Why Can’t We Experiment On Human Embryonic Stem Cells?

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?”