Diseases of the lungs are some of the most common causes of illness and death worldwide, particularly in individuals over age 50. Most research in lung diseases with induced pluripotent stem cells thus far has focused on chronic obstructive pulmonary disease, or COPD. In the near future, induced pluripotent stem cells will likely be used for larger-scale tissue regeneration purposes in patients who have lost significant areas of their lungs to cancerous tumors, and in patients suffering from diseases of autoimmune inflammation, such as bronchiolitis.
Typically, COPD is the focal point of research and the target of the most advanced treatments in lung disease as it is the most likely form of lung disease to lead to major cancers. Although genetics do play some role in the development of COPD, it is primarily known as an obstructive lung disease, in which airflow is reduced substantially by regular exposure to toxic inhaled compounds: tobacco and other smoke, air pollution, and occupationally-related fumes from dusts to paint and other chemicals. Because the tissues of the lungs repair themselves at a relatively slow rate relative to other body tissues, the prolonged, repeated exposure to toxins that is characteristic in most cases of COPD is often impossible for the body to overcome by itself.
In COPD, gradual buildup of contaminants within the lungs, as well as an inflammatory response to those contaminants, causes a gradual breakdown of the connective tissue within the lungs, reducing their response to the expansions and contractions of the lungs that ultimately move air in and out of the body. This results in progressively worsening shortness of breath, reduced lung capacity, and increased vulnerability to infections and environmental irritants.
At present, research on induced pluripotent stem cells (iPSCs) in lung disease has focused on increasing the lungs' natural rate of self-repair by introducing undifferentiated cells - i.e., cells that have not yet been transformed into lung tisue in the lab - into damaged areas of the lungs and using those cells to accelerate the healing of damaged tissues while removing the primary cause of exacerbation, generally cigarette smoke or chemical exposure. While this has shown to have some benefit, the greatest promise of regenerative medicine in lung disease likely lies in the cultivation of fully differentiated, new lung tissue to entirely replace diseased areas of the lung which, unlike transplanted tissue taken from human donors, will require no immunosuppressive therapy to maintain.