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  • Bone marrow contains many different types of cells

  • several of which have specialized roles in the blood.

  • In the early 1960s it was shown that if bone marrow was taken from one mouse and transplanted into another,

  • rare and unspecialized cells could travel to the spleen where they would divide and form small colonies

  • These colonies contained a mixture of different blood cell types.

  • Incredibly when these colonies were removed and retransplanted,

  • these rare cells formed new colonies in the spleen of a second mouse.

  • These reveal two defining properties of a stem cell.

  • First a stem cell must be able to self renew. That is, it must be able to divide and give rise to more cells like itself.

  • Second, it must be able to differentiate. In other words it must be able to divide and give rise to specialized cells.

  • Since these early experiments, many different types of stem cells have been discovered

  • And this general definition applies to all of them.

  • Following fertilization, the developing embryo contains a group of cells

  • known as the "inner cell mass" that will eventually go on to form all tissues in the body.

  • However at the early stage of development these cells have not yet committed to become a specific type of cell

  • and are said to be in an undifferentiated state.

  • If the cells of the "inner cell mass" are isolated

  • they can grow indefinitely in a plastic dish and maintain this undifferentiated state.

  • These cells are known as "embryonic stem cells" or ES cells

  • Like cells in the developing embryo

  • ES cells retain the ability to form any type of cell in the adult body

  • Thus ES cells are said to be "pluripotent"

  • By studying the signals required to control how ES cells develop into specific cell types

  • scientists may be able to develop therapies capable of restoring damaged tissues

  • Most of the cells in our bodies are not stem cells.

  • For example blood and skin cells have become specialized to perform a specific function in the body.

  • By a process known as differentiation, that is normally not reversible.

  • However, if some adults cells are taken grown in plastic dishes and given specific genetic instructions over time,

  • a small number of these cells will reverse from their differentiated state and develop the ability to redifferentiate into any cell type in the body.

  • This newfound ability is known as "pluripotentcy", and therefore these cells are known as "induced pluripotent stem cells" or IPS cells.

  • The creation of IPS cells from individual patients may one day allows us to develop replacement tissues that are a perfect genetic match to the patient.

  • In addition, the creation of IPS cells from patients with specific diseases will allow scientists to develop new drugs to treat a wide variety of disorders.

Bone marrow contains many different types of cells

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B1 develop specific specialized divide bone marrow stem cell

StemCellShorts - Stem cells animation parts 1, 2 & 3

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    keep seeing posted on 2014/04/23
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