What are the sources of stem cells?

Stem cells can be sourced from embryos, adult tissues, umbilical cord blood, and through induced pluripotent stem cells.

Stem cells are unique cells that have the potential to develop into many different cell types in the body. They serve as a sort of repair system for the body, dividing essentially without limit to replenish other cells. There are several sources of stem cells, each with their own advantages and disadvantages.

Embryonic stem cells are derived from embryos that are three to five days old. At this stage, an embryo is called a blastocyst and has about 150 cells. These are pluripotent stem cells, meaning they can divide into more stem cells or can become any type of cell in the body. This versatility allows embryonic stem cells to be used to regenerate or repair diseased tissue and organs.

Adult stem cells are found in small numbers in most adult tissues, such as bone marrow or fat. Compared with embryonic stem cells, adult stem cells have a more limited ability to give rise to various cells of the body. Until recently, it was believed adult stem cells could only create similar types of cells. For instance, researchers thought that stem cells residing in the bone marrow could give rise only to blood cells. However, emerging evidence suggests that adult stem cells may be able to create unrelated types of cells. For example, bone marrow stem cells may be able to create bone or heart muscle cells.

Umbilical cord blood, like the bone marrow, is rich in blood-forming stem cells. Parents can choose to store the blood from their newborn’s umbilical cord, which can be used to treat diseases later in life.

Lastly, scientists have recently discovered how to turn regular adult cells into stem cells, called induced pluripotent stem cells (iPSCs). This is done by introducing certain genes into a regular cell. These iPSCs can then be grown in the lab and used for research or therapeutic purposes.