Most of the 300 trillion cells that make up the human body are fully specialized for particular functions in organs such as the heart or the brain, or in tissues like muscle, fat and bone. Others play a supply or defensive role in the blood or immune system. Each cell type has a specific lifespan and function, which is dependent on the desired activity of the cell. Some cells are replaced; others live for the duration of a person’s life. For example, blood cells only live for a few weeks, and are replaced at a rate of several billion each day, where as brain cells, may last a lifetime. Stem Cells are the foundation of normal growth and development of any organism and serve as a biological repair system for the body. Stem Cells, the “building blocks” of the body, have the remarkable potential to develop into many different cell types. Serving as a repair system for the body, they can theoretically divide without limit to replenish other cells. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, a nerve cell, a heart cell or a brain cell, just to mention a few.
Stem Cells are the body's master cells and differ from other kinds of cells in the body. All stem cells—regardless of their source—have three general properties:
- Stem Cells are capable of dividing and renewing themselves for long periods through cell division and contribute to the body's ability to renew and repair its tissues.
- Stem Cells remain unspecialized until a signal from the body tells them to develop into specific cells like a heart, nerve, or skin cell.
- Stem Cells can develop, or "differentiate" to become cells with more specialized functions