Rebuilding a diseased lung: repair and regeneration.

C hronic lung diseases, including chronic obstructive pulmonary disease, asthma, lung cancer and pulmonary fibrosis, are the second leading cause of death in the world. Currently, only limited therapeutic options exist for chronic lung diseases; in particular, causative therapeutic approaches are missing. Lung transplantation remains the only available therapy for many patients with end-stage lung disease; however, the number of patients listed for lung transplantation by far surpasses the number of suitable donor organs.