Tissue Specific (adult) stem cells are undifferentiated cells found in the tissues and organs of the body. They are capable of self-renewal. Their differentiation is mainly restricted to forming the cell types of that tissue or organ.
The chief role of adult stem cells is to maintain and repair the tissue in which they are found.
Skin stem cells, for example, give rise to new skin cells, ensuring that old or damaged skin cells are replenished.
It now appears that all tissues probably contain adult stem cells, but only in very small numbers. In each tissue, they are used to produce new mature cells as old ones die. They may also remain dormant until activated by disease or injury. Their small numbers make adult stem cells difficult to isolate but they have been successfully isolated from the brain, bone marrow, blood, muscle, skin, pancreas and liver. Most research has been carried out on haematopoietic (blood forming) stem cells isolated from bone marrow and umbilical cord blood.
See
Fact Sheet 2 - Types of Stem Cells for more information.
The image on this page shows adult stem cells isolated from bone marrow as seen under a microscope and magnified 400 times. The cells express green fluorescent protein used to examine cell shape and the DNA within the nucleus is stained blue. These cells are used to research stem cell treatments for heart disease.