Stem Cell Research
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In the face of extraordinary advances in disease prevention and treatment devastating illnesses such as cancer, Parkinsons disease and neuromuscular dysfunction continue to deprive people of health, independence, and well-being. Stem cell research offers hope of a cure for millions in an age of hopelessness. While scientists are still miles away from finding actual cures each day they inch their way closer towards cures.
To fully understand the potential of stem cells, it is important to view them in the context of human development. At the time of fertilization, when the sperm and egg join, the cells produced are capable of forming an entire organism. These cells are classified as totipotent, which means that the potential of the cells is unlimited. At this point these cells can still develop into any type of specialized cell. Specialization starts almost immediately, as the multiplying cells form a ball called a blastocyst. Inside the blastocyst are “pluripotent” or “embryonic” stem cells that can form just about every cell type except those of the placenta.
There are two ways in which scientists harvest embryonic stem cells. One uses
in vitro fertilization in which an egg is fertilized by a sperm in a laboratory and allowed to grow until it forms a blastocyst and then the cells can be harvested. These are the totipotent cells with an infinite possibility. This process is called embryonic stem cell research. The cells taken from this process can hopefully be coaxed by scientist to form any cell in the human body. Scientists also can harvest stem cells from aborted fetuses. This process is much like embryonic stem cell research except in this process scientists can utilize many more stem cells and more fully perform their research.
Embryonic stem cells are important to scientists because of three characteristics. First they can replicate indefinitely without undergoing aging, death or mutation. Second they are genetically normal and most importantly they can differentiate into many cell types. These include neurons, blood cells, skeletal muscle and cardiac tissue.
A third type of stem cells are those found in Adults. Adult stem cell research has both advantages and limitations. It deals with the pluripotent cells which means that they are limited in their ability to differentiate. These cells are usually taken from the bone marrow. The stem cells from the bone marrow have limited possibilities in terms of what they can become. Scientists have been performing this process on cancer patients for some time now. The advantage of these type of therapy is that since it uses the patients own cells there is no risk of rejection or infection from contamination. It also does not give rise the moral, ethical and legal questions raised by embryonic stem cell therapies.
Securing stem cells for research, whether from children, adults, aborted fetuses, or embryos, must be done under strict conditions with extreme care for several reasons. These are to protect the donors, to reassure the public that boundaries are not being overstepped, and to assure the highest quality of research and outcomes.
As already noted, there are three different types of stem cells, derived from three different sources. Obtaining the first type, adult stem cells is almost commonly practiced now and does not pose any new threat to the donors health or any ethical issues. The second source is cells derived from aborted fetuses. This process occurs only when a woman both wants an abortion and is willing to give up her aborted fetus for scientific use. The third source, pre-implantation embryos, requires the greatest care. Human embryonic stem cells can be obtained from two sources. The first are so-called “spare” embryos, these are embryos that are remaining after a couple has decided that they have no further use for their stored embryos. The second are embryos belonging to infertile couples who are willing to give up their embryos.
Stem cell research will potentially lead to new treatment for many human diseases. These most likely will include type 1 diabetes in children, diseases of the nervous system, immunodeficiency diseases, diseases of the bone and cartilage and cancer.
Many nervous system diseases result from loss of nerve cells. Mature nerve cells cannot divide to replace those that are lost. Thus, without a “new” source of functioning nerve tissue many people are forced to live with terrible muscular dysfunctions. In Parkinsons disease, nerve cells that make the chemical dopamine die. In Alzheimers disease, cells that are responsible for the production of certain neurotransmitters die. In amyotrophic lateral sclerosis, the motor nerve cells that activate muscles die. In spinal cord injury, brain trauma, and even stroke, many different types of cells are lost or die. In multiple sclerosis, glia, the cells that protect nerve fibers are lost. Perhaps the only hope for treating such individuals comes from the potential to create new nerve tissue restoring function from pluripotent stem cells.
In patients with type1 diabetes, the only treatment currently available is pancreatic transplant. This treatment is limited by the availability of healthy organs for transplant as well as the problems of compatibility and anti rejection therapies. Pluripotent stem cells could theoretically be instructed by researchers to differentiate into a particular type of pancreatic cell and could provide enough therapeutically effective material to transplant. They also could engineer such cells to effectively resist immune attack as well as rejection.
Immunodeficiency diseases are characterized by a failure of the immune system which results in increased susceptibility to infection and are often associated with anemia, arthritis,