The term stem cell refers to any cell which is found in a developed organism that has two properties: the ability to divide and create another cell like itself and also divide and create a cell more differentiated than itself.
Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues.
In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions.
A significant potential application of stem cells is making cells and tissues for medical therapies. Stem cells are important for living organisms for many reasons. In many adult tissues, such as bone marrow, adipose, muscle, and brain, discrete populations of adult stem cells generate replacements for cells that are lost through normal wear and tear, injury, or disease. Thus, treatment using stem cells is termed “regenerative medicine” and has many potential uses for a wide variety of diseases and injuries.