How Stem Cell Works
Microscopic view of a colony
of undifferentiated human embryonic stem cells being studied
in developmental biologist James Thomson's research lab at
the University of Wisconsin-Madison.
Photo courtesy University of Wisconsin-Madison
to How Stem Cells Work
kill cells within organs, claiming lives or
impairing a person's ability to live a normal
life. For example, about 5.8 million Americans
have heart failure and 670,000 people are
diagnosed with it each year [source: Centers for
Disease Control]. In heart failure, much of the
heart muscle itself dies, so the heart cannot
sufficiently pump blood.
Similarly, about 23.6 million Americans have
diabetes [source: NIDDK, NIH]. Five to 10
percent of these people have Type I diabetes in
which the insulin-producing cells of the
pancreas are dead. Finally, about 1 million
Americans live with Parkinson's disease [source:
Parkinson's Disease Foundation]. In this
disease, cells that make the neurotransmitter
dopamine, which helps control movement, die.
Patients with Parkinson's disease have tremors
and uncontrollable movements. But what if these
dead cells could be replaced with fresh cells?
Could the patients be treated and live normal
lives? That's the goal of stem cell research.
In this article, we'll look at stem cells,
starting with the accompanying picture above. In
the photo, the embryonic stem cell colonies are
the rounded, dense masses of cells. The flat
elongated cells are fibroblasts used as "feeder
cells." We'll also find out how stem cells work,
discover their potential to treat disease and
get inside the ongoing debate surrounding their
research and use. But first, let's cover some
Photo courtesy of Lee Dempsey
(How Stuff Works)
2. Stem Cell
A stem cell is essentially the building block of
the human body. Stem cells are capable of
dividing for long periods of time, are
unspecialized, but can develop into specialized
cells. The earliest stem cells in the human body
are those found in the human embryo. The stem
cells inside an embryo will eventually give rise
to every cell, tissue and organ in the fetus's
body. Unlike a regular cell, which can only
replicate to create more of its own kind of
cell, a stem cell is pluripotent. When it
divides, it can make any one of the 220
different cells in the human body. Stem cells
also have the capability to self-renew -- they
can reproduce themselves many times over.
There are several types of stem cells,
Embryonic Stem Cells - Embryonic stem
cells include those found within the embryo, the
fetus or the umbilical cord blood. Depending
upon when they are harvested, embryonic stem
cells can give rise to just about any cell in
the human body.
Adult Stem Cells - Adult stem cells can
be found in infants, children and adults. They
reside in already developed tissues such as
those of the heart, brain and kidney. They
usually give rise to cells within their resident
Induced Pluripotent Stem Cells (IPSC)-
These stem cells are adult, differentiated cells
that have been experimentally "reprogrammed"
into a stem cell-like state.
So how do all these types of stem cells work?
And what are their potential uses? Let's find
out -- starting with embryonic stem cells.
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