The internationally recognized limit for how long a human embryo can be grown in a lab
is 14 days. But in light of advancements that may
now make it possible to culture embryos beyond those 14 days, scientists and ethicists are discussing:
should growing human embryos in a lab beyond this point be allowed?
Okay, hold up. What do we mean when we talk about lab-grown embryos? Typically,
these are fertilized embryos that have been donated to scientific research by in vitro fertilization clinics because
the embryo is no longer viable for an IVF treatment. These embryos are different from embryoids.
Embryoids are structures that resemble an early human embryo but they lack some of the cell types and
structure to develop into something fully viable. These are often created in a lab from embryonic
stem cells, and they can be a useful tool for studying lots of aspects of human development.
One recent groundbreaking method uses another kind of stem cell. Scientists take skin cells and hit
rewind: they reverse them into pluripotent stem cells, or cells that can essentially develop into
any tissue type.
And by exposing them to the right environment, those cells can be coaxed
into forming a structure that's really similar to
the earliest stage of a human embryo, called a blastocyst. But because these didn’t develop
from an actual embryo, they are not quite the same as a real blastocyst, they are called blastoids instead.
The existing 14-day limit on lab-mediated human embryo or embryoid development was suggested after the first
IVF babies were born in the 1970s. The media started to refer to these individuals as ‘test
tube babies’, and the scientific community wanted to make it very clear that embryos were not being
developed into fully viable fetuses in a test tube. Instead, IVF is when an egg is fertilized
with sperm in a petri dish, and those fertilized eggs usually grow for 2 to 5 days in a lab
before being transferred to the patient’s uterus—and that’s technically a lab-grown embryo.
Now, growing an embryo into a fully fledged baby in a lab, something called ectogenesis, is still
totally in the realm of science fiction. But after the development of IVF, there was growing concern
that maybe developing embryos were being experimented on or thrown away past certain points in development.
And as the debate rages worldwide about when life begins, this is and was
understandably a very thorny issue. So a U.S. regulating body proposed
the 14-day rule just as a guideline, and that limit actually became a law in at least a dozen countries.
Why 14 days in particular?
That’s the point at which an embryo develops something called the primitive streak, which
is the beginning of the body differentiating into its separate building blocks. It’s also the point
at which becoming a twin is no longer possible, so that's where ‘individuality’ is assigned.
And until recently we didn’t even know how to keep human embryos or something similar
alive in the lab longer than nine days, so this wasn’t really that pressing of a question.
But 2016 was the year that a couple research teams got all the way to 13 days.
And ever since, the scientific community has been grappling with how to deal with these advances
in the face of the limit... or if the limit should be changed altogether.
Because of the advancements in our ability to grow these structures in the lab for longer,
and the exciting developments in blastoid and embryoid research, there’s now the possibility
of investigating parts of human development we’ve never had access to before. This could
help us understand why some miscarriages happen, or how some birth defects develop.
We’d be able to see the effects of all kinds of chemicals and medications on embryonic development
and maybe make IVF safer and more effective.
But would a new time limit only mean good things?
What about the possibility of genetically modifying human embryos in
new ways—we’re gonna need to think about that one REAL hard. And at what point can
scientists ethically say that a blastocyst is no longer a clump of cells and is instead,
a fetus? And what do we do with a lab-grown embryo at that point?
We're going to need plans in place for all of this.
Ever since the 14-day rule was first proposed in the 1970s,
experts in this field from scientists to philosophers have known that we would one day
have to revisit this because of scientific advancements. And that day has arrived.
The International Society for Stem Cell Research, or the ISSCR,
released its updated guidelines for culturing human embryos and embryoids.
They are calling for a public conversation with ethicists, scientists, and regulators
about the social and ethical issues associated with going past 14 days. How this may translate
into legal changes in some countries remains to be seen, and lots of questions we talked about before remain unanswered.
What do you think about extending the 14 day rule? If you're interested in these public
conversations make sure you check out the link in our description for more details.
Make sure to subscribe to Seeker for all of your boundary-pushing biomedical news.
And if you have another stem cell development you want us to cover on the channel,
let us know. As always, thanks so much for watching and I’ll see ya next time.