American Progress Senior Fellow, Jonathan D. Moreno, co-authored the National Academy guidelines released Tuesday, April 26, aimed at all U.S. researchers who perform experiments with human embryonic stem cells.

In 1998, James Thomson and co-workers became the first scientists to derive and successfully culture human embryonic stem cells (hES cells) from a human blastocyst, an early human embryo of approximately 200 cells, donated by a couple who had completed infertility treatments. Although ES cells had been derived from mouse blastocysts since 1981, this achievement with human cells was significant because of its implications for improved health. The dual capacity of hES cells for self-renewal and for differentiation into repair cells offers great potential for understanding disease development and progression, for regenerative medicine, and for targeted drug development.

In addition to that research accomplishment, the cloning of Dolly the sheep in 1997 using a technique called somatic cell nuclear transfer (SCNT) or, more simply, nuclear transfer (NT) provided a means of generating ES cells with defined genetic makeup. hES cell preparations could potentially be produced by using NT to replace the nucleus of a human oocyte, trigger development, and then isolate hES cells at the blastocyst stage. The advantage of using NT to derive hES cells is that the nuclear genomes of the resulting hES cells would be identical with those of the donors of the somatic cells. One obvious benefit is that this would avoid the problem of rejection if cells generated from the hES cells were to be transplanted into the donor. A more immediate benefit would be facilitation of a wide array of experiments to explore the underpinnings of genetic disease and possible forms of amelioration and cure. Some such experiments will not be possible using hES cells derived from blastocysts generated by in vitro fertilization (IVF), in which the nuclear genomes are not defined. Although the promise of using NT for such research is as yet unrealized, most researchers believe that it will be a critical source of both important knowledge and clinical resources. Use of NT for biomedical research, as distinct from its use to create a human being, has been considered by several advisory groups to be ethically acceptable provided that such research is conducted according to established safeguards against misuse and has undergone proper prior review. However, there is nearly universal agreement that use of NT to attempt to produce a child should not be allowed at present. The medical risks are unacceptable, and many people have additional objections to using this procedure for attempts at human procreation.

hES cells currently can be derived from three sources: blastocysts remaining after infertility treatments and donated for research, blastocysts produced from donated gametes (oocytes and sperm), and the products of NT. Ethical concerns about those sources of hES cells-combined with fears that the use of NT for research could lead to its use to produce a child-have fostered much public discussion and debate. In addition, concern has been expressed about whether and how to restrict the production of human/nonhuman chimeras in hES cell research. Research using chimeras will be valuable in understanding the etiology and progression of human disease and in testing new drugs, and will be necessary in preclinical testing of hES cells and their derivatives.

Because there is widespread agreement in the international scientific community about the potential value of hES cell research, the volume of this research has expanded since 1998, despite restrictions in the United States. First, federal legislation forbids the use of federal monies for any research that destroys an embryo; this effectively prevents any use of federal funds to derive hES cells from blastocysts. Second, research with established hES cell lines is limited by a policy announced by President George W. Bush in 2001 that restricts federal funding to research conducted with specific federally approved hES cell lines already in existence before August 9, 2001. Despite the restricted use of federal funds for research of this kind, the derivation of new cell lines is proceeding legally in the private sector and in academic settings with private funds except in those states where such research has been partially or totally banned.

Privately funded hES cell research is subject to some regulation or other constraints primarily through human subjects protections regulations, limits placed on licensees by the holders of NT and hES cell patents, animal care and use regulations, state laws, and self-imposed institutional guidelines at companies and universities that are now doing or contemplating this research. Those aiming to produce biological therapies are also subject to Food and Drug Administration (FDA) regulation. However, because of the absence of federal funding for most current hES cell research, some standard protections may be lacking, and the implementation of protections is not uniform across the country. Moreover, the techniques for deriving the cells do not yet amount to fully developed standard research tools, and the development of any therapeutic application remains some years away. The best way to move forward with hES cell research in pursuit of scientific goals and new therapies is with a set of guidelines to which the U.S. scientific community will adhere. Heightened oversight also is essential to assure the public that such research is being conducted in an ethical manner.

Established criteria for deriving hES cell lines and reviewing research will help to ensure that the derivation, storage, and maintenance of cells meet a standard set of requirements for provenance and ethical review. Because not all scientists want or have the resources to derive new hES cell lines, the ability to share cell lines will create greater access for qualified scientists to participate in stem cell research. The tradition of sharing materials and results with colleagues speeds scientific progress and symbolizes to the nonscientific world that the goals of science are to expand knowledge and to improve the human condition. One key reason for the remarkable success of science since its emergence in modern form-besides the application of the scientific method itself-is the communal nature of scientific activity.

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