Via EurekAlert!: researchers "have identified a new stem cell that participates in the repair of the large airways of the lungs, which play a vital role in protecting the body from infectious agents and toxins in the environment. The airways protect the body by producing and clearing mucus from the airways. The mucus is largely produced by specialized mucus glands in the airway and the mechanisms of normal and excessive mucus production are not well understood. However, this newly discovered lung stem cell for the mucus glands will likely yield new insights into this critical process. ... The study [represents] the first time anyone has found the cell of origin for the many types of cells that make up the mucus glands and that can also repair the surface epithelium. The finding, the study states, is of 'major importance to the field of lung regeneration.' ... For example, there currently are no treatments for excess mucus production, which we see in cystic fibrosis, asthma and chronic obstructive pulmonary disease (COPD). But if we can understand the mechanisms of how these stem cells repair the mucus glands, then we may be able to find a way to put the brakes on the system and prevent mucus over production."