Stem Cells: The Basics
Stem cells form part of a class of cells that are able to differentiate into specialized cell types. There are three main sources for obtaining stem cells- adult cells, cord cells, and embryonic cells. Adult stem cells can be extracted from bone marrow, which is a rich source of stem cells, or from the peripheral system. Extraction from bone marrow may cause certain amounts of damage to the bone marrow. On the other hand, extraction from peripheral stem cells does not cause as much damage to the bones, but this process is much lengthier than bone marrow extraction. These stem cells can also be found in the brain, blood, skeletal muscles, skin, and liver, and they are able to self-renew indefinitely. These cells are seen as more useful than both umbilical cord and embryonic stem cells because there is always an exact DNA match (Medical News Today).
Stem cells extracted from the umbilical cord provide a very rich source of cells. These cells are extracted during pregnancy and are then stored in cryogenic cell banks as a type of insurance policy for future use for the newborn. These cells may also be used by the mother or father, and therefore can be very useful if the family has planned ahead. In comparison with adult cells and embryonic cells, the umbilical cord produces by far the richest source of stem cells, and they can be stored so that they are available in the future. Umbilical cord blood stem cell transplants are less prone to rejection than both bone marrow and peripheral blood stem cells because the cord cells have not yet developed the features that can be recognized and attacked by the recipient’s immune system (American Cancer Society). Scientists have also developed methods to increase the transferability and reduce the risk of providing the cells to a recipient who does not have an exact DNA match with the donor. Another benefit of the lack of developed immune cells contained in the umbilical cord blood reduces the risk that the transplanted cells will attack the recipient’s body (Genetic Science Learning Center). For all of these reasons, umbilical cord blood stem cells are a very potent resource for transplant therapies.
The last type of stem cells are the embryonic stem cells, which are extracted from a four or five day-old human embryo in the blastocyst phase of development. These embryos usually are extras from in vitro fertilization clinics where only one is actually implanted into the female. After the male’s sperm fertilizes a female’s egg to form the single zygote cell, a series of divisions occur. Before these cells are implanted in the uterus this bunch of cells is called the blastocyst. This mass consists of an inner cell mass and an outer cell mass. The outer cell mass will become a part of the placenta; whereas the inner cell mass will continue to differentiate to become the different structures of the adult organism. It is these inner cell masses, called totipotent cells, which are the source of embryonic stem cells because they are able to develop into any cell in the body. In the normal pregnancy the blastocyst stage continues and eventually implants the embryo in the uterus, which therefore becomes a fetus (See figure 1). When extracting embryonic stem cells, the blastocyst stage signals when to isolate the stem cells by placing the inner cell mass portion of the blastocyst into a culture dish. This controlled culture prohibits them from further differentiating but allows them to divide and replicate, continuing to double in number every two to three days (“Pros and Cons…”). Eventually these undifferentiated cells can be stimulated to create specialized cells.
Where It All Began:
Stem cell research began with the study of teratocarcinomas, which were first worked on with the mouse, by Leroy Stevens. These are complex tumors that contain a mix of differentiated cell types and undifferentiated cells termed embryonic carcinoma cells. These were shown to give rise to cell types in the ectoderm, mesoderm, and endoderm embryonic germ layers. For this reason, we can say that since the 1970’s, when these studies were going on, the idea that pluripotent EC cells could provide a source of therapy was existent. Two biologists, Martin Evans and Matt Kaufman, decided to put blastocysts that had been kept in delayed implantation, into specific culture conditions (Lovell-Badge). The study was successful in proving that EC cells truly had many different options for healing, and led the way to where we are now with stem cell research.
Benefits of Stem Cell Research:
Stem cell research provides enormous potential in health and medicine. In order to fully comprehend this potential, scientists continue to study how stem cells differentiate into specialized cells to from humans. This understanding is so crucial because many diseases such as cancer or birth defects are thought to occur because of problems that happen in the differentiation process. Therefore, having an understanding of these developmental issues can help us understand how to treat them. Although this is an important element of the benefits of stem cell research, far and above this is the use of stem cells for cell-based therapies. For example, stem cells have allowed for the substitution of damaged organs and tissues for donated ones. Stem cells offer a great source of replacement cells to treat diseases such as Parkinson’s, Huntington’s, Type One Diabetes, arthritis, burn victims, and cardiovascular diseases. By manipulating the stem cells to differentiate into specialized cell types, there is an exciting possibility for renewable sources of replacement cells for those people who suffer from these diseases (Genetic Science Learning Center). For example, brain cells that are destroyed in the condition known as Parkinson’s disease may be reversed by replacing these brain cells with new and healthy cells. There is even potential to address genetic defects by replacing these cells with functioning cells. Another amazing way that stem cells are being used to heal is with burn victims, where they are used to produce new and healthy tissues to heal their skin cells.
Stem cell research has created much debate, and there is a clear line between the people who are for the federal funding of this project and the people that strongly vote against it. In July of 2011, a lawsuit was brought against the grants from the National Institutes of Health and other similar agencies to aid stem cell research. The suit asserted that federal support for this research was violating a 1996 law that prohibited government spending when an embryo is damaged or destroyed. Judge Lamberth ruled against this claim, and for that reason the federal government can continue to finance research on embryonic stem cells. Supporters of embryonic stem cell research applauded this result. Alan I. Leshner, chief executive officer of the American Association for the Advancement of Science, said, “the scientific consensus is that embryonic stem cell research is an extremely promising approach to developing more effective diagnostics and treatments for devastating conditions such as diabetes, spinal-cord injuries, and Parkinson’s disease.” (Fischman) The supporters of this research focus on the benefits side of the debate, and say that the cure that stem cells are able to produce is truly amazing and that further funding is necessary to realize the full potential of stem cells in healing terrible diseases. On the other side of the debate are those that are pro-life. Steven H. Aden, senior counsel member for the Alliance Defense Fund, which was one of the groups supporting the suit, said, “Americans should not be forced to pay for experiments that destroy human life, have produced no real-world treatments, and violate federal law.” (Fischman) There are many people who are against stem cell research on the basis of several ethical issues.
The Ethical Debate:
Stem cell research has raised ethical, legal, religious, and policy questions. The most crucial of these arguments is with embryonic stem cells, and centers on the idea of what life is. Figure two represents the opinions of the public on stem cell research according to various categories, including religion, race, and sex. It turns out that the most important part of the debate is the personal ethical side to the argument, rather than any specific religious or gender-based ideals. David T. Scadden, MD, stated, “Some who oppose embryonic stem cell research have provided a list of 69 conditions putatively treated by adult stem cells. The implicit message is that adult stem cell therapies are sufficient and that scientists underemphasize the power of adult stem cells in order to justify embryonic stem cell research.” (Scadden) He argues that this is not true, and that embryonic stem cells have already shown signs of much potential, so the research should not be put on hold. In focusing on the ethical issues of extracting stem cells from human embryos, I will look at it in the context of utilitarianism and deontology.
To get at the root of the problem, however, is the definition of life. There are people who believe that the stem cell research is killing life, and as Daniel Eisenberg, M.D. explains on behalf of these believers, “A life-threatening situation for another adult would not justify our killing a fetus.” (Eisenberg) If we can say that at the stage of development the embryo is in when extracting the cells is not yet at the beginning of life, then clearly the number of people who can be saved outweighs the cost of such extraction. My argument is that individual human life does not exist at fertilization, as it can still go on to split into two separate individuals. Therefore, the blastocysts destroyed for embryonic stem cells do not have human life. Another one of the huge arguments is that in vitro fertilization generates large numbers of unused embryos, and using them for scientific research utilizes a resource that would otherwise be wasted. These arguments are crucial in understanding the ethical dilemma in general as well as through the eyes of philosophers Mill and Kant.
Mill’s utilitarian principle says that everything we do should be done in order to benefit the greatest number of people and provide the most happiness in the world. If we look at the ethical debate of stem cell research through the eyes of Mill, the question becomes: are we obligated to do what we can to aid the suffering of millions of people? This therefore makes us look at the issue to see if the social, economic, and personal costs of the diseases that embryonic stem cells have the potential to treat are greater than the costs associated with the destruction of embryos. The utilitarian would say that the benefits of stem cell research far outweigh the costs in terms of embryonic life. One of the main reasons is that the blastocysts that are used in the process are a cluster of human cells that have not differentiated into any distinct organ tissue, and therefore they are not actually humans. Also, utilitarianism asks us to set aside our personal interests for the sake of improving the world. Therefore, if we were true utilitarian’s, the debate about human life would not matter, since more lives are saved in the process. Plus, the utilitarian thinks in a consequentialist manner, in that the only thing that matters is what the end result is. “It [utilitarianism] tells us that an act’s rightness or wrongness is determined solely by the act’s consequences and not by any feature of the act itself.” (Snoeyenbos, 17) For that reason, ends justify the means. In this way, the fact that the research is saving many lives negates the fact that some possible “lives” may falter in the process, and this is a necessary means to some end. As stated before, a big part of this debate is the difference between using adult stem cells, which have a lot less of an ethical downfall, and ignoring embryonic stem cells. The problem with this, according to the utilitarian, would be that embryonic stem cells are actually more useful. One reason is because they divide more rapidly than adult stem cells, which makes them more readily available for treatment. Another issue is that more DNA abnormalities are found in adult stem cells. Lastly, an aspect of the debate that adds to the utilitarian viewpoint is that these embryonic cells are going to be destroyed anyways. For that reason, why not use them to create an overall better world?
If we take a look at this issue from a deontological perspective, the question becomes: is it right to use human embryos or do we have a duty to preserve life? We can look at Kant’s three main duties to analyze this dilemma. The first is to “Act only on maxims which you can will to be universal laws of nature.” (Bowie, 2) Therefore, we need to ask ourselves if the use of embryonic stem cells should become a universal law. Do we want it to be a universal law that embryos that will be destroyed should be used for the greater good instead? The maxim to use spare embryos for stem cell research could be universal, but the maxim to create embryos for stem cell research is not, because there would be no embryos left to develop into humans. Therefore, this duty may be unclear in the eyes of Kant. The second duty is “Always treat the humanity in a person as an end, and never as a means merely.” (Bowie, 2) Therefore, adhering to this imperative entails that human embryos should not be disaggregated to obtain stem cells for research. This, however, is only true if we characterize the embryo as a human. Kant did not use the term “humanity” to denote a biological species, but rather the capacity to set ends according to reason. Therefore, only those that are able to reason may be treated as humans. Kant also distinguished between the three types of beings: People (rational), people with partial rights, and things. If embryos are classified as things, then Kant may have justified embryonic research on the basis that they can be treated as a means to an end. The third is “act as if you were a member of an ideal kingdom of ends in which you were both subject and sovereign at the same time.” (Bowie, 2) This last idea lends itself to what we know as the Golden Rule, meaning that you should only treat others the way you would want to be treated. It is difficult to think about this in terms of stem cell research, because we would need to think about it as if we were an embryo, what would we want to happen to us? I do not think that embryos are capable of this type of mental dilemma until after the stage at which cells are extracted, so therefore I would say that this duty does not apply in this case. We could also look at this duty from the perspective of the woman whose embryos are in question and ask ourselves if we would want our own embryonic stem cells to be extracted. Knowing that the embryonic cells they would take are cells that would otherwise be destroyed, I would say that it is better to get use out of them than to toss them aside. This part of Kant’s formulation may be viewed differently from a man and a woman’s perspective, since it is the woman’s body that is in question. However, as I did research I found that support for this research was relatively equal across the board (See figure 3).
The debate on stem cell research is one that has characterized our generation. It can be described as a cost-benefit debate, in that we must weigh the costs of lost “life” to the benefits of renewed life and solutions to horrible diseases. This debate is an example of how people value things differently. After doing all of this research, I would have to say that I am pro stem cell research. The main critique to this is the question of what life is. Personally, I believe that life does not exist until later in the process of fertilization, after stem cells would have been extracted. The ethics behind stem cell research are important to analyze in order to foster communication and intelligence and to make continuous improvements in scientific research and in our lives.