Study Shows Embryonic Stem Cells Rejected by Immune Systems.

Embryonic stem cells (ESCs) have failed another test to determine if they could ever be used in medical treatments. The immune systems of mice injected with human ESCs attacked the cells, which died within a matter of days. Even when treated with anti-rejection drugs, the cells proliferated for only 28 days before they also died, according to Scientific American. Diseases cannot be cured if the cells intended for treatment are rejected by the body.

Scientists at Stanford University School of Medicine published a report in the August 18 online Proceedings of the National Academy of Sciences detailing the failed experiment. The results show yet again that ESCs, beyond the serious moral objections because they are derived by destroying human embryos, are ineffective for practical reasons, and may never be useful in treating diseases.

The Stanford researchers were testing the theory that immune systems would not reject ESCs. This supposition was based on the fact that the mother's body needs to accommodate an unborn baby, who has genetic material from both the mother and the father. Therefore, according to this theory, there may be something in the ESCs or in immune systems that allows this type of "foreign" material to be accepted by the body.

The researchers injected human ESCs into mice with either compromised or functioning immune systems, according to a Stanford University news release. Using a molecular imaging technique that allowed them to watch the progression of the cells in real time, they could see whether the cells grew and multiplied.

In the mice with faulty immune systems, the cells grew. However, working immune systems attacked and killed the ESCs within 7 to 10 days, the news release reported. When more ESCs were injected into these mice, the new cells died even more rapidly.

"It's getting harder and harder to believe that these cells are immunoprivileged," said Dr. Joseph Wu, assistant professor of cardiovascular medicine and of radiology, said in the press release. "In fact, the rejection of these cells confirms our ...