Stem Cells and the Controversy Surrounding the Issue
Research on stem cells is one of the most promising areas of biology, scientists study the mechanism of development from a single cell into an organism and how healthy cells can replace defected ones. (Stem Cell Research and Applications)
Let's start from definition - what the stem cells are. "Stem cells" is a term to define cells that are able to differentiate into specialized tissue cell types. Stem cells come from two sources: embryonic stem cells and adult stem cells. (What are Stem Cells)
Embryonic stem cells are taken from a 4-5-day-old human embryo and usually obtained from vitro fertilization clinics where several eggs are fertilized in a tube, but only one is implanted into a woman. Embryonic stem cells are a hollow microscopic ball of cells - the blastocyst, which consists of two layers. The cells the inner layer can differentiate to form all the tissues of an organism, and this mass is the source of embryonic stem cells. (What are Stem Cells) (Stem Cell Research and Applications)
Adult stem cells are derived from mature tissue and are found throughout the body. They remain in a stable state until activated by disease or tissue injury; besides, many cells of the organism need to be replaced regularly. The function of adult stem cells is to maintain and renew the tissues in which they are located. Adult stem cells are considered to possess limited ability to differentiate into any tissue, i.e. they can develop into their original tissue.
All stem cells are generally characterized by three general properties:
- Potency - ability to develop into another type of cell with a specialized function. Totipotent or pluripotent types are able to become any type of cell, but pluripotent can not develop into an organism. There are also multipotent cells, which are able to differentiate to a limited number of tissues, and unipotent, which are able to develop into cells of their own type.
- Self-renewal - the ability to divide and renew themselves.
- They are unspecialized. (Stem Cell Research and Applications) (The Potential of Stem Cells)
There are many reasons why scientists are interested in stem cells research. Since stem cell can develop into any cell type, it makes them a means of regenerating damaged tissues and in that way to cure many diseases. Some birth defects, and also cancer, are influenced by abnormal cell growth and differentiation, therefore new therapies for such diseases can be worked out. Stem cell research is considered useful in study of evolution of the human organism. Stem cell research is aimed to find out the functions that genes play in determining genetic features and mutations. (What are Stem Cells)
The activity of biologists can solve a problem of a lack of in vitro models constraining investigation of many diseases, and also a number of viruses including AIDS and hepatitis C virus which can grow only in human or chimpanzee cells.
Transplantation is one of the most important possible applications of stem cell research. Since pluripotent stem cells could be grown into a particular type of tissue or organ, they can create an unlimited supply of tissues or even organs. Currently the demand for organs to be transplanted far exceeds supply.
Then, creating new types of drugs is another reason to pursue stem cell research. Biologists could test a drug's on tissue grown from stem cells and estimate its effect rather than engage human volunteers.
As for diseases that could be cured with stem cells, we can mention following.
Diseases of Bone and Cartilage. Differentiated stem cells are able to affect degenerative conditions in which bones suffer from deficient in numbers or defects in function. Cells could be grown and introduced into damaged areas of joints in cases of osteoarthritis or into gaps in bone occurred through various reasons.
Type 1 Diabetes in Children. At the present time method of treating patients with human islet transplantation is hindered by limited quantity of donated pancreas available, and pluripotent stem cells could create a needed material to transplant.
Brain and Nervous System Diseases. A loss of nerve cells leads to many nervous system diseases, such as Parkinson's disease or Alzheimer's disease. Nerve cells cannot restore, and no effective therapy exists without a source of functioning nerve tissue. Replacement of damaged cells by those grown from stem cells may become a hope for such individuals.
Cancer. Currently, bone marrow stem cells are used together with chemotherapy, but these recovered cells have limited ability to restore immune function. It is believed that introductions of differentiated stem cells can completely repair immunity of patients undergoing bone marrow transplantation.
As it is known, stem cell research aroused debates involving social, ethical and religious viewpoints. Methods by which stem cell are obtained are the major stumbling block of the debates. The main objection is that a destruction of a human blastocyst is required, so a fertilized egg is not given the opportunity to develop into a human being. The ethical status of human embryonic stem cells is different for those who consider that the early embryo has no moral status and for those who regard the embryo as protectable - for them destroying it by removing the blastocyst in order to obtain stem cells is similar to murder.
The problem lies in understanding of the embryo. A series of criteria has been suggested to determine the moral status of the pre-implanation embryo, such as a possession of a complete human genome, its potential to grow into a human being and the presence of consciousness. A party standing on the position that the embryo has moral status equal to that of a human being mark possession of a human genome and the potential for development into a human being.
Most cells possess a unique genome but are not considered morally protectable, so the answer whether stem cells are morally equal to somatic cells or embryos depends on an understanding of stem cells' potential. Can it be asserted that stem cells have similar moral status because of their potential to become a human being? Potentiality is meant as "natural potentiality," therefore the moral status of a stem cell can be defined depending on whether its potential to develop into a human being is natural (as it is with embryos), or artificial, as for the cells grown in laboratory. The ability of a stem cell to grow into a human being seems to be similar to a somatic cell that could be cloned than like an embryo. Extracted from the structure of the embryo, such cells will not form the outer layer of cells of the embryo or other structures. Stem cells are pluripotent rather than totipotent, i.e. they can not develop into a functioning organism. Thus, it can be concluded that stem cells should be considered and treated as any other cells of human body.
The promise to gain a cure for chronic diseases with the help of stem cell research is so great that it is wise to think seriously about the best way of developing such research according to the commitment of scientists to the protection of human life and the promotion of human health on one hand and taking into account public opinion with respect for the views of others on the other hand. But it is necessary to separate the scientific factors from the ethical and religious arguments mixed with efforts to pervert advancement of knowledge and misinterpret the goals of scientists. (The Ethics and Politics)
1. What are Stem Cells? http://www.medicalnewstoday.com/info/stem_cell/whatarestemcells.php
2. James C Bobrow, MD*. "The ethics and politics of stem cell research".
The official National Institutes of Health resource for stem cell research.
3. Audrey R. Chapman, Ph.D., Mark S. Frankel, Ph.D., Michele S. Garfinkel, Ph.D. (November 1999). "Stem Cell Research and Applications". Produced by the American Association for the Advancement of Science and Institute for Civil Society.
4. Hans R. Schler. (2007). "The Potential of Stem Cells: An Inventory".