A stem cell line is a family of constantly dividing cells, the product of a single embryo. It is obtained from cells found in human or animal tissues and can replicate for long periods of time in vitro (out of the body).

In August 2001, George W. Bush signed legislation that restricted US federal funding to research involving only the 80(?) ‘stem cell lines’ then in existence. Of the more than 60 such lines then said to be available, only 18 actually ended up for use, for a fee, by researchers on a National Institutes of Health registry.

Embryonic Line creation

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Embryonic stem cell lines are created from embryos. A single cell from the embryo is placed in a petri dish (without agar) and provided with nutrients and growth factors that simulate those found in the womb. The resulting cell line will continue to divide as long as it receives sufficient chemical signals telling it to stay undifferentiated.

Adult Stem cell line creation

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Adult stem cell lines isolated from mature tissues are also commonly used in stem cell research.

New Techniques

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Typically, stem cells have been maintained using tissue culture methods that essentially date from the 1950's. In particular, they are often "fed" using mouse embryonic fibroblasts ("feeder cells") while being simultaneously suspended in a nutrient solution ("media"). However, many scientists are recognizing the importance of using media that is completely free of animal ingredients. This not only liberates cell lines from animal feeder cells, but also brings the in-vivo therapeutic use of stem cells one step closer to reality.

Sources:

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• http://gslc.genetics.utah.edu/units/stemcells/sccreate/