For some time, governmental funding of research involving human embryos has been a controversial topic in the United States. In 1979, the U.S. Health and Human Services Department disbanded an advisory board that reviewed federally funded research on human sperm, eggs, and embryos. Subsequently, Presidents Reagan and Bush blocked federal funding for all research on human embryos. Signaling a shift in policy, President Clinton assigned the task of drafting guidelines for studies on human embryo research to the National Institutes of Health. The consequent Human Embryo Research Panel recommended that research should be allowed only if the embryos were less than 14 days old, if the studies could not be performed with animal embryos, and only if researchers could demonstrate a compelling reason why the studies should be performed. The panel also decided that researchers should not be limited to surplus embryos from in vitro fertilization procedures, and that researchers could create embryos in vitro for research purposes. President Clinton rejected the last recommendation, and he issued an Executive Order that government funded scientists shall not be allowed to create human embryos for research.

As a result of the President's announcement, researchers could only use embryos that remained after in vitro fertilization treatments. Even this limited authorization, however, did not sit well with Congress. In July 1995, the House Appropriations Committee approved a proposal, which stated that federal funds may not be used for the creation of a human embryo for research purposes or for research in which a human embryo is destroyed, discarded, or knowingly subjected to risk of injury or death that would be greater than the risk allowed for research on fetuses in utero. During the following January, President Clinton signed a continuing resolution to keep the federal government open. This resolution included the prohibition against the use of federal funds for research on human embryos. During the following years, Congress has continued to attach a ban on funding of human embryo research in a rider to the Health and Human Services appropriations legislation. In its Fiscal Year 1998 appropriations act directive, Congress amended the appropriations rider to include an expanded definition of "human embryo."

The current ban includes a prohibition against funding for research in which a human embryo is destroyed, or knowingly subjected to risk of injury or death. The precise meaning of this prohibition was called into question by the news of three privately funded research projects during the fall of 1998.

Geron Corporation (Menlo Park, CA) announced that it had supported two research teams, who had discovered ways to derive cultured human pluripotent stem cells, cells that are capable of giving rise to most tissues. One research team derived stem cells from fresh or frozen cleavage stage human embryos, which participants of in vitro fertilization programs had donated with informed consent. The second research team devised a method for establishing human pluripotent stem cell lines from primordial germ cells of five- to nine-week postfertilization embryos or fetuses, which were the product of therapeutic terminations of pregnancy. Around the same time, Advanced Cell Technology, Inc. (Worcester, MA) announced that its scientists had developed a method for producing primitive human embryonic stem cells by fusing a human somatic cell with a bovine egg that lacked a nucleus.

It did not escape attention that Advanced Cell Technology's researchers had created their cells using a nuclear transfer technique similar to the one used to clone Dolly the sheep. In response to Advanced Cell Technology's announcement, President Clinton asked the National Bioethics Advisory Commission to consider the ethical implications of the Advanced Cell Technology announcement. Meanwhile, a Senate hearing was called to determine whether federal dollars should support research on human stem cells. Parties on both sides of the issue voiced their concerns in Congress and in the press.

Opponents of federal funding for embryonic stem cell research have taken the position that legislators should not make a moral decision on behalf of all taxpayers to subsidize human experimentation. Opposition exists to any research that relies upon embryonic cells, and this includes research on cells harvested from frozen embryos. The Advanced Cell Technology method, which utilizes adult human cells, is also not deemed acceptable, because it is not clear whether the new hybrid cell with a human nucleus begins, even for a brief time, to grow and to develop as an early human life form. If so, then this technique requires the creation and destruction of human embryos.

Those who support federal funding for human stem cell research argue that these studies may lead to new therapies, as well as new cell culture systems that may streamline the drug discovery process. Proponents for federal funding have also expressed concern that restricting human stem cell research to the private sector would result in a corporate monopoly on the new therapeutic techniques, and a lack of public review.

There does appear to be no disagreement that human stem cell research has the potential to provide new therapies. The challenge, therefore, is to identify the means that society will tolerate to realize this potential. Such tolerance varies according to the source of human stem cells. One clear message is that the federal government will not fund studies requiring the creation of a human embryo for the express purpose of research. The National Bioethics Advisory Commission, which has taken a generally progressive posture on human stem cell funding, has also suggested that the federal government should not support the Advance Cell Technology method of producing hybrid cells.

Researchers have shown that stem cell cultures can be derived from tissue obtained following a therapeutic abortion. However, some have opined that federal funding of this approach would "legitimize abortion." In addition, a recent study casts doubt on the notion that embryonic germ cells obtained from aborted fetal tissue provide an adequate substitute for stem cells extracted from an embryo.

At this time, the best source for obtaining therapeutically useful human stem cells appears to be the frozen spare embryo of in vitro fertilization programs. These embryos have been a center of controversy, because opinions vary about the moral status of the embryos. The National Bioethics Advisory Commission observed that, although "most would agree that human embryos deserve respect as a form of human life, disagreements arise regarding both what form such respect should take and what level of protection is required at different stages of embryonic development."

One perspective is that human life begins with the fertilized ovum, a belief that is expressed by opponents to federal support for research involving frozen embryos. The other viewpoints are that human life begins at birth, or that human life begins sometime between fertilization and birth. Proponents of federal support have often expressed the latter view.

During the 1980's, there was a turbulent debate about embryo research in the United Kingdom, which gave rise to the Human Fertilisation and Embryology Act of 1990. One underlying premise of the Act is that the human embryo undergoes a fundamental change in status around day 14, and that after this time, the embryo should be considered a human individual, which must not be used for experimental purposes. The 1994 National Institutes of Health panel also pointed to this 14-day milestone. The 14-day theory is also consistent with biological observations, which indicate that there is no reason to believe that a multicellular biologically integrated human individual exists from fertilization to about 16 days in embryonic development. Accordingly, there is a rationale for supporting federal funding of stem cell research with spare frozen embryos, which fall within the 14-day window. This is a position that National Bioethics Advisory Commission advocates.

A division in opinion has arisen regarding the eligibility of federal funding for research involving the acquisition of cells from embryos, and funding for the use of these cells. In a joint report, the American Association for the Advancement of Science and the Institute for Civil Society asserted that activities involved in the isolation of embryonic stem cells should not be eligible for public funding. Similarly, in its draft guidelines for research on human pluripotent stem cells, the National Institutes of Health explained how to qualify for funding of stem cell research, while asserting that the derivation of the stem cells from early human embryos is ineligible for federal funding. The message, here, is that the government should fund research on cells that are the product of studies conducted by the private sector.

On the other hand, the National Bioethics Advisory Commission recognizes that there may be a distinction, but not a meaningful difference, between the act of obtaining cells from an embryo and the act of studying those cells. It does seem inconsistent to promote the latter, while disregarding the morality of the former.

It remains to be seen whether the decision to provide federal support for any activity that requires, at some stage, the use of frozen embryos will be informed by a thorough discussion of various viewpoints. In the end, the answer may be determined by the mere balance of political power.