What's a Stem Cell?
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The term “stem cells” has become part of the mainstream lexicon, likely to be overheard in conversations anywhere from a baseball game to cocktail get-togethers.
Along with phrases, “that’s just immoral,” or “stem cells could be the end-all cure,” one could easily weave in some technical tidbits about these microscopic, yet significant, cells.
So what’s really so special about stem cells? Three properties give stem cells reasons to strut their stuff: The cells can divide to replenish themselves for long periods of time; they aren’t specialized; they can develop into specialized cell types. For instance, stem cells aren’t equipped with structures that would allow them to function as red blood cells or nerve cells. But when given the appropriate signals, they can transform into these working cells — a process called differentiation.
Heated debate abounds over the ethics of using embryonic stem cells for research. Why not just collect stem cells from adults? Research suggests adult stem cells can only differentiate to yield the cell types of the tissue or organ from which they originated. Human embryonic stem cells are derived from eggs fertilized in vitro (outside of the body) and are somewhat pristine. These stem cells are prized for their flexibility in being able to morph into any human-body cell.
When stem cells are grown in a laboratory under certain conditions for several months, they can remain unspecialized and produce millions of stem cells indefinitely. The resulting batch of cells is referred to as a stem-cell line.
The National Institutes of Health said 64 stem-cell lines existed as of August 2001 when President Bush announced the federal policy describing the restraints on funds for stem-cell research. However, further examination has led scientists to lower that number and to question whether the existing lines had sufficient genetic diversity to ensure the resulting stem-cell research is applicable to the range of diseases and patients.
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