According to Dictionary.com, a stem cell is, "an undifferentiated cell of a multi cellular organism which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation." To simplify, Astem cells are a basic group of identical cells which have the ability to develop into any type of cell in the human body. Stem cells are the building blocks of our body. The ability to develop into any type of cell in our body is called specialization and every stem cell goes through this process. HowStuffWorks, explains that the embryo is where the very first stem cell is 'born'. The stem cells would then begin to reproduce and eventually develop the tissues, organs and other types of cells in the fetus's body.
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| Figure 1: Visual representation of all of stem cell's possibilities of specialization. |
It is also important to note that a stem cell is pluripotent. This means that upon diving a stem cell is able to specialize into any of the 220 different cells in our body.
Embryonic Stem Cells
Embryonic
stem cells are obtained from a human embryo, whose age ranges from four-five
days and is in the very beginning phase of development called blastocyst. The
creation of an embryo is the result of reproduction, where the men’s sperm
fertilizes the female’s egg, first creating a zygote. A zygote is a single cell
which when created begins dividing. Upon division the now created cells are
called a blastocyst. The blastocyst is made up of an inner mass cell and an
outer mass cell also known as the embryoblast and trophoblast. The embryoblast
or the inner mass cell becomes a group of cells which will develop and
specialize in order to become the various structures in an adult organism,
while the outer mass cells or the trophoblast develops into a placenta. This then
becomes the source of embryonic stem cells, which are then capable of
developing/ specializing into any of the 220 different cells in our body.
Adult Stem Cells
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| Figure 2: The adult stem cells in their particular tissues |
Adult stem cells are cells
which are located in specific tissues all over our body. They ‘specialize’ in
specific parts of their tissues. These cells have the ability to self-renew
(basically means that they are able to divide/reproduce themselves over and
over) which ensures that there is always a supply of cells ready to further specialize
into specific cell types, when needed. Scientists have found these stem cells
in several tissues from bone marrow, to the brain, the reproductive systems of
both genders, skin, teeth etc. Adult stem cells are multipotent which means
they are able to specialize into several kinds of cells within their tissues.
However it is key to know adult stem cells do not generate cell types for other
tissues. (Liver stem cells do not generate brain cells for example)
Therapeutic Potential of Stem Cells
For
several decades now stem cells have been used to aid when curing certain types
of cancer. Scientists have found that when patients undergo chemotherapy stem
cells are destroyed which resulted in them removing these cells and then rejecting
patients after their chemotherapy. They found that when doing so the stem cells
produce a large amount of red and white blood cells which help fight infection
and keep the body healthy. When scientists began to discover this, the cells
were being removed and then reinjected from the bone-marrow, however since the
late 1930’s they have been removed and then reinjected through the blood instead.
Although the amount of ‘Peripheral blood cells’ (the cellular components of
blood) is usually scarce, the amount can be increased with the use of
particular drugs. This too, occurs post chemotherapy to ensure the survival of
the stem cells.
Ethical Issues of Stem Cell Therapy
There are 3 main
ethical issues raised when scientists bring up stem cell therapy.
1. Respect for human life: this has to do
with showing respect for the human embryos. Embryonic stem cell research is
believed to be unethical and inhumane as the embryo is destroyed during the
process of stem cell line derivation. Many go as far as to accuse scientists of
murder when conducting experiments with embryonic stem cells. One other major
concern when dealing with respect for human life is the topic of cloning. The
creation of embryos for the purpose of research, otherwise known as cloning may
lead to ‘de-sensitization’ of the human life.
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| Figure 3: Process of cloning an embryonic cell |
2. Human dignity: this
concept is very unclear as it has no true meaning. Most people take human
dignity as our essential humanity or what makes us human. This concept is again
directly related to the human embryo.
3. Status of the human embryo:
many consider the human embryo to have the same moral status as a human being
thus believing that the destruction and/or cloning of an embryo is to be
considered murder. However, many also believe that through the later stages of
development the moral value is gained. When expanded upon this means that it is
in the belief of some that an embryo is not a living human yet and only gains
moral status when it begins to expand and develop.
For any further interest in the ongoing debates concerning ethical issues of stem cell therapy click here.
If you wish to see a quick overview of the stem cells, and it's therapeutic potentials view this video.
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ReplyDeleteWWW: I am very impressed Ajda, this post is very informative. I can see you growing in your vocabulary, congratulations. Back to the post, the pictures are informative and flow with the writing. You reached the expectations in all aspects and topics of the post. Great work.
ReplyDeleteEBI: I enjoyed everything about your post, although, the online dictionary may not be the most reliable source, you should have gone with another site focusing on stem cells. I would also enjoy if you extended your explanation of the therapy aspect.
WWW: Very detailed and seems like you did a lot of research for this blog. I like how you put three different issues on the ethical issues of stem cell research.
ReplyDeleteEBI: There were some vocab words that were hard, and it would have been better if the words were explained. Some parts of the blog were in white highlight and light grey letters, so it was very hard to read.