Scientists from the U.K. and U.S have now developed a new technique that enables a human embryo to live outside the womb far longer than before. However, any future experiments are sure to be fraught with ethical issues.
For the first time ever, researchers have grown human embryos outside of the uterus for 13 days, which is a significant improvement from the previous record of nine days. This development would give us a better understanding into the little understood stages of human ontogenesis.
This accomplishment, however, has put research that involves in vitro human embryos on a “collision course” with international regulations that has a 14-day limit on laboratory studies of embryos.
For decades now, scientists have been able to make and study human embryos in their labs; however, keeping them alive outside a woman’s womb for more than about a week has proven difficult — until now.
The two leading labs created a chemical environment in which the embryo is tricked into thinking it is in a womb while it remained in a petri dish.
The embryos thrived until day 13, and then the scientists were forced to terminate to avoid breaching the international regulations, as both the U.S. and the U.K. forbid scientific experiments on human fetuses over two weeks old.
“This new technique provides us with a unique opportunity to get a deeper understanding of our own development during these crucial stages and help us understand what happens, for example, during miscarriage.
“Implantation is a milestone in human development as it is from this stage onward that the embryo really begins to take shape and the overall body plans are decided. It is also the stage of pregnancy at which many developmental defects can become acquired. But until now, it has been impossible to study this in human embryos.”
Ali Brivanlou, a biologist at Rockefeller University in New York City, and who headed the U.S. team, said:
“It’s really embarrassing at the beginning of the twenty-first century that we know more about fish, and mice, and frogs, than we know about ourselves.”
In their research, both teams had found a mystery cell cluster that appeared on day 10 of development, which had disappeared on day 12. This suggests that there is a previously unknown biological process taking place. There were also “significant differences” found in the developmental cycles of mice, which are frequently used as stand-ins for humans in laboratory research.
While the scientific benefits of the experiments are hard to deny, the 14-day experiment deadline was adopted due to ethical reasons. The scientists argue that the limit is reached long before the ethical issues should become a practical concern.
Ethical issues should begin when the clusters of cells stop merging and splitting, and become distinct individual entities that eventually grow into a human fetus. Daniel Brison from the University of Manchester told BBC:
“Given the potential benefits of new research in infertility, improving assisted conception methods, and in early miscarriage and disorders of pregnancy, there may be a case in the future to reconsider the 14-day limit.”
However others expressed concerns. Daniel Sulmasy, a doctor and bioethicist at the University of Chicago, told NPR:
“The 14-day rule has kept it pretty limited in terms of what scientists could do. Once that goes, then it begins to sort of say: ‘it’s open season on human embryos, anything goes.
“The question has to be: ‘Are there any limits to what we will do to human beings in order to gain scientific knowledge?’ And then who counts as a human being?”
Even though Zernicka-Goetz believes that just a few days extra could bring vast discoveries, she has conceded that she wouldn’t lobby to overturn the current limitations. However, the Nuffield Council of Bioethics, who is the U.K. body which decides on sensitive scientific research, has stated that it will review the current experiment limits.
“We will learn things we cannot even imagine.
“It’s as if you say: ‘If I look at new sets of Hubble Space Telescope pictures that I haven’t seen yet, what will I learn from them?’ It’s difficult to say until you look at them.”
The comparison is not the best one; there are a lot of differences between them. However, even the researchers admit the current restrictions can still accommodate an entirely new field of research.