Mouse embryos conceived without sperm or egg: how far do we want to go?

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Mouse embryos conceived without sperm or egg: how far do we want go?

Weizmann Institute of Science Synthetic post-gastrulation embryos, synthesized outside the uterus

In a study published in the scientific journal Cell , Israeli researchers have shown that synthetic post-gastrulation embryos (sEmbryos) can be synthesized outside the uterus using embryonic stem cells from mouse skin.

Real embryos from stem cells?

Cultivating an embryo from scratch has been the dream of some scientists for several years. According to a paper published Aug. 8, to achieve this feat, scientists had to flood mouse stem cells with a chemical treatment that returned them to a “naive state,” where they remained ripe for transformation into various cell types. (eg, liver, heart, brain, etc.), vital for the assembly of a mouse fetus. The embryo-like structure had an intestinal tract, a brain, and even a beating heart.

According to Megan Munsie, a professor at the University of Melbourne in Australia, it should be noted that it is not really an embryo, but an “embryoid” organism. Even if they reproduce certain aspects of the development of embryos derived from the fertilization of eggs by spermatozoa, their development potential differs from the “real ones”. The research team could not develop these embryoid organisms beyond eight days, whereas a normal gestation in mice lasts 20 days. For Munsie, “the production of human embryo models of a complexity equivalent to that obtained with a mouse model remains a distant proposition, but which must be considered”.

The ethical limits of science have they been crossed?

As with similar experiments, experts say research into later stages is important because many mysteries remain about the physiology of typical human embryonic development. Alex Meissner, an expert stem cell biologist at the Max Planck Institute for Molecular Genetics, believes that this type of experiment on mice is a starting point for thinking about how we want to approach this in humans: until where do we want to go? As scientists develop methods for artificial fertilization without uterus, without eggs and without sperm, the ethical debate on this subject should move a little faster, to catch up with scientific advances.

Conception without uterus, eggs or spermatozoa, a potential solution to the drop in the birth rate

Recently, China would also have designed robotic uteri, which would make it possible to increase the birth rate without relying on women. It is a connected container filled with nutrient fluids in which embryos (of mice for now) grow and develop using artificial intelligence. Each embryo is observed, documented and adjusted manually. Algorithms act as a “nanny” to monitor embryos down to the millimetre. AI makes it possible to observe the tiniest changes in embryos and to fine-tune CO₂, nutrition and environmental inputs. According to the article published last November, this technology could be used to eliminate the need for a woman to carry her baby for nine months, allowing her fetus to “develop outside her body in a safe, yet effective”.