Good Immune System, Bad Stem Cell Reaction?

Stem cells have taken center stage in the scientific and research communities over the past decade. The cells' potential to heal and impede or stop the development of numerous diseases is one of the brightest prospects in medicine today. And while much advancement in the field of stem cell research have been encouraging, persisting concerns about negative immune system responses have come to the forefront of the discussion again.

The core of the immune system issue is a basic but serious one; if the body will reject and destroy the injected stem cells, all of their potential benefits are moot. A solution being researched is a medication given to the cell recipient called an anti-rejection compound, but it is feared that this procedure may only prolong but not prevent the inevitable damage of the stem cells by keen immune system responses.

What has brought this immune system concern back to the headlines is a recent study by researchers at the Stanford University School of Medicine, the findings of which were recently published in the Proceedings of the National Academy of Sciences journal. Joseph Wu, M.D., Ph.D., and assistant professor of cardiovascular medicine and radiology at Stanford was the senior author of the study, which was co-authored by Mark David, M.D., Ph.D., and professor of microbiology and immunology. The experiment included the injection of human embryonic stem cells into mice, and the result was the death of those cells in the furry rodents with healthy immune systems.

The hope for embryonic stem cells was the very essence of their positive characteristic for this transplant purpose-that the immune system ignores them in order for a fetus to grow. However, once transplanted into a mouse, the new immune system recognized that the cells were foreign. Stem cells in mice with normal immune systems died within 7 to 10 days, and further injections caused the cells to die even more quickly due to the more efficient recognition of the foreign cells and the body's hurried response to destroy them. While the use of the aforementioned anti-rejection compound did allow cells to last in some cases up to 28 days, the stem cells still ultimately met their demise. On the other hand, cells in those with damaged immune systems did survive and multiply.

Wu noted, "It's getting harder and harder to believe that these cells are immunoprivileged. In fact, the rejection of these cells confirms our suspicions that they do cause an immune response." And with regard to a possible varying human response, he added, "Based on these results, we believe that transplanting these cells into humans would also cause an immune response."

While the results of this most recent study are not particularly encouraging for stem cell researchers, it does expose a problem that will receive more detailed attention. Not only will more in-depth studies be dedicated to finding the exact cause of the immune system's response to the transplanted stem cells, but more efforts will be put into anti-rejection medications that will prolong the cells' life, therefore giving it more of an opportunity to be accepted by the body and perform its intended role.

Human experiments are further down the scientific road. But it is the benefits to humans that are being watched by the world with an anxious eye. The potential healing and disease prevention powers that stem cells may hold are more than encouraging; they provide hope for sufferers of some of the world's most devastating diseases.