Stem cells are the body's master cells, the
raw material from
which we are built. Unlike normal body cells, they can reproduce an indefinite
number of times and, when manipulated in the right way. can turn themselves
into any type of
cell in the body. The most versatile stem cells are those found in the embryo
at just a few days old. This ball of a few dozen stem cells eventually goes on
to form everything that makes up a person.
In 1998, James Thompson announced that he had
isolated human embryonic stem cells in the laboratory. At last, these powerful
cells were within the grasp of scientists to experiment with, understand, and develop into fixes for the
things that go wrong.