Stem Cell Research/Research using Fetal Tissue

2012-09-11 05:13:54

What Are Stem Cells?

Stem cells are unspecialized cells that have the potential to develop into specialized cells that could form any part of the human body.

Why Are They Important?

Stem cells are important precisely because they can develop into any part of the human body. This opens the possibility that they could be used for regenerative therapies to treat illnesses and injuries. Some potential applications of this type of therapy might include the creation or regeneration of damaged organs to eliminate the need for transplantation, the treatment of degenerative neurological conditions such as Parkinson’s and Alzheimer’s disease, and the regeneration of nerves for those with spinal injuries. Although science is only just beginning to investigate the potential medical applications of stem cells, at this stage their potential seems almost unlimited.

Where Do Stem Cells Come From?

In adults, there are very small quantities of stem cells located inside tissues throughout the body. These cells are difficult to isolate and seem to possess the ability to develop into only a limited number of types of cells determined by their location within the body. Stem cells that can only develop into a limited number of specialized cells are called multipotent stem cells.

Stem cells can be recovered from embryos in the blastocyst stage of development (five to seven days after fertilization). These cells are easier to recover and possess the ability to develop into any type of specialist cell. These are called pluripotent stem cells. Once the cells are isolated, they can be made to produce a theoretically unlimited number of genetically identical stem cells. This self-sustaining group of cells is called a stem cell line. At any time, a group of these cells can be removed and stimulated to grow into the required type of cell.

Stem cells can also be recovered from later stage embryos and fetuses. Such recovery would destroy the viability of the embryo or fetus and usually occurs after an abortion. Fetal stem cells are multipotent but easier to acquire and isolate.

Why Are Stem Cells Controversial?

Embryonic and fetal stem cells are controversial primarily because the process of their collection destroys the embryo or the fetus. This divides opinion roughly along the lines of abortion, although the collection of embryonic stem cells has the additional dimension of the destruction of the embryo possibly leading to lifesaving and life-enhancing therapies for thousands of people. The source of adult stem cells makes them less controversial.

History and Early Use of Stem Cells

Although the potential of stem cells is only just being explored, they have been used for medical purposes for a number of years. Starting in 1959, scientists began successfully transplanting bone marrow, which introduced hematopoietic stem cells (cells capable of developing into blood) into patients whose own stem cells were destroyed in cases of leukemia or as a side effect of chemotherapy treatments. In the 1990s, these hematopoietic cells were also found to be present in the blood of the umbilical cord, which was also less prone to rejection than cells from adults, leading to the creation of banks to store umbilical cord blood and calls for collection to be made a routine part of child delivery.

Early stem cell procedures mainly involved the transplantation of fetal stem cells, which required a steady stream of aborted fetuses. It was not until 1998 that the University of Wisconsin successfully created the first self-sustaining lines of pluripotent cells, opening the possibility of manufacturing the required cells in a laboratory setting rather than harvesting them directly from the fetus.

Early research focused on embryonic stem cells, with the origin and presence of stem cells in adult tissues remaining a mystery. Scientists later discovered more than forty different types of stem cells in the adult body, each capable of forming a limited variety of specialized cells. This limited ability to develop into other types of cells made them less attractive for study and therapeutic use than the pluripotent embryonic stem cells. More recent studies have shown that adult stem cells are capable of developing into broader range of specialist cells than first thought, although a long-term goal of scientists working with adult stem cells is to find ways to make them pluripotent by reverting them to the blastocyst cell type. If this were to be achieved, it would eliminate the need to harvest stem cells from embryos and fetuses.

Sources of Embryonic Stem Cells

The potential sources of embryonic stem cells are from unwanted in vitro fertilization (IVF) embryos and from embryos created specifically for experimental and therapeutic purposes.

Since IVF techniques were pioneered in the 1970s, one of the hallmarks of the treatment has been the creation of multiple fertilized embryos. Drugs are given to stimulate ovulation and allow for the harvesting of multiple eggs. The eggs are fertilized, frozen, and then implanted one at a time until a successful full-term pregnancy is achieved. Upward of twenty embryos can be produced because of the comparatively low chance of success with any one embryo. Many couples using IVF treatments end up with a number of frozen embryos that they do not intend to use. These embryos are stored and eventually destroyed. Because these frozen embryos are not going to be used for implantation and are at a very early stage of development, they are seen by some as an ideal source of stem cells, others who believe in the sanctity of life from conception argue that the destruction of any embryo is immoral regardless of any reason behind its destruction.

Apart from harvesting stem cells as a by-product of the destruction of unwanted embryos, the embryonic stem cells can be created for the specific purpose of scientific and therapeutic purposes. This can be achieved with the fertilization of an egg and sperm given expressly for experimental purposes, although the creation of an embryo for the sole purpose of its destruction is viewed by many as highly unethical.

Stem cells can also be created by a process known as therapeutic Cloning. This involves removing the nucleus of a donated egg and replacing it with the genetic material of the patient to be treated with the stem cells. The cell is then made to divide and ultimately produce the required cells, which can then be implanted into the patient with no chance of provoking an immunological rejection. The distinction between this and reproductive Cloning is that there is no intention to implant the clone into a uterus and ultimately bring about the birth of a genetic clone. However, the unease that many feel about Cloning is added to ethical issues surrounding the creation of something that could develop into another human life solely to acquire cells for medical treatment to make this highly controversial.

Ethical Approaches

The principal ethical position against the use of embryonic and fetal stem cells relies on the absolute right of the fetus to life that begins at the moment of conception. For proponents of this position there can never be any factor capable of mitigating the destruction of the fetus/embryo and draw the analogy between this and killing an otherwise healthy person solely to harvest their organs to give to others. This position is associated with many of the more conservative strands of Christianity and in particular with the position of the Catholic Church. They argue that the creation of any human life for scientific experimentation or medical treatment cheapens and commodifies all human life.

Those in favor of the use of stem cells argue for a balancing approach to evaluate its moral status. They argue that a right to life is not an absolute right. It may be a very important right, but it should be balanced against the potential good to be gained from the use of stem cell–based therapies. Some also argue that an embryo does not have an independent right to life before the point of viability, or that this right to life is lessened until the fetus reaches viability.

Embryonic Stem Cells as a Political Issue

The United States was one of the leading countries in the development of embryonic stem cells and related medical treatments. However, ethical concerns over the development of this branch of science led to this becoming a politically charged issue. In 1995, Congress initiated a ban on the use of federal funds for projects involving the destruction of an embryo. This continued until August 2000, when President William J. Clinton issued guidelines allowing the use of federal funds for embryonic stem cell research if the embryo would have been destroyed anyway and only if private money was used to finance the actual destruction of the embryo and recovery of the cells.

The role of the federal government in funding stem cell research became an issue in the 2000 presidential election and President George W. Bush to announce his compromise policy on the use of federal funding for embryonic stem cell research in his speech on August 9, 2001, stating that federal funds would only be available for research using any of the more than sixty preexisting stem cell lines. This compromise would ensure that federal funding would not aid in the destruction of any future embryos but not ignore the scientific potential offered by stem cells derived from embryos that had already been destroyed. The compromise was criticized by opponents of the use of stem cells claiming that this legitimized the prior destruction of the embryos. Advocates of stem cell research criticized the policy for hampering the development of new stem cell lines and treatments and placing the United States at a disadvantage to other countries in this emerging branch of science. The policy was also criticized for the moral arbitrariness in picking a cutoff date for stem cell lines to be eligible for federal funding.

The Bush compromise on federal funding for stem cell research did not stop the ethical and political debate over whether the U.S. government should sponsor scientific research in this field, and if so, what the extent the sponsorship should be. Several high-profile campaigns by celebrities with diseases or conditions that could potentially benefit from stem cell–based therapies ensured that the issue remained in the media spotlight. Perhaps the most important development was the position of the family of President Ronald Reagan who died in 2004 from Alzheimer’s disease. Stem cell–related therapies offer the possibility of developing a cure for this condition, and the Reagan family, including former First Lady Nancy Reagan, voiced an increasingly public support for federal funding of stem cell research, with Ronald Reagan, Jr. speaking against the compromise in the 2004 Democratic Party convention. This was all the more significant given President Reagan’s association with the religious right and strongly pro-life sections of the Republican Party.

Although scientists in the United States were constrained in their research by the Bush compromise, different political climates in other countries have aided stem cell research abroad and placed increasing pressure on the United States to follow suit. In May 2004, Britain became the first country in the world to open its own national stem cell bank as part of its policy of assisting researchers by increasing their access to as many stem cell lines as possible. In July 2004, President Bush announced plans for the United States to create its own national stem cell bank but only containing the stem cell lines created before August 2001.

Stem cell research is a very young field that offers the hope of miraculous leaps in medical capacity. That the clinical applications of its more extreme possibilities are decades away from realization have not dampened the hope and enthusiasm for a new dawn of medicine. The ethical debate over embryonic stem cell uge seems to be insoluble, but without great advances in adult stem cell research, the pressure of international competition and the promise of this new age of medicine seems to be pushing the United States toward greater support for its scientific community in this area.


References and Further Reading

  • Green, Ronald M. The Human Embryo Research Debates: Bioethics in the Vortex of Controversy. Oxford University Press, 2001.
  • Holland, Suzanne, Karen Lebacqz, and Laurie Zoloth, eds. The Human Embryonic Stem Cell Debate: Science, Ethics, and Public Policy. MIT Press, 2001.
  • Kiessling, Ann A., and Scott C. Anderson. Human Embryonic Stem Cells: An Introduction to the Science and Therapeutic Potential. Jones and Bartlett Publishers, 2003.
  • The President’s Council on Bioethics. ‘‘Monitoring Stem Cell Research’’ (2004–)
  • Ruse, Michael, and Christopher A. Pynes, eds. The Stem Cell Controversy: Debating the Issues. Prometheus Books, 2003
  • Snow, Nancy E. Stem Cell Research: New Frontiers in Science and Ethics. University of Notre Dame Press, 2004.
  • Waters, Brent, and Ronald Cole-Turner, eds. God and the Embryo: Religious Voices on Stem Cells and Cloning. Georgetown University Press, 2003.

See also Planned Parenthood of Missouri v. Danforth, 428 U.S. 52 (1976); Reproductive Freedom; Roe v. Wade, 410 U.S. 113 (1973); Webster v. Reproductive Health Services, 492 U.S. 490 (1989)