Yoonsik Park
1. What Are Stem Cells?
1. What Are Stem Cells?
According to the IB-guides website, they are cells that have not been fully differentiated, however, they have the ability to divide and differentiate into different types of cells. For example, a stem cell can differentiate into a brain cell, or a blood cell. As you can see in (picture 1), a stem cell can duplicate itself or differentiate into many cell types. They are necessary in embryonic development because all of the cells in an adult organism come from stem cells.
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| (Picture 1) http://nas-sites.org/stemcells/files/2013/01/What-Is-Download.jpg |
Development of embryonic stem cells: A zygote is formed when an egg cell from the female and a sperm cell from the male fuse. The zygote then divides into a two celled embryo. That embryo will keep dividing into a 4 celled, 8 celled and so on. In the early stages of development, the embryo cells are stem cells because they have the potential to become any type of cell. As the embryo cells divide, they eventually start to be committed to a specific path. (For example, as you can see in picture 2, some cells will become committed to liver cells, nerve cells, cardiac cells, blood cells, or something else)
At this point, although they still have the ability to differentiate, they can only differentiate into the type of cells that they are committed to. (For example, if an embryo cell is committed to a kidney cell, they can only differentiate into that, not liver or blood cells.) So they are no longer stem cells, but they are uni-potent.
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| (Picture 2) http://www.extremetech.com/wp-content/uploads/2014/07/stem-cells.jpg |
Adult Stem Cells: There are still some stem cells in an adult organism. (Can be found in the skin, bone marrow, and liver) They are able to differentiate into different cells but not as much as the embryonic stem cells. So they are not as effective. However, they still benefit adult organisms greatly by regenerating and repairing damaged tissues.
2. Therapeutic Potential of Stem Cells
Since stem cells can differentiate many times and into different cells, they are the best for therapeutic use in degenerative disease or tissue repair.
Therapeutic : "The branch of medicine that is concerned specially with the treatment of disease." (http://www.medicinenet.com/script/main/art.asp?articlekey=18811)
Therapeutic : "The branch of medicine that is concerned specially with the treatment of disease." (http://www.medicinenet.com/script/main/art.asp?articlekey=18811)
One example of therapeutic potential of stem cells-
Umbilical Cord Blood Stem Cells:
As you can see in (picture 3), the umbilical cord is no longer needed to the survival of the baby or the mother when the baby is born. So it is usually thrown away after the baby is born and is cut off from the baby and the mother's body. However, it has been discovered recently that the blood, rich of stem cells, from the umbilical cord can also be used to treat problems that are treated by bone marrow stem cells and peripheral blood stem cells.
Umbilical cord blood stem cell transplants have a lower possibility of rejection than other blood stem cells. This is believed to be because they are not as developed yet, which means that there are not as many immune cells; it is less possible that the cells will react badly in the transplant recipient's body. Because umbilical cord blood stem cells are capable of adapting easily, and are available very much, it makes them a potential resource for therapeutics.
Umbilical Cord Blood Stem Cells:
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| (Picture 3) https://upload.wikimedia.org/wikipedia/commons/f/f3/Umbilicalcord.jpg |
As you can see in (picture 3), the umbilical cord is no longer needed to the survival of the baby or the mother when the baby is born. So it is usually thrown away after the baby is born and is cut off from the baby and the mother's body. However, it has been discovered recently that the blood, rich of stem cells, from the umbilical cord can also be used to treat problems that are treated by bone marrow stem cells and peripheral blood stem cells.
Umbilical cord blood stem cell transplants have a lower possibility of rejection than other blood stem cells. This is believed to be because they are not as developed yet, which means that there are not as many immune cells; it is less possible that the cells will react badly in the transplant recipient's body. Because umbilical cord blood stem cells are capable of adapting easily, and are available very much, it makes them a potential resource for therapeutics.
3. Ethical Considerations of Stem Cell Therapy
Using stem cells to treat diseases and tissue repairs is very helpful in many ways. However, there has been some controversy over the studying, using, and destroying of human embryos for research and therapy using embryonic stem cells.
(Against embryonic stem cell therapy) Since the embryo is the result of the sperm and egg fusing and developing, many people consider destroying human embryos after the research or extraction of stem cells as unethical. As you can see in picture 4, since extracting the stem cells destroys them from developing further, they consider it murder; the embryos have the potential become new babies.
(For embryonic stem cell therapy) However, there are those who argue for embryonic stem cell research. One of their main arguments is that the embryo is only a few cells clumped together, so it cannot be considered as life yet. "It cannot survive outside the womb on its own so it cannot be considered life." Secondly, they claim that the research being done will benefit humans widely so it is justifiable. Also, according to the PubMed Central website, embryos that are used in research are donated by the woman or the couple.
(http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2726839/)
(Against embryonic stem cell therapy) Since the embryo is the result of the sperm and egg fusing and developing, many people consider destroying human embryos after the research or extraction of stem cells as unethical. As you can see in picture 4, since extracting the stem cells destroys them from developing further, they consider it murder; the embryos have the potential become new babies.
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| (Picture 4) - http://federation-pro-europa-christiana.org/wordpress/wp-content/uploads/2011/12/Stem-cell-research.jpg |
(For embryonic stem cell therapy) However, there are those who argue for embryonic stem cell research. One of their main arguments is that the embryo is only a few cells clumped together, so it cannot be considered as life yet. "It cannot survive outside the womb on its own so it cannot be considered life." Secondly, they claim that the research being done will benefit humans widely so it is justifiable. Also, according to the PubMed Central website, embryos that are used in research are donated by the woman or the couple.
(http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2726839/)
www: all questions are answered fully, the use of vocabulary is apropriate, citations are amazing along with the pictues and the general presentation is good
ReplyDeleteebi: the development of embryonic stem cells was not needed
WWW: -I think the ethical consideration part of your essay explains the perspectives well
ReplyDelete-described what therapeutic meant (I bet no one else did that)
EBI: -maybe more information about how stem cells are used against degenerating tissue or diseases
-captions for your pictures
-I don't think you see how the umbilical cord is useless in picture 3 (said it in essay)
www: Clearly explained Stem Cells
ReplyDeleteDiscussed ethic issues
Appropriate vocab used
Citations used
Well arranged blog
ebi: Explained some disease stem cells cure not just how we obtain them
Could have used hyperlinks
A bit more explaining of the vocabulary
www: The questions were answered, appropriate use of vocab
ReplyDeleteebi: Font is very disturbing, and at times hard to read, and use of hyperlinks
WWW: very detailed, informative, answer questions , good use of vocab
ReplyDeleteEBI: not that good organization and poor use of citations and hyperlinks