Adult+Stem+Cells

Adult stem cells, sometimes referred to as somatic stem cells, are rare undifferentiated or unspecialized cells found in mature tissue that are “capable of self-renewal for the lifetime of the organism.” They maintain homeostasis, the steady functioning of a cell, by replacing cells that have died in a living organism.
 * Adult stem cells **

“Ideally, adult stem cells should also be clonogenic… able to generate a line of genetically identical cells.” (2)


 * Very Brief History **

In the 1950s, two types of adult stem cells, hematopoietic stem cells and then mesenchymal stem cells **__,__**  were discovered in bone marrow. Then in the 1960s, scientists who were studying rats first noticed that two regions of the brain were capable of producing new nerve cells.


 * Where They're found and Uses**

Adult stem cells can be found in a variety of organs and tissues (including brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, teeth, heart, gut, liver, ovarian epithelium, and testis). Scientists believe adult stem cells are found in areas of tissue called “stem cell niches.”

Adult stem cells have been used for many years in treating blood or bone related illnesses and in bone marrow transplants.

Normally, adult stem cells divide to create needed mature cells of a particular tissue. Scientists are now considering using adult stem cells in one tissue to create the specialized cell types of another tissue—a characteristic termed “plasticity,” “unorthodox differentiation,” or “transdifferentiation.” The variety of cell types that adult stem cells can develop into is still limited, but scientists hope to one day employ adult stem cells in repairing damaged tissues or organs.

“In the experiments reported to date, adult stem cells may assume the characteristics of cells that have developed from the same primary germ layer or a different germ layer. Alternatively, adult stem cells may differentiate into a tissue that—during normal embryonic development—would arise from a different germ layer.” (2)


 * Types of Adult Stem Cells**

Some types of stem cells are Hematopoietic stem cells, Mesenchymal stem cells, and Umbilical cord blood stem cells.

//Hematopoietic stem cells// are found in bone marrow and provide the blood cells that fight infections. Hematopoietic stem cells are relatively easily obtained and have been successfully used in therapies to treat blood cancers. They are now also used in treating breast cancer and coronary artery diseases. Controversy surrounds the possibility of more advanced uses for Hematopoietic stem cells. 

//Mesenchymal stem cells// are another population of adult stem cells found in bone marrow and can be manipulated to produce a wide range of cell types including “fat cells, cartilage, bone, tendon and ligaments, muscles cells, skin cells, and even nerve cells. Mesenchymal stem cells can be cultured to produce quantities appropriate for clinical applications and tissue repair, take up and maintain genes that are introduced, and function normally after being frozen or preserved. Scientists hope to use patient-personalized Mesenchymal stem cells in bone marrow transplants to avoid the problem of rejection of foreign cells and tissue.

//Umbilical cord blood stem cells// are attained from umbilical cords after birth. Hematopoietic stem cells obtained from umbilical cords are referred to as neonatal stem cells, are less mature than other forms of adult stem cells, and may be used for treatment of blood disorders.

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