Stem cell research is an amazing demonstration of the promise and potential of science. It has the potential to cure many diseases, and the procedure itself demonstrates the exquisite intricacies that have evolved with the advancement of modern science. Over the past century alone, science has taken the human race to the moon, eradicated disease and unlocked the secrets of harnessing nuclear energy. Scientists from every area are making discoveries at an astounding rate, expanding our knowledge of such topics as chemistry, physics, and biology. The discovery and use of stem cells has emerged in only the past 45 years, and with that discovery has come a new form of hope for many people. There are hundreds, of crippling diseases that are caused by extensive cell loss. Stem cell treatments have the potential to cure all of them. Despite this profound potential, there remains much more research to be done before the science of stem cells is fully understood, and many questions to be answered before stem cell treatments can become prevalent.
The human body is an amazing machine, comprised of a number of different systems working in harmony to support the body as a whole. Organs themselves are made of tissues, and tissues, in turn, are comprised of billions of cells, each with a specific job to do. These tissue cells are known as specialized cells, and go through a process called differentiation, which is "the process by which a cell becomes a particular cell type (e.g. liver cell, brain cell)" (Freeman G-9). Before a cell is assigned to a specific job, it is referred to as an undifferentiated cell. Undifferentiated cells utilize environmental cues to figure out what they should become. For example, if you put an undifferentiated cell into a culture with liver cells, it will react to the presence of the liver cells and transform into one itself. Stem cells are a special kind of cell because they are undifferentiated, and remain undifferentiated as they divide until the right cues dictate what kind of cell they should be.
There are two major types of stem cells: adult stem cells, and embryonic stem cells. The type of stem cell depends upon its potency, which is the "the range of commitment options available to a cell" (Nature). There are several different types of potency, including pluripotent, multipotent, and unipotent. Pluripotency is usually characteristic of embryonic stem cells in reference to their ability to turn into almost any type of cell., while multipotency and unipotency are characteristic to adult stem cells. Adult stem cells are either multipotent, meaning they can produce a variety of cells that are closely related to them, or unipotent, meaning they can produce only one type of cell.
Adult stem cells, or somatic stem cells are "an undifferentiated cell found among differentiated cells in a tissue or organ, can renew itself, and can differentiate to yield the major specialized cell types of the tissue or organ" (NIH). The key factor to remember about adult stem cells is that they are "determined, but not differentiated" (Freeman 489). For example, skin stem cells are permanently fixated as skin cells, but they can divide into any type of skin cell that exists. There are several advantages to using adult stem cells. For example, a doctor could use a burn victim's own skin stem cells to regrow skin to be used for grafting as a form of cell-based therapy, therefore decreasing the patient's chance of his immune system rejecting this "donor" tissue.
Embryonic stem cells are the most powerful form of stem cells to work with. Given their source, however, they are also the most controversial. They are derived from human embryos that are four to five days old. At this stage of development, the embryo is known as a blastocyst. The embryos are usually obtained through in vitro fertilization clinics. The embryos that are used in stem cell research are the discarded embryos from these clinics. The term "in vitro" implies that the eggs have been removed from the mother and fertilized in a Petri dish in a laboratory. This method of harvesting stem cells has received much media and political attention, as the harvesting of stem cells destroys the young embryo. This controversy has slowed study of stem cells greatly, yet the debate has also made embryonic stem cells a well known topic throughout the world. Embryonic cells are easy to cultivate in a laboratory setting, which is beneficial because large quantities of cells are needed in stem cell replacement therapy. The problems associated with immune system rejection of pluripotent embryonic stem cells have not yet been given adequate study. Due to the controversy currently limiting embryonic stem cell research, testing on human subjects has not yet been performed.
The use of stem cell replacement therapy could benefit sufferers of a number of debilitating diseases. Parkinson's disease is a neurodegenerative disorder, meaning it affects the neurons of the brain, and it gets worse as time progresses. The nerve cells that control motor function deplete, and causing what Parkinson's is most famous for: uncontrollable tremors. "This disease affects 2 out of every 1,000 peopleÉit is one of the most common neurologic disorders of the elderly" (MedlinePlus). Patients sick with Parkinson's slowly lose more and more motor function until they die a premature death. The progression of the disease is difficult as much for the loved ones of the patient as for the patient himself.
Hope for Parkinson's patients everywhere lies within stem cell research. Within a laboratory setting, scientists have found that they can induce embryonic cells to differentiate into unafflicted brain cells when injected with the type of gene found in these brain cells. When these newly-created normal brain cells are transplanted into the brains of rats who have been inoculated with Parkinson's disease, it is shown that they have a reparative effect on the afflicted brain tissue. Findings such as these bring hope to those who suffer from Parkinson's, and generate new interest for further research investigating a cure.
Stem cells are an exciting new field of science, because they demonstrate a new level of potential that can only be brought on with the advancement of modern science. Not only is it an innovative discovery, but it has the potential to help millions of people who are reminded every day of why this is an important issue. Despite the controversy, the field of stem cell research continues to expand, and as new techniques and inventive minds are applied to the problems posed by these treatments, hope springs anew for all those who seek one day to bring the full weight of scientific propensity upon the diseases of man.
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Freeman, Scott. Biological Science. 2nd ed. Upper Saddle River, New Jersey: Pearson Prentice Hall, 2005. 484-489.
Kantor, Daniel. "Muscular Dystrophy." MedlinePlus. 10 Sept. 2006. National Library of Medicine. 25 Apr. 2007 (http://www.nlm.nih.gov/medlineplus/ency/article/001190.htm).
Kantor, Daniel. "Parkinson's Disease." MedlinePlus. 16 May 2006. National Library of Medicine. 24 Apr. 2007 http://www.nlm.nih.gov/medlineplus/ency/article/000755.htm).
"Stem Cell Basics." Stem Cell Information. 20 Dec. 2006. National Institute of Health. 25 Apr. 2007 http://stemcells.nih.gov/info/basics/.
Smith, Austin. "A Glossary for Stem-Cell Biology." Nature. 29 June 2006. University of Edinburgh. 17 Jan. 2008 http://www.nature.com/nature/journal/v441/n7097/full/nature04954.html.