Embryonic, pluripotent stem cells have the potential to differentiate into almost any cell in the body. In contrast, stem cells that are derived from adults tend to have the ability to develop into other cells that are derived from the same tissue (multipotent), or into only specific cell types (unipotent). Examples of these are blood stem cells and germ cells, respectively. A technique can be used to alter adult stem cells to become less mature or differentiated (induced pluripotent stem cells), providing greater promise to their use to treat degenerative conditions in organs that are unrelated to the site of origin of the stem cells. A related discovery is that some stem cells can alter reparative or inflammatory pathways in a tissue or organ without necessarily becoming incorporated or engrafted into its structure. These observations have led to the hope that stem cell therapy can be an important adjunct in the management of a condition such as COPD that is marked by both chronic inflammation and the loss of structural and functional integrity of the lung.