As improvements in scientific technology and techniques allow for better observations and insights into the natural world, so to do advancements in medical research occur on a seemingly daily basis. On such research topic that has found itself the center of a global debate is the issue of stem cell research. Hailed by some as one of the most dynamic areas of research ever to exist, it is thought to be the next big “revolution” in medicine, surpassing even the advent of anesthesia and antibiotics (Towns, 2004). Though the reputation does not come without controversy, stem cell research can be found in the headlines of news publications for changes in policy or position on the topic equally as much as breakthroughs in research. With the recent death of former President Ronald Reagan and his wife Nancy’s pledge to find a cure for the debilitating Alzheimer’s disease from which he suffered, stem cell research became a leading domestic issue in the President race of 2004.
Defined as “unspecialized cells that renew themselves for long periods through cell division” and “under certain physiological or experimental conditions. . . can be induced to become cells with special functions,” stem cells hold the key to many developmental mysteries for biologist (National, 2002). Originally described by Owen in 1945 when studying chimerism in a pair of twin cows (Cogle, 2003), stems cell research has gained momentum since the mid 1970’s culminating with the first successful culturing of human embryonic stem cells in November 1998 at the University of Wisconsin. Scientists currently working with both animal and human stem cells are currently working at identifying the factors behind stem cells’ ability to remain unspecialized and divide for a seemingly indefinite amount of time (National, 2002). Despite the controversy surrounding the study of stem cells, research has the potential of unlocking the mystery of cancer proliferation and curing degenerative diseases such as Alzheimer’s, Parkinson’s, type I diabetes, and heart failure.
Though stem cells can be harvested from a variety of sources, human embryonic stem cells culture lines are the type most often associated with stem cell research by the media. Donated by consenting couples, embryonic stem cells are harvested from left over embryos of the in vitro fertilization process (University, 2004). A fertilized egg is allowed to proliferate for 4-5 days until it reaches the blastocyst stage of development. At this point the embryo consists of a hollow ball of cells with an outer layer, called the trophectoderm, and an inner cell mass on the inside. As this inner cell mass gives rise to all three germ layers present in a fully developed human, the cells are referred to as being pluripotent, and are the target of stem cell harvesting (Towns, 2004). Most of the controversy associated with embryonic stem cells arises because the trophectoderm must be destroyed in order to get to the inner cell mass, effectively killing the embryo as well.
Another source of stem cells that does not raise nearly as much controversy are adult stem cells found in various tissues throughout the mature body. In fact, therapeutic medical techniques have been in practice for over a decade in the form of bone marrow transplants for patients suffering from diseases such as leukemia (Vogel, 2001). Adult stem cells fit the definition of stem cells in that they self-rejuvenate and have the potential to differentiate into various types of more specialized cells. They also demonstrate obvious advantages over embryonic stem cells in that they do not require the destruction of an embryo and are relatively easily harvested in large quantities (Kuehnle, 2002).
One clear disadvantage currently associated with adult stem cells is the uncertainty of the plasticity of these cells. While the multipotent nature of the cells is well documented within tissue lines, the ability of adult stem cells to revert back into a pluripotent state remains in question even today, despite recent research that strongly supports at least haematopoietic stem cells’ ability to differentiate into endothelial, skeletal, neural, liver, and cardiac tissues (Kuehnle, 2002). Recent studies have even shown that bone marrow stem cells are able to migrate throughout the body, helping to rejuvenate neural and cardiac damage caused by trauma or heart attack (Vogel, 2001). Researchers at the University of Florida warn that such results may be deceiving. In separate studies done by Florida and researchers in the United Kingdom, adult stem cells were shown not to differentiate but rather fuse with target cells, creating a hybrid with twice the chromosomes of a normal cell (Frankish, 2002). Findings such as these cause researchers to proceed with caution when working with adult stem cells, as much is still unknown about the actual plasticity of these cells.
Applications of Stem Cell Research
Despite the controversy associated with embryonic stem cells and the uncertainty of plasticity in adult stem cells, research continues to be conducted in a variety of areas. While not the most visible use of stem cell research, studies linking the activity of cancerous cells to that of stem cells may in fact prove to be some of the most beneficial findings. Striking similarities in the cellular activity of cancerous cells and stem cells, such as various regulating pathways including the Notch, Sonic hedgehog, and Wnt pathways point to direct correlations between the proliferation of both cell types (Reya, 2001). Researchers also believe that the longevity of stem cells leave them more susceptible to accumulating mutations. In fact, mutations commonly observed in hematopoietic stem cells are indicative of the development of leukemia (Reya, 2001). Though the better understanding of stem cell activity, it is hoped that the occurrence of numerous types of cancer can be reduced.
However, stems cells are also beginning to play an increasingly important role in the treatment of various types of cancer. In the treatment of T-cell lymphomas, stem cell transplants are used to rejuvenate the depleted immune system associated with the high radiation levels necessary to combat aggressive forms of lymphoma (Jantunen, 2003). In addition, multiple stem cell transplants have recently been associated with increased survival and decreased relapse rates in patients treated for multiple myeloma. In one study the seven-year survival rate for the multiple transplant patients was double that of patients that only received one transplant (Attal, 2004). While cancer treatment currently only utilizes stem cells as supplementary treatments, research continues to be conducted into the direct combat of cancerous cells using stem cell knowledge.
One area in which the use of stem cells are being investigated as a possible cure is with degenerative diseases affecting various body systems, including the circulatory and heart. One of the leading causes of death in the U.S. today is cardiac disease and myocardial infarctions, which are characterized by “lose of cardiac tissue and contractile function” (Graham, 2002). Clinical trials now allow persons who have suffered a severe heart attack the option of receiving a bone marrow treatment, of a sample taken from the patient’s own hip. While no official results have been released, it is hoped that the stem cells will help regenerate the damaged tissue without the need to use embryonic stem cells (Stem, 2003). Other methods still being tested in animals utilize embryonic stem cells; however, preliminary results have not shown a significant improvement but have revealed an increased susceptibility to the development of tumors associated with embryonic stem cells (Graham, 2002).
Another degenerative disease in which stem cell cures are currently being sought after is diabetes mellitus. Caused by the late onset of an autoimmune reaction with insulin-producing cells within the pancreas, type I diabetes mellitus is associated with chronic eye, kidney, and circulatory complications (Read, 2003). Unfortunately, positive identification of pancreatic stem cells has yet to be achieved, forcing researchers to turn to the conversion of embryonic and hematopoietic stem cells into insulin-producing cells as the only current option (Serup, 2000). While researchers have been able to induce the differentiation of embryonic cells into pancreatic cells in in vitro studies, current in vivo procedures have yet to produce significant level increases within mice.
Perhaps the most highly anticipated application of stem cell research is their use in curing neurological degenerative diseases such as Alzheimer’s disease. Current techniques employed to reverse the effects of neurological diseases involve transplanting neural tissues from aborted fetuses. While marginally successful, high levels of variability within tissue samples inhibit the widespread use of these procedures (Bradbury, 2001). Current studies in mice have produced varying degrees of success in getting stem cells to differentiate into the desired cell types. Researchers attribute these results to environmental differences associated with different parts of the brain, with the best results associated with implantation into the hippocampus and subventricular zone (Le Belle, 2002).
In research geared specifically toward the treatment of Parkinson’s disease, researchers have taken strides forward with the use of embryonic stem cells. Parkinson’s disease is caused by the degradation of dopaminergic neurons within the brain. Researchers at Harvard Medical School were able to successfully transplant embryonic cells into previously treated mice brains that exhibited the same qualities as a Parkinson’s patient’s brain. Dissection of the brains after a 14 week period showed increased levels of dopaminergic neurons and increased production of dopamine (Love, 2002). Researchers have also learned that embryonic stem cells treated with Nurr1, a transcription factor for the differentiation of dopaminergic neurons, helped to significantly reduce the risk of tumor development associated with the use of embryonic stem cells (Sayles, 2004).
Government Policy on Stem Cell Research
While President Bush’s declaration that federal funds could not be used to support embryonic stem cell research in August of 2001 put the spotlight on the regulation of stem cell research, legislature banning the use of federal funds had been in place for quite some time. President Bush’s allowance of existing culture lines to benefit from federal funding actually relaxed a ban put in place by Congress years earlier (Duffy, 2002). Despite the apparent relaxation of the standards, researchers still feel that any ban will have a detrimental affect on the U.S.’s position as a leader in bioengineering, and in response states such as California and New Jersey have passed legislature promoting stem cell research through state funding (McCarthy, 2004). Private investors have also helped to fill the void created by the federal government and in conjunction with Harvard University made available 17 additional embryonic stem cell lines.
The U.S., however, is not the only country struggling with the issue of stem cell research. Throughout the world, international and domestic policies take the shape of a wide variety of stances. The European Union recently adopted a moratorium on the development of new embryonic stem cell lines that, like the Bush’s stance, still allows research to be conducted on existing lines. However, individual nations still hold laws that contradict the official position of the Union. In nations like the United Kingdom, Sweden, and Belgium embryonic research is permitted. However, these nations are contrasted with neighboring nations Italy, Austria, and Ireland, which prohibit embryo research of any kind (Vogel, 2002). The United Kingdom has even gone as far as to open an embryonic stem cell bank. Officials there hope the bank will promote the ethical development of techniques and research associated with stem cells (Pincock, 2004).
Opposition to Stem Cell Research
As seen with the wide variety of political stances displayed by the governments of the world, it is not surprising to discover that within the world population there are also a wide variety of stances on the subject of embryonic stem cell research. Numerous religious and professional groups have taken public stances on the issue and created official statements. According to recently issued Catholic publication, the church led by Pope John Paul II rejects the notion that embryos have yet to achieve the status of a human and any destruction of an embryo would be the equivalent of murder (Shannon). The article goes on to cite the stratification of social classes as an additional reason the church opposes stem cell research. There is a fear that the new technology would only serve those with enough money to afford it, and that those less fortunate would be left out.
The Christian Orthodox Church’s stance on stem cell research mirrors that of the Roman Catholic Church. In a statement issued by the Theodosius, the Archbishop of Washington, the Orthodox Church commends President Bush for attempting to find a compromise between the advancement of science and the ethical treatment of embryos. Citing numerous biblical texts, the document goes on to claim that the act of profiting from the result of an evil is in itself evil, even if the end result is good. The document also claims that because embryos are not capable of giving consent to be experimented on, it is unethical to do so (Theodosius, 2001).
The foundation Do No Harm: The Coalition of Americans for Research Ethics has also formulated an official response to the subject of stem cell research. The group, dedicated to stopping embryonic stem cell research, relies heavily on the existence adult stem cell cultures as a means to justify their stance. With the discovery of pluripotent cells within adult tissues, the organization sees the use of embryos an unnecessary measure (Do No Harm, 1999).
While there are many ethical issues involved with stem cell research, there also remains an untapped wealth of knowledge to be gained through further research. As is the case with almost every ethical issue, almost by definition, there is no clear cut answer to the question of whether the use of embryos in the name of scientific discovery is ethically appropriate. When considering this issue, one must weigh personal conviction with the progression of knowledge for the good of the general public. As pointed out by the Christian Orthodox Church, allowing the use of embryos for stem cell research does force us to walk the slippery slope between abuse of power and controlled research (Theodosius, 2001).
Ultimately, the use of in vitro fertilized embryos that would be destroyed regardless of whether used for research or not, does not appear to be a drastic ethical violation. In fact, nearly 60 % of such cells are rejected as nonviable due to an arrest in cellular division (Landry, 2004). Such cells have no longer have possess the potential to grow into a mature human being, but the cells could still be used for stem cell research. By holding an honest view of what constitutes human potential, it should be possible for a universal accepted stance on stem cell research that satisfies all parties involved.
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