bioethical concerns regarding the use of human stem cells involve their source and their research implications. Ethical issues surrounding the source of human embryonic stem cells used in research has historically evoked the most intense debates and other ethical issues have surfaced concerning the origin of other human embryonic stem cell -- like cells that have the capability to differentiate into all different types of human tissue.
From the time human embryonic stem cells were first isolated and cultured in 1998 human embryonic stem cell research has been generated vast controversy (Cohen, 2007). Much of the controversy is related to the historical public suspicion concerning the potential negative impact of scientific progress and research centered around genetic cloning. Human embryonic stem cell research has become equated with fears about human cloning, the modification of human biological material, and myths of regenerative immortality in wealthy people. All of these vague fears have been projected onto a new, relatively embryonic, scientific field of stem cell research. However, given this, much of the earlier discussion has been centered on the debate over embryo collection and the destruction of embryos. Nisbet (2004) found that many objected to the fact that five-day-old pre-implantation embryos are destroyed when harvesting their stem cells. Many people opposing human embryonic stem cell research believe that all pre-implantation embryos should be morally defined as living persons whether they are developed in a Petri dish or in the womb, thus equating the research with mass murder despite the aims and potential good the research may bring. However, according to Buddhist, Hindu, Islamic, as well as many Western Christian views, the moral standing or definition of what constitutes a human being occurs much later in development, with some religious views maintaining that a "person" is defined as such when they reach viability outside of the womb (Cohen, 2007).
Further opposition to human embryonic stem cell research maintained that all pre-implantation embryos will potentially become human beings, thus it is always morally wrong to destroy this embryos with this potential. However, supporters of stem cell research question the notion that all potential human life should be realized (e.g., there should be no acceptable birth control methods then). Moreover, it is simply false to believe that all early-stage embryos express the potential for a complete human life because many of these fertility clinic embryos are of very poor quality and are not capable of producing a pregnancy (Cohen, 2007).
One thing that stem cell research critics often overlook is that the term "potentiality" does not guarantee anything. It is estimated that 75% -- 80% of all embryos created via sexual intercourse fail to implant and are lost most often as a result of genetic abnormalities (Cohen, 2007). With respect to embryos eligible for human embryonic stem cell research, most do not have a good potential for full human development since the choice not implant these in a woman's uterus (Hyun & Jung, 2006).
However, we should acknowledge that a pluralistic society like the United States will have to tolerate differences in religious or and personal opinions regarding theoretical matters like this. Therefore, it becomes a legislative issue in much the same manner that homosexual marriage has become. For example, the Bush administration followed a protectionist position by putting in place legislature that restricted federal funding for stem cell research to only cell lines that were already in existence on August 9, 2001, even though many claimed that these cell lines on the federal registry were inadequate to support the full range of stem cell research because they lacked genetic diversity, had been grown on mouse feeder layers that increase the possibility of them becoming contaminated with animal viruses, and were accumulating genetic mutations. In 2005 the President's Council on Bioethics recommended that alternative sources of pluripotent stem cells be pursued that do not involve harm or the destruction of embryos (see The President's Council on Bioethics, 2005). There were four suggested approaches mentioned in this report to deal with the issue such as getting stem cells from deceased embryos, obtaining cells from embryos by a nondestructive biopsy, obtaining cells from bioengineered embryo-like relics, and obtaining cells from dedifferentiated somatic cells. There were subsequently two studies that followed two of those suggested alternatives one using live embryo biopsies and one using bioengineered embryo-like artifacts (Chung et al., 2006; Meissner & Jaenisch, 2006). However, there were practical as well as legal challenges facing both of these methods. Both methods require human embryo use in the research either by involving live human embryo biopsy or the creation of special human embryos. As a result such studies could not be funded by the National Institute of Health (NIH) under the Dickey-Wicker Amendment that prohibited federal funding for any research that directly involves harm to human embryos. Thus, for the remainder of the Bush administration states and private organizations had to fund such research.
After the Busch administration the stance of president Obama's administration was more friendly toward human embryonic stem cells cell research and the main ethical considerations are more of how do conduct this research as opposed to whether it should be undertaken at all. In addition a big breakthrough in methodology, the introduction of human induced pluripotent stem (iPS) cells in 2006, which are dermal fibroblasts that are genetically engineered to behave like human embryonic stem cells, was a big step in the research (Takahashi & Yamanaka, 2006). However, there have been questions as to whether the development of iPS cells (as well as others alternative sources of stem cells) can put an end to the need for ongoing human embryonic stem cell research. For instance, actual human embryonic stem cells must be used as controls to determine the behavior and utility of iPS cells or other similar alternatives. So human embryonic stem cells are still needed. In addition, iPS cells might not answer important questions about human development, so again human embryonic stem cells would be needed to answer such questions. Moreover, the process of generating iPS cells might lead to damaging mutations in the resulting cells later which can be a problem.
While iPS cells do not require human embryos for their development their use raises other ethical concerns. Since iPS cells are developed from living donors, certain other ethical concerns arise such as the tracking of the donors, what should be done with findings that may influence a cell donor's health, and the determination of donors' rights to the research uses and financial returns of their genetically matched iPS cell lines (Wolf, 2008). As is often the case new research and new techniques simply result in the exchange of one set of ethical issues for a completely new set of ethical concerns. While few disease specific stem cell lines have been developed from the new technology, iPS cells still represent promise.
A possible way of developing disease-specific lines stem cells is by means of research cloning that allows for the production of human embryonic stem cells that are genetically matched to a specific the patient and their disease (somatic cell nuclear transfer, SCNT). So far this technique has been successful in the laboratory with primates and holds promise (Byrne et al., 2007). But NIH funds cannot be used for research that use embryos created specifically for research purposes and women have been not been willing to donate their eggs for SCNT research without receiving any compensation for their efforts. Getting financial compensation for egg donations for research is against the law in some states and frowned upon by the National Academy of Sciences' Guidelines for human embryonic stem cell research (National Research council, 2005). Still, some headway has been made as states like New York have recently allowed donor compensation for providing eggs for research. There is also a fairly recently organized oversight body that watches over new stem cell research. All privately and publicly funded stem cell researchers are encouraged or required to get their research proposals approved by a Stem Cell Research Oversight (SCRO) committee which is composed scientists, physicians, ethicists, and legal experts. These committees also contact local ethics review boards to make sure that donors are treated fairly and of course that informed consent achieved. This is especially important for somatic cell donors since the individuals represent a living genetic source of the resulting genetically matched stem cell lines. It is also essential for patient donors who donate cells for disease-specific studies as they might harbor the false expectation that they will benefit directly from future medical applications of their donations.
Until 2008 there were no guidelines for researchers who wanted to translate stem cell research into clinical applications, but the International Society for Stem Cell Research released a set of international guidelines for such a move (ISSCR, 2008). Moving from the research laboratory to the clinic will involve many complex steps, many of which are quite scientifically technical and many of which will fuel even more ethical debates and most likely resurrect old ones.