The Science Behind Stem Cell Research

President Bush's recent decision to allow federal funding of limited research using embryonic stem cells followed weeks of heated debate among scientists, policymakers, medical experts, and patient advocates. At the heart of the controversy are the complicated moral and legal issues surrounding the source of these stem cells, since those that are most valuable to scientists can only be obtained from human embryos. Yet stem cells may offer unprecedented opportunities for developing new therapies for many of the most debilitating medical conditions--including Parkinson's and Alzheimer's diseases, spinal cord injuries, stroke, heart disease, and diabetes. The ethical and legal concerns regarding the use of cells from human embryos cannot be ignored. However, so much attention has been paid to these issues that an understanding of the state of the science behind stem cell research has often been overlooked. This is especially troubling given that the policy decisions that are made now will affect scientific progress in the future and have long-range implications for all of us. I recently chaired a committee of the National Research Council and the Institute of Medicine that examined the scientific and therapeutic potential of stem cell research. Despite what some media coverage would suggest, stem cell research is still very much in its infancy. It's true that animal studies using transplanted stem cells have produced some remarkable results, but reproducing these results in humans is still a long way off. A great deal of basic research is required for stem cells to reach their potential and bring tangible benefits. Because of the many scientific challenges that remain, government funding will be essential to the research effort. Understandably, private companies are reluctant to invest in research that could take many years before any profitable commercial applications are developed. Government-funded research will encourage many more scientists to pursue embryonic stem cell research and will provide more opportunities for regulatory oversight and public scrutiny--ensuring that the research is scientifically justified and complies with strict ethical guidelines. The administration has proposed that federal support of research using existing embryonic stem cells will be permitted, but that funding for developing new lines of stem cells would not be allowed. Though much can be learned from existing cell lines, it is also clear that new stem cell lines will be needed in the future. Most of the existing embryonic stem cell lines have been cultured with animal cells or serum, which could pose health risks in humans. Harmful genetic mutations, which are known to accumulate in all cell lines, are likely to decrease the viability and usefulness of the existing cell lines over time. And novel technologies for creating new embryonic cell lines will likely be developed in the future, offering the potential for improvements and broader applications in regenerative medicine. Regardless of how many stem cell lines are available for research, scientists face other formidable obstacles in turning stem cell research into medical advances. One of the biggest is preventing the human body from rejecting transplanted stem cells. All tissue transplantation entails a risk that the body's immune system will reject the transplanted material, and new ways of overcoming tissue rejection must be found to make stem cells useful for treating illnesses. In particular, our committee recommended that scientists be allowed to pursue a controversial technique that can be used to create stem cells that are a genetic match to a patient. This method involves removing the nucleus of an egg cell, replacing it with genetic material from the transplant patient, and triggering cell division. The method is controversial because it is similar to techniques used for reproductive cloning. However, unlike reproductive cloning, the resulting embryo will not be used to produce a child but rather to derive stem cells for the transplant patient. Clearly, the ethical dilemmas and scientific uncertainties involved in stem cell research are real and need careful monitoring. The government should create a national advisory body of leading scientists, ethicists, and other stakeholders to monitor proposals for federal funding and ensure that such studies are justified on scientific grounds and also meet federal ethical guidelines. The scientific obstacles surrounding stem cell research are just as real as the ethical or legal concerns. If the nation wants to reap the benefits of stem cell research, then these barriers also must be overcome. Bert Vogelstein is a professor of oncology and pathology at the Johns Hopkins University School of Medicine in Baltimore and Investigator of the Howard Hughes Medical Institute. He recently chaired a committee of the National Research Council and Institute of Medicine that wrote the report Stem Cells and the Future of Regenerative Medicine, www.nap.edu/catalog/10195.html.

The Science Behind Stem Cell Research

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