26 October 2019 | New Scientist | 17FOR the first time, artificial
embryos made without sperm
or eggs have started to form live
fetuses after being implanted
in female mice. However, the
embryos were malformed,
and we are still a long way
from being able to make
human babies this way.
The artificial mouse embryos
were made using extended
pluripotent stem cells. These
have the ability to generate the
three cell types found in early
embryos, such as those that
will become the placenta.Jun Wu at the University of
Texas Southwestern Medical
Center and his team coaxed
the stem cells to turn into the
three embryo cell types and
self-assemble into embryo-
like structures by soaking
them in nutrients and growth
stimulants. “They essentially did
the job on their own,” he says.
The team then transferred
the artificial embryos to the
uteruses of mice, where 7 per
cent successfully implanted.
A week later, the implanted
embryos were surgically
removed. They had started
to form early fetal structures,
albeit with major malformations
(Cell, doi.org/dcvw).
This is the first time artificial
embryos have started to develop
into fetuses in a uterus. Other
groups have made artificial
mouse embryos from stem cells
but they haven’t successfully
implanted or have been able
to form only placental cells
and not the other cell types.
The challenge now will be to
fine-tune the artificial mouseembryos so they can develop
into perfectly formed fetuses,
says Wu. This may involve
growing them in a mix of
nutrients and growth stimulants
that more closely matches the
environment that embryos are
normally exposed to, he says.
Wu says the purpose of the
experiments isn’t to generate
offspring. Testing the ability
of artificial embryos to grow
in the womb allows us to see
how realistic those embryos are,
he says. Once they are realistic
enough, researchers will be able
to use them as substitutes for
real embryos that are normally
obtained from mice.
These realistic artificial
embryos could be studied in
dishes to better understand
early mammalian development,
optimise IVF conditions and
screen drugs for their potential
to cause birth defects, says Wu.
Nevertheless, the findings do
hint that it may be possible to
generate offspring from such
embryos, says Wu. Some of
the stem cells his team used
to make the artificial embryos
were originally made by
reprogramming ear cells from
adult mice. Hypothetically
speaking, if we could do the
same with human ear, skin or
other non-reproductive cells,
we could generate viable human
embryo-like structures without
sperm or eggs. “But this remains
science fiction,” says Wu.
There are no good medical
reasons to make human babies
from artificial embryos created
without sperm or eggs, says
Nicolas Rivron at the Institute
of Molecular Biotechnology
in Vienna, Austria. However,
artificial embryos made this
way could potentially be used
to study fertility problems in
the future, he says. ❚HUMANS have only ever put about
9000 satellites in space. But that
number will be dwarfed if SpaceX’s
plan to launch tens of thousands
of satellites comes to fruition.
Documents filed by the space
firm with telecommunications
authorities show that it has plans
to launch 30,000 small satellites.
The documents were filed with the
International Telecommunication
Union, a UN agency that
coordinates satellite launches.
The plans will need approval from
other bodies, however, and it may
be several years before the first
batch of satellites can be launched.
SpaceX already has permission
to launch nearly 12,000 satellites
to low Earth orbit, and 60 of these
are already up there. It plans to use
these to create a wireless internet
service called Starlink.
The firm says the 30,000 extra
satellites are also part of its plans
for internet services. But they
will be well situated for Earth
observation too. They will operate
between 330 and 580 kilometres
above the planet’s surface, whichSpaceX plans to send
up 40,000 satellites
Communications Stem cellsMark Harris Alice KleinSPACEX
means they could be used for
taking high-resolution pictures
or video of things happening at
ground level.
At such altitudes, there will be
little risk of creating long-term
orbital debris because the
atmosphere there is thick enough
to drag satellites or pieces of
space junk down so they will burn
up. SpaceX also wants to make the
satellites black to reduce their
impact on astronomy.
However, the numbers are
unprecedented. “With that many
satellites, there does need to be
a very, very close look at the
collision risk, disposal and
re-entry risks,” says Hugh Lewis
at the University of Southampton,
UK. “SpaceX will have learned
a lot from their first generation
of 60 Starlinks, but the more
satellites you have in a given
volume of space, the more close
approaches you will have.”
SpaceX told New Scientist
that demand for fast, reliable
internet is escalating and that
it is “taking steps to responsibly
scale Starlink’s total network
capacity and data density to
meet the growth in users’
anticipated needs”. ❚SpaceX launched
60 Starlink satellites
into orbit earlier this yearMouse embryos
made without
sperm or eggs
“This is the first time
artificial embryos have
developed into fetuses
in the uterus”