For more information , please contact: Heather Rieff, Ph.D., FASEB Office of Public Affairs, 301-571-0657, hrieff@opa.faseb.org
¨ What are the basic differences between reproductive cloning and nuclear transplantation to produce stem cells?
Both processes begin with a technique called nuclear transplantation (also known as Somatic Cell Nuclear Transfer). First, the genetic material is removed from an ooctye, or egg cell. Then, the nucleus containing the genetic material from a somatic (or body associated) cell is transplanted into this enucleated egg cell. The resulting product is stimulated to begin dividing. At this point, the processes of reproductive cloning and nuclear transplantation to produce stem cells diverge:
Reproductive cloning: The cells resulting from nuclear transplantation are transferred to a uterus, which provides critical factors for further development. Therefore, reproductive cloning will result in a new human being (or animal).
Nuclear transplantation to produce stem cells: The cells resulting from nuclear transplantation are grown in a culture dish in the presence of special nutrients for only a few days, when they will comprise a cluster of about 120 cells that can be used to derive stem cells. Therefore, because the cells are never transferred to a uterus they cannot develop into a human being (or animal) on their own.
¨ How are nuclear transplantation and stem cell research related?
As described above, the process of nuclear transplantation can be used to produce stem cells. The advantage of using this technique to produce stem cells is that the cells would have the same genetic makeup as the individual who donated the body cell. This would be beneficial for cellular therapies since the individual’s immune system should not reject the stem cells. Stem cells lines derived by nuclear transplantation using specific patients’ cells would also allow scientists to study the basic properties of a disease and help develop appropriate treatments.
¨ What are the differences between adult and embryonic stem cells?
Scientists think that embryonic stem cells have a much greater utility and potential than the adult stem cells, because embryonic stem cells may develop into virtually every type of cell in the human body. Adult stem cells, on the other hand, may only be able to develop into a limited number of cell types. Embryonic stem cells also continue to divide indefinitely while this may not be the case for adult stem cells. Both adult and embryonic stem cell research should continue simultaneously as they are critical to our understanding of the etiology, progression and treatment of disease.
¨ How can we distinguish between the technologies used in cloning and stem cell research and the intent of these applied procedures?
In reproductive cloning, the intent is to create another human being. In order for this to happen, the nuclear transplantation product must be implanted into a uterus. On the other hand, nuclear transplantation to produce stem cells results in the generation of stem cells that are genetically identical to a patient. There is never implantation into a uterus, and the stem cells on their own cannot produce another human being. These cells can be used for therapeutic and scientific research purposes – they will facilitate scientific research into understanding and treating disease and in developing new cellular therapies.
¨ How does nuclear transplantation to produce stem cells differ from in vitro fertilization?
Embryos derived for in vitro fertilization purposes can also be used to derive stem cells. These cells will not be genetically identical to a patient, and therefore may not be as useful in cellular therapies as stem cells derived by nuclear transplantation. In the case of in vitro fertilization, an egg cell is fertilized by sperm and then allowed to develop. In the case of nuclear transplantation to produce stem cells, the egg cell is not fertilized.
¨ How will biomedical research and its translation to the practice of medicine be compromised if nuclear transplantation to produce stem cells is prohibited?
It would severely hinder scientific research if the use of a basic scientific technique such as nuclear transplantation were prohibited. Scientific discoveries and translation of these discoveries into medical advances rely on exploring the potential of new technologies. To limit the technologies available to U.S. scientists would jeopardize the pre-eminent position of the U.S. as a world leader in health research. The track record of U.S. scientists in using new technologies to benefit humankind is the best in the world. An example is the use of recombinant DNA technology, which invoked considerable debate in the 1970’s but has proven to be a mainstay of modern biomedical research and has produced an understanding of the genetic basis of many diseases, including cystic fibrosis. The evolution of these previous controversial issues has resulted in saving lives and managing devastating diseases as well as increased prosperity for U.S. citizens and their families.
¨ Will countries other than the U.S. develop therapies based on nuclear transplantation technology and would patients in the U.S. have access to these?
It is likely that other countries will develop therapies based on nuclear transplantation to produce stem cells. Proposed legislation in the Senate would prohibit the importation of these therapies into the U.S., thus severely limiting the number of patients who would have access to such treatments in our country.
¨ Will endless sources of eggs from women be required to develop this technology?
Eggs contain special factors to “reprogram” the genes in the nucleus so that the resulting cells are undifferentiated and totipotent, meaning that they can become virtually any cell type. As we learn more about control of genes and this process of reprogramming, alternative methods of creating cell lines to replace or correct defective tissues will be available.
¨ Why can’t animal models be used in this type of research?
Research in animal models has demonstrated the utility and immense potential of embryonic stem cells in developing therapies for previously untreatable conditions. While animal models provide useful data and research using animal models must continue, only through research on human cells will the mechanisms of interest in human disease be discovered.
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