For centuries, scientists have
known that certain animals
can regenerate missing parts
of their bodies. Humans actually
share this ability with animals like the
starfish and the newt. Although we can't replace a
missing leg or a finger, our bodies are
constantly regenerating blood, skin,
and other tissues. The identity of
the powerful cells that allow us
to regenerate some tissues was
first revealed when experiments
with bone marrow in the 1950s
established the existence of stem
cells in our bodies and led to the development
of bone marrow transplantation, a therapy
now widely used in medicine. This discovery raised
hope in the medical potential of regeneration. For
the first time in history, it became possible for physicians
to regenerate a damaged tissue with a new
supply of healthy cells by drawing on the unique
ability of stem cells to create many of the
body's specialized cell types.
Once they had recognized the medical
potential of regeneration through the success
of bone marrow transplants, scientists
sought to identify similar cells within the
embryo. Early studies of human development had
demonstrated that the cells of the embryo were
capable of producing every cell type in the human
body. Scientists were able to extract embryonic stem
cells from mice in the 1980s, but it wasn't until 1998
that a team of scientists from the University of
Wisconsin-Madison became the first group to isolate
human embryonic stem cells and keep them
alive in the laboratory. The team knew that they had
in fact isolated stem cells because the cells could
remain unspecialized for long periods of time, yet
maintained the ability to transform into a variety
of specialized cell types, including nerve,
gut, muscle, bone, and cartilage cells.
Stem cell research is being pursued in the hope
of achieving major medical breakthroughs.
Scientists are striving to create therapies
that rebuild or replace damaged cells with
tissues grown from stem cells and offer
hope to people suffering from cancer, diabetes,
cardiovascular disease, spinal-cord
injuries, and many other disorders. Both adult
and embryonic stem cells may also provide a route
for scientists to develop valuable new methods of
drug discovery and testing. They are also powerful
tools for doing the research that leads to a better
understanding of the basic biology of the human
body. By drawing on expert scientists,
doctors, bioethicists, and others, the National
Academies have examined the potential of stem
cell technologies for medicine and provided a forum
for discussing the ethical implications and moral
dilemmas of stem cell research.
This Web page is based on
Understanding Stem Cells: An Overview of the Science and Issues from the National Academies.
