The tissues and organs of the human body are made of diverse and specialized cells. During development, specific genes in cells are turned on or turned off in an incredibly complex series of steps, culminating in the specialized adult or somatic (resting) cells which make up newborn babies. Each of these specialized cell types is designed to do a few tasks proficiently and very little else. This cell specialization is permanent, the cells cannot revert back to a less-specialized cell. Because of this, If something goes wrong in one of the cell types or tissues, there are no other cells available to "fill in" and perform the specialized tasks and the life of the person is put in jeopardy. Stem cells differ from somatic cells because they are not yet completely specialized. When stem cells are placed in the proper environment with the right conditions, they can divide, multiply, and become any of a number of different cell types. You can picture stem cells as trunks or stems from which other cell types branch in the cell lineage family tree. Still present from early development, stem cells are highly abundant in umbilical cord blood. Currently, the safest, most plentiful, and least costly source of stem cells is umbilical cord blood.