mouse lung called bronchioalveolar stem cells (BASCs). BASCs help to repair specialized lung cells needed for lung function if they are damaged. Dr. Kim’s lab now studies the different molecules that regulate the lung stem cells’ growth and activity, which will help them find a similar cell that may exist in human lungs. This work will help in understanding and treating diseases such as bronchopulmonary dysplasia, emphysema, chronic lung disease, bronchiolitis obliterans and lung cancer. Dr. Kim is one of only a few scientists in the world who know how to isolate, cultivate and study lung stem cells.
Kim’s lab is also developing ways to isolate mouse lung stem cells and re-grow them in other mice. Observing the ability of these cells to grow and produce more specialized lung cells in such a transplant setting will help scientists understand the specific traits that make a lung stem cell. Once this method has been perfected, it can be used to identify lung stem cells in humans and, in the long run, may help in creating ways to use knowledge of stem cells to treat diseases such as cystic fibrosis.
In the future, it may be possible to heal the fragile, underdeveloped lungs of premature babies using adult bone marrow stem cells (BMSCs). Stella Kourembanas, MD, in the Division of Newborn Medicine at Children’s Hospital Boston and an affiliate member of the Stem Cell Program at Children’s, is exploring the potential use of BMSC conditioned media, the liquid in which the cells are grown in the lab. Her research shows that this media is full of paracrine factors, chemical messengers one cell secretes to communicate with a neighboring cell. In experiments performed in mouse models of bronchopulmonary dysplasia, BMSC conditioned media alone was powerful enough to protect the lungs from inflammation and prevent chronic lung disease. Intriguingly, the media proved to be a more effective treatment than the stem cells themselves.
This experiment suggests that stem cell treatment may not actually require a stem cell transplant to have therapeutic effects. In addition, conditioned media may be a more desirable treatment because they can be produced more economically in large amounts and are easier to handle than actual cells. Stem cell media can be tested to treat diseases of multiple other organs including the brain and heart.