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Stem cell controversy



Stem cell controversy is the ethical debate centered around research involving the creation, usage and destruction of human embryonic stem cells. Some opponents of the research argue that this practice is a slippery slope to reproductive cloning and fundamentally devalues the worth of a human being. Contrarily, medical researchers in the field argue that it is necessary to pursue embryonic stem cell research because the resultant technologies could have significant medical potential, and that excess embryos created for in vitro fertilisation could be donated with consent and used for the research. This in turn, conflicts with opponents in the pro-life movement, who advocate for the protection of human embryos. The ensuing debate has prompted authorities around the world to seek regulatory frameworks and highlighted the fact that embryonic stem cell research represents a social and ethical challenge.

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Contents

Stem cells

Main article: Stem cell

Stem cells are cells that are able to differentiate into specialized cell types but also retain the ability to renew themselves through cell division. They were first identified in embryos. In an embryonic blastocyst, stem cells of the inner cell mass proceed to develop into all of the tissues and organs of the body. In adults, progenitor cells and possibly multipotent adult stem cells act as a repair system for the body, replenishing more specialized cells. The existence of truly pluripotent stem cells in adult human beings is still scientifically controversial.

Therapies

Main article: Stem cell treatments

Since stems cells have the potential to be differentiated into basically all cell types, they offer promise in the development of medical treatments for a wide range of conditions. These include damage to the brain, spinal cord, skeletal muscles, and the heart. Treatments that have been proposed follow either physical trauma (e.g. spinal cord injuries), degenerative conditions (e.g. Parkinson's disease), or even genetic diseases (in combination with gene therapy).

Much success and potential has been demonstrated from research using adult stem cells. There are no approved treatments or human trials using embryonic stem cells. Nevertheless, some are of the opinion that the differentiation potential of embryonic stem cells is broader than most adult stem cells. In addition, embryonic stem cells are considered more useful for nervous system therapies, as researchers have struggled to identify and isolate neural progenitors from adult tissues. Embryonic stem cells, however, might be rejected by the immune system - a problem which wouldn't occur if the patient received his or her own stem cells.

Alternative sources

Some stem cell researchers are working to develop techniques of isolating stem cells that are as potent as embryonic stem cells, but do not require a human embryo.

Some believe that human somatic cells can be coaxed to "de-differentiate" and revert to an embryonic state. Researchers at Harvard University, led by Kevin Eggan, have attempted to transfer the nucleus of a somatic cell into an existing embryonic stem cell, thus creating a new stem cell line.[1] Another study published in August 2006 also indicates that differentiated cells can be reprogrammed to an embryonic-like state by introducing four specific factors.[2]

Researchers at Advanced Cell Technology, led by Robert Lanza, reported the successful derivation of a stem cell line using a process similar to preimplantation genetic diagnosis, in which a single blastomere is extracted from a blastocyst.[3] At the 2007 meeting of the International Society for Stem Cell Research (ISSCR) [4], Lanza announced that his team had succeeded in producing three new stem cell lines without destroying the parent embryos. "These are the first human embryonic cell lines in existence that didn't result from the destruction of an embryo." Lanza is currently in discussions with the National Institutes of Health (NIH) to determine whether the new technique sidesteps U.S. restrictions on federal funding for ES cell research.[5]

According to a January 9, 2007 Daily Telegraph (London) article reporting on a statement by Dr. Anthony Atala of Wake Forest University, there is another "ethical" source of stem cells. The fluid surrounding the fetus has been found to contain stem cells, that, when utilized correctly, "can be differentiated towards cell types such as fat, bone, muscle, blood vessel, nerve and liver cells", according to the article. The extraction of this fluid does not harm the fetus in any way as well. "Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well," said Dr Atala.[6]

Patents

The patents covering a lot of work on human embryonic stem cells are owned by the Wisconsin Alumni Research Foundation (WARF). WARF does not charge academics to study human stem cells but does charge commercial users. WARF sold Geron Corp. exclusive rights to work on human stem cells but later sued Geron Corp. to recover some of the previously sold rights. The two sides agreed that Geron Corp. would keep the rights to only three cell types. In 2001 WARF came under public pressure to widen access to human stem-cell technology.[7]

These patents are now in doubt as a request for review by the US Patent and Trademark Office has been filed by non-profit patent-watchdogs The Foundation for Taxpayer & Consumer Rights and the Public Patent Foundation as well as molecular biologist Jeanne Loring of the Burnham Institute. According to them, two of the patents granted to WARF are invalid because they cover a technique published in 1992 for which a patent had already been granted to an Australian researcher. Another part of the challenge states that these techniques, developed by James A. Thomson, are rendered obvious by a 1990 paper and two textbooks.

The outcome of this legal challenge is particularly relevant to the Geron Corp. as it can only license patents that are upheld.[8][9]

Viewpoints

The status of the human embryo and human embryonic stem cell research is a controversial issue as, with the present state of technology, the creation of a human embryonic stem cell line requires the destruction of a human embryo. Stem cell debates have motivated and reinvigorated the pro-life movement, whose members are concerned with the rights and status of the embryo as an early-aged human life. They believe that embryonic stem cell research instrumentalizes and violates the sanctity of life and constitutes murder.[10] The fundamental assertion of those who oppose embryonic stem cell research is the belief that human life is inviolable, combined with the opinion that human life begins when a sperm cell fertilizes an egg cell to form a single cell.

A portion of stem cell researchers use embryos that were created but not used in in vitro fertility treatments to derive new stem cell lines. Most of these embryos are to be destroyed, or stored for long periods of time, long past their viable storage life. In the United States alone, there have been estimates of at least 400,000 such embryos.[11] This has led some opponents of abortion, such as Senator Orrin Hatch, to support human embryonic stem cell research.[12]

Medical researchers widely submit that stem cell research has the potential to dramatically alter approaches to understanding and treating diseases, and to alleviate suffering. In the future, most medical researchers anticipate being able to use technologies derived from stem cell research to treat a variety of diseases and impairments. Spinal cord injuries and Parkinson's disease are two examples that have been championed by high-profile media personalities (for instance, Christopher Reeve and Michael J. Fox). The anticipated medical benefits of stem cell research add urgency to the debates, which has been appealed to by proponents of embryonic stem cell research.

Recently, researchers at Advanced Cell Technology of Worcester, Mass., succeeded in obtaining stem cells from mouse embryos without killing the embryos.[13] If this technique and its reliability are improved, it would alleviate some of the ethical problems related to embryonic stem cell research.

Another technique announced in 2007 may also defuse the longstanding debate and controversy. Research teams in the United States and Japan have developed a simple and cost effective method of reprogramming human skin cells to function much like embryonic stem cells by introducing artificial viruses. While extracting and cloning stem cells is complex and extremely expensive, the newly discovered method of reprogramming cells is much cheaper. However, the technique may disrupt the DNA in the new stem cells, resulting in damaged and cancerous tissue. More research will be required before non-cancerous stem cells can be created.[14][15][16][17]

Endorsement

Utilitarianism

The benefits of stem cell research outweigh the cost in terms of embryonic "life"

  • Embryonic stem cells have the capacity to grow indefinitely in a laboratory environment and can differentiate into almost all types of bodily tissue. This makes embryonic stem cells an attractive prospect for cellular therapies to treat a wide range of diseases.[18]
  • The social, economic and personal costs of the diseases that embryonic stem cells have the potential to treat are far greater than the costs associated with the destruction of embryos.

Human potential and humanity

The value of an embryo should not be placed on par with the value of a child or adult

This argument often goes hand-in-hand with the utilitarian argument, and can be presented in several forms:

  • Embryos, while of value, are not equivalent to human life while they are still incapable of existing outside the womb (i.e. they only have the potential for life).
  • Approximately 18% of zygotes do not implant after conception. Thus far more embryos are lost due to chance than are proposed to be used for embryonic stem cell research or treatments.
  • Blastocysts are a cluster of human cells that have not differentiated into distinct organ tissue; making cells of the inner cell mass no more "human" than a skin cell .[18]
  • Some parties contend that embryos are not humans, believing that the life of Homo sapiens only begins when the heartbeat develops, which is during the 5th week of pregnancy,[19] or when the brain begins developing activity, which has been detected at 54 days after conception.[20]

Consequentialism

The ends (i.e. new treatments and cures) justify the means (i.e. the destruction of embryos)

This can be seen as a more extreme view of the utilitarianism argument.

Efficiency

If an embryo is going to be destroyed anyway, isn't it more efficient to make practical use of it?

  • In vitro fertilization (IVF) generates large numbers of unused embryos (e.g. 70,000 in Australia alone).[18] Many of these thousands of IVF embryos are slated for destruction. Using them for scientific research utilizes a resource that would otherwise be wasted.[18]
  • While the destruction of human embryos is required to establish a stem cell line, no new embryos have to be destroyed to work with existing stem cell lines. It would be wasteful not to continue to make use of these cell lines as a resource.[18]
  • Abortions are legal in many countries and jurisdictions. A logical argument follows that if these embryos are being destroyed anyway, why not use them for stem cell research or treatments?

Superiority

Embryonic stem cells can be considered far more useful therapeutically than adult stem cells

This is usually presented as a counter-argument to using adult stem cells as an alternative that doesn't involve embryonic destruction.

  • Embryonic stem cells make up a significant proportion of a developing embryo, while adult stem cells exist as minor populations within a mature individual (e.g. in every 10,000 cells of the bone marrow, only 10 will be usable stem cells). Thus, embryonic stem cells are likely to be easier to isolate and grow ex vivo than adult stem cells.[18]
  • Embryonic stem cells divide more rapidly than adult stem cells, potentially making it easier to generate large numbers of cells for therapeutic means. In contrast, adult stem cell might not divide fast enough to offer immediate treatment.[18]
  • Embryonic stem cells have greater plasticity, allowing them to treat a wider range of diseases.[18]
  • Adult stem cells from the patient's own body might not be effective in treatment of genetic disorders. Allogeneic embryonic stem cell transplantation (i.e. from a healthy donor) may be more practical in these cases than gene therapy of a patient's own cell.[18]
  • DNA abnormalities found in adult stem cells that are caused by toxins and sunlight may make them poorly suited for treatment.[18]
  • Embryonic stem cells have been shown to be effective in treating heart damage in mice.[18]

Beginning of life

  • Clones can be produced without fertilization taking place, and the clones are alive.
  • Before the primitive streak is formed when the embryo attaches to the uterus at approximately 14 days after fertilization, a single fertilized egg can split in two to form identical twins. Also, rarely, two separately fertilized eggs can, instead of resulting in fraternal twins, fuse together and develop into a single human individual (a tetragametic chimera).[21]
  • Therefore before the primitive streak is formed, an individual human life does not exist at fertilization, as it can go on to split into two separate individuals. Therefore, an individual human life begins when the primitive streak is formed — beyond which the cell group cannot split to make twins — and not before. Therefore the blastocysts destroyed for embryonic stem cells do not have human life, and it is ethical to use them. [21]

Objection

Value of life

An embryo is actually a human; it should be valued as highly as a human life.

The reasoning can be summed up by the fact that, once an egg is fertilized, unless inhibited, it will develop into a fully-developed adult. This opinion is often related to religious doctrines which assert that conception marks the beginning of human life or the presence of a soul. Based upon this reasoning, the subsequent argument against embryonic stem cell research is that human life is inherently valuable and cannot be involuntarily destroyed to save another life.

As an extension of this, it is argued that the tendency by some supporters of embryonic stem cell researchers to dismiss the ethical significance of embryo destruction may act to devalue human life.[citation needed] Moreover, it has been argued that "the line at which an embryo becomes a human life remains as arbitrary as ever".[22]

Viability is another standard under which embryos and fetuses have been regarded as human lives. In the United States, the 1973 Supreme Court case of Roe v. Wade concluded that viability determined the permissibility of abortions performed for reasons other than the protection of the woman's health, defining viability as the point at which a fetus is "potentially able to live outside the mother's womb, albeit with artificial aid."[23] The point of viability was 24 to 28 weeks when the case was decided and has since moved to about 22 weeks due to advancement in medical technology. If further technological advances allow a sperm and egg to be combined and fully developed completely outside of the womb, an embryo will be viable as soon as it is conceived, and under the viability standard, life will begin at conception.

Better alternatives

Embryonic stem cells should be abandoned in favor of alternatives, such as those involving adult stem cells.

This argument is used by opponents of embryonic destruction as well as researchers specializing in adult stem cell research.

It is often claimed by pro-life supporters that the use of adult stem cells from sources such as umbilical cord blood has consistently produced more promising results than the use of embryonic stem cells.[24] Furthermore, adult stem cell research may be able to make greater advances if less money and resources were channeled into embryonic stem cell research.[25]

Adult stem cells have already produced therapies, while embryonic stem cells have not.[26][27] Moreover, there have been many advances in adult stem cell research, including a recent study where pluripotent adult stem cells were manufactured from differentiated fibroblast by the addition of specific transcription factors. [28] Newly created stem cells were developed into an embryo and were integrated into newborn mouse tissues, analogous to the properties of embryonic stem cells.

This argument remains hotly debated on both sides. Those critical of embryonic stem cell research point to a current lack of practical treatments, while supporters argue that advances will come with more time and that breakthroughs cannot be predicted.

Scientific flaws

The use of embryonic stem cell in therapies may be fundamentally flawed.

For instance, one study suggests that autologous embryonic stem cells generated for therapeutic cloning may still suffer from immune rejection.[29] The researchers note that: "Our results raise the provocative possibility that even genetically matched cells derived by therapeutic cloning may still face barriers to effective transplantation for some disorders." In other words, therapeutic cloning may not always produce matched tissues. In contrast, there are reports of adult stem cells being successfully reintegrated into an autogenic animal.

Another concern with embryonic stem cell treatments is a tendency of stem cells from embryos to create tumors. [26][30] However, the tumorigenic potential of embryonic stem cells remains poorly described.

Overstatement of research potential

Scientists have long promised spectacular results from embryonic stem cell research, and this has not yet occurred[22][31][32]

Conspicuously, such criticism has even come from researchers themselves. For example, in November 2004, Princeton University president and geneticist Shirley Tilghman said, "Some of the public pronouncements in the field of stem-cell research come close to overpromising at best and delusional fantasizing at worst."[33] Similarly, fertility expert and former president of the British Association for the Advancement of Science, Lord Winston has warned of a public backlash against stem cell research if it fails to deliver on some of the "hype" surrounding potential treatments.[34]

Policy debate in the United States

Origins

In 1969, the first human in vitro fertilization was accomplished and in 1973, Roe v. Wade legalized abortion nationwide. These developments prompted the federal government to create regulations barring the use of federal funds for research that experimented on human embryos. In 1995, the NIH Human Embryo Research Panel advised the Clinton administration to permit federal funding for research on embryos left over from in vitro fertility treatments and also recommended federal funding of research on embryos specifically created for experimentation. In response to the panel's recommendations, the Clinton administration, citing moral and ethical concerns, declined to fund research on embryos created solely for research purposes,[35] but did agree to fund research on left-over embryos created by in vitro fertility treatments. At this point, the Congress intervened and passed the Dickey Amendment in 1995 (the final bill, which included the Dickey Amendment, was signed into law by Clinton) which prohibited all federal funding for research that resulted in the destruction of an embryo regardless of the source of that embryo. The Dickey Amendment remains the law to this day.

In 1998, privately funded research led to the breakthrough discovery of hESC (Human Embryonic Stem Cells). This prompted the Clinton Administration to re-examine guidelines for federal funding of embryonic research. In 1999, the president's National Bioethics Advisory Commission recommended that hESC harvested from embryos discarded after in vitro fertility treatments, but not from embryos created expressly for experimentation, be eligible for federal funding [1]. Even though embryos are always destroyed in the process of harvesting hESC, the Clinton Administration decided that it would be permissible under the Dickey Amendment to fund hESC research as long as such research did not itself directly cause the destruction of an embryo. Therefore, HHS issued its proposed regulation concerning hESC funding in 2001. Enactment of the new guidelines was delayed by the incoming Bush administration which decided to reconsider the issue.

President Bush announced, on August 9, 2001 that federal funds, for the first time, would be made available for hESC research on currently existing stem cell lines; however, the Bush Administration chose not to permit taxpayer funding for research on hESC cell lines not currently in existence, thus limiting federal funding to research in which "the life-and-death decision has already been made".[36] The Bush Administration's guidelines differ from the Clinton Administration guidelines which did not distinguish between currently existing and not-yet-existing hESC. Both the Bush and Clinton guidelines agree that the federal government should not fund hESC research that directly destroys embryos.

Neither Congress nor any administration has ever prohibited private funding of embryonic research. Also, public and private funding of research on adult and cord blood stem cells is unrestricted[citation needed].

Congressional response

In April 2004, 206 members of Congress signed a letter urging President Bush to expand federal funding of embryonic stem cell research beyond what Bush had already supported.

In May 2005, the House of Representatives voted 238-194 to loosen the limitations on federally funded embryonic stem-cell research — by allowing government-funded research on surplus frozen embryos from in vitro fertilization clinics to be used for stem cell research with the permission of donors — despite Bush's promise to veto the bill if passed. [2] On July 29, 2005, Senate Majority Leader William H. Frist (R-TN), announced that he too favored loosening restrictions on federal funding of embryonic stem cell research.[37] On July 18, 2006, the Senate passed three different bills concerning stem cell research. The Senate passed the first bill (Stem Cell Research Enhancement Act), 63-37, which would have made it legal for the Federal government to spend Federal money on embryonic stem cell research that uses embryos left over from in vitro fertilization procedures.[38] On July 19, 2006 President Bush vetoed this bill. The second bill makes it illegal to create, grow, and abort fetuses for research purposes. The third bill would encourage research that would isolate pluripotent, i.e., embryonic-like, stem cells without the destruction of human embryos. Stem Cell Research Currently, the National Institutes of Health has 399 funding opportunities for researchers interested in hESC [3]. In 2005 the NIH funded $607 million worth of stem cell research, of which $39 million was specifically used for hESC [4]. Of the 514 currently recruiting clinical trials that are using stem cells as treatment, the federal government is supporting 206 of them; however, none of these trials are using hESC [5].

Bush vetoed another bill, the Stem Cell Research Enhancement Act of 2007 (S. 5), that would have amended the Public Health Service Act to provide for human embryonic stem cell research. The bill passed the Senate on April 11 by a vote of 63-34, then passed the House on June 7 by a vote of 247-176. President Bush vetoed the bill on June 19, 2007.[39]

See also

References

  1. ^ C.Cowan, J. Atienza, D. Melton and K. Eggan. (August 26, 2005) "Nuclear reprogramming of somatic cells after fusion with human embryonic stem cells." Science, 309:1369.
  2. ^ Takahashi K and Yamanaka S. "Induction of Pluripotent Stem Cells from Mouse Embryonic and Adult Fibroblast Cultures by Defined Factors". Cell 126: 663-676.
  3. ^ Irina Klimanskaya, Young Chung, Sandy Becker, Shi-Jiang Lu & Robert Lanza. (August 23, 2006) "Human embryonic stem cell lines derived from single blastomeres." Nature. doi:10.1038.
  4. ^ http://abcnews.go.com/Health/wireStory?id=3307505
  5. ^ http://sciencenow.sciencemag.org/cgi/content/full/2007/619/3/
  6. ^ Clout, Laura; and Agencies. ""Scientists report alternative stem cell source"", Daily Telegraph (UK), 2007-09-01. Retrieved on 2007-20-09. 
  7. ^ Regalado, Antonio, David P. Hamilton (July 2006). "How a University's Patents May Limit Stem-Cell Researcher." Wall Street Journal. Retrieved on July 24, 2006.
  8. ^ Kintisch, Eli (July 18, 2006) "Groups Target Stem Cell Patents." ScienceNOW Daily News. Retrieved August 15, 2006.
  9. ^ Associated Press. (July 19, 2006) "Stem Cell Patents Come Under Fire." Retrieved August 15, 2006.
  10. ^ "The stated reason for President Bush's objection to embryonic stem cell research is that 'murder is wrong'" (BBC)
  11. ^ Weiss, Rick. (May 8, 2003) "400,000 Human Embryos Frozen in U.S.," Washington Post. Retrieved August 24, 2006.
  12. ^ Connolly, Ceci. (July 30, 2005) "Frist Breaks With Bush On Stem Cell Research." Washington Post. Retrieved August 24, 2006.
  13. ^ Deriving Stem Cells Without Killing Embryo. Medical News Today (2006). Retrieved on 2007-12-26.
  14. ^ New stem cell breakthrough. inthenews.co.uk (2007). Retrieved on 2007-12-26.
  15. ^ Biologists Make Skin Cells Work Like Stem Cells. The New York Times (2007). Retrieved on 2007-12-26.
  16. ^ Scientists Use Skin To Create Stem Cells. The Washington Post (2007). Retrieved on 2007-12-26.
  17. ^ Scientists Convert Mouse Skin Cells to Stem Cells. Public Broadcasting Service (2007). Retrieved on 2007-12-26.
  18. ^ a b c d e f g h i j k Arguments For Stem cell Research. Spinneypress (2006). Retrieved on 2007-12-26.
  19. ^ Greenfield, Marjorie. “Dr. Spock.com". Retrieved 2007-01-20.
  20. ^ Singer, Peter. Rethinking life & death: the collapse of our traditional ethics, page 104 (St. Martins Press 1996). Retrieved 2007-03-04.
  21. ^ a b West, Michael D.(2005) The Ethics of Genetic Engineering (At Issue Series). (pp 100-107) USA: Thomson Gale
  22. ^ a b Parry, S. (August 2003). "The politics of cloning: mapping the rhetorical convergence of embryos and stem cells in parliamentary debates." New Genetics and Society. pp. 145-168. Retrieved on August 7, 2006.
  23. ^ Roe v. Wade, 410 U.S. 113 (1973). Findlaw.com. Retrieved 2007-05-15
  24. ^ Prentice, David. (October 17, 2005) "Live Patients & Dead Mice". Christianity Today. Retrieved on August 24, 2006.
  25. ^ The Coalition of Americans for Research Ethics. "The "Political Science" of Stem Cells". Retrieved on July 16, 2006.
  26. ^ a b Clarke, Michael F. and Michael W. Becker. (July 2006). "Stem Cells: The Real Culprits in Cancer?" Scientific American. Retrieved on August 8, 2006.
  27. ^ Anonymous (September 24, 2006) "Cloning/Embryonic Stem Cells." National Human Genome Research Institute. Retrieved September 24, 2006.
  28. ^ Cyranoski. "Simple switch turns cells embryonic". Nature 6 June 2007.
  29. ^ Americans for Banning Cloning.(2002) [http://cloninginformation.org/info/unsuccessful_mouse_therapy.htm "Why the "Successful" Mouse "Therapeutic" Cloning Really Didn't Work "] Stem Cell Research. Retrieved April 13, 2007.
  30. ^ Dolan, Kerry. (July 21, 2006) "Despite Bush Veto, Stem Cell Research Abounds." Forbes. retrieved July 21, 2006.
  31. ^ Nerensini, F. (2000) "And Man Descended from the Sheep: The Public Debate on Cloning in the Italian Press." Public Understanding of Science, vol. 9, pp.359-382.
  32. ^ Nisbet, M.C., Brossard, D. & Kroepsch, A. (2003) "Framing Science: The Stem Cell Controversy in an Age of Press/Politics." The Harvard International Journal of Press/Politics. Vol. 8, No. 2, pp. 36-70 DOI: 10.1177/1081180X02251047.
  33. ^ Tilghman, Shirley M. (November 11, 2004) "Address to the Stem Cell Institute of New Jersey," Retrieved August 22, 2006.
  34. ^ Amos, Jonathan. (September 5, 2005) "Winston warns of stem cell 'hype'." BBC News. Retrieved August 14, 2006.
  35. ^ "President Clinton's Comments on NIH and Human Embryo Research". U.S. National Archives. Retrieved on July 19, 2006.
  36. ^ The White House, Press Release, August 9, 2001
  37. ^ Connolly, Ceci (July 2005). ""Despite Bush Veto, Stem Cell Research Abounds"". Washington Post: A01. Retrieved on July 21, 2006.
  38. ^ Kellman, Laurie. "Senate Approves Embryo Stem Cell Bill". Associated Press. Retrieved on July 18, 2006.
  39. ^ "Senate Approves Embryonic Stem Cell Bill", David Espo, Associated Press, April 12, 2007
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Stem_cell_controversy". A list of authors is available in Wikipedia.
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