The Need for Further Research
Right now, the published evidence that these STAP cells might be actual embryos is fairly scant. In a shorter article accompanying their paper, Obokata and her colleagues reported that when they injected STAP cells into ten early-stage mouse embryos, descendants of the STAP cells were found in the placenta and embryo in six cases. Embryonic stem cells or iPS cells almost never contribute to the development of the placenta, so this was a striking finding.
But the wide range of developmental potential these cells have does not necessarily make them embryos. There’s an old motto in biology, attributed to the great seventeenth-century anatomist William Harvey: “omne vivum ex ovo,” or “all life from eggs.” In the animal kingdom, this doctrine still holds true; embryos are fertilized egg cells, and the egg cell provides a great deal of material necessary for the embryo’s early development. Just because an adult cell has been “reprogrammed” to a state of developmental immaturity that allows it to branch off into any of the different cell lineages, that does not mean that it will be able to undergo the highly coordinated development of an embryo on its own, or even together with other such reprogrammed cells.
We should still take the possibility seriously, however, that this new method of reprogramming might make embryos. Rumors are already circulating that scientists have attempted this in mice. According to a story in the New Scientist, one of the co-authors of the study, Charles Vacanti, said that he asked an unnamed collaborator to transfer a spherical cluster of STAP cells to a mouse. Vacanti reports that the cells began to develop as a fetus, but that halfway through the pregnancy, the fetus stopped developing normally. According to Vacanti, “There was some sort of glitch—which is probably a good thing due to the ethical issues that would occur if we were able to create a live clone.” But if it is true that these cells are able to develop as embryos, then the fact they develop defectively is not reassuring. Okotaba, for her part, said that her team was interested in regenerative medicine, not human cloning.
Scientific and Ethical Questions
Although the research has not been published, Vacanti has claimed that he has already applied the technique to human cells, and has even sent images of what he says are clusters of human STAP cells to the magazine the New Scientist. Until Vacanti’s results are published in a peer-reviewed journal, it is difficult to know much with certainty about whether the human cells he created were totipotent cells—embryos—or simply pluripotent cells. It is possible that, as research develops, boundaries might be discovered that would set ethical limits on how STAP cells are created and used.
The most serious ethical concern raised by the possibility that STAP cells have the characteristics of embryos is not that the new technology could be misused by unscrupulous parties, but that the very act of creating and experimenting on these cells would be an unethical exploitation of human life. To determine whether this is so, we must answer a question that is at once scientific and ethical: Just what is an embryo? Or, put somewhat differently, what is that makes something an individual organism, as opposed to a mere “clump of cells?”
Moral seriousness demands that we take this scientific question seriously before we embark on the use of this new technology with human cells. It would perhaps be convenient for our society to ignore the instrumentalization and destruction of human life by pretending that developments in biotechnology render the distinction between organisms and their parts meaningless. But such willful ignorance is no excuse, especially for a civilization that prides itself on scientific sophistication. Biologists should take confusion over how to determine when the life of an individual human (or for that matter, any other animal) begins not as a license for experimentation on beings whose organic unity is ambiguous, but as an embarrassment for their discipline, and as a scientific puzzle worth solving.