The Moral Status of Human Stem Cells

Human embryonic germ (EG) cells are derived from the gonadal ridge tissue of an aborted fetus within five to eight weeks after conception. The procedure is analogous to the harvesting of organs from a cadaver. Here the ethical issue is not so much the status of the aborted fetus, but whether those who consider abortion an illicit act, despite its legality, can participate in the research on tissues so derived.

The ethical status of human embryonic stem cells partly hinges on the question of whether they should be characterized as embryos or specialized bodily tissue. Although the answer to this question will be less important to those who believe that the early embryo has little or no moral status, it will shape the views of those who regard the embryo as significantly protectable.

One way of approaching this question is by looking first at ways in which the embryo has been understood. In the context of the abortion and human embryo research debates, a series of criteria has been proposed to determine the moral status of the pre-implanation human embryo. Among these are an entity’s possession of a full human genome; its potential for development into a human being; sentience; and the presence of well-developed cognitive abilities such as consciousness, reasoning ability, or the possession of self-concept. Those taking the position that the early embryo has full moral status (equal to that of any child or adult human being) usually stress the first two of these criteria: possession of a unique human genome and the potential for development into a human being are regarded as sufficient for ascribing full moral status to it.

Since most cells in the human body possess a unique diploid genome and are not regarded as morally protectable, the question of whether ES cells are morally equivalent to somatic cells or whether they are more like human embryos largely hinges on an understanding of stem cells’ potentiality. Here the matter calls for further refinement since, as developments in mammalian cloning technology suggest, any human cell (or tissue) may have the potential to become a person. To avoid this problem, potentiality arguments typically appeal to some consideration of normal or natural processes: embryos have a natural potentiality to become a person in that the natural development of an embryo, unlike tissue, is to become a human being. Of course, the interpretation and significance of the word “natural” is controversial.

Can we conclude that stem cells have equivalent moral status because of their potential to become a human being? Since potentiality is being understood here as “natural potentiality,” determining the moral status of a stem cell rests in part on whether its potential to become a person is natural, as it is with embryos, or contrived, as it would be with cells that are cloned. Being natural or contrived does not refer to the ease or facility of the process or the need for technological intervention. Regardless of how cloning technology may develop, for example, it will not be seen as a natural process by those who hold that embryos have a natural potential to become a full human being. To fail to distinguish between the natural and contrived development of the embryo would otherwise, among other things, unreasonably commit us to the full moral protection of every human cell.

The potential of a stem cell to become a human being seems to be much more like that of a somatic cell that could be cloned than like an embryo. The natural development of the individual cells of the embryonic disk (from which stem cells are derived) is to become parts of a human being. Isolated from the total structure of the embryo or blastocyst, these cells, even under favorable growth conditions, will not develop the trophoblast (the outer layer of cells of the embryo) or other structures needed for continued development. Another way of putting this is to say that stem cells are pluripotent rather than totipotent. It is true that advanced technology might be able to render these cells effectively (if not actually) totipotent. Research undertaken in Canada in 1993 involving the aggregation of mouse stem cells with a genetically manipulated embryo led to the cells’ subsequent growth and population of the entire organism. However, such manipulations are arguably even less “natural” than is current cloning technology. Insofar as potentiality considerations alone are concerned, therefore, stem cells would not seem to have the same moral status as embryos. For those following this line of reasoning, including those who accord significant moral status to the embryo, stem cells may thus be regarded and treated as any other form of human bodily tissue.

Potentiality is a complex idea, drawing on even more complex and undeveloped notions of “nature” and “the natural.” Rather than entirely clarifying these matters, biology complicates them by indicating the developmental continuum always present in human growth and maturation. Continuing discussion will be needed involving the many viewpoints around the question about how we can best protect the multiple values evoked by research at life’s beginnings. These include values such as our commitment to the protection of human life generally, the promotion of human health, and respect for the views of others in a civil, democratic society.

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