Obeying ethical guidelines is easy – when they’re only hypothetical. But what happens when the day comes when you actually have to apply the rule in practice? Scientists were faced with exactly this dilemma last summer, when human developmental technology finally caught up to a nearly 40-year rule on embryonic research.
The 14-Day Rule
It’s called the 14-day rule. First developed in 1979 by an ethical board that would later become the U.S. Department of Health and Human Services, the 14-day rule specifies that research on human embryos must not allow fetal development to continue past 14 days.
Now implemented in 17 countries, the rule was originally created long before scientists could even get within a week of the limit. In normal embryonic development, the point of implantation – when the group of cells implants in the uterine lining – occurs about 7 days after fertilization. No embryo had been able to survive outside the womb past that point, until last year.
In a 2016 Nature and Nature Cell Biology article, research teams led by Magdalena Zernicka-Goetz of the University of Cambridge and Ali Brivanlou at Rockefellar University first published images of human embryos at 11, 12, and 13 days. The embryos had “implanted” onto a transparent plastic substrate, allowing them to be studied and photographed. On day 13, the researchers had to halt their studies and destroy the embryos. It was the first known observation of the 14-day rule.
“The Primitive Streak”
The breakthrough is causing some bioethicists to revisit the rule. At 14 days, the human embryo is said to develop the “primitive streak,” the group of cells that indicates the point at which an embryo can no longer fuse or split. Some religious bioethicists believe that this is the point of unique human potentiality, what some might term a soul. If the embryo hasn’t at this point split into twins – two souls – it won’t be able to going forward.
But carrying on research past 14 days could unlock the mystery of early miscarriage. Experts estimate that as many as 30% of pregnancies end in miscarriage – many of which end before the woman is even aware she is pregnant. It’s impossible to know the rate for sure.
A Question of Ethics
Insoo Hyun, a bioethicist at Case Western Reserve University in Cleveland, is now questioning the rule and calling for a re-evaluation. The rule, he says, was somewhat arbitrarily determined, and meant as a policy tool to allow for embryonic study in the first place. “It shouldn’t be thought of as a hard and fast moral pronouncement.”
Yet opinions on the matter differ. Marcy Darnovsky, executive director of the Center for Genetics and Society in Berkeley, California argues that the rule was “very much intended to be a bright line.” In her view, research on human embryos is a morally sticky situation. As technological advancement brings what was once considered science fiction into the realm of the possible, ignoring the rule could set a dangerous precedent for the future of biomedical research.
Leroy Walters, former director of the Center for Bioethics at Georgetown University, who was a member of the original board, said that the consensus was that 14 days seemed like a reasonable, if distant, upper limit. Still, the question is worth asking. If we could study the human embryo beyond 14 days to learn how to reduce miscarriages, would the ends justify the means? Hyun emphasized the importance of consensus-building around matters of bioethics. “If you even entertain changing it, it needs to involve a wide group of stakeholders.”
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