Studies on human embryonic stem cells are highly controversial, and the current law
says that embryos must be destroyed after 14-days.
But why 14-days?
What’s so significant about the two week limit, and should we even keep using it?
Hi there my science buddies.
Julian here for DNews.
Human embryonic stem cells are one of the most legally and morally contentious areas
of study.
On the one hand, stem cells, both adult and embryonic, are valuable for researching a
huge range of illnesses and diseases, from cancer to diabetes to Alzheimer’s.
On the other hand, many people believe that this benefit to medicine comes at the cost
of potential human lives.
If you want a bit of background on the moral and medical controversy surrounding stem cells,
you can check out either of these videos on screen.
Originally, the 14-day limit comes from a 1979 United States Department of Health, Education,
and Welfare report.
A committee of theologians, psychologists, and doctors came to a compromise: human embryonic
stem cells could be studied for two weeks after fertilization, beyond which time the
cells would have to be destroyed.
But this limit was fairly arbitrary, as at the time, scientists could not keep embryos
alive in vitro for more than a few days.
A later report, organized in 1984 by British existential philosopher Mary Warnock, justified
the two week limit.
The report states that on the 14th or 15th day, a faint line of cells appears on the
embryo, called the “primitive streak”.
This, it was argued, is a moment that signifies that the embryo has become an individual being,
as before this time the embryo could potentially split into twin organisms.
One of the reasons this stage appealed to those who objected on moral grounds, was that
if an embryo could split into two people, then it could not yet be an individual person.
The rule codified an easy to measure mark, coupled with an unambiguous time frame; making
the question less about conception or “a soul”, while still allowing for a religious
and moral compromise.
Additionally, a 2002 report from California stated that less than half of all fertilized
embryos, both in vitro and in vivo, ever reach the primitive streak, meaning that most of
embryos used for research would have been unlikely to make it to term anyway..
But recent advances have made it possible for scientists to keep embryos alive for longer
than two weeks, by simulating womb-like conditions.
With the potential for further research using stem cells, the question has been forced again:
is the 14-day limit still valid?
Some scientists say no.
Arguing that they could use the research in preventing miscarriages, infertility, and
birth defects which they believe to be more important than a more or less arbitrary time
limit.
For example, in 2014, researchers were able to cure “induced Parkinson's disease”
in rats Neuroscientists used human embryonic stem cells to create neurons that produce
dopamine, which is missing in those who suffer from the disease.
Although no human clinical trials have been done, these early results with animals have
been very promising.
That said, other researchers in bioethics have pointed out that even an arbitrary limit
is better than no limit at all.
As more restrictions are lifted, the very real question becomes “where is the limit
on human experimentation in the pursuit of knowledge?”