Hal E. Broxmeyer, PhD
Distinguished Professor of Microbiology and Immunology, Indiana University School of Medicine
Here we go again! On August 23, U.S. District Judge Royce Lamberth issued a decision blocking federal funding for human embryonic stem cell (hESC) research based on his interpretation that such studies violate the Dickey-Wicker Amendment. That amendment prohibits the Department of Health and Human Services from using appropriated funds for the creation of human embryos for research purposes and for research in which human embryos are destroyed. Then in September, we received the news that the U.S. Court of Appeals for the District of Columbia issued a decision that will keep the Lamberth limitations from going into effect while the case makes its way through the courts. It is clear that the outcome is still in limbo. ASH will continue to provide updates on the status of this situation on our website, but to follow this saga in more detail you can refer to recent news articles.1,2,3
It is important to emphasize that, while the U.S. Court of Appeals’ decision was welcome news and allows research to move forward again, this whipsaw-like environment presents serious concerns for investigators currently working in, or who wish to get into, this line of research, as it affects Bush administration-approved hESC lines and is a problem for those who don’t have private funding for such work or who can’t clearly separate government from private funds. Unless the situation is clarified so that the government can fund ESC research, it will put a great damper on progress in the United States in this rapidly advancing area of research. Human ESC research is crucial to unlocking the mysteries of stem cell growth and differentiation — information invaluable not only for potential clinical use of hESCs, but also for a better understanding of how to modulate other stem cell sources for future treatments, such as those envisioned and supported by ASH4 for regenerative medicine.
Presently hESCs, when used responsibly,5 have much to offer the scientific and medical community. Their self-renewal capacity, the ability to make more of oneself, is truly exceptional, and under the right culture conditions in vitro these cells differentiate into most, if not all, tissues and cells in the body. The strongest reason for studying hESCs may not be their potential for regenerative medicine, but for truly understanding the mechanisms involved in self-renewal and differentiation — still poorly understood events. This information can be translated into functional use of other stem cell sources, including, but not limited to, human hematopoietic (hHSC), mesenchymal, and other tissue-specific stem cells from adults (e.g., bone marrow, blood) and newborns (e.g., cord blood). We still cannot adequately expand human HSCs for clinical advantage. Learning how to harness the self-renewal capacity of hHSCs from information obtained with hESCs may overcome the problem of inadequate expansion of hHSCs. The recent advent of human induced pluripotent stem (hiPS) cell technology, whereby many immature and mature adult cell types can be induced to an ESC-like state for subsequent differentiation, has opened up the possibility that we may eventually be able to work with neonatal or adult cells for future regenerative medicine, but this time has not yet come.6 Understanding hiPS cells requires extensive knowledge of hESC biology. We must use hESCs as controls for hiPS cell studies in order to determine the true potential of iPS cells. It is not clear how soon the iPS cell technology will translate, if at all, to clinical utility. A recent paper7 and accompanying review8 notes a potential problem with iPS cell generation that entails epigenetic memory.
It is not now nor may it ever be the right time to ignore and/or limit experimentation on a source of cells that are vital to understanding the well-kept secrets of how stem cells self-renew and differentiate and that may in the future be of use to help treat and cure human disease. Our health-care system cannot afford to miss the opportunity to adequately and rigorously explore possibilities that can enhance the well-being of our current and future populations. Congress must act definitively by passing legislation to make the issue of federal funding for ESC unambiguous, removing the possibility of repeated litigation intended to disrupt this important research and permanently allowing NIH-supported ESC research to continue.
- Wadman M. Shorter NIH grant form launches. Nature. 2010;463:12-13
- Wadman M. US stem-cell chaos felt abroad. Nature. 2010;467:138-139.
- Wadman M. Temporary reprieve for stem cells. Nature. 2010;467:258-259.
- Williams DA, Keating A. Enhancing research in regenerative medicine. Blood. 2010;116:866-867.
- Daley GQ, Ahrlund Richter L, Auerbach JM, et al. Ethics. The ISSCR guidelines for human embryonic stem cell research. Science. 2007;315:603-604.
- Broxmeyer HE. Will iPS cells enhance therapeutic applicability of cord blood cells and banking? Cell Stem Cell. 2010;6:21-24.
- Kim K, Doi A, Wen B, et al. Epigenetic memory in induced pluripotent stem cells. Nature. 2010;467:285-290.
- Zwaka TP. Stem cells: Troublesome memories. Nature. 2010;467:280-281.
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