"Embryonic stem cells have the ability to develop into virtually any cell in the body, and they may have the potential to treat medical conditions such as diabetes and Parkinson's disease. In August 2001, President Bush announced that for the first time federal funds would be used to support research on human embryonic stem cells, but funding would be limited to 'existing stem cell lines.' The National Institutes of Health (NIH) has established the Human Embryonic Stem Cell Registry, which lists 78 stem cell lines that are eligible for use in federally funded research. However, only 22 embryonic stem cell lines are currently available. Scientists are concerned about the quality, and longevity of these stem cell lines. For a variety of reasons, many believe research advancement requires new embryonic stem cell lines, and for certain applications, stem cells derived from cloned embryos may offer the best hope for progress in understanding and treating disease. A significant cohort of pro-life advocates support stem cell research; those opposed are concerned that the isolation of stem cells requires the destruction of embryos. Some have argued that stem cell research be limited to adult stem cells obtained from tissues such as bone marrow. They argue that adult stem cells should be pursued instead of embryonic stem cells because they believe the derivation of stem cells from either embryos or aborted fetuses is ethically unacceptable. Other scientists believe adult stem cells should not be the sole target of research because of important scientific and technical limitations. Some scientists are exploring the possibility of obtaining human embryonic stem cells that bypass the destruction of living human embryos. The President's Council on Bioethics identified four potential alternative sources of human embryonic stem cells in a paper released in May 2005."
CRS Report for Congress, RL31015
U.S. Department of State, Foreign Press Centers: http://www.fpc.state.gov/