This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.
Stem cells are specialized cells that have the ability to divide for an indefinite period and can give rise to a wide variety of specialized cell types (Panno 13). In humans, stem cells have been identified in the inner cell mass of the early embryo, some tissues of the fetus, the umbilical cord, and in several adult organs. Embryonic stem cells (ESCs), which are derived from an early-stage embryo, can be removed from the blastocyst and maintained in an undifferentiated state in cell culture lines in the laboratory for prolonged periods until needed to be differentiated into appropriate tissues from transplantation into patients (Newton 34). However, unlike ESCs, adult stem cells are difficult to identify and purify, and when grown in culture, are difficult to maintain in the undifferentiated state (Ruse and Pynes 78). Even though no major ethical concerns have been raised against adult stem cell research, research on human embryonic stem cells is controversial, given the diverse views held in our society about the moral and legal status of the early embryo (National Bioethics Advisory Commision). The controversy has encouraged provocative and conflicting claims both inside and outside the scientific community about the biology and biomedical potential of both adult and embryonic stem cells. Thus, it has urged the scientific community to debate whether "do the potential benefits provided by embryonic stem cell research outweigh the moral costs"?
The discoveries of murine and human embryonic stem cells by Martin Evans and Matthew Kaufman in 1981 and by James Thomson and John Gearhart in 1998 (Gardiner D2) were honored by scientists for numerous reasons. Primarily, these findings opened up the possibility that embryologists would have a much better opportunity to study one of the fundamental unsolved problems in their science: How does an organism grow, develop, and differentiate? The question as to the mechanism by which a single fertilized egg evolves into a complex complete organism has long been one of the most fundamental questions in biology. These discoveries provide scientists with the opportunity of examining the very earliest stages of a living entity, the stem cells from which the rest of the organism would eventually grow, and observing the changes that take place in those cells over time (Snow 34). By studying the differentiation of stem cells, biologists now have the opportunity of discovering those factors inherent within an organism itself and those from its surrounding environment that make possible and direct the evolution of a fertilized cell (Newton 24). Also, some of the most serious medical conditions, such as cancer and birth defects, are due to abnormal cell specialization and division. A better understanding of normal cell processes will allow us to further delineate the fundamental errors that cause these illnesses (Ruse and Pynes 16). Another possible application of stem cell research is its use in drug development (Studer 303). Many steps must be completed before a new chemical compound can be approved as a drug. After the chemical itself has been invented and synthesized, it must be tested both for toxicity and for effectiveness. Stem cells can be used more easily and at less expense in place of rats, mice, and other experimental animals for the early stages of drug testing. Compounds found to be toxic to stem cells would then not be advanced to other stages of testing (Newton 78), saving significant amounts of time and money for a pharmaceutical firm.
Perhaps the most far-reaching potential application of stem cells is the generation of cells and tissues that could result from disruption of cellular function or destruction of tissues of the body (Newton 79). Pluripotent stem cells which can be stimulated to develop into specialized cells, offer the possibility of a renewable source of replacement cells and tissue to treat Parkinson's and Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis (National Bioethics Advisory Board). There is almost no realm of medicine that might not be touched by this innovation.
Currently, human embryonic stem cells can be derived from the inner cell mass of a blastocyst (Panno 18). These cells, present in the earliest stages of embryo development, can generate all of the human cell types, and are capable of self-renewal. A relatively renewable tissue culture source of human cells that can be used to generate a wide variety of cell types would have broad applications in basic research, transplantation, and other important therapies, and a major step in realizing this goal was taken in 1998 with the demonstration that human embryonic cells can be grown in culture (Ruse and Pynes 45). They are important not only for in-vitro studies of normal human embryogenesis, but also for human gene discovery and gene therapy.
Because human embryonic stem cells have only recently become available for research, and because public funding for such research has been limited, studies of how well these tissues perform physiologic functions has been largely conducted with mouse models. Ron McKay described progress made in "coaxing the in vitro differentiation of human ESCs into insulin-producing cells that might be useful in treating diabetes", but he also noted that "studies have already been conducted with analogous mouse cells transplanted into mice that have diabetes and that partial restoration of insulin regulation was observed" (Lumelsky, . 1386). Other studies have demonstrated that mouse embryonic stem cells can be successfully transplanted into rodents that have Parkinson's disease symptoms and partially relieve these symptoms (Studer et al. 302). Similarly, current studies suggest that mouse embryonic stem cells can be transplanted into animals that have spinal-cord injuries and partially restore neural function (McDonald et al. 1416). These studies provide promise, but not definite evidence, that similar treatments could be effective in humans.
As the science advances, it is essential that scientists, religious, moral, and political leaders and society as a whole continue to evaluate and communicate about the ethical implications of stem cell research. One of the controversial issues over embryonic stem cell research touches on some of the same fundamental questions that society has grappled with in the debates over contraception, abortion, and in vitro fertilization (National Bioethics Advisory Commission). The questions at the center of the controversy concern the nature of early human life and the legal and moral status of the human embryo. Embryonic stem cell research often involves removing the inner cell mass from "excess" blastocysts that are unneeded by couples who have completed their fertility treatment (Newton 67). This prevents those blastocysts from continuing to develop. Although such blastocysts would likely be discarded and destroyed by the clinics in any case (Panno 89), some believe that this does not make it morally acceptable to use them for research or therapeutic purposes.
The most basic objection to embryonic stem cell research is rooted in the fact that such research deprives a human embryo of any further potential to develop into a complete human being (Ruse and Pynes 103). For those who believe that the life of a human being begins at the moment of conception, this research violates tenets that prohibit the destruction of human life and the treatment of human life as a means to some other end, no matter how noble that end might be (Evolution). There are widely divergent views on this subject. For example, in testimony to the National Bioethics Advisory Commission, Rabbis Elliot tradition the embryo has no moral status until 40 days after implantation. Until it is born, the child is viewed as a part of its mother's body, and its own life is believed to begin only when the child is born. Eggs and sperm mixed together in a petri dish have no legal status, because they are not even part of a human being unless implanted in a woman's womb (National Bioethics Advisory Commission).n In the same forum, Abdulaziz Sachedina discussed the Muslim tradition, which accords legal and moral status to the fetus only after ensoulment takes place, at the end of the fourth month of pregnancy. Because in both of the belief systems there is a mandate to save human life wherever possible, human embryonic stem cell research can be deemed acceptable if it is conducted reasonably and ethically (National Bioethics Advisory Commission).
For those who hold the views that human life begins at conception and that the moral obligation to preserve human life outweighs any potential heath benefits of ESC research for regenerative medicine, the only morally acceptable position would be to adopt a complete prohibition on human ESC research without regard to the method of embryo production or whether the research is publicly or privately funded (Newton 97). There are indeed potential alternatives that have been researched by numerous scientists around the world. Recently, to avoid the controversy surrounding these cells, scientists around the world have explored reprogramming mature cells to make them just as potent, with the hope being that such induced pluripotent stem (iPS) cells might one day help replace diseased or damaged tissue (Choi). Rapid progress is being made toward controlled differentiation of human iPS cells into specific tissue types, such as heart, neuron, liver, pancreas and eye (Snow 35). At first they found that human iPS cells could indeed generate blood vessel, blood precursor and retinal cells with characteristics similar to ones derived from embryonic stem cells, albeit with significantly reduced efficiency. Further study, however, revealed cells derived from iPS cells had significantly higher rates of cell death, or apoptosis, than ones from embryonic stem cells (Choi). Although no clinical trials involving therapies derived from iPS cells are on the books, researchers are currently testing drugs on them.
The debate over stem cell research has been waged on many fronts. Scientists, for example, disagree as to the relative potential value offered by different types of stem cells. However, the most steaming debates have focused on ethical questions. Stem cell research offers unprecedented opportunities for developing new treatments for debilitating diseases for which there are few or no cures. Stem cells also present a new way to explore fundamental questions of biology, such as shaping the basic fundamental questions of biology. However, our society holds diverse views about the morality of using early embryos for research, and the general public finds itself searching for a consensus on how to proceed with this new avenue of research. The use of embryonic stem cells is not the first scientific advance to raise public concerns about ethical and social issues in biomedical research (Gardiner D2). Recombinant-DNA techniques likewise raised questions and were subject to intense debate as well. For these reasons, a national advisory board was established at the NIH (National Institutes of Health) to ensure that the research was met with the highest scientific and ethical standards (Gardiner D2). Similarly, if the National Bioethics Advisory Commission works towards their goal of establishing such standards, it would ease the burdens imposed upon those that favor embryonic stem cell research, and rationally value the opinions of those that find the research unethical at its forefront.