Senate Hearing: July 13, 2005
William B. Hurlbut, M.D.
Program in Human Biology
Thank you, it's an honor to speak to you. I want to say from the onset that I agree with Senator Specter on the moral imperative of biomedical research and the scandal of priorities in our consumer society.
It's clear to me that both sides of this difficult debate are defending important human goods. And both of these goods, opening avenues for advance in biomedical science and preserving the fundamental moral principles on which our society are based, are important to all of us.
In 1999 President Clinton's National Bioethics Advisory Commission issued a report entitled: "Ethical Issues in Human Stem Cell Research." Acknowledging that a week old human embryo is a form of human life that deserves respect, the Commission stated:
"In our judgment, the derivation of stem cells from embryos remaining following infertility treatments is justifiable only if no less morally problematic alternatives are available for advancing the research."
Two months ago the President's Council on Bioethics issued a White Paper entitled "Alternative sources of Pluripotent Stem Cells," which discusses such less morally problematic alternatives. After analyzing the scientific feasibility, practicality and moral acceptability of a range of approaches, the Council endorsed, for preliminary animal studies, three proposals for the production of pluripotent stem cells (the functional equivalent of ES cells).
One of these proposals Altered Nuclear Transfer, is a broad concept with a range of possible approaches worthy of exploration. Altered Nuclear Transfer would, draw on the basic technique of SCNT (popularly known as 'therapeutic cloning') but with an alteration such that pluripotent cells are produced without the creation and destruction of human embryos.
In standard nuclear transfer the cell nucleus is removed from an adult body cell and transferred into an egg cell that first has its own nucleus removed. The egg then has a full set of DNA and, after it's electrically stimulated, starts to divide like a naturally fertilized egg. This is how Dolly the sheep was produced.
Altered Nuclear Transfer uses the technology of nuclear transfer but with a preemptive alteration that assures that no embryo is created. The adult body cell nucleus or the enucleated egg's contents (or both) are first altered before the adult body cell nucleus is transferred into the egg. The alterations cause the adult body cell DNA to function in such a way that no embryo is generated, but pluripotent stem cells are produced.
There may be many ways ANT can be used to accomplish the same end. One recent variation of this proposal, called Oocyte Assisted Reprogramming, has been put forward by Markus Grompe, Director of the Stem Cell Center at OHSU. In this variation of ANT, alterations of the nucleus of the adult body cell and the enucleated egg's contents before nuclear transfer would force early expression of genes characteristic of a later and more specialized cell type that is capable of producing pluripotent stem cells. Such a creation, from it's very beginning, would never have the actual configuration or potential for development that characterizes a human embryo and would therefore not have the moral standing of a human being.
As described in a recent op-ed in the WSJ and documented in a joint statement posted at the Ethics and Public Policy Center website, this proposal has drawn wide endorsement from leading scientists, moral philosophers and religious authorities.
Altered Nuclear Transfer, in its many variations, could provide a uniquely flexible tool and has many positive advantages that would help advance embryonic stem cell research.
----Unlike the use of embryos from IVF clinics, ANT would produce an unlimited range of genetic types for the study of disease, drug testing and possibly generation of therapeutically useful cells.
---- By allowing controlled and reproducible experiments, ANT would provide a uniquely flexible research tool for a wide range of useful studies of gene expression, imprinting, and intercellular communication.
---- Furthermore, the basic research essential to establishing the technique would advance our understanding of developmental biology and might serve as a bridge to transcendent technologies such as direct reprogramming of adult cells.
---- Moreover, as a direct laboratory technique, ANT would unburden embryonic stem cell research from the additional ethical concerns of the 'left over' IVF embryos, including the attendant clinical and legal complexities in this realm of great personal and social sensitivity.
I have discussed this proposal with many of the leading molecular and cell biologists and the general response is that ANT is technically feasible, might be rapidly developed (in12-24 months or maybe sooner), and would not burden stem cell research with excessive cost or inconvenience.
The present conflict over the moral status of the human embryo reflects deep differences in our basic convictions and is unlikely to be resolved through deliberation or debate. Yet a purely political solution will leave our country bitterly divided, eroding the social support and sense of noble purpose that is essential for the public funding of biomedical science. In offering a 'third option,' ANT defines with clarity and precision the boundaries that our moral principles are seeking to preserve while opening fully the promising possibilities of ESCR.
As described by my colleagues today, ANT is just one of a range of hopeful proposals. Specific legislation to support exploration and development of these complementary ways of obtaining pluripotent stem cells would greatly encourage this research. And I want to say, I would favor a stand alone bill, unencumbered with other political agendas----one small island of unity in our sea of controversy.
As we enter the coming era of rapid advance in biotechnology, this kind of legislation would set a positive precedent for maintaining constructive ethical dialogue and encouraging creative use of our scientific knowledge. In recognizing the important values being defended by both sides of our difficult national debate over embryonic stem cell research, this approach could open positive prospects for scientific advance while honoring the diversity of opinion concerning our most fundamental moral principles. Such a solution is in keeping with the American spirit and would be a triumph for our nation as a whole.