Stem cells, unlike other cells, can renew themselves for long periods of time though cell division, and under certain laboratory conditions, they can be stimulated into becoming cells with special functions, like insulin producing cells normally found in the pancreas. One of the major hopes is that researching stem cells is they could potentially offer a renewable source of a transplantable tissues, and have a significant impact on the treatment of Parkinson's, Alzheimer's, diabetes, spinal cord injures, and other diseases. Recent research at Johns Hopkins University shows however that spinal cord injuries, for example, can heal through normal patterns of activity without the need for stem cells.

There are both embryonic stem cells, which are derived from embryos that have been fertilized in-vitro and have been donated for research, and adult stem cells. The major difference between embryonic and adult stem cells is that embryonic stem cells have the ability to become many different cells in the body.

While stem cell research offers many possibilities in the treatment of disease, it remains controversial because, among other concerns, in order to create embryonic stem cells, the embryo must be destroyed in order to create embryonic stem cells. At least, that used to be the case. On June 19th, researchers at the Advanced Cell Technology Company announced that they had found a way to create embryonic stem cells without having to destroy the embryo. This process is an adaptation of a common genetic test used in fertility clinics, known as pre-implantation genetic diagnosis.

In a press release from the Advanced Cell Technology Company Ronald Green, Ph.D., Director of Dartmouth College's Ethics Institute and Chairman of ACT's Ethics Advisory Board is quoted as saying, "One of the major ethical objections of those who oppose the generation of human embryonic stems cells is that all techniques, until now, have resulted in the destruction of the embryo," and that "This technique overcomes this hurdle and has the potential to play a critical role in the advancement of regenerative medicine. It also appears to be a way out of the current political impasse in this country and elsewhere." The current US policy does not allow use of embryos harvested made past August of 2001. On June 20, 2007, the president vetoed a bill that would allow embryos from past that date to be used, and encouraged alternative means of producing stem cells.

The president's veto drew strong response from several sources, including the American Fertility Association, who pointed to a study published the same day which showed that, in a survey of 1,000 couples who had stored embryos 60 % said they would donate embryos for stem cell research. This study was done by researchers at Duke University Medical Center and John Hopkins University, and published in the online version of Science Express. The executive director of the American Fertility Foundation claimed that, "The study confirms what the AFA has said repeatedly: Federal policy does not reflect the preferences of the majority of our members."

Embryonic stem cell research will continue to be a subject of strong debate. In the meantime, it remains to be seen whether hopes for stem cell research become a reality or whether it simply represents another means for funneling funds to the biotech industry which remains long on promises and short on results, particularly as we heard towards the next presidential elections.