Following the fertilization of the egg, embryonic stem cells develop into cells, tissues and organs in an unborn baby. Harvesting the embryonic stem cells, however, as some scientists are attempting to do for research purposes, would require the destruction of human embryos.
Proponents of embryonic stem cell research point to the cell's pluripotent ability - or its capacity to become nearly all cell types and tissues in the body - claiming that it holds the cure for debilitating diseases such as Alzheimer, Parkinson's disease, and diabetes.
Pro-lifers, meanwhile, have argued the research is unethical and have pointed to other successful stem cell research that do not kill embryos as alternatives.
Some scientists say that research on adult stem cells show more promise in providing real results without destroying human life.
"There are all sorts of promises on what embryonic stem cell research might produce," Greg Koukl, founder and president of Stand to Reason, said in an interview with the Christian Post last month. "But the fact is that there is not a single therapy that has ever been produced through embryonic stem cell research.
"Yet there are over 100 therapies in play right now through adult stem cell research," said Koukl.
David Prentice, a scientist and senior fellow for Life Sciences at Family Research Council, said during a Life Issues panel at a recent pro-family conference that embryonic stem cells are especially vulnerable to developing tumors when grown in a dish.
"The bottom line is, it is the adult stem cells that are the most promising," said Prentice at The Family Impact Summit held in Brandon, Fla., two weeks ago.
"Number one, you don't have to kill the donor, and number two, they work."
Prentice, who believes pro-family supporters should stand up and defend life, accused scientists who push for embryonic stem cell research despite its lack of results of doing so in hopes of getting "money to keep their labs going."
Like Clinton, other Democratic presidential hopefuls are in support of federally funding for embryonic stem cell research.
Meanwhile, the issue has divided Republicans vying for presidency.
Former New York Mayor Rudy Giuliani, the Republican front runner, has supported limited federally funded research as long as it did not involve creating new life to destroy it. Former Massachusetts Gov. Mitt Romney opposes using embryos from fertility clinics.
