The stem cell controversy is the consideration of the ethics of research involving the development, use, and destruction of human embryos. Most commonly, this controversy focuses on embryonic stem cells. Not all stem cell research involves human embryos. For example, adult stem cells, amniotic stem cells, and induced pluripotent stem cells do not involve creating, using, or destroying human embryos, and thus are minimally, if at all, controversial. Many less controversial sources of acquiring stem cells include using cells from the umbilical cord, breast milk, and bone marrow, which are not pluripotent.
For many decades, stem cells have played an important role in medical research, beginning in 1868 when Ernst Haeckel first used the phrase to describe the fertilized egg which eventually gestates into an organism. The term was later used in 1886 by William Sedgwick to describe the parts of a plant that grow and regenerate. Further work by Alexander Maximow and
Leroy Stevens introduced the concept that stem cells are pluripotent. This significant discovery led to the first human bone marrow transplant by
E. Donnal Thomas in 1956, which although successful in saving lives, has generated much controversy since. This has included the many complications inherent in stem cell transplantation (almost 200 allogeneic marrow transplants were performed in humans, with no long-term successes before the first successful treatment was made), through to more modern problems, such as how many cells are sufficient for engraftment of various types of hematopoietic stem cell transplants, whether older patients should undergo transplant therapy, and the role of irradiation-based therapies in preparation for transplantation.
The discovery of adult stem cells led scientists to develop an interest in the role of embryonic stem cells, and in separate studies in 1981 Gail Martin and Martin Evans derived pluripotent stem cells from the embryos of mice for the first time. This paved the way for Mario Capecchi, Martin Evans, and Oliver Smithies to create the first knockout mouse, ushering in a whole new era of research on human disease. In 1995 adult stem cell research with human use, patented (US PTO with effect from 1995). In fact human use published in World J Surg 1991 & 1999 (B G Matapurkar). Salhan, Sudha (August 2011). Textbook of Gynecology. JP Medical Ltd. pp. 625–. ISBN978-93-5025-369-4.
Bharadwaj, Aditya; Glasner, Peter E. (2009). Local Cells, Global Science: The Rise of Embryonic Stem Cell Research in India. Taylor & Francis. ISBN978-0-415-39609-7
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In 1998, James Thomson and
Jeffrey Jones derived the first human embryonic stem cells, with even greater potential for drug discovery and therapeutic transplantation. However, the use of the technique on human embryos led to more widespread controversy as criticism of the technique now began from the wider non-scientific public who debated the moral ethics of questions concerning research involving human embryonic cells.7
Potential use in therapy
Since pluripotent stem cells have the ability to differentiate into any type of cell, they are used in the development of medical treatments for a wide range of conditions . Treatments that have been proposed include treatment for physical trauma, degenerative conditions, and genetic diseases (in combination with gene therapy). Yet further treatments using stem cells could potentially be developed due to their ability to repair extensive tissue damage.
Great levels of success and potential have been realized from research using adult stem cells. In early 2009, the FDA approved the first human clinical trials using embryonic stem cells. Only cells from an embryo at the morula stage or earlier are truly totipotent, meaning that they are able to form all cell types including placental cells. Adult stem cells are generally limited to differentiating into different cell types of their tissue of origin. However, some evidence suggests that adult stem cell plasticity may exist, increasing the number of cell types a given adult stem cell can become.
Points of controversy
Many of the debates surrounding human embryonic stem cells concern issues such as what restrictions should be made on studies using these types of cells. At what point does one consider life to begin? Is it just to destroy an embryo cell if it has the potential to cure countless numbers of patients? Political leaders are debating how to regulate and fund research studies that involve the techniques used to remove the embryo cells. No clear consensus has emerged. Other recent discoveries may extinguish the need for embryonic stem cells.
Much of the criticism has been a result of religious beliefs, and in the most high-profile case, US PresidentGeorge W Bush signed an executive order banning the use of federal funding for any cell lines other than those already in existence, stating at the time, "My position on these issues is shaped by deeply held beliefs," and "I also believe human life is a sacred gift from our creator." This ban was in part revoked by his successor Barack Obama, who stated "As a person of faith, I believe we are called to care for each other and work to ease human suffering. I believe we have been given the capacity and will to pursue this research and the humanity and conscience to do so responsibly." 
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.
Foremost among these was the discovery in August 2006 that adult cells can be reprogrammed into a pluripotent state by the introduction of four specific transcription factors, resulting in induced pluripotent stem cells. This major breakthrough won a Nobel Prize for the discoverers, Shinya Yamanaka and John Gurdon.
In an alternative technique, researchers at Harvard University, led by Kevin Eggan and Savitri Marajh, have transferred the nucleus of a somatic cell into an existing embryonic stem cell, thus creating a new stem cell line.
Researchers at Advanced Cell Technology, led by Robert Lanza and Travis Wahl, 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. At the 2007 meeting of the International Society for Stem Cell Research (ISSCR), 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 to determine whether the new technique sidesteps U.S. restrictions on federal funding for ES cell research.
Anthony Atala of Wake Forest University says that the fluid surrounding the fetus has been found to contain stem cells that, when used correctly, "can be differentiated towards cell types such as fat, bone, muscle, blood vessel, nerve and liver cells". The extraction of this fluid is not thought to harm the fetus in any way. He hopes "that these cells will provide a valuable resource for tissue repair and for engineered organs, as well".