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Politics & Government Regulations
Ethical considerations aside, the field of embryonic stem cell research is highly regulated, with numerous restrictions on the donation of embryonic materials, and these restrictions apply to all research, whether federally or privately funded. In other words, even privately funded research is subject to complex restrictions and "guidelines" (recently drafted by the President's Council on Bioethics), which are necessary in order to oversee the quality of the materials. A case in point is Proposition 71 in California, which allows for the privately funded California Institute of Regenerative Medicine, which was proposed in order to bypass the Presidential Executive Order, issued on August 9th, 2001, which banned federal funding for any embryonic stem cell lines established after that date. Even privately funded embryonic stem cell research conducted at this Institute, however, will still be very tightly regulated, and still subject to numerous restrictions. Such "red tape" does not apply to research conducted on adult stem cells, in which only informed consent of the participants is required.
Since none of the embryonic stem cell lines already in existence have any genetic diseases, it has been pointed out by Dr. Irving Weissman of Stanford University, among other researchers, that embryonic stem cell lines with genetic diseases should be established. This would allow the production of human pluripotent stem cell lines for the treatment of people with specific genetic diseases, but it would also require the transfer of genetic information from an adult stem cell into an unferlized egg in order to establish the genetic cell line. Among the risks involved in such procedures is the possibility of creating a (genetically diseased) blastocyst capable of producing gametes. Such controversial procedures shall be addressed in further detail in the section on "Therapeutic Cloning."
A blastocyst contains approximately 200 cells, and even for an expert in developmental biology it is difficult to distinguish a human blastocyst from that of any other species. In establishing a stem cell line from human embryonic stem cells, the culturing of the human embryo occurs for no longer than 14 days, at which point the "primitive streak" forms: this is the stage at which the embryo ceases to be an undifferentiated ball of cells but now has a front and a back, with an early formation of the nervous system and other physiological attributes characteristic of the human species.
In order to obtain the stem cells that are needed to establish an embryonic cell line, the developing embryo is then destroyed. For this reason, President George W. Bush banned the federal funding of research on embryonic and fetal stem cell lines established after August 9th, 2001, the date on which he announced his Presidential Executive Order. Prior to his administration, however, Congress had passed, and President Clinton had signed, legislation prohibiting the use of federal money for the destruction of embryos for research purposes. By the time President Bush inherited the dilemma, he responded by restricting federal funding for research to the limited set of stem cell lines that had already been established. Although more than sixty cell lines were listed as having already been in existence on this date, August 9th, 2001, many were later shown not to be viable, due to contamination or other problems. Today, only 17 of these cell lines are available for distribution.
The NIH Stem Cell Registry was then created to document existing cell lines and their availability, and to carry out initial tests to assess the quality of these lines.
Some organizations have pointed out the risk of cross transfer of animal viruses and other disease agents in these cell lines. As the London based Institute of Science in Society has written,
"All existing lines have been cultured on feeder layers of mouse cells, and are hence unsuitable for transplant, because it risks transferring mouse viruses and other disease agents to human patients and creating an epidemic." (From www.i-sis.org.uk).
In response to the scarce availability of human embryonic stem cell (hESC) lines, some researchers have begun to create their own hESC lines, even though research with such cells is barred from federal funding. A case in point is the Harvard biologist Doug Melton, who, in March of 2004, created 17 new hESC lines. Since researchers who wish to work with these particular cell lines are prohibited from using federal money to do so, the cell lines are available for privately funded research only. However, as researchers are discovering, private dollars are even more scarce than cell lines. Furthermore, as with the existing hESC lines, even these new hESCs are all still grown on mouse feeder cells, and therefore,
"their usefulness in clinical applications will be limited. There have been attempts to develop alternative feeder or feeder free culture systems, but these were not optimal for deriving and growing clinical grade hES cells, as they all use animal products of one kind or another, and carry the risk of cross transfer of animal viruses and other disease causing agents." (From www.i-sis.org.uk).
Regardless of their ultimate safety or viability, such cell lines have been characterized as "embryonic" by the detection of surface antigen markers specific to embryonic stem cells, and by determining if the cells are pluripotent, and by demonstrating that the cells are undifferentiated. In order to qualify for federal funding, all cells are required to have been removed from the embryo prior to August 9th, 2001, the date on which the President announced his policy. To ensure that all criteria are met, all stem cell lines are listed in NIH's Stem Cell Registry. Stem cells that are not listed in this registry have not met the criteria established by President Bush on August 9th, 2001, and therefore may not be supported by federal research funding.
Organizations currently addressing the ethical questions surrounding embryonic stem cells include:
- The President's Council on Bioethics
- The Kennedy Institute of Ethics at Georgetown University
- The American Association for the Advancement of Science & the Institute for
Civil Society, which together issued the publication, "Stem Cell Research & Applications; Monitoring the Frontiers of Biomedical Research"
- The International Society for Stem Cell Research, which issued the publication, "The Ethics of Human Embryonic Stem Cell Research"
- The European Union, which issued the publication entitled, "Report On Human Embryonic Stem Cell Research"
Ethically, morally, and politically, human embryonic stem cells are a charged and sensitive topic, not only in the U.S. but internationally as well. However, even disregarding the ethical dilemmas presented by embryonic stem cells, the scientific reasons alone are sufficient to classify such cells as undesirable. Due to the risk of teratoma (tumor) formation from such cells, both Germany and Norway have prohibited research on fertilized eggs, with Norway banning both the derivation of and the use of embryonic stem cell lines altogether.
It is not commonly known, but there have been no scientific studies which were able to successfully demonstrate any ability of embryonic stem cells to treat disease. In other words, there remains no concrete proof that embryonic stem cells are useful in treating disease, although this is not widely advertised. As we shall see in a forthcoming section, this lack of evidence is dramatically different from placental, umbilical cord and other types of adult stem cells, where there is ample scientific proof demonstrating the efficacy of such cells in treating a wide range of disease.
In response to the question, "Have human embryonic stem cells been used successfully to treat any human diseases yet?", the National Institutes of Health (NIH) has posted the following answer on their website:
"Scientists have only been able to do experiments with human embryonic stem cells (hESC), since 1998 when a group led by Dr. James Thomson at the University of Wisconsin developed a technique to isolate and grow the cells."
In other words, human embryonic stem cells have not yet actually been used to treat any human diseases. hESCs are still in the laboratory, experimental phase.
The NIH then points out:
"Adult stem cells such as blood-forming stem cells in bone marrow (called hematopoietic stem cells, or HSCs) are currently the only type of stem cell commonly used to treat human diseases. Doctors have been transferring HSCs in bone marrow transplants for over 40 years. More advanced techniques of collecting, or 'harvesting', HSCs are now used in order to treat leukemia, lymphoma and several inherited blood disorders. The clinical potential of adult stem cells has also been demonstrated in the treatment of other human diseases that include diabetes and advanced kidney cancer. However, these newer uses have involved studies with a very limited number of patients." (From http://stemcells.nih.gov).
The NIH continues:
"Pluripotent stem cells offer the greatest therapeutic potential, yet formidable technical challenges still need to be overcome. First of all, scientists must learn how to control their development into all the different types of cells in the body. Second, the cells now available for research are likely to be rejected by a patient's immune system. Another serious consideration is that the idea of using stem cells from human embryos or human fetal tissue troubles many people on ethical grounds."
As previously mentioned, adult stem cells, typically considered to be multipotent or monopotent rather than pluripotent, have been thought to offer less flexibility. Now, however, it has been repeatedly shown that some adult stem cells exhibit strong pluripotency, yet as recently as 2001 even the NIH subscribed to this previous, now outdated view:
"Adult stem cells that could give rise to all cell and tissue types have not yet been found. Adult stem cells are often present in only minute quantities and can therefore be difficult to isolate and purify. There is also evidence that they may not have the same capacity to multiply as embryonic stem cells do. Finally, adult stem cells may contain more DNA abnormalities - caused, for example, by sunlight, toxins, and errors in making more DNA copies during the course of a lifetime." (From http://stemcells.nih.gov).
The NIH has not yet issued an updated publication on stem cells, incorporating recent discoveries. Nevertheless, in describing the overall importance of stem cell research, the NIH adds:
"The development of stem cell lines that can produce many tissues of the human body is an important scientific breakthrough. This research has the potential to revolutionize the practice of medicine and improve the quality and length of life."
They continue, however,
"Human embryonic stem cells are thought to have much greater developmental potential than adult stem cells."
More specifically, the key concept is that pluripotent stem cells have much greater developmental potential than do multipotent or monopotent stem cells. To reiterate, the important question is not so much a matter of embryonic versus adult stem cells, but rather, it is a matter of pluripotent versus multipotent and monopotent stem cells.
The policies of other countries regarding stem cell and cloning (please see the section on "therapeutic cloning") research include:
- In the United Kingdom: Research on embryos is allowed up to 14 days after conception, using embryos that were created for reproduction or solely for research purposes. Therapeutic cloning has been approved, although it is currently on hold under judicial review. The first human embryonic stem cell bank in the UK opened in May of 2004, by which time the House of Lords had recommended human embryonic stem cell research exclusively for the treatment of patients with organ failure. New evidence was then introduced in which adult stem cells are shown to exhibit as much transdifferentiation capability and flexibility as do embryonic stem cells. The debate is still ongoing.
- In France, Australia, and Canada, debates are also ongoing. The use of human embryonic stem cells has been permitted, along with the derivation of stem cells from embryos which are no longer needed by their genetic parents for reproduction. However, the creation of new embryos purely for research is not allowed. A ban on cloning has been proposed in France and Canada, and the proposal has been passed in Australia.
- In Germany, the derivation of human embryonic stem cells for research is banned, although the importation of such cells is allowed, within limits. There is also a ban on cloning.
Other countries, as well as the European Union and the United Nations, are still debating both the scientific and the ethical issues of stem cell research and cloning.
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