THE TRUTH ABOUT STEM CELLS
By Stephanie Watson
Inside an embryo no bigger than the period at the end of this sentence are
dozens of stem cells. Initially, these cells are blank slates, meaning that their
fate is undecided. But they have great potential. Stem cells are pluripotent,
which means that they can develop into every cell, every tissue and every
organ in the human body.
Their almost limitless potential has made stem cells a significant focus of
medical research. Imagine having the ability to return memory to an Alzheimer's
patient, replace skin that was lost during a terrible accident or enable a
wheelchair-bound person to walk again. But before scientists can use stem
cells for medical purposes, they must first learn how to harness their power.
They can't treat disease until they learn how to manipulate stem cells to get
them to develop into specific tissues or organs.
In this article, we will look at stem cells, find out how they work, discover their
potential to treat disease and get inside the fierce debate surrounding their
research and use.
Stem Cell Basics
A stem cell is essentially the building block of the human body. The stem cells
inside an embryo will eventually give rise to every cell, organ and tissue 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 two types of stem cells: embryonic stem cells, and adult stem
cells. Embryonic stem cells come from an embryo -- the mass of cells in the
earliest stage of human development that, if implanted in a woman's womb, will
eventually grow into a fetus. When the embryo is between three and five days
old, it contains stem cells, which are busily working to create the various organs
and tissues that will make up the fetus.
Adults also have stem cells in the heart, brain, bone marrow, lungs and other
organs. They are our built-in repair kits, regenerating cells damaged by
disease, injury and everyday wear and tear. Adult stem cells were once
believed to be more limited than stem cells, only giving rise to the same type of
tissue from which they originated. But new research suggests that adult stem
cells may have the potential to generate other types of cells, as well. For
example, liver cells may be coaxed to produce insulin, which is normally made
by the pancreas. This capability is known as plasticity or transdifferentiation.
So where do scientists get the stem cells they use in their
research?
Acquiring Stem Cells for Research
In the early 1980s, scientists learned how to pull embryonic stem cells from a
mouse and grow them in a laboratory. In 1998, they first reproduced human
embryonic stem cells in a lab.
Where do researchers get human embryos?
Embryos can either be made via reproduction -- merging sperm and egg -- or
by cloning. Researchers aren't likely to create an embryo with sperm and egg,
but many use fertilized embryos from fertility clinics. Sometimes, couples who
are trying to have a baby create several fertilized embryos and don't implant
them all. They may donate the ones that are left over to science.
Another way to create an embryo is via a technique called therapeutic cloning.
This technique merges a cell (from the patient who needs the stem cell
therapy) with a donor egg. The nucleus is removed from the egg and replaced
with the nucleus of the patient's cell. (See How Cloning Works for a detailed
look at the process). This egg is stimulated to divide either chemically or with
electricity, and the resulting embryo carries the patient's genetic material, which
significantly reduces the risk that his or her body will reject the stem cells once
they are implanted.
Both methods -- using existing fertilized embryos and creating new embryos
specifically for research purposes -- are controversial. But before we get into
the controversy, let's find out how scientists get stem cell to replicate in a
laboratory setting in order to study them.
Replicating Stem Cells in a Lab
An embryo that has developed for three to five days is called a blastocyst. A
blastocyst is a mass of about 100 or so cells.
The stem cells are the inner cells of the blastocyst. They will ultimately develop
into every cell, tissue and organ in the body.
Scientists remove stem cells from the blastocyst and culture them (grow them in
a nutrient-rich solution) in a Petri dish in the laboratory. After the cells have
replicated several times and are becoming too numerous for the culture dish,
they are removed and placed into several other dishes. In just a few months,
several stem cells can become millions of stem cells. Embryonic stem cells that
have been cultured for several months without differentiating are referred to as
a stem cell line. Cell lines can be frozen and shared between laboratories.
Adult stem cells are much harder for scientists to work with because they are
more difficult to extract and culture than their embryonic counterparts. Stem
cells not only are hard to find in adult tissue, but scientists also have difficulty
getting them to replicate in the laboratory.
But even embryonic stem cells, which can be grown effectively in the lab, are
not easy to control. Scientists are still struggling to get them to grow into
specific tissue types.
The State of Stem Cell Research
Ideally, scientists would like to be able to grow a particular type of cell
in the laboratory and then inject it into a patient, where it would
replace diseased tissue. But stem cells are not yet being used to treat
disease because scientists still haven't learned how to direct a stem
cell to differentiate into a specific tissue or cell type (brain vs. liver, for
example) and to control that differentiation once the cells are injected
into a person.
Inside an embryo no bigger than the period at the end of this sentence are
dozens of stem cells. Initially, these cells are blank slates, meaning that their
fate is undecided. But they have great potential. Stem cells are pluripotent,
which means that they can develop into every cell, every tissue and every
organ in the human body.
Their almost limitless potential has made stem cells a significant focus of
medical research. Imagine having the ability to return memory to an Alzheimer's
patient, replace skin that was lost during a terrible accident or enable a
wheelchair-bound person to walk again. But before scientists can use stem
cells for medical purposes, they must first learn how to harness their power.
They can't treat disease until they learn how to manipulate stem cells to get
them to develop into specific tissues or organs.
In this article, we will look at stem cells, find out how they work, discover their
potential to treat disease and get inside the fierce debate surrounding their
research and use.
Stem Cell Basics
A stem cell is essentially the building block of the human body. The stem cells
inside an embryo will eventually give rise to every cell, organ and tissue 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 two types of stem cells: embryonic stem cells, and adult stem
cells. Embryonic stem cells come from an embryo -- the mass of cells in the
earliest stage of human development that, if implanted in a woman's womb, will
eventually grow into a fetus. When the embryo is between three and five days
old, it contains stem cells, which are busily working to create the various organs
and tissues that will make up the fetus.
Adults also have stem cells in the heart, brain, bone marrow, lungs and other
organs. They are our built-in repair kits, regenerating cells damaged by
disease, injury and everyday wear and tear. Adult stem cells were once
believed to be more limited than stem cells, only giving rise to the same type of
tissue from which they originated. But new research suggests that adult stem
cells may have the potential to generate other types of cells, as well. For
example, liver cells may be coaxed to produce insulin, which is normally made
by the pancreas. This capability is known as plasticity or transdifferentiation.
So where do scientists get the stem cells they use in their
research?
Acquiring Stem Cells for Research
In the early 1980s, scientists learned how to pull embryonic stem cells from a
mouse and grow them in a laboratory. In 1998, they first reproduced human
embryonic stem cells in a lab.
Where do researchers get human embryos?
Embryos can either be made via reproduction -- merging sperm and egg -- or
by cloning. Researchers aren't likely to create an embryo with sperm and egg,
but many use fertilized embryos from fertility clinics. Sometimes, couples who
are trying to have a baby create several fertilized embryos and don't implant
them all. They may donate the ones that are left over to science.
Another way to create an embryo is via a technique called therapeutic cloning.
This technique merges a cell (from the patient who needs the stem cell
therapy) with a donor egg. The nucleus is removed from the egg and replaced
with the nucleus of the patient's cell. (See How Cloning Works for a detailed
look at the process). This egg is stimulated to divide either chemically or with
electricity, and the resulting embryo carries the patient's genetic material, which
significantly reduces the risk that his or her body will reject the stem cells once
they are implanted.
Both methods -- using existing fertilized embryos and creating new embryos
specifically for research purposes -- are controversial. But before we get into
the controversy, let's find out how scientists get stem cell to replicate in a
laboratory setting in order to study them.
Replicating Stem Cells in a Lab
An embryo that has developed for three to five days is called a blastocyst. A
blastocyst is a mass of about 100 or so cells.
The stem cells are the inner cells of the blastocyst. They will ultimately develop
into every cell, tissue and organ in the body.
Scientists remove stem cells from the blastocyst and culture them (grow them in
a nutrient-rich solution) in a Petri dish in the laboratory. After the cells have
replicated several times and are becoming too numerous for the culture dish,
they are removed and placed into several other dishes. In just a few months,
several stem cells can become millions of stem cells. Embryonic stem cells that
have been cultured for several months without differentiating are referred to as
a stem cell line. Cell lines can be frozen and shared between laboratories.
Adult stem cells are much harder for scientists to work with because they are
more difficult to extract and culture than their embryonic counterparts. Stem
cells not only are hard to find in adult tissue, but scientists also have difficulty
getting them to replicate in the laboratory.
But even embryonic stem cells, which can be grown effectively in the lab, are
not easy to control. Scientists are still struggling to get them to grow into
specific tissue types.
The State of Stem Cell Research
Ideally, scientists would like to be able to grow a particular type of cell
in the laboratory and then inject it into a patient, where it would
replace diseased tissue. But stem cells are not yet being used to treat
disease because scientists still haven't learned how to direct a stem
cell to differentiate into a specific tissue or cell type (brain vs. liver, for
example) and to control that differentiation once the cells are injected
into a person.
The People's National Commentary Section | How To Post Stories & Commentaries | Free On-Line Newspapers
Contrary to what many activist claim is the truth,
Scientists still have not yet reached the stage where
they can get stem cells to differentiate reliably.
Scientists still have not yet reached the stage where
they can get stem cells to differentiate reliably.
The Weekly American welcomes your comments. Go to the top of this page
and click on "How To Post Stories & Commentaries"
and click on "How To Post Stories & Commentaries"
Get Your Business
Off The Ground
And Start Making
A Profit
Stop Wasting Your
Money On
Expensive Pay Per
Click Advertising
When You
Advertise On
WeeklyAmerican
You Pay A Low
Fixed Rate Fee.
Your Ad Runs
24 Hours A day,
7 Days A Week.
The Thousands Of
People Who Visit
WeeklyAmerican
Will See Your Ad
Prominently
Displayed.
Get Going Today!!
CLICK HERE
Off The Ground
And Start Making
A Profit
Stop Wasting Your
Money On
Expensive Pay Per
Click Advertising
When You
Advertise On
WeeklyAmerican
You Pay A Low
Fixed Rate Fee.
Your Ad Runs
24 Hours A day,
7 Days A Week.
The Thousands Of
People Who Visit
WeeklyAmerican
Will See Your Ad
Prominently
Displayed.
Get Going Today!!
CLICK HERE