Cloning/Embryonic Stem Cells
The term cloning is used by scientists to describe many different processes that involve making duplicates of biological material. In most cases, isolated genes or cells are duplicated for scientific study, and no new animal results. The experiment that led to the cloning of Dolly the sheep in 1997 was different: It used a cloning technique called somatic cell nuclear transfer and resulted in an animal that was a genetic twin -- although delayed in time -- of an adult sheep. This technique can also be used to produce an embryo from which cells called embryonic stem (ES) cells could be extracted to use in research into potential therapies for a wide variety of diseases.
Thus, in the past five years, much of the scientific and ethical debate about somatic cell nuclear transfer has focused on its two potential applications: 1) for reproductive purposes, i.e., to produce a child, or 2) for producing a source of ES cells for research.
The technique of transferring a nucleus from a somatic cell into an egg that produced Dolly was an extension of experiments that had been ongoing for over 40 years. In the simplest terms, the technique used to produce Dolly the sheep - somatic cell nuclear transplantation cloning - involves removing the nucleus of an egg and replacing it with the diploid nucleus of a somatic cell. Unlike sexual reproduction, during which a new organism is formed when the genetic material of the egg and sperm fuse, in nuclear transplantation cloning there is a single genetic "parent." This technique also differs from previous cloning techniques because it does not involve an existing embryo. Dolly is different because she is not genetically unique; when born she was genetically identical to an existing six-year-old ewe. Although the birth of Dolly was lauded as a success, in fact, the procedure has not been perfected and it is not yet clear whether Dolly will remain healthy or whether she is already experiencing subtle problems that might lead to serious diseases. Thus, the prospect of applying this technique in humans is troubling for scientific and safety reasons in addition to a variety of ethical reasons related to our ideas about the natural ordering of family and successive generations.
Several important concerns remain about the science and safety of nuclear transfer cloning using adult cells as the source of nuclei. To date, five mammalian species -- sheep, cattle, pigs, goats, and mice -- have been used extensively in reproductive cloning studies. Data from these experiments illustrate the problems involved. Typically, very few cloning attempts are successful. Many cloned animals die in utero, even at late stages or soon after birth, and those that survive frequently exhibit severe birth defects. In addition, female animals carrying cloned fetuses may face serious risks, including death from cloning-related complications.
An additional concern focuses on whether cellular aging will affect the ability of somatic cell nuclei to program normal development. As somatic cells divide they progressively age, and there is normally a defined number of cell divisions that can occur before senescence. Thus, the health effects for the resulting liveborn, having been created with an "aged" nucleus, are unknown. Recently it was reported that Dolly has arthritis, although it is not yet clear whether the five-and-a-half-year-old sheep is suffering from the condition as a result of the cloning process. And, scientists in Tokyo have shown that cloned mice die significantly earlier than those that are naturally conceived, raising an additional concern that the mutations that accumulate in somatic cells might affect nuclear transfer efficiency and lead to cancer and other diseases in offspring. Researchers working with clones of a Holstein cow say genetic programming errors may explain why so many cloned animals die, either as fetuses or newborns.
The announcement of Dolly sparked widespread speculation about a human child being created using somatic cell nuclear transfer. Much of the perceived fear that greeted this announcement centered on the misperception that a child or many children could be produced who would be identical to an already existing person. This fear is based on the idea of "genetic determinism" -- that genes alone determine all aspects of an individual -- and reflects the belief that a person's genes bear a simple relationship to the physical and psychological traits that compose that individual. Although genes play an essential role in the formation of physical and behavioral characteristics, each individual is, in fact, the result of a complex interaction between his or her genes and the environment within which he or she develops. Nonetheless, many of the concerns about cloning have focused on issues related to "playing God," interfering with the natural order of life, and somehow robbing a future individual of the right to a unique identity.
Several groups have concluded that reproductive cloning of human beings creates ethical and scientific risks that society should not tolerate. In 1997, the National Bioethics Advisory Commission recommended that it was morally unacceptable to attempt to create a child using somatic cell nuclear transfer cloning and suggested that a moratorium be imposed until safety of this technique could be assessed. The commission also cautioned against preempting the use of cloning technology for purposes unrelated to producing a liveborn child.
Similarly, in 2001 the National Academy of Sciences issued a report stating that the United States should ban human reproductive cloning aimed at creating a child because experience with reproductive cloning in animals suggests that the process would be dangerous for the woman, the fetus, and the newborn, and would likely fail. The report recommended that the proposed ban on human cloning should be reviewed within five years, but that it should be reconsidered "only if a new scientific review indicates that the procedures are likely to be safe and effective, and if a broad national dialogue on societal, religious and ethical issues suggests that reconsideration is warranted." The panel concluded that the scientific and medical considerations that justify a ban on human reproductive cloning at this time do not apply to nuclear transplantation to produce stem cells. Several other scientific and medical groups also have stated their opposition to the use of cloning for the purpose of producing a child.
The cloning debate was reopened with a new twist late in 1998, when two scientific reports were published regarding the successful isolation of human stem cells. Stem cells are unique and essential cells found in animals that are capable of continually reproducing themselves and renewing tissue throughout an individual organism's life. ES cells are the most versatile of all stem cells because they are less differentiated, or committed, to a particular function than adult stem cells. These cells have offered hope of new cures to debilitating and even fatal illness. Recent studies in mice and other animals have shown that ES cells can reduce symptoms of Parkinson's disease in mouse models, and work in other animal models and disease areas seems promising.
In the 1998 reports, ES cells were derived from in vitro embryos six to seven days old destined to be discarded by couples undergoing infertility treatments, and embryonic germ (EG) cells were obtained from cadaveric fetal tissue following elective abortion. A third report, appearing in the New York Times, claimed that a Massachusetts biotechnology company had fused a human cell with an enucleated cow egg, creating a hybrid clone that failed to progress beyond an early stage of development. This announcement served as a reminder that ES cells also could be derived from embryos created through somatic cell nuclear transfer, or cloning. In fact, several scientists believed that deriving ES cells in this manner is the most promising approach to developing treatments because the condition of in vitro fertilization (IVF) embryos stored over time is questionable and this type of cloning could overcome graft-host responses if resulting therapies were developed from the recipient's own DNA.
For those who believe that the embryo has the moral status of a person from the moment of conception, research or any other activity that would destroy it is wrong. For those who believe the human embryo deserves some measure of respect, but disagree that the respect due should equal that given to a fully formed human, it could be considered immoral not to use embryos that would otherwise be destroyed to develop potential cures for disease affecting millions of people. An additional concern related to public policy is whether federal funds should be used for research that some Americans find unethical.
Since 1996, Congress has prohibited researchers from using federal funds for human embryo research. In 1999, DHHS announced that it intended to fund research on human ES cells derived from embryos remaining after infertility treatments. This decision was based on an interpretation "that human embryonic stem cells are not a human embryo within the statutory definition" because "the cells do not have the capacity to develop into a human being even if transferred to the uterus, thus their destruction in the course of research would not constitute the destruction of an embryo." DHHS did not intend to fund research using stem cells derived from embryos created through cloning, although such efforts would be legal in the private sector.
In July 2001, the House of Representatives voted 265 to 162 to make any human cloning a criminal offense, including cloning to create an embryo for derivation of stem cells rather than to produce a child. In August 2002, President Bush, contending with a DHHS decision made during the Clinton administration, stated in a prime-time television address that federal support would be provided for research using a limited number of stem cell colonies already in existence (derived from leftover IVF embryos). Current bills before Congress would ban all forms of cloning outright, prohibit cloning for reproductive purposes, and impose a moratorium on cloning to derive stem cells for research, or prohibit cloning for reproductive purposes while allowing cloning for therapeutic purposes to go forward. As of late June, the Senate has taken no action. President Bush's Bioethics Council is expected to recommend the prohibition of reproductive cloning and a moratorium on therapeutic cloning later this summer.
Prepared by Kathi E. Hanna, M.S., Ph.D., Science and Health Policy Consultant
Last Reviewed: April 2006
Continue reading here:
Cloning/Embryonic Stem Cells - National Human Genome Research ...
- Stem Cell Research Article, Embryonic Cells Information ... [Last Updated On: May 6th, 2015] [Originally Added On: May 6th, 2015]
- Practical Problems with Embryonic Stem Cells [Last Updated On: May 6th, 2015] [Originally Added On: May 6th, 2015]
- What are embryonic stem cells? [Stem Cell Information] [Last Updated On: May 6th, 2015] [Originally Added On: May 6th, 2015]
- Embryonic stem cell - Science Daily [Last Updated On: May 7th, 2015] [Originally Added On: May 7th, 2015]
- What is Wrong With Embryonic Stem Cell Research? [Last Updated On: May 22nd, 2015] [Originally Added On: May 22nd, 2015]
- Destructive Embryonic Stem Cell Research | Antiochian ... [Last Updated On: June 13th, 2015] [Originally Added On: June 13th, 2015]
- NIH Human Embryonic Stem Cell Registry - Research Using ... [Last Updated On: June 22nd, 2015] [Originally Added On: June 22nd, 2015]
- Embryonic Stem Cell Research Pros and Cons | HRF [Last Updated On: July 2nd, 2015] [Originally Added On: July 2nd, 2015]
- Embryonic stem cells: where do they come from and what can ... [Last Updated On: July 2nd, 2015] [Originally Added On: July 2nd, 2015]
- Embryonic Stem Cells - HowStuffWorks [Last Updated On: July 2nd, 2015] [Originally Added On: July 2nd, 2015]
- Pros & Cons of Embryonic Stem Cell Research [Last Updated On: July 3rd, 2015] [Originally Added On: July 3rd, 2015]
- Children's Hospital Boston Glossary - Stem cell [Last Updated On: July 31st, 2015] [Originally Added On: July 31st, 2015]
- 1. Embryonic Stem Cells [Stem Cell Information] [Last Updated On: August 23rd, 2015] [Originally Added On: August 23rd, 2015]
- Embryonic stem cell - ScienceDaily [Last Updated On: August 23rd, 2015] [Originally Added On: August 23rd, 2015]
- Researchers control embryonic stem cells with light [Last Updated On: August 30th, 2015] [Originally Added On: August 30th, 2015]
- Embryonic stem cells controlled with light: Study reveals ... [Last Updated On: August 30th, 2015] [Originally Added On: August 30th, 2015]
- Embryonic stem cell research: an ethical dilemma | Europe ... [Last Updated On: September 5th, 2015] [Originally Added On: September 5th, 2015]
- Scientists reveal how stem cells defend against viruses [Last Updated On: September 22nd, 2015] [Originally Added On: September 22nd, 2015]
- An Overview of Stem Cell Research | The Center for ... [Last Updated On: October 3rd, 2015] [Originally Added On: October 3rd, 2015]
- Scientific Experts Agree Embryonic Stem Cells Are ... [Last Updated On: October 8th, 2015] [Originally Added On: October 8th, 2015]
- Myths and Misconceptions About Stem Cell Research ... [Last Updated On: October 12th, 2015] [Originally Added On: October 12th, 2015]
- Embryonic Stem Cell Maintenance & Differentiation (Human) [Last Updated On: October 23rd, 2015] [Originally Added On: October 23rd, 2015]
- Are embryonic stem cells and artificial stem cells equivalent? [Last Updated On: October 31st, 2015] [Originally Added On: October 31st, 2015]
- What are human embryonic stem cells used for? | Europe's stem ... [Last Updated On: August 30th, 2016] [Originally Added On: August 30th, 2016]
- Stem Cell Basics I. | stemcells.nih.gov [Last Updated On: September 17th, 2016] [Originally Added On: September 17th, 2016]
- Stem Cell Basics III. | stemcells.nih.gov [Last Updated On: September 17th, 2016] [Originally Added On: September 17th, 2016]
- Pros and Cons of Stem Cell Research - thebalance.com [Last Updated On: September 22nd, 2016] [Originally Added On: September 22nd, 2016]
- Embryonic Stem Cells and the Germ Cell Lineage | InTechOpen [Last Updated On: September 22nd, 2016] [Originally Added On: September 22nd, 2016]
- Embryonic stem cell research - alsa.org [Last Updated On: September 22nd, 2016] [Originally Added On: September 22nd, 2016]
- Embryonic Stem Cells | Stem Cells Freak [Last Updated On: October 4th, 2016] [Originally Added On: October 4th, 2016]
- Embryonic Stem Cells | stemcells.nih.gov [Last Updated On: October 9th, 2016] [Originally Added On: October 9th, 2016]
- Embryonic stem cell - Wikipedia [Last Updated On: October 17th, 2016] [Originally Added On: October 17th, 2016]
- Stem-cell therapy - Wikipedia [Last Updated On: October 19th, 2016] [Originally Added On: October 19th, 2016]
- Stem cell - Wikipedia [Last Updated On: October 23rd, 2016] [Originally Added On: October 23rd, 2016]
- What are embryonic stem cells or ES cells? [Last Updated On: October 25th, 2016] [Originally Added On: October 25th, 2016]
- Embryonic Stem Cell Research - rtl.org [Last Updated On: November 8th, 2016] [Originally Added On: November 8th, 2016]
- Guest View: No to embryonic stem cells - htrnews.com [Last Updated On: November 9th, 2016] [Originally Added On: November 9th, 2016]
- Blood-Forming Stem Cell Transplants - National Cancer Institute [Last Updated On: December 5th, 2016] [Originally Added On: December 5th, 2016]
- How Embryonic Stem Cells Become Tissue Specific | TFOT [Last Updated On: December 12th, 2016] [Originally Added On: December 12th, 2016]
- Embryonic Stem Cell Research - An Ethical Dilemma [Last Updated On: December 12th, 2016] [Originally Added On: December 12th, 2016]
- Scientists reprogram embryonic stem cells to expand their ... [Last Updated On: January 15th, 2017] [Originally Added On: January 15th, 2017]
- Embryonic Stem Cell Research Threatened - Hartford Courant [Last Updated On: January 27th, 2017] [Originally Added On: January 27th, 2017]
- Embryonic stem (ES) cells - eurostemcell.org [Last Updated On: February 5th, 2017] [Originally Added On: February 5th, 2017]
- Researchers engineer new thyroid cells - Science Daily [Last Updated On: February 8th, 2017] [Originally Added On: February 8th, 2017]
- Yes There's Hope, But Treating Spinal Injuries With Stem Cells Is Not A Reality Yet - IFLScience [Last Updated On: February 11th, 2017] [Originally Added On: February 11th, 2017]
- SEQUEIRA: Stem cell research must remain in foreground - University of Virginia The Cavalier Daily [Last Updated On: February 11th, 2017] [Originally Added On: February 11th, 2017]
- Stem cells: a miracle cure or playing God? - The Student [Last Updated On: February 11th, 2017] [Originally Added On: February 11th, 2017]
- How does the Catholic Church resolve new bioethical questions? - The Tidings [Last Updated On: February 11th, 2017] [Originally Added On: February 11th, 2017]
- Possible key to regeneration found in planaria's origins - Phys.Org [Last Updated On: February 13th, 2017] [Originally Added On: February 13th, 2017]
- Novel Nanofiber Matrix Improves Stem Cell Production - R & D Magazine [Last Updated On: February 14th, 2017] [Originally Added On: February 14th, 2017]
- Your brain's got rhythm: Synthetic brain mimics - Science Daily [Last Updated On: February 15th, 2017] [Originally Added On: February 15th, 2017]
- Nanofiber matrix sends stem cells sprawling in all directions - New Atlas [Last Updated On: February 15th, 2017] [Originally Added On: February 15th, 2017]
- Vitamins and aminoacids regulate stem cell biology - Phys.Org [Last Updated On: February 16th, 2017] [Originally Added On: February 16th, 2017]
- How does the Catholic Church resolve new bioethical questions? - Catholic Free Press [Last Updated On: February 17th, 2017] [Originally Added On: February 17th, 2017]
- New Nanofiber Matrix Enhances Stem Cell Production - Drug Discovery & Development [Last Updated On: February 17th, 2017] [Originally Added On: February 17th, 2017]
- Transplanted Human Embryonic Stem Retinal Pigment Cells Survive 22 months in a Human Recipient - MedicalResearch.com (blog) [Last Updated On: February 18th, 2017] [Originally Added On: February 18th, 2017]
- Iowa GOP takes aim at research - The Daily Iowan [Last Updated On: February 21st, 2017] [Originally Added On: February 21st, 2017]
- Nanofiber Matrix Improves Stem Cell Growth - Asian Scientist Magazine [Last Updated On: February 22nd, 2017] [Originally Added On: February 22nd, 2017]
- The clone armies never happened, but Dolly the sheep still changed the world - Quartz [Last Updated On: February 23rd, 2017] [Originally Added On: February 23rd, 2017]
- Harvard scientist worries we're 'reverting to a pre-Enlightenment form of thinking' - Washington Post [Last Updated On: February 25th, 2017] [Originally Added On: February 25th, 2017]
- 20 Years After Dolly the Sheep, Potential of Cloning Remains Unclear - FOX40 [Last Updated On: February 25th, 2017] [Originally Added On: February 25th, 2017]
- Harvard scientist worries we're 'reverting to a pre-Enlightenment form of thinking' - SCNow [Last Updated On: February 28th, 2017] [Originally Added On: February 28th, 2017]
- Stem cells derived neuronal networks grown on a chip as an alternative to animal testing - Science Daily [Last Updated On: March 3rd, 2017] [Originally Added On: March 3rd, 2017]
- Facts About Cloning - Live Science [Last Updated On: March 3rd, 2017] [Originally Added On: March 3rd, 2017]
- Exclusive: CBMG CEO Talks Stem-Cell Therapies, Cancer Treatments, Financials & The Chinese Market - Benzinga [Last Updated On: March 3rd, 2017] [Originally Added On: March 3rd, 2017]
- Artificial Mouse Embryo Created in Culture - Technology Networks [Last Updated On: March 3rd, 2017] [Originally Added On: March 3rd, 2017]
- Artificial embryo grown in a dish from two types of stem cells - New Scientist [Last Updated On: March 3rd, 2017] [Originally Added On: March 3rd, 2017]
- Artificial mouse embryo created out of stem cells - BioNews [Last Updated On: March 7th, 2017] [Originally Added On: March 7th, 2017]
- Scientists Have Created the First Artificial Embryo Without Using an ... - Gizmodo [Last Updated On: March 8th, 2017] [Originally Added On: March 8th, 2017]
- Artificial Mouse 'Embryo' Created from Stem Cells for First Time - Laboratory Equipment [Last Updated On: March 8th, 2017] [Originally Added On: March 8th, 2017]
- Role of Stem Cell Reprogramming Factor Uncovered - Technology Networks [Last Updated On: March 8th, 2017] [Originally Added On: March 8th, 2017]
- COMMENTARY: Saving a 10-year-old's life but at what cost? - Globalnews.ca [Last Updated On: March 10th, 2017] [Originally Added On: March 10th, 2017]
- No egg? No sperm? No problem. First artificial embryo made from stem cells - Genetic Literacy Project [Last Updated On: March 10th, 2017] [Originally Added On: March 10th, 2017]
- For The First Time Ever, Scientists Have Successfully Created An ... - Wall Street Pit [Last Updated On: March 13th, 2017] [Originally Added On: March 13th, 2017]
- Treating sickle cell disease with gene therapy - Jamaica Observer [Last Updated On: March 13th, 2017] [Originally Added On: March 13th, 2017]
- Here's the first 3D glimpse of how DNA is packaged up in a single cell - Ars Technica [Last Updated On: March 13th, 2017] [Originally Added On: March 13th, 2017]
- The craftsmanship of mimicking embryogenesis in a dish - BioNews [Last Updated On: March 13th, 2017] [Originally Added On: March 13th, 2017]
- Stem Cells Used to Create Artificial Embryo for the First Time Ever - TrendinTech [Last Updated On: March 15th, 2017] [Originally Added On: March 15th, 2017]
- Scientists create first 3D structure of active DNA - The Indian Express [Last Updated On: March 15th, 2017] [Originally Added On: March 15th, 2017]
- Ralph Shortey, Oklahoma Lawmaker, Hit With Child Prostitution Charges - NBCNews.com [Last Updated On: March 16th, 2017] [Originally Added On: March 16th, 2017]