Stem cell research received a big boost in January, when the U.S. Food and Drug Administration approved the first-ever human trial using embryonic stem cells as a medical treatment. Geron Corp., a California-based biotech company, was given the OK to implant embryonic stem cells in eight to 10 paraplegic patients who can use their arms but can't walk.
In 2001, then-President Bush limited federal funding for stem cell research only to human embryonic stem cell lines that already existed.
The decision prompted some scientists to worry that the United States would fall behind other countries in the drive to unlock the potential of stem cell research.
Embryonic stem cells are the most basic human cells, believed to be capable of growing into any type of cell in the body. Working as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells. The scientific hope is that stem cells may, at some point in the future, become capable of treating a variety of diseases and conditions, such as Parkinson's disease, diabetes, heart disease and spinal cord injuries, according to the NIH.
National polls continue to find that the majority of Americans favor embryonic stem cell research, although some surveys have found that that support has declined somewhat in recent years.
Many people object to the use of embryonic stem cells, contending that the research requires the destruction of potential life, because the cells must be extracted from human embryos.
The stem cells being used in the recently approved Geron trial were obtained from one of the Bush administration's approved stem cell lines. And no federal funds were used in the development of this treatment.
Since the restrictions on embryonic stem cell research took effect, many research institutions have redirected their focus to other types of stem cells, such as adult stem cells.
Adult stem cells can give rise to all the specialized types of cells found in tissue from which they originated, such as skin. But, scientists don't agree on whether adult stem cells may yield cell types other than those of the tissue from which they originate, according to the NIH.
To learn more about stem cells, visit the U.S. National Institutes of Health.
SOURCES: March 6, 2009, statement, Peter T. Wilderotter, president and CEO, Christopher And Dana Reeve Foundation, Short Hills, N.J.; March 6, 2009, statement, Philip Pizzo, M.D., dean, Stanford School of Medicine, California; March 9, 2009, news release, American Medical Association, Chicago; The New York Times; Associated Press