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Stem cells are cells that are obtained from organism and have the ability to differentiate into specialized cells. They divide through mitosis and can self renew into more stem cells. There are two types of stem cells namely embryonic stem cells and adult stem cells (also known as somatic stem cells).
Embryonic stem cells are obtained from embryos. An embryo is a multi-cellular organism in early stages of development, before hatching from an egg. Most of the embryonic stem cells are obtained from eggs that have been fertilized in vitro( Latin word for "in glass") i.e. in laboratory dishes. This is done in an vitro-fertilization clinic. The embryonic stem cells are not fertilized in women. The embryonic stem are then extracted from a sphere-like structure called blastocyst. A blastocyst usually take around three to five days to be formed (when the number of cells during cell division reaches about 150). Stem cells have the ability to differentiate into a variety of specialized cells such as nerve cells, red blood cells, brain cells, muscle cells and other type of cells.
Adult stem cells are undifferentiated cells found in organs and tissues. They have the ability to renew and differentiate into other specialized cell types of the tissue and organ.
Stem cells are divided into 3 classes namely, totipotent, pluripotent and multipotent. Totipotent cells(e.g. unfertilized egg) can divide and transform into any cells required for proper development of the foetus. A pluripotent cell derived from totipotent cells have the ability to become specialized cells for the three main body tissues namely ectoderm, mesoderm and endoderm but cannot develop into a foetus. Lastly, a multipotent stem cell is one which has undergone further specialization than the pluripotent stem cells.
b. How do scientists produce, harvest, and use embryonic stem cells?
Above is a drawing of a blastocyst. A micro pipette is inserted into the blastocyst and the inner cell mass (embryoblast). The latter is chosen as they can develop into any type of cell of the body. The collected cells are then transferred into dishes containing nutrients and growth factors so as to continue cell division. The growth factor ( protein or hormone) is a substance that is able to regulate cell division. The cells are then allowed to multiply and by adding different growth factors, the stem cells can develop into certain type of cells. This process is referred to as subculture.
The embryonic stem cells are the analyzed by undergoing several tests so as to know their characteristics. Undifferentiated cells are also harvested. But to do so, the undifferentiated cells must first be identified. The undifferentiated cells contain surface markers that help in their detection. The surface markers are specialized protein called receptor that bind with molecules hence allowing cell communication.
Stem cells are also produced without the destruction of the embryos. Some examples are Somatic Cell Nuclear Transfer ( SCNT ), Altered Nuclear Transfer (ANT ) and Blastomere Extraction. These methods help to collect human pluripotent cells which have the same functions as embryonic stem cells thus preventing the destruction of human embryos.
SCNT is used in embryonic stem cell research and in regenerative medicine which is referred as therapeutical cloning. The nucleus of a somatic cell is removed and is incorporated into an egg cell whose nucleus has been removed. Then the nucleus of the somatic cell is reprogrammed by the host cell. A small electric shock is given which will stimulate cell division. After several mitotic division, a blastocyst (about 100 cells) is formed. The embryoblast is then collected.
Altered nuclear transfer is also a method whereby no embryos are destroyed. It is the same principle as SCNT but this time, the somatic cell nucleus and the cytoplasm of the egg cell is intentionally modified before incorporating the somatic cell nucleus in the egg cell. This intentional modification results in the production of pluripotent cells without any generation of embryo.
In blastomere extraction, a single cell (blastomere) is removed from the inner cell mass of the blastocyst. The latter is cultured to obtain embryonic stem cell. Hence the embryo is not harmed and can continue to grow into a human being. However some researchers say that it is impossible for an embryo to grow properly after the extraction of a blastomere.
Some cell, when given an electric shock, change the way they function and develop. Hence the cells develop into a specific cell for e.g. liver cells. These cells are then used in cell therapy to treat diseases. The liver cells are transplanted into the affected organ and the latter are allowed to multiply thereby restoring the organ. This process is known as tissue engineering. Tissue engineering is used to create new products that will help to improve the tissues to regenerate damaged organs. Hence Alzheimer, Parkinson, Blood cancer and other diseases are most of the time cured using tissue engineering.
c. What is the value of using stem cells?
After looking in details in stem cells and understanding the latter, it is found that the use of stem cells in unlimited. It has brought an understanding to the development of beings, though not completely. Diseases such as cancer are found to originate from uncontrollable cell division and occurs because of problems in differentiation process. Therefore stem cells are used to allow scientists to understand what happens in normal cells and treat the developmental errors that can occur. Stem cells form tissues and cells that are of very important use in medical therapies. Today many people have defective organs and as such they are placed on a waiting list go get donated organ. But unfortunately the number of donated organs are very limited and many people die every year while waiting for and organ. Hopefully, stem cells help to created specialized cells that are specific in their function. As such they are transplanted into the defective organ and then help in its regeneration. Another point is that new drugs are tested on stem cells so as to know if it is effective and have any side effect. Then only it can be tested on humans as accurate results are obtained when performing results on stem cells. Sometimes burn victims tend to suffer a lot from their wound. Instead of using donated tissues, stem cells are used to produce fresh and healthy tissues. A very small piece of skin is then allowed to grow and used to cover the burn which is often bigger than the piece of skin originally used.
d. What are the risks of and arguments against using stem cells?
Because we do not master stem cell technology perfectly, we are unable to evaluate the potential risks whether it is significant or not. There is a risk of uncontrolled cell development and the possible growth of tumors which will inevitably lead to complications. The source of the stem cells can have implications for the body's acceptance or rejection of the transplant. Stem cells originating from the patient himself or from another person may contain latent viruses or infectious agents which start to develop once transplanted to another host. During stem cell culture risk of contamination by nutrients will impart diseases to the cell receptor organs ,thereby leading to health complications. Since our knowledge on how stem cell differentiate is limited, specialized cell produced in laboratories might not be exactly the one we are looking for. This could give rise to rejection and malformation . Before transplantation of cells ,normally their immune system is suppressed by the use of drugs.
The unprotected cells are prone to infections and the drugs used can prove dangerous in terms of toxicity to the receptor organs.
One of the main argument against the use of stem cells is the respect for life of life on the very first day when fertilization has occurred. This argument is still maintained mostly in all religious cultures. For them , god gives life and he is the only one to take it back. Another argument is that stem cells are not completely understood and can lead to development and propagation of new diseases and infections. Last but not the least many people are against the use of stem cell fearing that one day man will lose his originality as a unique specimen.
Describe three reasons to use embryonic stem cells in research and manufacturing. Give three reasons to not use them. Consider legal, financial, medical, personal, social, and environmental aspects.
Embryonic stem cells has been of great importance in the drug testing field. Since stem cells can differentiate into many types of cells, a specific drug can be used to test for desired effect. For e.g. a drug can be used on lung cells rather than being used directly in the person's body system. A question that scientists have been asking for years and are still doing research on it is "how genes function?" With the use of stem cells, scientists will be able to study failures of development and know why the genes malfunction. This would ultimately increase our understanding of genes and scientists will be able to create drug to fight for specific diseases. In some countries, abortion is legal. Hence instead of destroying the embryo, the latter it would be of great use in scientific research and advances in science such as curing cancers will be made.
While scientific research should go on, people health and life should also be cared of and one should respect other peopleââ‚¬â„¢s belief. Any method that cause the destruction of the embryo should not be used because the latter has the right to live and develop into a human being. Stem cells belong to the embryo and no one has the right to steal them and more no one has the right to kill the embryo which is like doing a crime and this is immoral. Cloning and raising embryos in laboratories is a kind of torture to these minute beings which, after sometimes, will be destroyed and moreover these research involves lots of financial implications. Alternative methods should be used to clear out any misunderstanding between those for and against stem cells use.
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