Where stem cells are found in the body?
Adult or somatic stem cells exist throughout the body after embryonic development and are found inside of different types of tissue. These stem cells have been found in tissues such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and the liver.
Embryonic stem cells. These stem cells come 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 (ploo-RIP-uh-tunt) stem cells, meaning they can divide into more stem cells or can become any type of cell in the body.
- Human pluripotent stem cell: One of the "cells that are self-replicating, are derived from human embryos or human fetal tissue, and are known to develop into cells and tissues of the three primary germ layers.
- Pluripotent adult stem cells are rare and generally small in number, but they can be found in umbilical cord blood and other tissues. The quantity of bone marrow stem cells declines with age and is greater in males than females during reproductive years.
- Adult stem cells can be isolated from the body in different ways, depending on the tissue. Blood stem cells, for example, can be taken from a donor's bone marrow, from blood in the umbilical cord when a baby is born, or from a person's circulating blood.
Pluripotent cells can give rise to all of the cell types that make up the body; embryonic stem cells are considered pluripotent. Multipotent cells can develop into more than one cell type, but are more limited than pluripotent cells; adult stem cells and cord blood stem cells are considered multipotent.
- Embryonic cells within the first couple of cell divisions after fertilization are the only cells that are totipotent. Pluripotent cells can give rise to all of the cell types that make up the body; embryonic stem cells are considered pluripotent.
- Induced pluripotent stem cells (iPSCs) are adult cells that have been genetically reprogrammed to an embryonic stem cell–like state by being forced to express genes and factors important for maintaining the defining properties of embryonic stem cells.
- Most embryonic stem cells are derived from embryos that develop from eggs that have been fertilized in vitro—in an in vitro fertilization clinic—and then donated for research purposes with informed consent of the donors. They are not derived from eggs fertilized in a woman's body.
Pluripotent stem cells, i.e. cells that can give rise to any fetal or adult cell type, can be found in a number of tissues, including umbilical cord blood. Using genetic reprogramming, pluripotent stem cells equivalent to embryonic stem cells have been derived from human adult skin tissue.
- Regenerative medicine is a branch of translational research in tissue engineering and molecular biology which deals with the "process of replacing, engineering or regenerating human cells, tissues or organs to restore or establish normal function".
- The hollow blastocyst—which is where embryonic stem cells come from—contains a cluster of 20-30 cells called the inner cell mass. These are the cells that become embryonic stem cells in a lab dish. The process of extracting these cells destroys the embryo. Don't forget that the embryos were donated from IVF clinics.
- Cell therapies would use stem cells, or cells grown from stem cells, to replace or rejuvenate damaged tissue. Scientists also want to use stem cells to understand disease and find drugs that might treat it. Embryonic stem cells could be used to make more specialized tissues that have been lost to disease and injury.
Updated: 3rd October 2019