What are Stem Cells?

Simply put, stem cells are cells in an organism that are able to divide and transform into other, different types of cells in the body. They are able to both divide into additional unspecialized stem cells, or transform into particular cell types in the body such as blood, bone or muscle cells.

Because stem cells are able to develop into other types of cells in the body as well as divide near indefinitely in the right conditions; they have the ability to aid in a number of degenerative diseases (see stem cell treatments for more information on current treatments and research studies.)

A visualization of a stem cell.

There are certain unique characteristics among stem cells:

Stem cells are unspecialized:
Different types of cells in the body have their own specific functions. Blood cells work to carry oxygen through the blood stream, and brain cells process and transmit signals through the nervous system as examples.

Stem cells perform none of these specific functions, however they essentially "manufacture" those cells that do.

Stem cells can divide and renew themselves:
Other types of cells in the body typically do not divide and/or replicate by themselves, whereas stem cells are able to divide near indefinitely. This is known as the ability to proliferate.

Stem cells can create specialized cells:
While they start off without a specific cell function; in addition to their ability to divide - stem cells can transform into specialized cells in the body. This process is known as differentiation, during which the stem cell goes through multiple stages while becoming a specific cell type.

Stem Cell Types:

There are three main classifications of stem cells:

• Totipotent:
  Those that have the ability to become any other type of cell in the body.
• Pluripotent:
  Stem cells that have the potential to produce most types of cells in the body, excluding embryonic tissue.
• Multipotent:
  Stem cells that are able to produce a limited number of cell types. For example; able to create different types of blood cells - but blood cells only.

Cord blood contains two multipotent types; both hematopoietic stem cells and mesenchymal stem cells, as well as embryonic-like stem cells that are pluripotent.

For more information, see also:

• What diseases can stem cells treat?
• Information from the International Society for Stem Cell Research (ISSCR) (external site)