Monday, August 2, 2010

Manipulation of Stem Cells For Clinical Purposes


   Diagram above shows stem cells.



What are stem cells?
Stem cells are undifferentiated cells. These cells able to divide throughout life and differentiate into any specialized cells to repair damaged tissues or organs.
There are two types of stem cells:
(a) embryonic stem cells
(b) adult stem cells

EMBRYONIC STEM CELLS


Diagram above shows the directed differentiation of mouse embryonic stem cells.(http://stemcells.nih.gov/info/basics/basics3.asp)


Embryonic stem cells are derived from the embryos that develop through in vitro fertilization. The embryonic stem cells can remain undifferentiated if they grown in favorable conditions. If the embryonic stem cells clumped together to form embryoid bodies, then the cells can differentiate spontaneously to form muscle cells, nerve cells and other cell types.

ADULT STEM CELLS

Diagram above shows the hematopoietic and stromal stem cell differentiation.


Adult stem cells are derived from different parts of body such as bone marrow, blood and the brain. Adult stem cells undergo normal differentiation pathway. Normal differentiation pathway is that the adult stem cells will divide when needed and differentiate into any mature cell types which have specific structures and specialized functions of a particular tissue. Adult stem cells can also differentiate into other cell types other than the expected cells. For example, brain stem cells which normally differentiate into blood-forming cells can also be differentiated into cardiac muscle cells. This process is known as transdifferentiation.

Potency – the ability of stem cells to differentiate into a variety of cells due to their potential. These different potentials are divided into a few categories:
1. Pluripotent- the ability to differentiate into most types of cells
2. Multipotent- the ability to differentiate into cells which are closely related.
3. Oligopotent- the ability to differentiate into a few cells.
4. Unipotent- the ability to reproduce and differentiate into the same cell type which the cells will have the self-renewal property.
5. Totipotent- the ability to differentiate into all types of cells.


Advantages and Disadvantages of Stem Cell
ADVANTAGES
1. Diseases such as cystic fibrosis and spinal bifida can be detected and cured before birth of a child.
2. It is true that primitive blood cells, harvested from adults, can be used for treating some blood disorders. It is also possible that stem cells from the blood may occasionally be capable of being turned into another cell type, such as liver cells.
3. They are not likely to be rejected by the new body system (providing the stem cells come from the original patient
4. Cells derived from an embryo four or five days after fertilisation offer the most hope for creating new human tissues artificially.
5. Stem cells are likely to be valuable in treating strokes, or possibly to repair the spinal cord in paraplegics.
6. Thousands of people suffer from diabetes so stem cells could probably be used to regrow their insulin by producing pancreatic cells.

DISADVANTAGES
1. The major drawback of these methods is that the therapeutic gene frequently integrates more or less randomly into the chromosomes of the target cell.
2. These phenomena are referred to as insertional mutagenesis. In extreme cases, such as in the X-linked SCID gene therapy trials, these mutations contribute to the malignant transformation of the targeted cells, ultimately resulting in cancer.
3. Another major limitation of using adult stem cells is that it is relatively difficult to maintain the stem cell state during ex vivo manipulations.
4. Under current suboptimal conditions, adult stem cells tend to lose their stem cell properties and become more specialized, giving rise to mature cell types through a process termed differentiation.The process whereby an unspecialized embryonic cell acquires the features of a specialized cell such as a heart, liver, or muscle cell.
5. They are harder to find and harvest for patients.


The Ethics
As it has been mentioned, stem cells are different with the other type of cells in human body, based on their ability that capable to replicate themselves for long period, and also to develop into many types of different cells in human body, based on where it is transplanted. That was why, the development and application of stem cell, would sure be very helpful for those who suffered from any disease that cannot be cured by common treatment, such as diabetes, heart disease, Alzheimer, and even genetic disease. More over, recently the numbers of people who suffer from a broken or disfunction organ keep going to increase, while the donated organs available for transplantation are limited. In this case, the potency of stem cells is very needed to replace those disfunction cells or tissues, instead of replacing the whole organ with the new one. Beside, there is also a possibility in the further research that this cell can be cultured in laboratory to be developed into a whole specific organ for those who have organ disorder since birth, or in the other words, human cloning. Based on those facts, it is not a surprising thing that many countries nowadays have invested much of their money for this research of stem cell.
The research of stem cell has become an issue that often to be debated by many people nowadays. Whether or not this research should be continued, always clashes with the ethic’s matters in society. Up until recent years, the issues that have been always debated are around the controversy of embryonic stem cells, which are taken from the aborted embryo tissues. Many people are against with this research, due to the use of human embryonic tissues to be studied. The issue is same as abortion. As it has been known this embryo supposedly would develop into a new life of human, taking out someone’s life even if it is only in its very first week is not acceptable. However, people who against with this research should consider more with the beneficial that would be obtained if it is successful just like Dr. Michael McCabe from New Zealand Catholic Bioethics Centre praised the potential of stem cells in the treatment of illness. Many of human’s life can be saved by this embryonic stem cell, further more than the numbers which are sacrificed. Moreover, if many people nowadays are doing abortion, instead of wasting the embryo, why do not just use it for something more useful? Beside, the research by using adult stem cell is not efficient, due to the different properties with stem cells that extract from embryo. In the other words, everything in the world, no matter how small or big is not free, it needs sacrifices to be obtained. And with those sacrifices, the bigger benefits can be gained.

As mentioned above the research of stem cells is disagreeing by some people in various fields in society. This opposition may due to some reasons. For example in United States, people in Catholic religion claim that the research of stem cells is against the teaching of Pope. They might also think that the researches of stem cells are adopting the role of God. They said that the development of stem cells from embryos for different purposes can bring huge implications for economic, religious or even political. Even though the research of stem cells can bring benefits and happier life for human, it is so sad but has to say that obtaining the stem cells of an embryo is actually requiring the death of an embryo which is equivalent to the killing of an embryo, a life.
In morality aspects, there are two types of people or two side or moral and ethic view which is the pro-lifers and the pro-choicers. To pro-lifers, the obtaining of embryo stem cells involves the murder of a life. This activity is scarifying a newborn life and can be said as an abortion. Whereas to pro-choicers, an embryo is a potential human life but it is not an actual or real person yet. Killing it before it attains personhood in order to harvest the stem cells is a ethically and defensible act. The previous president of U.S Bush is opposing the research of stem cells because the extraction of stem cells actually is the destruction of an innocent embryo. But in 2009, president Obama is trying to cancel Bush policy. The president of one of the organization in U.S.A, Tony Perkins said that “Today's news that President Obama will open the door to direct taxpayer funds for embryonic stem cell research that encourages the destruction of human embryos is a slap in the face to Americans who believe in the dignity of all human life. I believe it is unethical to use human life, even young embryonic life, to advance science. While such research is unfortunately legal, taxpayers should not have to foot the bill for experiments that require the destruction of human life.” This shows that the opposition of the research of stem cells is rational and reasonable.


Conclusion

To conclude, stem cells are special cells that can divide and multiply for long period, compare with the other type of cells, and also have the ability to assemble with the host cell where it was transplanted. Stem cells are divided into two types, the first type is embryonic stem cells, which derived from the embryo that develop through in vitro fertilization, and the second type is adult stem cells, which derived from different parts of body tissues. The embryonic stem cells are considered better than adult stem cells, because it can derive into any specialized cells in any part of the body. It is different with the adult stem cells, which only can be used in the specific part of body, where it had been extracted.
However, if it is looked from the ethical issue, obtaining the embryonic stem cells require the death of an embryo, which is same as killing a live. Whereas, for the adult stem cells, it does not need to sacrifice someone’s life to obtain the stem cells in order for clinical purpose. There is always a pro and contra about this issue, because for some people saving a life is important, but not by killing another life, killing someone to save others is not ethic. While for some people, sacrificing somethings to get the other things that more valuable cannot be avoided, even though it is life.
But in the end, the use of stem cells have a positive side and negative side, and it depends on us to choose which one is better, whether we want to follow the morality or the advance of technology.

video

References

MediLexicon International Ltd, 2010.What are stem cells [Online].Available from: http://www.medicalnewstoday.com/info/stem_cell/ [Accessed 1 August 2010].

National Institutes of Health(NIH), 2009.What are embryonic stem cells [Online].Available from: http://stemcells.nih.gov/info/basics/basics3.asp [Accessed 1 August 2010].

National Institutes of Health(NIH), 2009.What are adult stem cells[Online].Available from: http://stemcells.nih.gov/info/basics/basics4.asp [Accessed 1 August 2010].

Experiment Resources. 2008. Stem Cell Research - Pros and Cons. Retrieved on 1 August 2010 from Experiment Resources: http://www.experiment-resources.com/stem-cell-pros-and-cons.html
Thomson JA, Itskovitz-Eldor J, Shapiro SS, et al.(1998),4th edition ,Embryonic stem cell lines derived from human blastocysts. Science, USA, page 1145–1147.

Steven Ertelt, "IPS Cells, An Embryonic Stem Cell Research Alternative, Make Major Advance," LifeNews, 2009-MAR-02. Available from http://www.lifenews.com/ [Accessed 2 Aug 2010]




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