BACKGROUND: Many experts say stem cells are one the most promising areas of research for the future of medicine. These cells have two distinguishing characteristics. First, they are unspecialized cells that can renew themselves through division. Second, under certain conditions, they can be induced to become cells with special functions, such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas. There are currently two types of stem cells used in research: embryonic, or pluripotent, and adult. Embryonic stem cells can develop into any kind of cell in the human body. They come from either fetal tissue from miscarriages and abortions, or embryos created for in-vitro infertility treatment, but not selected for implantation. Adult stem cells have less ability than embryonic stem cells to develop into other types of cells and they are found in bone marrow and a few organs. (Source: The National Institutes of Health and The American Heart Association)

ETHICAL CONTROVERSY: Because of the origin of embryonic stem cells, some people are ethically opposed to scientists using them in research. The "stem cell controversy" that has erupted because of research involving human embryos has even reached the White House. In 2005, Senate Majority Leader Bill Frist, in "a shift that infuriated religious conservatives," supported legislation to lift President Bush's restrictions on federally-funded embryonic stem cell research. Despite restricted national funding for stem cell research involving embryos, local funding is carrying it forward.

STEM CELL RESEARCH AND THERAPY: According to the International Society for Stem Cell Research, "The development of a range of human tissue-specific and embryonic stem cell lines will provide researchers with the tools to model disease, test drugs and develop increasingly effective therapies." Cell therapy, or replacing diseased cells with healthy cells, is a promising use of stem cells in the medical field. Currently, stem cells used for therapy are those found in bone marrow. The International Society for Stem Cell Research says these have been used by doctors for more than 40 years and are now being used to treat blood disorders like leukemia and lymphoma. Research is also taking place using other types of stem cells. This research is paving the way for possible future stem cell treatments for degenerative diseases like Parkinson's disease, stroke, heart disease and muscular dystrophies.

ADULT STEM CELL THERAPY: Some research shows that adult stem cells can be used to strengthen damaged organs like hearts and livers. Experimental treatments are being conducted to treat women with stress incontinence by strengthening the urethra with stem cells. The cells are used to treat patients with heart failure and peripheral vascular disease by strengthening muscles and stimulating blood flow. An important benefit of treatment with stem cells from your own body is that it drastically reduces the likelihood of rejection and other complications. "So far, we haven't seen any deleterious effects, and this makes sense considering these are the patient's own cells," Emerson Perin, M.D., Ph.D., medical director of the Stem Cell Center at the Texas Heart Institute, told Ivanhoe.