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NRL News
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 suspicions that they do cause an immune response.” The scientists tried to mitigate the immune system response by injecting the mice with tacrolimus and sirolimus, two anti-rejection medications given after organ transplants. However, the cells were killed again after growing for only 28 days. This rejection not only occurs when human ESCs are used in mice; previous studies have also shown that mice ESCs are also attacked by their immune systems, Scientific American reported. (Humans cannot be used for trials with ESCs, since the cells have also been shown to cause cancerous tumors, according to the magazine.) Scientists at Stanford’s School of Medicine, which has received millions of dollars from California’s embryonic stem cell research grant program, tried to put the best face on the study’s outcome. “[This result is] not a disappointment, it’s more of a reality check,” Wu told Scientific American. “I think there’s some promise [to human ESCs], but you don’t want to be foolish and say these cells are going to cure things in the next five years.” Opponents of lethal embryonic research pointed out that alternatives to ESCs are being used to treat diseases right now. In addition, induced pluripotent stem cells (iPSCs), which have the versatility of ESCs but are obtained directly from the patient rather than by killing human beings, have shown promise in early testing. “The very pronounced difficulties with ESC research should color our thinking about where we want to put public money in research—even without considering the ethical objections that have raised such a fuss for the last 10 years,” Wesley J. Smith wrote on bioethics.com. “It seems clear to me that based on the emerging science alone, public funding should favor iPSCs—which will not have the immune response problem (but as pluripotent cells, still have tumor issues)—and adult/umbilical cord blood stem cells.” |