South Korean Researchers Extract Stem Cells From Cloned Human Embryo
South Korean researchers have extracted stem cells from a cloned human embryo that was grown to the blastocyst stage, according to a study to be presented on Thursday at a meeting of the American Association for the Advancement of Science and published on Friday in the journal Science, USA Today reports (Vergano, USA Today, 2/12). Researchers administered a one-month course of hormones to the study participants, who were not paid for their participation and were told that they would not benefit from the research, according to the Washington Post. After removing the eggs, researchers removed the "central packet" of DNA from each egg cell (Weiss, Washington Post, 2/12). Researchers obtained 242 eggs and of those, selected 176 eggs deemed to have the potential to be the most successful for the experiment. Researchers removed the genetic material from each egg and replaced it with DNA contained in cumulus cells obtained from the women's ovaries. Researchers varied the timing of the process, determining when it was best to add the cumulus cell to the egg and when it was best to "activate" the egg to begin cell division, the New York Times reports. Their method produced embryos that grew into blastocysts 26% of the time (Kolata, New York Times, 2/12).
The experiment yielded a total of 30 blastocysts, from which researchers extracted 20 inner cell masses. One of the cell masses grew into a stem cell line (Cook, Boston Globe, 2/12). Lead researcher Hwang Woo Suk of Seoul National University said, "Our approach opens the door for the use of these specially developed cells in transplantation medicine" (Washington Post, 2/12). He added that the research team's next step, which is "now under way, is to study how to direct which tissues those cells form" (Yonhap English News, 2/12). Even if scientists can successfully extract stem cells from cloned embryos, much more research needs to be conducted before the cells can be used in therapies (Washington Post, 2/12). Stem cells have the potential to grow into any of the body's 220 cell types. Some researchers believe that stem cells could be used to replace damaged or defective cells or to treat illnesses, such as Parkinson's disease and spinal cord injuries, the Atlanta Journal-Constitution reports (Wahlberg, Atlanta Journal-Constitution, 2/12). Obtaining the stem cells from clones is considered important because patients could conceivably receive tissue that is genetically identical to themselves, thereby reducing the risk that their immune systems would reject the tissue (Mestel, Los Angeles Times, 2/12).
The results of the study are expected to "ratchet up" the political and ethical debate over human cloning, according to the Journal-Constitution (Atlanta Journal-Constitution, 2/12). Stem cell research advocates say that it is "not surprising" that the research presented today was completed overseas because "opposition to such research is so strong" in the United States, the New York Times reports. Currently, the federal government has not passed any legislation on cloning, although the House last year passed a measure that would have banned both reproductive cloning and cloning for research purposes. In addition, sources for stem cells in the United States are "limited" because of restricted federal funding for the research, according to the Times (Grady, New York Times, 2/12). President Bush on Aug. 9, 2001, announced a policy limiting federally funded stem cell research to embryonic stem cell lines created on or before that date. The policy allows federal funding for experiments involving stem cells already derived from embryos but not for research that would cause the destruction of additional embryos (California Healthline, 7/18/03).
The following broadcast programs reported on the South Korean scientists' extraction of stem cells from a cloned human embryo:
- NPR's "All Things Considered": NPR's Joe Palca reports on the scientists' work and its implications (Palca, "All Things Considered," NPR, 2/11). The complete segment is available online in RealPlayer.
- NPR's "Morning Edition": The segment includes comments from Jose Cibelli, a cloning researcher at Michigan State University and a study co-author; Dr. George Daley, an embryonic stem cell specialist at the Whitehead Institute and Harvard Medical School; and a member of the Korean team of scientists (Palca, "Morning Edition," NPR, 2/12). The complete segment is available online in RealPlayer.
- NPR's "Morning Edition": NPR's Bob Edwards interviews Dr. Jeffrey Kahn, director of the University of Minnesota Center for Bioethics, about the ethical debate surrounding research on human embryos, human reproductive cloning and cloning for research purposes (Edwards, "Morning Edition," NPR, 2/12). The complete segment is available online in RealPlayer.