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Stem Cell Research

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Stem Cell Research

Stem Cells are very unique cells. Stem Cells have the amazing ability to develop into several distinct cell types in the body. Thus Stem Cells can be used as a repair system for the body. Stem Cells can theoretically divide without limit in a living human or animal in order to replenish various types of cells. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function (i.e. a muscle cell, a red blood cell, a brain cell, etc.). All Stem Cells have the same three general properties as follows:

  • Stem Cells can divide and renew themselves for long periods of time
  • Stem Cells are unspecialized
  • Stem Cells can divide and become specific specialized cell types of the body

Stem Cell Research is being conducted on both Adult Stem Cells and Embryonic Stem Cells.

An Adult Stem Cell is an UndifferentiatedCell found among differentiated cells in a tissue or an organ. Adult Stem Cells can renew themselves and can differentiate themselves to become the major specialized cell types of a tissue or an organ. The principal roles of Adult Stem Cells in a living organism are to maintain and repair the tissue in which they are found. Some scientists now use the term Somatic Stem Cell instead of Adult Stem Cell. Bone marrow contains at least two kinds of stem cells. One Stem Cell type, called a hematopoietic stem cell, forms all the types of blood cells in the body. A second Stem Cell type, called a bone marrow stromal cell (mesenchymal stem cells), is a mixed cell population that generates bone, cartilage, fat, and fibrous connective tissue. The brain does contain stem cells that are able to generate the brain's three major cell types, which are as follows:

  • astrocytes (non-nerve cells)
  • oligodendrocytes (non-nerve cells)
  • neurons (nerve cells)

The possibility exists that stem cells from one tissue may be able to give rise to cell types of a completely different tissue, a phenomenon known as plasticity or transdifferentiation (i.e. blood cells becoming neurons). Unlike Embryonic Stem Cells, which are defined by the blastocyst inner cell mass, the origin of adult stem cells in mature tissues is unknown.

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. Embryonic Stem Cells are never derived from eggs fertilized inside of a woman's body. The embryos from which Human Embryonic Stem Cells are derived are typically four or five days old and are a hollow microscopic ball of cells called the blastocyst. The blastocyst includes the following three structures:

  • trophoblast (a layer of cells that surrounds the blastocyst)
  • blastocoel (a hollow cavity inside the blastocyst)
  • inner cell mass (a group of approximately 30 cells at one end of the blastocoel)