Stem cells are diverse
Stem cells have the unique capability to develop into several different cell types in the body. This is essential during early development for the proper growth of tissues and organs in the embryo. Later, tissue-specific stem cells guarantee the continuing maintenance of vital organs and blood cells, and functioning of the immune system. Depending on their origin and their potential for differentiation, stem cells are classified as embryogenic or adult. While embryogenic stem cells are pluripotent, and can develop into multiple cell types, adult stem cells are tissue specific and can only produce cells of the same type.
The third, quite recently developed class of stem cells are induced pluripotent stem cells (IPSCs). They are generated in the laboratory by reprogramming tissue-specific adult stem cells into pluripotent ones. IPSCs offer all the many advantages of pluripotent embryogenic stem cells but they are ethically innocuous because they don’t derive from early human embryos.