How do we give special respect for human embryos

On first examination, the concept of "special respect" seems untenable. How could it be that we can both choose to respect the human embryo and choose to use that embryo for the purpose of research? The answer is that this kind of value judgment is, in fact, one we make often. Rather than making absolute judgments, we are comfortable with shades of gray. For example, it is against the law to exceed the speed limit, but we typically have more tolerance for breaking this law than for armed robbery. In research with human subjects, an important principle is beneficence (National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research, 1979), "to do no harm"; but for testing new chemotherapeutic agents for melanoma, we may ask research subjects to accept the risk of harm in exchange for the possibility of finding a new and more effective treatment for an aggressive cancer. In animal research, our society has accepted the principle that research can be conducted on animal subjects, but this research does not occur without restriction. By Federal regulations, all animal research is subject to review by an Institutional Animal Care and Use Committee (Office of Laboratory Animal Welfare, 2002). A central principle of that review is that a necessary condition for approvable animal research is that it satisfies three principles proposed by Russell and Burch (1959): replacement, reduction, and refinement. A similar goal could be applied in our expectations for hESC research.

The principles of replacement, reduction, and refinement (the three Rs) are an obvious way in which research involving hESCs can proceed, but with special respect. If research can be conducted without the need to use human embryos, then consideration for the possibility of replacement with a comparable or better approach would be one standard for measuring the ethical merits of a proposal. If the research goals can be achieved by improvements in experimental methodology or without the need to destroy a human embryo, then the principle of refinement would be an appropriate ethical standard. If the statistical outcomes of an experiment can be accomplished with fewer human embryos then according to the principle of reduction, the ethical goal would be to choose to do so. It is noteworthy that these ethical goals can be practical as well. Replacement, refinement, and reduction will often mean a less costly study.

The three Rs are clearly a minimal standard by which researchers can demonstrate special respect in their use of human embryos (Table 29.1). More generally, the very fact of having a review process to consider the relative merits of different research strategies is also important. In conjunction with the three Rs, an ethical review should reasonably consider all dimensions of the research including species, stage of development, experimental methods, purpose of the research, and the quality of the science.

ble 29.1 Checklist for ethics review of hESC research: Replacement, refinement, and reduction

Category Questions

Replacement Can the research goals be met without destroying a human embryo, and with an alternative approach that raises less severe ethical challenges?

Refinement If the research goals are best met by using human embryos, is it possible to do so without destroying the embryo or it is possible to do so by means that will not impair possible future development of the embryo?

Reduction Can the research goals be met with the use of fewer human embryos?

le 29.2 Checklist for ethics review of hESC research: What will be studied?



Oocytes Zygotes Blastocysts



Child or adult

Will this project involve human tissue? Non-human primates? Mixing of human and non-human species?

Who will be the donors? Will the research require that human oocytes, zygotes, or blastocysts be destroyed, discarded, or damaged?

Who will be the donors? How did the fetal tissue become available?

Who will be the donors? What tissues will be donated?

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