5December - Stem Cells 5 December 2005 What is Stem Cell Stem cells have the remarkable potential to develop into many different cell types in the body

5December - Stem Cells 5 December 2005 What is Stem Cell...

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Stem Cells 5 December 2005
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What is Stem Cell? Stem cells have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person or animal is still alive (self-renewable) 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, such as a muscle cell, a red blood cell, or a brain cell (differentiation).
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Unique properties of all stem cells All stem cells—regardless of their source—have three  general properties:  they are capable of dividing and renewing themselves for  long periods;  they are unspecialized;  and they can give rise to specialized cell types. 
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Stem cells are capable of dividing and renewing  themselves for long periods. starting population of stem cells that proliferates for  many months in the laboratory can yield millions of  cells. If the resulting cells continue to be  unspecialized, like the parent stem cells, the cells are  said to be capable of long-term self-renewal. 
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Questions related to their long-term self-renewal: 1. why can embryonic stem cells proliferate for a year or more in the laboratory without differentiating, but most adult stem cells cannot; and 2. what are the factors in living organisms that normally regulate stem cell proliferation and self-renewal?
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Discovering the answers to these questions may make it possible to understand how cell proliferation is regulated during normal embryonic development or during the abnormal cell division that leads to cancer. Importantly, such information would enable scientists to grow embryonic and adult stem cells more efficiently in the laboratory.
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Stem cells are unspecialized A stem cell does not have any tissue-specific structures that  allow it to perform specialized functions.  A stem cell cannot work with its neighbors to pump blood through  the body (like a heart muscle cell);  it cannot carry molecules of oxygen through the bloodstream (like a  red blood cell);  and it cannot fire electrochemical signals to other cells (like a nerve  cell).  However, unspecialized stem cells can give rise to specialized  cells, including heart muscle cells, blood cells, or nerve cells.
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Stem cells can give rise to specialized cells The signals inside and outside cells that trigger stem cell  differentiation are just beginning to be understood.  The internal signals are controlled by a cell's genes,  the external signals for cell differentiation include chemicals  secreted by other cells, physical contact with neighboring  cells, and certain molecules in the microenvironment
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