Scientists have been aware of the existence of these stem cells for many years but have only recently realized the potential medical applications of the cells. More than a decade ago, scientists discovered that if the normal connections between the early cellular progeny of the fertilized egg were disrupted, the cells would fall apart into a single cell progeny that could be maintained in a culture. These dissociated cells, otherwise known as embryonic stem cell lines, continue to divide in culture, producing large numbers of cells at a fast pace. However, these early embryonic cells would lose the coordinated activity.
Scientists quickly discovered that these cells retain the ability to generate a great number of mature cell types in culture if they are provided with appropriate molecular signals (Reaves, 2001). Scientists have made significant progress in discovering these signals and are still working on it. While it is a difficult task, scientists are pursuing it with great excitement because it is widely believed that cultured embryonic stem calls can be induced to generate all the mature cell types in the body. These cells could possibly be used to replace damaged or sick cells in patients with injuries or degenerative diseases.
In the most controversial method, scientists can take the stem cells from aborted fetuses, first asking for signed consent from a patient who had previously decided to terminate her pregnancy. This is the procedure most often highlighted by pro-life activists who oppose supporting stem cell research.
However, there are other less-controversial methods in which stem cells can be utilized, such as umbilical cord blood stem cell use. Umbilical cord blood stem cells are the youngest safely available stem cells and are the product of live birth. Freezing these cells basically stops the clock and prevents aging and damage that may occur to the cells later in life. Another category of stem cells is adult stem cells, such as those found in bone marrow. Adult stem cells serve very specialized roles in children and adults and are not as proliferative as those found in cord blood. These types of stem cells are far less controversial than embryonic stem cells, and will be the focus of this paper.
Umbilical cord blood, in particular, offers great hope for the future of stem cell research and use. It has been approved for use by the FDA and other authorities since the late 1980's. The first umbilical cord blood transfusion cured a blood cancer in 1988. Over 1,000 cord blood transfusions, frequently used for children with leukemia, have been successfully performed in the United States with little side effects. Recent research has shown that umbilical cord blood stem cells have similar powers and health promoting benefits as do embryonic stem cells.
Advances are being made each day in providing greater safety to the patient. New methods of separating the stem cells from all other blood components have resulted in a product that consists of only stem cells. Since these umbilical cord stem cells have not developed ABO and HLA antigens on their surfaces, they do not induce graft vs. host reactions nor other problems that may occur with embryonic and adult bone marrow stem cells. Since the umbilical cord stem cells do not contain mature blood or tissue cells, foreign protein reactions are minimized. This paper will examine the potential of these types of stem cells, in an effort to demonstrate how stem cells from umbilical cord blood may help scientists solve the ethical debate and enhance humanity.
Background on Stem Cells
Stem cells are cells in the body that have the unique ability to regenerate and change shape (How Stuff Works, 2003). Unlike other types of cells, stem cells can change into other types of cells. Stem cells are at the center of an innovative field of science known as regenerative medicine. Because stem cells can become bone, muscle, cartilage and other specialized types of cells, scientists believe that they have the potential to treat a variety of diseases, including Parkinson's, Alzheimer's, diabetes and cancer. Eventually, stem cells may also be used to regenerate organs, eliminating the need for organ transplants and other surgeries.
Stem cells are like little kids who, when they grow up, can enter a variety of professions," says Dr. Marc Hedrick of the UCLA School of Medicine (How Studd Works, 2003). "A child might become a fireman, a doctor or a plumber, depending on the influences in their life -- or environment. In the same way, these stem cells can become many tissues by making certain changes in their environment."
Stem cells can be broken down into four basic types (How Stuff Works, 2003):
Embryonic stem cells - Stem cells found in human embryos
Fetal stem cells- Stem cells found in aborted fetal tissue
Umbilical stem cells - Stem cells found in umbilical cords
Adult stem cells - Stem cells found in adult tissue
Embryonic and fetal stem cells have the potential to change into a greater variety of cells than adult stem cells do. In April 2001, researchers at UCLA and the University of Pittsburgh found stem cells in fat sucked out of liposuction patients. Prior to this discovery, stem cells were found only in bone marrow, brain tissue and fetal tissue -- sources that have caused both logistical and ethical problems. Stem cells from fat have the ability to mature into other types of specific cells, including muscle, bone and cartilage, but how many other types is still unknown.
As stem cells research advances, scientists are discovering more and more about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. This promising area of science is giving scientists hope that cell-based therapies can be used to successfully treat disease.
Stem cells have two major characteristics that set them apart from other types of cells (National Institute of Health, 2002). First, stem cells are unspecialized cells that renew themselves for long periods through the process of cell division. The second is the fact that under certain physiologic or experimental conditions, stem cells can be induced to become cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas.
Most of today's scientific research is performed using two types of stem cells from animals and humans: embryonic stem cells and adult stem cells, both of which have different functions and characteristics. More than two decades ago, scientists discovered ways to obtain or derive stem cells from early mouse embryos. After a detailed study of the biology of mouse stem cells, scientists discovered, in 1998, how to isolate stem cells from human embryos and grow these cells in laboratories. These cells are known as human embryonic stem cells. The embryos used in these studies were developed for infertility purposes through in vitro fertilization procedures. After they were no longer needed, they were donated for research with the donor's consent.
Stem cells are of great significance for living organisms today for a variety of reasons. In the three to five-day-old embryo, which is known as a blastocyst, a small group of approximately 30 cells known as the inner cell mass creates the hundreds of highly specialized cells that make up an adult organism. In the developing fetus, stem cells in developing tissues create the multiple specialized cell types that make up the heart, lung, skin, and other tissues. In some adult tissues, such as bone marrow, muscle, and brain, discrete populations of adult stem cells generate replacements for cells that are destroyed by age, injury, or disease.
Stem cells are different from all other kinds of cells in the body. All stem cells -- regardless of their source -- have three general properties (National Institute of Health, 2002):
They are capable of dividing and renewing themselves for long periods;
They are unspecialized; and They can give rise to specialized cell types.
Because a stem cell does not have any tissue-specific structures enables it to perform specialized functions. (National Institute of Healt, 2002). A stem cell cannot work with its neighbors to pump blood through the body (like a heart muscle cell can); it cannot carry molecules of oxygen through the bloodstream (like a red blood cell can); and it cannot fire electrochemical signals to other cells that allow the body to move or speak (like a nerve cell can). However, unspecialized stem cells can create specialized cells, including heart muscle cells, blood cells, or nerve cells.
Unlike muscle cells, blood cells, or nerve cells -- which cannot replicate themselves -- stem cells can replicate many times. When cells replicate themselves many times it is known as proliferation. A starting population of stem cells that proliferates for many months in the laboratory can create millions of cells. If the resulting cells continue to be unspecialized, like the parent stem cells, the cells may be capable of long-term self-renewal.
Scientists believe that stem cells may be effective in treating diseases such as Parkinson's disease, diabetes, and…