AACR forum to discuss stem cells and cancer research: Public policy issues
Washington, D.C. – Few issues in science have generated as much excitement and furor as the potential use of stem cells for the benefit of humanity.
For many, stem cells represent not just a potential new way of treating disease and disorders, but may provide an entire new way of practicing "regenerative" medicine. Others, however, have raised ethical concerns about the use of stem cells, particularly those obtained from frozen embryos concerned through in vitro fertilization. The issue also has been caught up and sometimes confused with talk about human cloning and the use of fetal tissue for transplantation.
To help put the research into a public policy context as it relates to cancer, the American Association for Cancer Research (AACR) has assembled a group of eminent scientists to speak at a Forum during its Annual Meeting. The Forum -- scheduled for 8:45 a.m. – 10 a.m., Sunday, July 13 -- is appropriately titled "Scientific and Public Policy Issues in Embryonic and Adult Stem Cell Research."
Speakers include Drs. Curt Civin, with the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Md.; Darwin Prokop, Gene Therapy Center, Tulane University, New Orleans, La.; and Irving Weissman, Stem Cell Institute, Stanford University, Stanford, Calif.
The group will turn much of its attention to the potential value of embryonic stem cells versus (or in addition to) adult stem cells, and the potential uses of therapeutic cloning as clearly and importantly distinguished from reproductive cloning. In particular, they will discuss the current debate over specific legislation at the federal level and also in certain states, including bills proposed in California and Maryland.
In essence, a stem cell is an individual cell that renews itself when it divides, yielding another cell that is also a stem cell. In turn, this cell produces progeny that gives rise to mature cells for any organ of the body, such as blood, brain and liver.
Some stem cells are "totipotent." They have the potential to give rise to every cell in the body or a fully developed organism. Following its fourth day, the zygote becomes the morula (eight-cell stage) and then continues to divide to form a donut-like structure called the blastocyst. Its outer layer of cells forms the placenta; the inner mass forms the first stage of the new embryo itself.
These cells continue to divide until their number reach about 200. Technically, these more restricted cells are called "pluripotent" stem cells that can self-renew and give rise to every other cell in the body. Today, they are known as embryonic stem cells.
About 25 days after fertilization, after the embryo is implanted in the womb, separate groups of more mature stem cells take up residence in different organs of the body and remain there throughout life. Though these tissue-specific stem cells can be found in adulthood, they are more abundant in the fetus. These cells are called "multipotent" or adult stem cells. Recently, several groups have reported that there are small numbers of more pluripotent stem cells in adults that rival the "plasticity" of embryonic stem cells.
Among other questions scientists are now asking is whether adult stem cells have a wider range of potential therapeutic uses than was previously thought. Can adult stem cells develop into many types of cell lineages? And there's another step that excites many scientists: tailoring stem cells for the individual patient to avoid any possibility of tissue rejection. This can be accomplished through somatic cell nuclear transfer or "therapeutic cloning." Here, you take an unfertilized egg, and remove the nucleus. Then, you inject the DNA-containing nucleus from an adult cell, say a skin cell, into the egg and allow it to grow into an embryo. Once it reaches the blastocyst stage, you harvest stem cells that are identical to the adult donor's genetic makeup.
This process is distinct from reproductive cloning, which, as many now understand, results in the creation of an identical living organism a la Dolly, the cloned sheep. All scientific panels have cautioned against reproductive cloning as scientifically unfeasible in humans, medically dangerous and ethically unsure (at best).
The U.S. Congress is now debating bills that would ban all cloning, both reproductive and therapeutic cloning. State legislators in California and Maryland are proposing bills that would permit donation of certain tissue for research, including therapeutic cloning, human embryonic germ cells and human adult stem cells, all conducted under the watchful eye of an Institutional Review Board.
Founded in 1907, the American Association for Cancer Research (AACR) is a professional society of more than 20,000 laboratory and clinical scientists engaged in cancer research in the United States and more than 60 other countries. AACR's mission is to accelerate the prevention and cure of cancer through research, education, communication and advocacy. Its principal activities include the publication of five major peer-reviewed scientific journals (Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention). AACR's annual meeting attracts more than 12,000 participants who share new and significant discoveries in the cancer field, and the AACR's specialty meetings throughout the year focus on all the important areas of basic, translational and clinical cancer research.
